Gymnastik- och idrottshögskolan, GIH

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  • 1.
    Apro, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Granberg, Jonas
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Andersson, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH.
    Intake Of Essential Amino Acids Stimulates Mtorc1 Signaling And Inhibits Autophagy Following Glycogen-depleted Resistance Exercise2020In: MEDICINE AND SCIENCE IN SPORTS AND EXERCISE. 52:17, Suppl. Meeting Abstract 125, Lippincott Williams & Wilkins, 2020, Vol. 52, no 17, p. 18-18Conference paper (Other academic)
  • 2.
    Apro, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Holmberg, Hans-Christer
    Mittuniversitetet.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    High intensity interval cycling performed prior to resistance exercise stimulates autophagy signaling2016In: Conference program & abstracts, 2016, p. 84-84Conference paper (Other academic)
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  • 3.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Rooyackers, O
    Holmberg, HC
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Leucine does not affect mTORC1 assembly but is required for maximal S6K1 activity in human skeletal muscle following resistance exerciseManuscript (preprint) (Other academic)
  • 4.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Hamilton, D Lee
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Rooyackers, Olav
    Holmberg, Hans-Christer
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Leucine does not affect mechanistic target of rapamycin complex 1 assembly but is required for maximal ribosomal protein s6 kinase 1 activity in human skeletal muscle following resistance exercise.2015In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 29, no 10, p. 4358-4373Article in journal (Refereed)
    Abstract [en]

    We examined how the stimulatory effect of leucine on the mechanistic target of rapamycin complex 1 (mTORC1) pathway is affected by the presence of the remaining essential amino acids. Nine male subjects performed resistance exercise on 4 occasions and were randomly supplied essential amino acids (EAAs) with or without leucine (EAA-Leu), leucine alone, or flavored water (placebo; control). Muscle biopsies were taken from the vastus lateralis before and 60 and 90 min after exercise. Biopsies were analyzed for protein phosphorylation, kinase activity, protein-protein interactions, amino acid concentrations, and tracer incorporation. Leucine alone stimulated ribosomal protein s6 kinase 1 (S6K1) phosphorylation ∼280% more than placebo and EAA-Leu after exercise. Moreover, this response was enhanced by 60-75% after intake of EAAs compared with that of leucine alone (P < 0.05). Kinase activity of S6K1 reflected that of S6K1 phosphorylation; 60 min after exercise, the activity was elevated 3.3- and 4.2-fold with intake of leucine alone and with EAAs, respectively (P < 0.05). The interaction between mammalian target of rapamycin and regulatory-associated protein of mammalian target of rapamycin was unaltered in response to both resistance exercise and amino acid provision. Leucine alone stimulates mTORC1 signaling, although this response is enhanced by other EAA and does not appear to be caused by alterations in mTORC1 assembly.-Apró, W., Moberg, M., Hamilton, D. L., Ekblom, B., Rooyackers, O., Holmberg, H.-C., Blomstrand, E. Leucine does not affect mechanistic target of rapamycin complex 1 assembly but is required for maximal ribosomal protein s6 kinase 1 activity in human skeletal muscle following resistance exercise.

  • 5.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Hamilton, L.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    van Hall, G.
    Holmberg, HC
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Resistance exercise induced S6K1 kinase activity is not inhibited in human skeletal muscle despite prior activation of AMPK by high intensity interval cycling.2015In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 308, no 6, p. E470-E481Article in journal (Refereed)
    Abstract [en]

    Combining endurance and strength training in the same session has been reported to reduce the anabolic response to the latter form of exercise. The underlying mechanism, based primarily on results from rodent muscle, is proposed to involve AMPK-dependent inhibition of mTORC1 signaling. This hypothesis was tested in eight trained male subjects who in a randomized order performed either resistance exercise only (R) or interval cycling followed by resistance exercise (ER). Biopsies taken from the vastus lateralis before and after endurance exercise and repeatedly after resistance exercise were assessed for glycogen content, kinase activity, protein phosphorylation and gene expression. Mixed muscle fractional synthetic rate was measured at rest and during 3h of recovery using the stable isotope technique. In ER, AMPK activity was elevated immediately after both endurance and resistance exercise (~90%, P<0.05) but was unchanged in R. Thr389 phosphorylation of S6K1 was increased several-fold immediately after exercise (P<0.05) in both trials and increased further throughout recovery. After 90 and 180 min recovery, S6K1 activity was elevated (~55% and ~110%, respectively, P<0.05) and eEF2 phosphorylation was reduced (~55%, P<0.05) with no difference between trials. In contrast, markers for protein catabolism were differently influenced by the two modes of exercise; ER induced a significant increase in gene and protein expression of MuRF1 (P<0.05), which was not observed following R exercise only. In conclusion, cycling-induced elevation in AMPK activity does not inhibit mTORC1 signaling after subsequent resistance exercise, but may instead interfere with the hypertrophic response by influencing key components in protein breakdown.

  • 6.
    Apró, William
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Holmberg, Hans-Christer
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Amino Acid-induced S6K1 Activity In Human Skeletal Muscle Is Mediated By Increased mTor/Rheb Interaction: 128 June 1, 11: 15 AM - 11: 30 AM.2016In: Medicine And Science In Sports And Exercise 2016 May; Vol. 48 (5S Suppl 1), pp. 17., 2016, Vol. 48, no 5S Suppl 1, p. 17-17Conference paper (Refereed)
    Abstract [en]

    Cell culture studies have shown that amino acids activate mTORC1 signaling by increasing the interaction between mTOR and its essential activator Rheb. However, the existence of this mechanism in human skeletal muscle remains to be determined.

    PURPOSE: To determine if increased mTORC1 signaling in response to amino acids in human skeletal muscle is due to an increased interaction between mTOR and Rheb.

    METHODS: Eight well trained men performed resistance exercise on two separate occasions. In connection with the exercise, subjects were supplemented with flavored water (Pla) and essential amino acids (EAA) in a double-blind, randomized cross-over design. Muscle biopsies were taken in the vastus lateralis muscle before, immediately after and 90 and 180 min post exercise. Activity of the mTORC1 pathway was assessed by a radiolabeled in-vitro kinase assay for its immediate downstream target S6K1. Protein-protein interactions were determined by western blot following co-immunoprecipitation of mTOR with Rheb. Co-immunoprecipitation was performed on pooled muscle samples from three of the eight subjects.

    RESULTS: Activity of S6K1 remained unchanged immediately after exercise in both trials. However, at 90 min post exercise, S6K1 activity increased by approximately 2- and 8-fold (p<0.05) from baseline the Pla and EAA trials, respectively. At the 180 min time point, S6K1 activity remained elevated in both trials being approx. 3-fold higher in the Pla trial and 5-fold higher (p<0.05) in the EAA trial. The fold-change in mTOR and Rheb interaction largely resembled the activity pattern of S6K1 in both trials; in the Pla trial the fold-change was 0.9, 1.3 and 1.4 while in the EAA trial the fold-change was 1.6, 2.9 and 1.9 immediately after, 90 min after and 180 min after exercise, respectively.

    CONCLUSIONS: The large increase in S6K1 activity following EAA intake appears to be mediated by an increased interaction between mTOR and its proximal activator Rheb. This is the first time this mechanism has been demonstrated in human skeletal muscle.

  • 7.
    Blackwood, Sarah J
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden..
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Extreme Variations in Muscle Fiber Composition Enable Detection of Insulin Resistance and Excessive Insulin Secretion.2022In: Journal of Clinical Endocrinology and Metabolism, ISSN 0021-972X, E-ISSN 1945-7197, Vol. 107, no 7, p. e2729-e2737, article id dgac221Article in journal (Refereed)
    Abstract [en]

    CONTEXT: Muscle fiber composition is associated with peripheral insulin action.

    OBJECTIVE: We investigated whether extreme differences in muscle fiber composition are associated with alterations in peripheral insulin action and secretion in young, healthy subjects who exhibit normal fasting glycemia and insulinemia.

    METHODS: Relaxation time following a tetanic contraction was used to identify subjects with a high or low expression of type I muscle fibers: group I (n=11), area occupied by type I muscle fibers = 61.0 ± 11.8%; group II (n=8), type I area = 36.0 ± 4.9% (P<0.001). Biopsies were obtained from the vastus lateralis muscle and analyzed for mitochondrial respiration on permeabilized fibers, muscle fiber composition and capillary density. An intravenous glucose tolerance test was performed and indices of glucose tolerance, insulin sensitivity and secretion were determined.

    RESULTS: Glucose tolerance was similar between groups, whereas whole-body insulin sensitivity was decreased by ~50% in group II vs group I (P=0.019). First phase insulin release (area under the insulin curve during 10 min after glucose infusion) was increased by almost 4-fold in group II vs I (P=0.01). Whole-body insulin sensitivity was correlated with % area occupied by type I fibers (r=0.54; P=0.018) and capillary density in muscle (r=0.61; P=0.005), but not with mitochondrial respiration. Insulin release was strongly related to % area occupied by type II fibers (r=0.93; P<0.001).

    CONCLUSIONS: Assessment of muscle contractile function in young healthy subjects may prove useful in identifying individuals with insulin resistance and enhanced glucose stimulated insulin secretion prior to onset of clinical manifestations.

  • 8.
    Blackwood, Sarah J
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden..
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Insulin resistance after a 3-day fast is associated with an increased capacity of skeletal muscle to oxidize lipids.2023In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 324, no 5, p. E390-E401Article in journal (Refereed)
    Abstract [en]

    There is a debate on whether lipid-mediated insulin resistance derives from an increased or decreased capacity of muscle to oxidize fats. Here we examine the involvement of muscle fiber composition in the metabolic responses to a 3-day fast (starvation, which results in increases in plasma lipids and insulin resistance) in two groups of healthy young subjects: 1, area occupied by type I fibers = 61.0 ± 11.8%; 2, type I area = 36.0 ± 4.9% (P<0.001). Muscle biopsies and intravenous glucose tolerance tests were performed after an overnight fast and after starvation. Biopsies were analyzed for muscle fiber composition and mitochondrial respiration. Indices of glucose tolerance and insulin sensitivity were determined. Glucose tolerance was similar in both groups after an overnight fast and deteriorated to a similar degree in both groups after starvation. In contrast, whole-body insulin sensitivity decreased markedly after starvation in group 1 (P<0.01), whereas the decrease in group 2 was substantially smaller (P=0.06). Non-esterified fatty acids and β-hydroxybutyrate levels in plasma after an overnight fast were similar between groups and increased markedly and comparably in both groups after starvation, demonstrating similar degrees of lipid load. The capacity of permeabilized muscle fibers to oxidize lipids was significantly higher in group 1 vs. 2, whereas there was no significant difference in pyruvate oxidation between groups. The data demonstrate that loss of whole-body insulin sensitivity after short-term starvation is a function of muscle fiber composition and is associated with an elevated rather than a diminished capacity of muscle to oxidize lipids.

  • 9.
    Borgenvik, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Supplementation with BCAA Reduces MAFbx Expression and Phenylalanine Concentration in Rested and Exercised Human Muscle2011In: Medicine & Science in Sports & Exercise, 2011, Vol. 43, no 5, p. 419-419Conference paper (Refereed)
  • 10.
    Borgenvik, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Intake of branched-chain amino acids influences the levels of MAFbx mRNA and MuRF-1 total protein in resting and exercising human muscle.2012In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 302, no 5, p. E510-21Article in journal (Refereed)
    Abstract [en]

    Resistance exercise and amino acids are two major factors that influence muscle protein turnover. Here, we examined the effects of resistance exercise and branched-chain amino acids (BCAA), individually and in combination, on the expression of anabolic and catabolic genes in human skeletal muscle. Seven subjects performed two sessions of unilateral leg press exercise with randomized supplementation with BCAA or flavored water. Biopsies were collected from the vastus lateralis muscle of both the resting and exercising legs before and repeatedly after exercise to determine levels of mRNA, protein phosphorylation, and amino acid concentrations. Intake of BCAA reduced (P < 0.05) MAFbx mRNA by 30 and 50% in the resting and exercising legs, respectively. The level of MuRF-1 mRNA was elevated (P < 0.05) in the exercising leg two- and threefold under the placebo and BCAA conditions, respectively, whereas MuRF-1 total protein increased by 20% (P < 0.05) only in the placebo condition. Phosphorylation of p70(S6k) increased to a larger extent (∼2-fold; P < 0.05) in the early recovery period with BCAA supplementation, whereas the expression of genes regulating mTOR activity was not influenced by BCAA. Muscle levels of phenylalanine and tyrosine were reduced (13-17%) throughout recovery (P < 0.05) in the placebo condition and to a greater extent (32-43%; P < 0.05) following BCAA supplementation in both resting and exercising muscle. In conclusion, BCAA ingestion reduced MAFbx mRNA and prevented the exercise-induced increase in MuRF-1 total protein in both resting and exercising leg. Further-more, resistance exercise differently influenced MAFbx and MuRF-1 mRNA expression, suggesting both common and divergent regulation of these two ubiquitin ligases.

  • 11.
    Borgenvik, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Nordin, Marie
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Mattsson, C. Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Enqvist, Jonas K.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Björn Ekblom's research group.
    Alterations in amino acid concentrations in the plasma and muscle in human subjects during 24 h of simulated adventure racing2012In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 112, p. 3679-3688Article in journal (Refereed)
    Abstract [en]

    This investigation was designed to evaluate changes in plasma and muscle levels of free amino acids during an ultra-endurance exercise and following recovery. Nine male ultra-endurance trained athletes participated in a 24-h standardized endurance trial with controlled energy intake. The participants performed 12 sessions of running, kayaking and cycling (4 x each discipline). Blood samples were collected before, during and after exercise, as well as after 28 h of recovery. Muscle biopsies were taken 1 week before the test and after exercise, as well as after 28 h of recovery. During the 24-h exercise, plasma levels of branched-chain (BCAA), essential amino acids (EAA) and glutamine fell 13%, 14% and 19% (P<0.05) respectively, whereas their concentrations in muscle were unaltered. Simultaneously, tyrosine and phenylalanine levels rose 38% and 50% (P<0.05) in the plasma and 66% and 46% (P<0.05) in muscle, respectively. After the 24-h exercise, plasma levels of BCAA were positively correlated with muscle levels of glycogen (r2=0.73, P<0.05), as was the combined concentrations of muscle tyrosine and phenylalanine with plasma creatine kinase (r2=0.55, P<0.05). Following 28-h of recovery, plasma and muscle levels of amino acids had either returned to their initial levels or were elevated. In conclusion, ultra-endurance exercise caused significant changes elevations in plasma and muscle levels of tyrosine and phenylalanine, which suggest an increase in net muscle protein breakdown during exercise. There was a reduction in plasma concentrations of EAA and glutamine during exercise, whereas no changes were detected in their muscle concentration after exercise.

  • 12.
    Cardinale, Daniele A.
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Elite Performance Centre, Bosön. Swedish Sports Confederation, Lidingö, Sweden.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Elings-Knutsson, Jona
    Karolinska Institutet, Stockholm, Sweden,.
    Helge, Torbjörn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Godhe, Manne
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Bermon, Stéphane
    LAMHESS, Université Côte d’Azur, Nice, France.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Flockhart, Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Hirschberg, Angelica Lindén
    Karolinska institutet, Stockholm, Sweden.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Enhanced Skeletal Muscle Oxidative Capacity and Capillary-to-Fiber Ratio Following Moderately Increased Testosterone Exposure in Young Healthy Women2020In: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 11, article id 585490Article in journal (Refereed)
    Abstract [en]

    Background: Recently, it was shown that exogenously administered testosterone enhances endurance capacity in women. In this study, our understanding on the effects of exogenous testosterone on key determinants of oxygen transport and utilization in skeletal muscle is expanded.Methods: In a double-blinded, randomized, placebo-controlled trial, 48 healthy active women were randomized to 10 weeks of daily application of 10 mg of testosterone cream or placebo. Before and after the intervention, VO<sub>2</sub> max, body composition, total hemoglobin (Hb) mass and blood volumes were assessed. Biopsies from the vastus lateralis muscle were obtained before and after the intervention to assess mitochondrial protein abundance, capillary density, capillary-to-fiber (C/F) ratio, and skeletal muscle oxidative capacity.Results: Maximal oxygen consumption per muscle mass, Hb mass, blood, plasma and red blood cell volumes, capillary density, and the abundance of mitochondrial protein levels (i.e., citrate synthase, complexes I, II, III, IV-subunit 2, IV-subunit 4, and V) were unchanged by the intervention. However, the C/F ratio, specific mitochondrial respiratory flux activating complex I and linked complex I and II, uncoupled respiration and electron transport system capacity, but not leak respiration or fat respiration, were significantly increased following testosterone administration compared to placebo.Conclusion: This study provides novel insights into physiological actions of increased testosterone exposure on key determinants of oxygen diffusion and utilization in skeletal muscle of women. Our findings show that higher skeletal muscle oxidative capacity coupled to higher C/F ratio could be major contributing factors that improve endurance performance following moderately increased testosterone exposure.

  • 13.
    Edman, Sebastian
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Acute Signaling Responses To Resistance Exercise In Previously Trained And Untrained Skeletal Muscle2020In: MEDICINE AND SCIENCE IN SPORTS AND EXERCISE. 52:17. Suppl. Meeting Abstract: 2979, Lippincott Williams & Wilkins, 2020, Vol. 52, no 17, p. 829-829Conference paper (Other academic)
  • 14.
    Edman, Sebastian
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Söderlund, Karin
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    mTORC1 Signaling in Individual Human Muscle Fibers Following Resistance Exercise in Combination With Intake of Essential Amino Acids2019In: Frontiers in Nutrition, E-ISSN 2296-861X, Vol. 6, article id 96Article in journal (Refereed)
    Abstract [en]

    Human muscles contain a mixture of type I and type II fibers with different contractile and metabolic properties. Little is presently known about the effect of anabolic stimuli, in particular nutrition, on the molecular responses of these different fiber types. Here, we examine the effect of resistance exercise in combination with intake of essential amino acids (EAA) on mTORC1 signaling in individual type I and type II human muscle fibers. Five strength-trained men performed two sessions of heavy leg press exercise. During exercise and recovery, the subjects ingested an aqueous solution of EAA (290 mg/kg) or flavored water (placebo). Muscle biopsies were taken from the vastus lateralis before and 90 min after exercise. The biopsies were freeze-dried and single fibers dissected out and weighed (range 0.95-8.1 mu g). The fibers were homogenized individually and identified as type I or II by incubation with antibodies against the different isoforms of myosin. They were also analyzed for both the levels of protein as well as phosphorylation of proteins in the mTORC1 pathway using Western blotting. The levels of the S6K1 and eEF2 proteins were similar to 50% higher in type II than in type I fibers (P < 0.05), but no difference was found between fiber types with respect to the level of mTOR protein. Resistance exercise led to non-significant increases (2-3-fold) in mTOR and S6K1 phosphorylation as well as a 50% decrease (P < 0.05) in eEF2 phosphorylation in both fiber types. Intake of EAA caused a 2 and 6-fold higher (P < 0.05) elevation of mTOR and S6K1 phosphorylation, respectively, in both type I and type II fibers compared to placebo, with no effect on phosphorylation of eEF2. In conclusion, protein levels of S6K1 and eEF2 were significantly higher in type II than type I fibers suggesting higher capacity of the mTOR pathway in type II fibers. Ingestion of EAA enhanced the effect of resistance exercise on phosphorylation of mTOR and S6K1 in both fiber types, but with considerable variation between single fibers of both types.

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  • 15.
    Ekblom, Maria
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden..
    Bojsen-Møller, Emil
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Blom, Victoria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Psychology, Stockholm University, Stockholm, Sweden..
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Wang, Rui
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Acute effects of physical activity patterns on plasma cortisol and brain-derived neurotrophic factor in relation to corticospinal excitability.2022In: Behavioural Brain Research, ISSN 0166-4328, E-ISSN 1872-7549, Vol. 430, article id 113926Article in journal (Refereed)
    Abstract [en]

    Brain-derived neurotrophic factor (BDNF) and cortisol are both capable of modulating synaptic plasticity, but it is unknown how physical activity-induced changes in their plasma levels relate to corticospinal plasticity in humans. Sixteen inactive middle-aged men and women participated in three separate interventions consisting of 3hours prolonged sitting (SIT); 3hours sitting interrupted every 30minutes with frequent short physical activity breaks (FPA); and 2.5hours prolonged sitting followed by 25minutes of moderate intensity exercise (EXE). These 3hour sessions were each followed by a 30min period of paired associative stimulation over the primary motor cortex (PAS). Blood samples were taken and corticospinal excitability measured at baseline, pre PAS, 5min and 30min post PAS. Here we report levels of plasma BDNF and cortisol over three activity conditions and relate these levels to previously published changes in corticospinal excitability of a non-activated thumb muscle. There was no interaction between time and condition in BDNF, but cortisol levels were significantly higher after EXE compared to after SIT and FPA. Higher cortisol levels at pre PAS predicted larger increases in corticospinal excitability from baseline to all subsequent time points in the FPA condition only, while levels of BDNF at pre PAS did not predict such changes in any of the conditions. Neither BDNF nor cortisol modified changes from pre PAS to the subsequent time points, suggesting that the increased corticospinal excitability was not mediated though an augmented effect of the PAS protocol. The relationship between cortisol and plasticity has been suggested to be U-shaped. This is possibly why the moderately high levels of cortisol seen in the FPA condition were positively associated with changes AURC, while the higher cortisol levels seen after EXE were not. A better understanding of the mechanisms for how feasible physical activity breaks affect neuroplasticity can inform the theoretical framework for how work environments and schedules should be designed. DATA AVAILABILITY: Data are available from the corresponding author upon reasonable request.

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  • 16.
    Holm, Lars
    et al.
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Dideriksen, Kasper
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Nielsen, Rie H
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Doessing, Simon
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Bechshoeft, Rasmus L
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Højfeldt, Grith
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group. Karolinska institutet.
    Reitelseder, Søren
    Institute of Sports Medicine and Department of Orthopedic Surgery M, Bispebjerg Hospital, Copenhagen, Denmark.
    van Hall, Gerrit
    University of Copenhagen, Denmark.
    An exploration of the methods to determine the protein-specific synthesis and breakdown rates in vivo in humans.2019In: Physiological Reports, E-ISSN 2051-817X, Vol. 7, no 17, article id e14143Article in journal (Refereed)
    Abstract [en]

    The present study explores the methods to determine human in vivo protein-specific myofibrillar and collagenous connective tissue protein fractional synthesis and breakdown rates. We found that in human myofibrillar proteins, the protein-bound tracer disappearance method to determine the protein fractional breakdown rate (FBR) (via 2 H2 O ingestion, endogenous labeling of 2 H-alanine that is incorporated into proteins, and FBR quantified by its disappearance from these proteins) has a comparable intrasubject reproducibility (range: 0.09-53.5%) as the established direct-essential amino acid, here L-ring-13 C6 -phenylalanine, incorporation method to determine the muscle protein fractional synthesis rate (FSR) (range: 2.8-56.2%). Further, the determination of the protein breakdown in a protein structure with complex post-translational processing and maturation, exemplified by human tendon tissue, was not achieved in this experimentation, but more investigation is encouraged to reveal the possibility. Finally, we found that muscle protein FBR measured with an essential amino acid tracer prelabeling is inappropriate presumably because of significant and prolonged intracellular recycling, which also may become a significant limitation for determination of the myofibrillar FSR when repeated infusion trials are completed in the same participants.

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  • 17.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Godhe, Manne
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Helge, Torbjörn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lindén Hirschberg, Angelica
    Karolinska institutet.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Fiber type-specific hypertrophy and increased capillarization in skeletal muscle following testosterone administration of young women.2020In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 128, no 5, p. 1240-1250Article in journal (Refereed)
    Abstract [en]

    It is well established that testosterone administration induces muscle fiber hypertrophy and myonuclear addition in men, however, it remains to be determined whether similar morphological adaptations can be achieved in women. The aim of the present study was therefore to investigate whether exogenously administered testosterone alters muscle fiber morphology in skeletal muscle of young healthy, physically active women. Thirty-five young (20-35 years), recreationally trained women were randomly assigned to either 10-week testosterone administration (10 mg daily) or placebo. Before and after the intervention, hormone concentrations and body composition were assessed, and muscle biopsies were obtained from the vastus lateralis. Fiber type composition, fiber size, satellite cell- and myonuclei content, as well as muscle capillarization were assessed in a fiber type-specific manner using immunohistochemistry. Following the intervention, testosterone administration elevated serum testosterone concentration (5.1-fold increase, P=0.001), and induced significant accretion of total lean mass (+1.9%, P=0.002) and leg lean mass (+2.4%, P=0.001). On the muscle fiber level, testosterone increased mixed fiber cross-sectional area (+8.2%, P=0.001), an effect primarily driven by increases in type II fiber size (9.2%, P=0.006). Whereas myonuclei content remained unchanged, a numerical increase (+30.8%) was found for satellite cells associated with type II fibers in the Testosterone group. In parallel with fiber hypertrophy, testosterone significantly increased capillary contacts (+7.5%, P=0.015) and capillary-to-fiber ratio (+9.2%, P=0.001) in type II muscle fibers. The current study provides novel insight into fiber type-specific adaptations present already after 10 weeks of only moderately elevated testosterone levels in women.

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  • 18.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Envall, Helena
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Student.
    Röja, Julia
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Student.
    Emanuelsson, Eric Bengt
    Karolinska Institute, Sweden.
    Sanz, Gema
    Karolinska Institute, Sweden.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institute, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institute, Sweden.
    Variablity in vastus lateralis fiber type distribution, fiber size and myonuclear content along and between the legs.2021In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 131, no 1, p. 158-173Article in journal (Refereed)
    Abstract [en]

    Human skeletal muscle characteristics such as fiber type composition, fiber size and myonuclear content are widely studied in clinical and sports related contexts. Being aware of the methodological and biological variability of the characteristics is a critical aspect in study design and outcome interpretation, but comprehensive data on the variability of morphological features in human skeletal muscle is currently limited. Accordingly, in the present study, m. vastus lateralis biopsies (10 per subject) from young and healthy individuals, collected in a systematic manner, were analyzed for various characteristics using immunohistochemistry (n=7) and SDS-PAGE (n=25). None of the analyzed parameters; fiber type % (FT%), type I and II CSA (fCSA), percentage fiber type area (fCSA%), myosin heavy chain composition (MyHC%), type IIX content, myonuclear content or myonuclear domain varied in a systematic manner longitudinally along the muscle or between the two legs. The average within subject coefficient of variation for FT%, fCSA, fCSA%, and MyHC% ranged between 13-18%, but was only 5% for fiber specific myonuclear content, which reduced the variability for myonuclear domain size to 11-12%. Pure type IIX fibers and type IIX MyHC were randomly distributed and present in <24% of the analyzed samples, with the average content being 0.1 and 1.1%, respectively. In conclusion, leg or longitudinal orientation does not seem to be an important aspect to consider when investigating human vastus lateralis characteristics. However, single muscle biopsies should preferably not be used when studying fiber type and fiber size related aspects given the notable sample to sample variability.

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  • 19.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
    Hirschberg, Angelica Lindén
    Department of Women´s and Children´s Health, Division of Neonatology, Obstetrics and Gynaecology, Karolinska Institutet, Stockholm, Sweden; Department of Gynaecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden..
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden..
    Molecular Regulators of Muscle Mass and Mitochondrial Remodeling Are Not Influenced by Testosterone Administration in Young Women.2022In: Frontiers in Endocrinology, E-ISSN 1664-2392, Vol. 13, article id 874748Article in journal (Refereed)
    Abstract [en]

    Testosterone (T) administration has previously been shown to improve muscle size and oxidative capacity. However, the molecular mechanisms underlying these adaptations in human skeletal muscle remain to be determined. Here, we examined the effect of moderate-dose T administration on molecular regulators of muscle protein turnover and mitochondrial remodeling in muscle samples collected from young women. Forty-eight healthy, physically active, young women (28 ± 4 years) were assigned in a random double-blind fashion to receive either T (10 mg/day) or placebo for 10-weeks. Muscle biopsies collected before and after the intervention period were divided into sub-cellular fractions and total protein levels of molecular regulators of muscle protein turnover and mitochondrial remodeling were analyzed using Western blotting. T administration had no effect on androgen receptor or 5α-reductase levels, nor on proteins involved in the mTORC1-signaling pathway (mTOR, S6K1, eEF2 and RPS6). Neither did it affect the abundance of proteins associated with proteasomal protein degradation (MAFbx, MuRF-1 and UBR5) and autophagy-lysosomal degradation (AMPK, ULK1 and p62). T administration also had no effect on proteins in the mitochondria enriched fraction regulating mitophagy (Beclin, BNIP3, LC3B-I, LC3B-II and LC3B-II/I ratio) and morphology (Mitofilin), and it did not alter the expression of mitochondrial fission- (FIS1 and DRP1) or fusion factors (OPA1 and MFN2). In summary, these data indicate that improvements in muscle size and oxidative capacity in young women in response to moderate-dose T administration cannot be explained by alterations in total expression of molecular factors known to regulate muscle protein turnover or mitochondrial remodeling.

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  • 20.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Larsen, Filip J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Philp, Andrew
    Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska institutet, Sweden.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Influence of sex- and fiber type on the satellite cell pool in human skeletal muscle.2021In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 31, no 2, p. 303-312Article in journal (Refereed)
    Abstract [en]

    The repair, remodeling and regeneration of myofibers is dependent on satellite cells (SCs), although, the distribution of SCs in different fiber types of human muscle remains inconclusive. There is also a paucity of research comparing muscle fiber characteristics in a sex-specific manner. Therefore, the aim of this study was to investigate fiber type-specific SC content in men and women. Muscle biopsies from vastus lateralis were collected from 64 young (mean age 27 ± 5), moderately trained men (n=34) and women (n=30). SCs were identified by Pax7-staining together with immunofluorescent analyses of fiber type composition, fiber size and myonuclei content. In a mixed population, comparable number of SCs were associated to type I and type II fibers (0.07 ± 0.02 vs 0.07 ± 0.02 SCs per fiber, respectively). However, unlike men, women displayed a fiber type-specific distribution, with SC content being lower in type II than type I fibers (P=0.041). Sex-based differences were found specifically for type II fibers, where women displayed lower SC content compared to men (P<0.001). In addition, positive correlations (r-values between 0.36-0.56) were found between SC content and type I and type II fiber size in men (P=0.03 and P<0.01, respectively), whereas similar relationships could not be detected in women. Sex-based differences were also noted for fiber type composition and fiber size, but not for myonuclei content. We hereby provide evidence for sex-based differences present at the myocellular level, which may have important implications when studying exercise- and training induced myogenic responses in skeletal muscle.

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  • 21.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Nordström, Fabian
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Satellite cell pool expansion induced by resistance exercise is not altered by acute normobaric hypoxia2022In: Svensk idrottsmedicin 2022:2, Svensk förening för fysisk aktivitet och idrottsmedicin , 2022, Vol. 41, p. 30-Conference paper (Other academic)
  • 22.
    Horwath, Oscar
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Nordström, Fabian
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    von Walden, Ferdinand
    Division of Pediatric Neurology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden..
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Solna, Sweden..
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institutet, Solna, Sweden..
    Acute hypoxia attenuates resistance exercise-induced ribosome signaling but does not impact satellite cell pool expansion in human skeletal muscle.2023In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 37, no 3, article id e22811Article in journal (Refereed)
    Abstract [en]

    Cumulative evidence supports the hypothesis that hypoxia acts as a regulator of muscle mass. However, the underlying molecular mechanisms remain incompletely understood, particularly in human muscle. Here we examined the effect of hypoxia on signaling pathways related to ribosome biogenesis and myogenic activity following an acute bout of resistance exercise. We also investigated whether hypoxia influenced the satellite cell response to resistance exercise. Employing a randomized, crossover design, eight men performed resistance exercise in normoxia (FiO2 21%) or normobaric hypoxia (FiO2 12%). Muscle biopsies were collected in a time-course manner (before, 0, 90, 180 min and 24 h after exercise) and were analyzed with respect to cell signaling, gene expression and satellite cell content using immunoblotting, RT-qPCR and immunofluorescence, respectively. In normoxia, resistance exercise increased the phosphorylation of RPS6, TIF-1A and UBF above resting levels. Hypoxia reduced the phosphorylation of these targets by ~37%, ~43% and ~ 67% throughout the recovery period, respectively (p < .05 vs. normoxia). Resistance exercise also increased 45 S pre-rRNA expression and mRNA expression of c-Myc, Pol I and TAF-1A above resting levels, but no differences were observed between conditions. Similarly, resistance exercise increased mRNA expression of myogenic regulatory factors throughout the recovery period and Pax7+ cells were elevated 24 h following exercise in mixed and type II muscle fibers, with no differences observed between normoxia and hypoxia. In conclusion, acute hypoxia attenuates ribosome signaling, but does not impact satellite cell pool expansion and myogenic gene expression following a bout of resistance exercise in human skeletal muscle.

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  • 23. Kazior, Zuzanna
    et al.
    Willis, Sarah J
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Calbet, José A L
    Holmberg, Hans-Christer
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Endurance Exercise Enhances the Effect of Strength Training on Muscle Fiber Size and Protein Expression of Akt and mTOR.2016In: PLOS ONE, E-ISSN 1932-6203, Vol. 11, no 2, article id e0149082Article in journal (Refereed)
    Abstract [en]

    Reports concerning the effect of endurance exercise on the anabolic response to strength training have been contradictory. This study re-investigated this issue, focusing on training effects on indicators of protein synthesis and degradation. Two groups of male subjects performed 7 weeks of resistance exercise alone (R; n = 7) or in combination with preceding endurance exercise, including both continuous and interval cycling (ER; n = 9). Muscle biopsies were taken before and after the training period. Similar increases in leg-press 1 repetition maximum (30%; P<0.05) were observed in both groups, whereas maximal oxygen uptake was elevated (8%; P<0.05) only in the ER group. The ER training enlarged the areas of both type I and type II fibers, whereas the R protocol increased only the type II fibers. The mean fiber area increased by 28% (P<0.05) in the ER group, whereas no significant increase was observed in the R group. Moreover, expression of Akt and mTOR protein was enhanced in the ER group, whereas only the level of mTOR was elevated following R training. Training-induced alterations in the levels of both Akt and mTOR protein were correlated to changes in type I fiber area (r = 0.55-0.61, P<0.05), as well as mean fiber area (r = 0.55-0.61, P<0.05), reflecting the important role played by these proteins in connection with muscle hypertrophy. Both training regimes reduced the level of MAFbx protein (P<0.05) and tended to elevate that of MuRF-1. The present findings indicate that the larger hypertrophy observed in the ER group is due more to pronounced stimulation of anabolic rather than inhibition of catabolic processes.

  • 24.
    Liegnell, Rasmus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology. Karolinska Institute, Sweden.
    Danielsson, Sebastian
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    van Hall, Gerrit
    University of Copenhagen, Denmark.
    Holmberg, Hans-Christer
    Mid Sweden University, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Elevated plasma lactate levels via exogenous lactate infusion do not alter resistance exercise-induced signaling or protein synthesis in human skeletal muscle.2020In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 319, p. E792-E804Article in journal (Refereed)
    Abstract [en]

    Lactate has been implicated as a potential signaling molecule. In myotubes, lactate incubation increases mTORC1- and ERK-signaling and induces hypertrophy, indicating that lactate could be a mediator of muscle adaptations to resistance exercise. However, the potential signaling properties of lactate, at rest or with exercise, have not been explored in human tissue. In a cross-over design study, 8 men and 8 women performed one-legged resistance exercise while receiving venous infusion of saline or sodium lactate. Blood was sampled repeatedly, and muscle biopsies were collected at rest and at 0, 90,180 min and 24 h after exercise. The primary outcomes examined were intracellular signaling, fractional protein synthesis rate (FSR), and blood/muscle levels of lactate and pH. Post-exercise blood lactate concentrations were 130% higher in the Lactate trial (3.0 vs 7.0 mmol×l-1, p<0.001) whereas muscle levels were only marginally higher (27 vs 32 mmol×kg-1 d.w., p=0.003) compared to the Saline-trial. Post-exercise blood pH was higher in the Lactate-trial (7.34 vs 7.44, p<0.001), with no differences in intramuscular pH. Exercise increased the phosphorylation of mTORS2448 (~40%), S6K1T389 (~3-fold), and p44T202/T204 (~80%) during recovery, without any differences between trials. FSR over the 24-h recovery period did not differ between the Saline (0.067 %/h) and Lactate (0.062 %/h) trials. This study does not support the hypothesis that blood lactate levels can modulate anabolic signaling in contracted human muscle. Further in vivo research investigating the impact of exercised versus rested muscle and the role of intramuscular lactate is needed to elucidate its potential signaling properties.

  • 25.
    Lilja, Mats
    et al.
    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden ; Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden..
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Martínez-Aranda, Luis Manuel
    Movement Analysis Laboratory for Sport and Health (MALab), Faculty of Sport, Catholic University of Murcia, Spain..
    Rundqvist, Håkan
    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden ; Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden..
    Langlet, Billy
    Department of Neurobiology, Karolinska Institutet, Stockholm, Sweden..
    Gustafsson, Thomas
    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden ; Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden..
    Lundberg, Tommy R
    Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden ; Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden..
    Limited effect of over-the-counter doses of ibuprofen on mechanisms regulating muscle hypertrophy during resistance training in young adults.2023In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 134, no 3, p. 753-765Article in journal (Refereed)
    Abstract [en]

    We have previously shown that maximal over-the-counter doses of ibuprofen, compared with low doses of acetylsalicylic acid, reduce muscle hypertrophy in young individuals after 8 weeks of resistance training. Because the mechanism behind this effect has not been fully elucidated, we here investigated skeletal muscle molecular responses and myofiber adaptations in response to acute and chronic resistance training with concomitant drug intake. Thirty-one young (aged 18-35 years) healthy men (n=17) and women (n=14) were randomized to receive either ibuprofen (IBU;1200mg daily; n=15) or acetylsalicylic acid (ASA; 75mg daily; n=16) while undergoing 8 weeks of knee extension training. Muscle biopsies from the vastus lateralis were obtained before, at week 4 after an acute exercise session, and after 8 weeks of resistance training and analyzed for mRNA markers and mTOR signaling, as well as quantification of total RNA content (marker of ribosome biogenesis) and immunohistochemical analyzes of muscle fiber size, satellite cell content, myonuclear accretion, and capillarization. There were only two treatment ´ time interaction in selected molecular markers after acute exercise (atrogin-1 and MuRF1 mRNA), but several exercise effects. Muscle fiber size, satellite cell and myonuclear accretion, and capillarization were not affected by chronic training or drug intake. RNA content increased comparably (~14%) in both groups. Collectively, these data suggest that established acute and chronic hypertrophy regulators (including mTOR signaling, ribosome biogenesis, satellite cell content, myonuclear accretion, and angiogenesis) were not differentially affected between groups and therefore do not explain the deleterious effects of ibuprofen on muscle hypertrophy in young adults.

  • 26.
    Lilja, Mats
    et al.
    Karolinska Institutet.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Mandić, Mirko
    Karolinska Institutet.
    Gustafsson, Thomas
    Karolinska Institutet.
    Lundberg, Tommy R.
    Karolinska Institutet.
    High versus Low doses of Anti-inflammatory Drugs Do Not Differentially Affect Muscle Molecular Response to Acute Resistance Exercise: 2008 Board #269 May 31 2:00 PM - 3:30 PM.2018In: Medicine & Science in Sports & Exercise. 2018 Supplement 1, Vol. 50, p488-488, 2018, Vol. 50, p. 488-488Conference paper (Other academic)
  • 27.
    Marcus, Moberg
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    van Hall, Gerrit
    Holmberg, Hans-Christer
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Lower body endurance exercise acutely affects resistance exercise induced transcriptional and translational signalling in the tricpes brachii muscleManuscript (preprint) (Other academic)
  • 28.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    ACSM Annual Meeting: Två dagar med fokus på muskelhypertrofi/atrofi2018In: Idrottsmedicin, ISSN 2001-3302, Vol. 37, no 3, p. 29-31Article in journal (Other (popular science, discussion, etc.))
  • 29.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Active voice: Human Skeletal Muscle Has a Molecular Muscle Memory to Resistance Training.2020In: Sports Medicine Bulletin, ISSN 0746-9306, no 18 AugArticle in journal (Other (popular science, discussion, etc.))
  • 30.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Effects of exercise and amino acid intake on mechanisms regulating protein synthesis and breakdown in human muscle2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Skeletal muscle adapts differently to specific modes of exercise, where resistance training results in muscle growth and endurance training induces mitochondrial biogenesis. These are results of molecular events that occur after each exercise session, increasing the expression of specific genes and the rate of both synthesis and breakdown of protein. The rate of protein synthesis is controlled by the mTORC1 signaling pathway, which is potently stimulated by resistance exercise and amino acid, and their combined effect is needed for muscle growth. The essential amino acids (EAA) are responsible for the stimulation of protein synthesis and here leucine has been attributed specific attention, but its particular role among the EAA, and the involvement of the other branched-chain amino acids (BCAA) is unclear. Endurance exercise activates the protein AMPK which, in animal models, has been shown to inhibit mTORC1 signaling and protein synthesis.  Suggesting that concurrent endurance and resistance exercise could restrain muscle growth, but it is unknown if this mechanism is relevant in exercising human muscle. Little is known about the regulation of protein breakdown and although much attention has been given the proteins MuRF-1 and MAFbx which target proteins for degradation, their role requires further investigation. The aim of thesis was to address the mentioned uncertainties by examining how different modes of exercise and amino acids affect mTORC1 signaling, protein synthesis and markers of protein breakdown in human muscle.

    In study I, the influence of high intensity endurance exercise on subsequent resistance exercised induced mTORC1 signaling was examined. Despite robust activation of AMPK by the endurance exercise there was no inhibition of mTORC1 signaling or protein synthesis during recovery from resistance exercise. Study II utilized a similar set up, but with the difference that resistance exercise was performed with the triceps. The cycling exercise reduced the resistance exercise stimulated mTORC1 signaling immediately after the exercise, but during the recovery period mTORC1 signaling and protein synthesis was similar between trials. Concurrent exercise induced the mRNA expression of MuRF-1 and that of PGC-1α, the master regulator of mitochondrial biogenesis, in both studies, despite that the exercise modes in study II were separated between legs and arms. In study III, the effect of an EAA supplement with or without leucine, in the stimulation of mTORC1 signaling in connection with resistance exercise was examined. Intake of EAA robustly stimulated mTORC1 signaling after exercise, but this was only minor when leucine was excluded from the supplement. In study IV, subjects were supplied with leucine, BCAA, EAA or placebo in a randomized fashion during four sessions of resistance exercise. Leucine alone stimulated mTORC1 signaling after the exercise, but both the amplitude and extent of stimulation was substantially greater with EAA, an effect that was largely mediated by the BCAA as a group.

    In conclusion, endurance exercise prior to resistance exercise using the leg or arm muscles does not affect mTORC1 signaling or protein synthesis during the three hour recovery period from exercise, supporting compatibility between resistance- and endurance exercise induced signaling. Concurrent exercise increases the expression of the proteolytic marker MuRF-1 compared to resistance exercise only, which could indicate both and increased demand of cellular adaptive remodeling or a more direct detrimental proteolytic effect. Leucine is crucial among the EAA in the stimulation of mTORC1 signaling after exercise, its effect is however potentiated by intake of the remaining EAA. As a supplement a mixture of EAA must be regarded preferable, although the effect is largely mediated by the BCAA as a group.  

     

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  • 31.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Effekt av kombinerad styrke- och konditionsträning2018In: Idrottsmedicin, ISSN 2001-3302, Vol. 37, no 3, p. 8-9Article in journal (Other academic)
    Abstract [sv]

    Det finns teorier om att kombinerad konditions- och styrketräning hämmar styrkeutvecklingen jämfört med enbart styrketräning. För att ta reda på om det stämmer genomfördes studier där cykling kombinerades med styrketräning.

  • 32.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institutet, Stockholm, Sweden..
    Cervenka, Igor
    Karolinska Institutet, Stockholm, Sweden..
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    van Hall, Gerrit
    University of Copenhagen, Copenhagen, Denmark..
    Holmberg, Hans-Christer
    Karolinska Institutet, Stockholm, Sweden..
    Ruas, Jorge L
    Karolinska Institutet, Stockholm, Sweden..
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Karolinska Institutet, Stockholm, Sweden..
    High-intensity leg cycling alters the molecular response to resistance exercise in the arm muscles.2021In: Scientific Reports, E-ISSN 2045-2322, Vol. 11, no 1, article id 6453Article in journal (Refereed)
    Abstract [en]

    This study examined acute molecular responses to concurrent exercise involving different muscles. Eight men participated in a randomized crossover-trial with two sessions, one where they performed interval cycling followed by upper body resistance exercise (ER-Arm), and one with upper body resistance exercise only (R-Arm). Biopsies were taken from the triceps prior to and immediately, 90- and 180-min following exercise. Immediately after resistance exercise, the elevation in S6K1 activity was smaller and the 4E-BP1:eIF4E interaction greater in ER-Arm, but this acute attenuation disappeared during recovery. The protein synthetic rate in triceps was greater following exercise than at rest, with no difference between trials. The level of PGC-1α1 mRNA increased to greater extent in ER-Arm than R-Arm after 90 min of recovery, as was PGC-1α4 mRNA after both 90 and 180 min. Levels of MuRF-1 mRNA was unchanged in R-Arm, but elevated during recovery in ER-Arm, whereas MAFbx mRNA levels increased slightly in both trials. RNA sequencing in a subgroup of subjects revealed 862 differently expressed genes with ER-Arm versus R-Arm during recovery. These findings suggest that leg cycling prior to arm resistance exercise causes systemic changes that potentiate induction of specific genes in the triceps, without compromising the anabolic response.

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  • 33.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Holmberg, Hans-Christer
    Swedish Winter Sports Res Ctr, Östersund, Sweden..
    van Hall, Gerrit
    Clin Metabol Core Facil, Copenhagen, Denmark..
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH.
    Effects Of Lactate Infusion On Resistance Exericse Induced MTORC1-signaling And Protein Synthesis In Human Muscle2020In: MEDICINE AND SCIENCE IN SPORTS AND EXERCISE. 52:17. Suppl. Meeting Abstract: 128, Lippincott Williams & Wilkins, 2020, Vol. 52, no 17, p. 19-19Conference paper (Other academic)
  • 34.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institute, Sweden.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institute, Sweden.
    Horwath, Oscar
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    van Hall, Gerrit
    University of Copenhagen, Denmark.; Rigshospitalet, Copenhagen, Denmark..
    Blackwood, Sarah J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Acute normobaric hypoxia blunts contraction-mediated mTORC1- and JNK-signaling in human skeletal muscle.2022In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 234, no 2, article id e13771Article in journal (Refereed)
    Abstract [en]

    AIM: Hypoxia has been shown to reduce resistance exercise-induced stimulation of protein synthesis and long-term gains in muscle mass. However, the mechanism whereby hypoxia exerts its effect is not clear. Here we examine the effect of acute hypoxia on the activity of several signaling pathways involved in regulation of muscle growth following a bout of resistance exercise.

    METHODS: Eight men performed two sessions of leg resistance exercise in Normoxia or Hypoxia (12% O2 ) in a randomized crossover fashion. Muscle biopsies were obtained at rest and at 0, 90,180 min after exercise. Muscle analyses included levels of signaling proteins and metabolites associated with energy turnover.

    RESULTS: Exercise during Normoxia induced a 5-10-fold increase of S6K1Thr389 phosphorylation throughout the recovery period, but Hypoxia blunted the increases by ~50%. Phosphorylation of JNKThr183/Tyr185 and the JNK target SMAD2Ser245/250/255 was increased by 30-40-fold immediately after exercise in Normoxia, but Hypoxia blocked almost 70% of the activation. Throughout recovery, phosphorylation of JNK and SMAD2 remained elevated following exercise in Normoxia, but the effect of Hypoxia was lost at 90-180 min post-exercise. Hypoxia had no effect on exercise induced Hippo- or autophagy-signaling and ubiquitin-proteasome related protein levels. Nor did Hypoxia alter the changes induced by exercise in high energy phosphates, glucose 6-P, lactate, or phosphorylation of AMPK or ACC.

    CONCLUSION: We conclude that acute severe hypoxia inhibits resistance exercise induced mTORC1- and JNK signaling in human skeletal muscle, effects that do not appear to be mediated by changes in the degree of metabolic stress in the muscle.

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  • 35.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Aminosyror ökar träningseffekten2013In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, Vol. 22, no 1, p. 45-49Article in journal (Other academic)
    Abstract [sv]

    Kostens sammansättning är viktig för prestation och återhämtning. Dess innehåll av protein och essentiella aminosyror kan påverka musklernas anpassning till träning. Ny forskning visar att vissa aminosyror har en viktigare roll än att enbart agera som byggstenar eller energigivande näringsämnen.

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  • 36.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    High-intensity cycling performed prior to resistance exercise does not influence mTORC1-signaling and the rate of muscle protein synthesis in the triceps brachii2014Conference paper (Other academic)
    Abstract [en]

    Introduction

    Endurance exercise can influence strength training adaptations when performed concurrently, with both inhibition (Kreamer 1995) and augmentation (Lundberg 2012) of muscular hypertrophy being reported. Our lab has set out to conduct a series of studies to examine the influence of endurance exercise on the acute stimulatory effect of resistance exercise on anabolic processes. In the present study, the effect of endurance exercise on a previously inactive muscle was investigated. The aim was to examine the influence of resistance exercise on mTORC1-signaling and rate of protein synthesis in the triceps brachii muscle with or without preceding intervals of high-intensity cycling. 

     

    Methods

    Eight trained males performed, in a randomized fashion, two sessions of heavy resistance exercise (RE) with the triceps muscles, where one session was preceded by intervals of high-intensity cycling (E+RE), 5 x 4 min at 85% of VO2 peak. Mixed muscle protein fractional synthetic rate (FSR) was measured at rest, prior to exercise, and during a 3 hour recovery period following exercise by continuous infusion of L-[ring-13C6] phenylalanine. Muscle biopsies from the triceps brachii was collected twice at rest separated by three hours, directly after resistance exercise and following 90 and 180 min of recovery. Signalling in the mTORC1-and AMPK-pathway was assessed using western blot technique.

     

    Results

    The same amount of work with regard to load, total number of repetitions and total time under tension was performed in the two trials. Muscle protein FSR increased from 0.050 ± 0.006 %/h at rest to 0.078 ± 0.008 and 0.082 ± 0.0016 %/h following E+RE and RE, respectively, with no difference between trials. Phosphorylation (P) of AMPKT172 was increased by 45-65% directly after exercise, similarly in both conditions, and regressed to a level approx. 20% lower than baseline following 180 min of recovery. P-mTORS2448 was increased 76 and 108% above rest directly after the E+RE and RE, respectively, and remained elevated in both trials during the entire recovery period. P-eEF2T56 was 20-36% higher directly after exercise but fell to a level that was 30-36% lower than pre-exercise and remained reduced during the entire recovery, with no difference between trials.

     

    Conclusion

    High-intensity endurance cycling does not influence the acute stimulation of anabolic signalling and muscle protein synthesis in the triceps brachii following resistance exercise.

     

     

    References

    Kreamer WJ et al. (1995) J Appl Physiol 78(3):976-989

    Lundberg T et al. (2013) J Appl Physiol 114: 81-89

  • 37.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Gerrit, van Hall
    Holmberg, Hans-Christer
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Activation of mTORC1 by leucine is potentiated by branched chain amino acids and even more so by essential amino acids following resistance exercise2016In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 310, no 11, p. C874-C884Article in journal (Refereed)
    Abstract [en]

    Protein synthesis is stimulated by resistance exercise and intake of amino acids, in particular leucine. Moreover, activation of mTORC1 signaling by leucine is potentiated by the presence of other essential amino acids (EAA). However, the contribution of the branched-chain amino acids (BCAA) to this effect is yet unknown. Here we compare the stimulatory role of leucine, BCAA and EAA ingestion on anabolic signaling following exercise. Accordingly, eight trained volunteers completed four sessions of resistance exercise during which they ingested either placebo, leucine, BCAA or EAA (including the BCAA) in random order. Muscle biopsies were taken at rest, immediately after exercise and following 90 and 180 min of recovery. Following 90 min of recovery the activity of S6K1 was greater than at rest in all four trials (Placebo<Leucine<BCAA<EAA; P<0.05 time x supplement), with a 9-fold increase in the EAA trial. At this same time-point phosphorylation of 4E-BP1 at Thr37/46 was unaffected by supplementation, while that of Thr46 alone exhibited a pattern similar to that of S6K1, being 18% higher with EAA than BCAA. However, after 180 min of recovery this difference between EAA and BCAA had disappeared, although with both these supplements the increases were still higher than with leucine (40%, P<0.05) and placebo (100%, P<0.05). In summary, EAA ingestion appears to stimulate translation initiation more effectively than the other supplements, although the results also suggest that this effect is primarily attributable to the BCAA.

  • 38.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Ohlsson, Inger
    Pontén, Marjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Villanueva, Antonio
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's and Mats Börjesson's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Absence of leucine in an essential amino acid supplement reduces activation of mTORC1 signalling following resistance exercise in young females.2014In: Applied Physiology, Nutrition and Metabolism, ISSN 1715-5312, E-ISSN 1715-5320, Vol. 39, no 2, p. 183-94Article in journal (Refereed)
    Abstract [en]

    The purpose of the study was to investigate the specific effect of leucine on mTORC1 signalling and amino acid metabolism in connection with resistance exercise. Comparisons were made between ingestion of supplements with and without leucine. Eight young women performed leg press exercise on 2 occasions. In randomized order they received either an aqueous solution of essential amino acids with leucine (EAA) or without leucine (EAA-Leu), given as small boluses throughout the experiment. Muscle biopsies were taken after an overnight fast before exercise and 1 and 3 h postexercise and samples of blood were taken repeatedly during the experiment. Plasma and muscle concentrations of leucine rose 60%-140% (p < 0.05) with EAA and fell 35%-45% (p < 0.05) with the EAA-Leu supplement. In the EAA-trial, plasma and muscle levels of tyrosine (not present in the supplement) and the sum of the EAA were 15%-25% (p < 0.05) lower during recovery. Phosphorylation of mTOR and p70S6k was elevated to a larger extent following 1 h of recovery with leucine in the supplement (120% vs. 49% (p < 0.05) and 59- vs. 8-fold (p < 0.05) for EAA and EAA-Leu, respectively). The levels of MAFbx and MuRF-1 mRNA and of the corresponding proteins were not significantly altered after 3 h recovery from exercise. In conclusion, the presence of leucine in the supplement enhances the stimulatory effect on mTORC1 signalling and reduces the level of tyrosine and the sum of the EAA in muscle and plasma, suggesting a stimulation of protein synthesis and (or) inhibition of breakdown, leading to improvement in net protein balance.

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  • 39.
    Moberg, Marcus
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Lindholm, Malene E
    Karolinska institutet, Stockholm, Sweden.
    Reitzner, Stefan M
    Karolinska institutet, Stockholm, Sweden.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Sundberg, Carl-Johan
    Karolinska institutet, Stockholm, Sweden.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Exercise Induces Different Molecular Responses in Trained and Untrained Human Muscle.2020In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 52, no 8, p. 1679-1690Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Human skeletal muscle is thought to have heightened sensitivity to exercise stimulus when it has been previously trained (i.e., it possesses "muscle memory"). We investigated whether basal and acute resistance exercise-induced gene expression and cell signaling events are influenced by previous strength training history.

    METHODS: Accordingly, 19 training naïve women and men completed 10 weeks of unilateral leg strength training, followed by 20 weeks of detraining. Subsequently, an acute resistance exercise session was performed for both legs, with vastus lateralis biopsies taken at rest and 1 h after exercise in both legs (memory and control).

    RESULTS: The phosphorylation of AMPK and eEF2 was higher in the memory leg than in the control leg at both time points. Post-exercise phosphorylation of 4E-BP1 was higher in the memory leg than in the control leg. The memory leg had lower basal mRNA levels of total PGC1α, and, unlike the control leg, exhibited increases in PGC1α-ex1a transcripts after exercise. In the genes related to myogenesis (SETD3, MYOD1, and MYOG), mRNA levels differed between the memory and the untrained leg; these effects were evident primarily in the male subjects. Expression of the novel gene SPRYD7 was lower in the memory leg at rest and decreased after exercise only in the control leg, but SPRYD7 protein levels were higher in the memory leg.

    CONCLUSION: In conclusion, several key regulatory genes and proteins involved in muscular adaptations to resistance exercise are influenced by previous training history. Although the relevance and mechanistic explanation for these findings need further investigation, they support the view of a molecular muscle memory in response to training.

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  • 40.
    Nilsson, Jonna
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden..
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Lövdén, Martin
    Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden; Department of Psychology, University of Gothenburg, Gothenburg, Sweden..
    The role of acute changes in mBDNF, cortisol and pro-BDNF in predicting cognitive performance in old age.2023In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 9418Article in journal (Refereed)
    Abstract [en]

    The interplay between biomarkers of relevance to neuroplasticity and its association with learning and cognitive ability in old age remains poorly understood. The present study investigated acute changes in plasma concentrations of mature brain-derived neurotrophic factor (mBDNF), its precursor protein (pro-BDNF), and cortisol, in response to acute physical exercise and cognitive training interventions, their covariation and role in predicting cognitive performance. Confirmatory results provided no support for mBDNF, pro-BDNF and cortisol co-varying over time, as the acute interventions unfolded, but did confirm a positive association between mBDNF and pro-BDNF at rest. The confirmatory results did not support the hypothesis that mBDNF change following physical exercise were counteracted by temporally coupled changes in cortisol or pro-BDNF, or by cortisol at rest, in its previously demonstrated faciliatory effect on cognitive training outcome. Exploratory results instead provided indications of a general and trait-like cognitive benefit of exhibiting greater mBDNF responsiveness to acute interventions when coupled with lesser cortisol responsiveness, greater pro-BDNF responsiveness, and lower cortisol at rest. As such, the results call for future work to test whether certain biomarker profiles are associated with preserved cognition in old age.

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  • 41.
    Nilsson, Jonna
    et al.
    Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
    Ekblom, Örjan
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Lebedev, Alexander
    Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
    Tarassova, Olga
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Laboratory for Biomechanics and Motor Control.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Lövdén, Martin
    Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
    Acute increases in brain-derived neurotrophic factor in plasma following physical exercise relates to subsequent learning in older adults.2020In: Scientific Reports, E-ISSN 2045-2322, Vol. 10, no 1, article id 4395Article in journal (Refereed)
    Abstract [en]

    Multidomain lifestyle interventions represents a promising strategy to counteract cognitive decline in older age. Brain-derived neurotrophic factor (BDNF) is essential for experience-dependent plasticity and increases following physical exercise, suggesting that physical exercise may facilitate subsequent learning. In a randomized-controlled trial, healthy older adults (65-75 years) completed a 12-week behavioral intervention that involved either physical exercise immediately before cognitive training (n = 25; 13 females), physical exercise immediately after cognitive training (n = 24; 11 females), physical exercise only (n = 27; 15 females), or cognitive training only (n = 21; 12 females). We hypothesized that cognition would benefit more from cognitive training when preceded as opposed to followed by physical exercise and that the relationship between exercise-induced increases in peripheral BDNF and cognitive training outcome would be greater when cognitive training is preceded by physical exercise. Greater increases of plasma BDNF were associated with greater cognitive training gains on trained task paradigms, but only when such increases preceded cognitive training (ß = 0.14, 95% CI [0.04, 0.25]). Average cognitive training outcome did not differ depending on intervention order (ß = 0.05, 95% CI [-0.10, 0.20]). The study provides the first empirical support for a time-critical but advantageous role for post-exercise increases in peripheral BDNF for learning at an interindividual level in older adults, with implications for future multidomain lifestyle interventions.

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  • 42.
    Nordström, Fabian
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Liegnell, Rasmus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Clinical Science, Intervention and Technology, Karolinska Institute, Sweden.
    Blackwood, Sarah J
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Katz, Abram
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics. Department of Physiology and Pharmacology, Karolinska Institute, Sweden.
    The lactate receptor GPR81 is predominantly expressed in type II human skeletal muscle fibers: potential for lactate autocrine signaling.2023In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 324, no 2, p. C477-C487Article in journal (Refereed)
    Abstract [en]

    GPR81 was first identified in adipocytes as a receptor for L-lactate, which upon binding inhibits cAMP-PKA-CREB signaling. Moreover, incubation of myotubes with lactate augments expression of GPR81 and genes and proteins involved in lactate- and energy metabolism. However, characterization of GPR81 expression and investigation of related signaling in human skeletal muscle under conditions of elevated circulating lactate levels are lacking. Muscle biopsies were obtained from healthy men and women at rest, after leg extension exercise, with or without venous infusion of sodium lactate, and 90 and 180 min after exercise (8 men and 8 women). Analyses included protein and mRNA levels of GPR81, as well as GPR81-dependent signaling molecules. GPR81 expression was 2.5-fold higher in type II glycolytic compared with type I oxidative muscle fibers, and the expression was inversely related to the percentage of type I muscle fibers. Muscle from women expressed about 25% more GPR81 protein than from men. Global PKA-activity increased by 5-8% after exercise, with no differences between trials. CREBS133 phosphorylation was reduced by 30% after exercise and remained repressed during the entire trials, with no influence of the lactate infusion. The mRNA expression of VEGF and PGC-1α were increased by 2.5 - 6-fold during recovery, and that of LDH reduced by 15% with no differences between trials for any gene at any time point. The high expression of GPR81-protein in type II fibers suggests that lactate functions as an autocrine signaling molecule in muscle; however, lactate does not appear to regulate CREB signaling during exercise.

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  • 43. Rundqvist, Håkan C
    et al.
    Esbjörnsson, Mona
    Rooyackers, Olav
    Apro, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Österlund, Ted
    Jansson, Eva
    Amino Acid Transport after Sprint Exercise and Oral Amino Acids: 90 Board #6 June 1, 92016In: Medicine & Science in Sports & Exercise: Volume 48(5S) Supplement 1, May 2016, p 5, 2016, Vol. 48, no 5 Suppl 1, p. 5-Conference paper (Other academic)
    Abstract [en]

    PURPOSE: To study if oral ingestion of essential amino acids (oral EAA) increases the amino acid transporter SNAT2, Akt/mTOR signaling and muscle protein synthesis (MPS) after sprint exercise.

    METHODS: 12 healthy subjects performed three 30-s sprints with 20 minutes rest in between. Subjects consumed EAA + maltodextrin solution or flavoured water (placebo) during the sprint exercise up to 15 min after the last sprint in a randomized order with one month interval. In vivo MPS rate was measured using a stable isotope technique. Subject received a stable isotope of phenylalanine (D5-phenylalanine) to label the precursor pool for protein synthesis. Continuous infusion started before the first sprint and was ended 200 min after the last sprint. Two post exercise biopsies (vastus lateralis) were obtained 80 min and 200 min after last sprint. The amount of labelled phenylalanine incorporated into muscle protein over these 2 hours represents the in vivo MPS rate and was expressed as fractional synthesis rate (FSR %) calculated by dividing amount of labelled phenylalanine incorporated during these 2 hours by the amount in the free amino acid (precursor) plasma pool. Biopsies were also analyzed for Akt/mTOR signaling and SNAT2 amino acid transporter by Western blot and for SNAT2 gene expression by real-time PCR. Blood samples were analyzed for amino acids, glucose, lactate, and insulin. Four subjects, involuntary vomiting after exercise during EAA condition, showed a minor increase in plasma leucine and were presented separately.

    RESULTS: Non-vomiting subjects (n=8): The expression of the amino acid transporter SNAT2 was higher both at the protein (P<0.05) and the mRNA (P<0.001) level after EEA than after placebo. Fold increase for phosphorylated Akt, mTOR and p70 was 1.7-3.6 (P<0.01 - P<0.001) comparing EAA with placebo. FSR % after EEA was increased by 25 % (P=0.02) compared to placebo. None of these variables were significantly increased in the subjects who vomited.

    CONCLUSION: Oral EAA increased MPS after sprint exercise. Enhanced capacity for amino acid transport and subsequent enhanced Akt/mTOR signaling are suggested to mediate the increased MPS.

  • 44.
    Samuelsson, Hedvig
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Apró, William
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Eva Blomstrand's research group.
    Intake of branched-chain or essential amino acids attenuates the elevation in muscle levels of PGC-1α4 mRNA caused by resistance exercise.2016In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 311, no 1, p. E246-E251Article in journal (Refereed)
    Abstract [en]

    The transcriptional co-activator PGC-1α is recognized as the master regulator of mitochondrial biogenesis. However, recently a novel isoform, PGC-1α4 that specifically regulates muscle hypertrophy was discovered. Since stimulation of mTORC1 activity is tightly coupled to hypertrophy, we hypothesized that activation of this pathway would upregulate PGC-1α4. Eight male subjects performed heavy resistance exercise (10 x 8-12 repetitions at ~75% of 1RM in leg press) on four different occasions, ingesting in random order a solution containing essential amino acids (EAA), branched-chain amino acids (BCAA), leucine or flavored water (placebo) during and after the exercise. Biopsies were taken from the vastus lateralis muscle before and immediately after exercise, as well as following 90 and 180 min of recovery. Signaling through mTORC1, as reflected in S6K1 phosphorylation, was stimulated to a greater extent by the EAA and BCAA than the leucine or placebo supplements. Unexpectedly, intake of EAA or BCAA attenuated the stimulatory effect of exercise on PGC-1α4 expression by ~50% (from a 10-fold to 5-fold increase with BCAA and EAA, P<0.05) 3 h after exercise, whereas intake of leucine alone did not reduce this response. The 60% increase (P<0.05) in the level of PGC-1α1 mRNA 90 min after exercise was uninfluenced by amino acid intake. Muscle glycogen levels were reduced and AMPKα2 activity and phosphorylation of p38 MAPK enhanced to the same extent with all four supplements. In conclusion, induction of PGC-1α4 does not appear to regulate the nutritional (BCAA or EAA) mediated activation of mTORC1 in human muscle.

  • 45.
    Tarassova, Olga
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Ekblom, Maria
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Karolinska institutet, Stockholm, Sweden.
    Moberg, Marcus
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Lövdén, Martin
    Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden..
    Nilsson, Jonna
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. Aging Research Center, Karolinska Institutet and Stockholm University, Stockholm, Sweden..
    Peripheral BDNF Response to Physical and Cognitive Exercise and Its Association With Cardiorespiratory Fitness in Healthy Older Adults.2020In: Frontiers in Physiology, E-ISSN 1664-042X, Vol. 11, article id 1080Article in journal (Refereed)
    Abstract [en]

    Physical exercise (PE) has been shown to improve brain function via multiple neurobiological mechanisms promoting neuroplasticity. Cognitive exercise (CE) combined with PE may show an even greater effect on cognitive function. Brain-derived neurotrophic factor (BDNF) is important for neuroplastic signaling, may reduce with increasing age, and is confounded by fitness. The source and physiological role of human peripheral blood BDNF in plasma (pBDNF) is thought to differ from that in serum (sBDNF), and it is not yet known how pBDNF and sBDNF respond to PE and CE. A training intervention study in healthy older adults investigated the effects of acute (35 min) and prolonged (12 weeks, 30 sessions) CE and PE, both alone and in combination, on pBDNF and sBDNF. Cross-sectional associations between baseline pBDNF, sBDNF and cardiorespiratory fitness (CRF) were also investigated. Participants (65-75 years) were randomly assigned to four groups and prescribed either CE plus 35 min of rest (n = 21, 52% female); PE [performed on a cycle ergometer at moderate intensity (65-75% of individual maximal heart rate)] plus 35 min of rest (n = 27, 56% female); CE plus PE (n = 24, 46% female), or PE plus CE (n = 25, 52% female). Groups were tested for CRF using a maximal treadmill ergometer test (VO2peak); BDNF levels (collected 48 h after CRF) during baseline, after first exercise (PE or CE) and after second exercise (PE, CE or rest); and cognitive ability pre and post 12-week training. At both pre and post, pBDNF increased after CE and PE (up to 222%), and rest (∼67%), whereas sBDNF increased only after PE (up to 18%) and returned to baseline after rest. Acute but not prolonged PE increased both pBDNF and sBDNF. CE induced acute changes in pBDNF only. Baseline pBDNF was positively associated with baseline sBDNF (n = 93, r = 0.407, p < 0.001). No changes in CRF were found in any of the groups. Baseline CRF did not correlate with baseline BDNF. Even though baseline pBDNF and sBDNF were associated, patterns of changes in pBDNF and sBDNF in response to exercise were explicitly different. Further experimental scrutiny is needed to clarify the biological mechanisms of these results.

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