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  • 1.
    Petré, Henrik
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, The Laboratory of Applied Sports Science (LTIV).
    Löfving, Pontus
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, The Laboratory of Applied Sports Science (LTIV).
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    The Effect of Two Different Concurrent Training Programs on Strength and Power Gains in Highly-Trained Individuals.2018In: Journal of Sports Science and Medicine (JSSM), ISSN 1303-2968, Vol. 17, no 2, p. 167-173Article in journal (Refereed)
    Abstract [en]

    The effects of concurrent strength and endurance training have been well studied in untrained and moderately-trained individuals. However, studies examining these effects in individuals with a long history of resistance training (RT) are lacking. Additionally, few studies have examined how strength and power are affected when different types of endurance training are added to an RT protocol. The purpose of the present study was to compare the effects of concurrent training incorporating either low-volume, high-intensity interval training (HIIT, 8-24 Tabata intervals at ~150% of VO2max) or high-volume, medium-intensity continuous endurance training (CT, 40-80 min at 70% of VO2max), on the strength and power of highly-trained individuals. Sixteen highly-trained ice-hockey and rugby players were divided into two groups that underwent either CT (n = 8) or HIIT (n = 8) in parallel with RT (2-6 sets of heavy parallel squats, > 80% of 1RM) during a 6-week period (3 sessions/wk). Parallel squat performance improved after both RT + CT and RT + HIIT (12 ± 8% and 14 ± 10% respectively, p < 0.01), with no difference between the groups. However, aerobic power (VO2max) only improved after RT + HIIT (4 ± 3%, p < 0.01). We conclude that strength gains can be obtained after both RT + CT and RT + HIIT in athletes with a prior history of RT. This indicates that the volume and/or intensity of the endurance training does not influence the magnitude of strength improvements during short periods of concurrent training, at least for highly-trained individuals when the endurance training is performed after RT. However, since VO2max improved only after RT + HIIT and this is a time efficient protocol, we recommend this type of concurrent endurance training.

  • 2.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll. Karolinska institutet, Inst för fysiologi och farmakologi / Dept of Physiology and Pharmacology .
    The effect of different exercise regimens on mitochondrial biogenesis and performance2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Endurance training is a powerful tool to improve both health and performance. Physical activity is now recognized as an effective treatment and prevention therapy for a wide range of diseases. One of the most profound adaptations to endurance training is increased mitochondrial function and content within the exercising muscles. Mitochondrial quality and quantity are closely related to several of the positive health effects reported after training. High mitochondrial content strongly correlates with muscle oxidative capacity and endurance performance. Even though it is well known that endurance training increases mitochondrial content, it is unclear which type of training is the most efficient to promote mitochondrial biogenesis. Therefore, the basis for current exercise recommendations relative to mitochondrial biogenesis is poor or absent. Thus, the main objective of this thesis was to evaluate the effect of different training strategies on mitochondrial biogenesis.

    Recent developments in molecular methods have made it possible to study the initial adaptations to training through measurement of mRNA gene expression of exercise induced genes. One such gene is transcriptional coactivator peroxisome proliferator–activated receptor-γ coactivator-1α (PGC-1α). PGC-1α is a key regulator of mitochondrial biogenesis and the expression of PGC-1α can therefore be used as a marker of this process.

    The first four studies presented in this thesis are acute exercise studies where two different exercise models were compared using a cross-over design. Muscle biopsies were obtained pre and post exercise and analysed for gene expression and glycogen, apart from study II. The final study was a long-term training study where muscle biopsies were obtained before and after the training period and analysed for mitochondrial enzyme activities and protein content.

    Study I: The expression of PGC-1α and related genes were examined after 90 min of continuous and interval exercise in untrained subjects. The exercise protocols influenced the expression of genes involved in mitochondrial biogenesis and oxidative metabolism in a similar manner. Both interval and continuous exercise were potent training strategies for relatively sedentary individuals.

    Study II: The expression of PGC-1α and related genes were examined after low-volume sprint interval (SIT) and high-volume interval (IE) exercise in highly trained cyclists. SIT induced a similar increase in PGC-1α expression as IE despite a much lower time commitment and work completed. Sprint interval exercise might, therefore, be a time efficient training strategy for highly trained individuals.

    Study III: The expression of PGC-1α and related genes, as well as the activity of upstream proteins, were examined after concurrent (ER: cycling + leg press) and single-mode (E: cycling only) exercise in untrained subjects. PGC-1α expression doubled after ER compared with E. It was concluded that concurrent training might be beneficial for mitochondrial biogenesis in untrained individuals.

    Study IV: The expression of PGC-1α and related genes were examined after exercise performed with low (LG) and normal (NG) muscle glycogen in well-trained cyclists. PGC-1α expression increased approximately three times more after LG compared with NG. This finding suggested that low glycogen exercise is a potent inducer of mitochondrial biogenesis in well-trained individuals.

    Study V: Mitochondrial enzyme activity, protein content and endurance performance were examined after eight weeks of concurrent (ES: cycling + leg press) or single-mode (E: cycling only) training in cyclists. ES did not affect enzyme activity, protein content or endurance performance differently than E. The beneficial effect previously observed in untrained subjects did not translate to higher numbers of mitochondria in trained individuals.

    In three of the studies, I, III, and IV, both glycogen and PGC-1α expression were measured after exercise. These data were then pooled and examined. The highest PGC-1α mRNA expression levels were identified when glycogen levels were low, and vice versa. This suggests that low glycogen might play an important role in the regulation of mitochondrial biogenesis also during interval and concurrent strength and endurance exercise.

    In conclusion, key markers of mitochondrial biogenesis can be effectively up-regulated by interval, concurrent and low glycogen exercise. A possible explanation for this might be that though the exercise protocols are quite divergent in nature, they all have a pronounced effect on muscle glycogen and/or perturbation in energetic stress.

  • 3.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Derakhti, Mikael
    Swedish School of Sport and Health Sciences, GIH.
    Åkerlund, John
    Swedish School of Sport and Health Sciences, GIH.
    Sunding, Kerstin
    Capio Atro Clinic, Sophiahemmet, Stockholm, Sweden.
    The cross-education effect in men and woman after unilateral strength training and detraining2016Conference paper (Refereed)
    Abstract [en]

    Introduction

    It is well known that muscle strength increases in both the untrained and trained limb after a period of unilateral strength training. However, it is not known how this so called cross-education effect (CE-effect) is affected by a long period of detraining, and if there are any sex differences. Also, there are conflicting results regarding the effect of unilateral training on muscle mass in the untrained limb.

    Aim

    The primary objective was to study the CE-effect in men and women after a period of unilateral strength training and detraining. The secondary objective was to study if training one limb would affect the muscle mass of the homologous opposite limb.

    Method

    Sixteen untrained individuals, 9 females and 7 males, completed the study. The training intervention was 10 weeks (34 sessions) of unilateral strength training (leg press (LP) and leg extension (LE) exercise). 1RM and muscle thickness (vastus lateralis) were measured pre-, post- and 20 weeks post-training.

    Results

    Strength (1RM) in the trained leg increased for both men and woman (LP: ~60%, LE ~20%, p<0.01), with no sex differences. However, only the men had a strength increase in the untrained leg (LP: 26%, LE: 10%, p<0.05) and the non-significant increase observed for the woman (LP: 10%, LE: 3%) was significantly smaller than the increase in the men (p<0.05). Muscle thickness increased similarly for both men and women (trained leg: ~14%, p<0.01; untrained leg: ~4%, p<0.05). The detraining period did not affect strength, but muscle thickness was reduced close to pre-training values in both men and women.

    Conclusion

    The results of the present study show that the CE-effect is larger in men than women, and that it is long lasting (at least 20 weeks). Further, strength training of one leg can increase the muscle mass of the homologous opposite leg.

  • 4.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Frank, Per
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Flockhart, Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Adding strength to endurance training does not enhance aerobic capacity in cyclists2015In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, no 4, p. e353-e359Article in journal (Refereed)
    Abstract [en]

    The molecular signaling of mitochondrial biogenesis is enhanced when resistance exercise is added to a bout of endurance exercise. The purpose of the present study was to examine if this mode of concurrent training translates into increased mitochondrial content and improved endurance performance. Moderately trained cyclists performed 8 weeks (two sessions per week) of endurance training only (E, n = 10; 60-min cycling) or endurance training followed by strength training (ES, n = 9; 60-min cycling + leg press). Muscle biopsies were obtained before and after the training period and analyzed for enzyme activities and protein content. Only the ES group increased in leg strength (+19%, P < 0.01), sprint peak power (+5%, P < 0.05), and short-term endurance (+9%, P < 0.01). In contrast, only the E group increased in muscle citrate synthase activity (+11%, P = 0.06), lactate threshold intensity (+3%, P < 0.05), and long-term endurance performance (+4%, P < 0.05). Content of mitochondrial proteins and cycling economy was not affected by training. Contrary to our hypothesis, the results demonstrate that concurrent training does not enhance muscle aerobic capacity and endurance performance in cyclists.

  • 5.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Frank, Per
    Flockhart, Mikael
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Research group for Mitokondriell funktion och metabolisk kontroll.
    Exercise with low glycogen increases PGC-1α gene expression in human skeletal muscle.2013In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 113, no 4, p. 951-963Article in journal (Refereed)
    Abstract [en]

    Recent studies suggest that carbohydrate restriction can improve the training-induced adaptation of muscle oxidative capacity. However, the importance of low muscle glycogen on the molecular signaling of mitochondrial biogenesis remains unclear. Here, we compare the effects of exercise with low (LG) and normal (NG) glycogen on different molecular factors involved in the regulation of mitochondrial biogenesis. Ten highly trained cyclists (VO(2max) 65 ± 1 ml/kg/min, W (max) 387 ± 8 W) exercised for 60 min at approximately 64 % VO(2max) with either low [166 ± 21 mmol/kg dry weight (dw)] or normal (478 ± 33 mmol/kg dw) muscle glycogen levels achieved by prior exercise/diet intervention. Muscle biopsies were taken before, and 3 h after, exercise. The mRNA of peroxisome proliferator-activated receptor-γ coactivator-1 was enhanced to a greater extent when exercise was performed with low compared with normal glycogen levels (8.1-fold vs. 2.5-fold increase). Cytochrome c oxidase subunit I and pyruvate dehydrogenase kinase isozyme 4 mRNA were increased after LG (1.3- and 114-fold increase, respectively), but not after NG. Phosphorylation of AMP-activated protein kinase, p38 mitogen-activated protein kinases and acetyl-CoA carboxylase was not changed 3 h post-exercise. Mitochondrial reactive oxygen species production and glutathione oxidative status tended to be reduced 3 h post-exercise. We conclude that exercise with low glycogen levels amplifies the expression of the major genetic marker for mitochondrial biogenesis in highly trained cyclists. The results suggest that low glycogen exercise may be beneficial for improving muscle oxidative capacity.

  • 6.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Kristoffer, Toldnes Cumming
    NIH, Norwegian School of Sport and Health Sciences, Oslo, Norway.
    Engström, Björn
    Capio Atro Clinic, Sophiahemmet, Stockholm, Sweden.
    Ekblom, Björn
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences.
    Raastad, Truls
    2NIH, Norwegian School of Sport and Health Sciences, Oslo, Norway .
    Retention of myonuclei after grave atrophy in human skeletal muscle, a case study2017In: Acta Physiologica Volume 219, Issue S710 February 2017, 2017, Vol. 219, p. 14-43Conference paper (Refereed)
    Abstract [en]

    Introduction: the current textbook model suggests that the myonuclear domain size is constant for muscle fibers in both their atrophic and hypertrophic state. However, recent animal studies show that myonuclear content is maintained after atrophy leading to a decreased myonuclear domain size (Gundersen et al. J Physiol. 2008 Jun 1;586(11):2675-81). This remains to be investigated in human skeletal muscle and the aim of the present study was therefore to study the effect of grave atrophy on myonuclear content and domain size in the vastus medialis muscle.

    Materials and Methods: biopsies were obtained from vastus medialis on a 22 year old female patient before and 6 weeks after an anterior cruciate ligament reconstructionand meniscus repair surgery. Histochemical analyses were done to analyze fiber cross sectional area (CSA), fiber type composition and number of myonuclei per fiber.

    Results: the CSA of type II muscle fibers decreased by 35% (from 4297±55 to 2807±64 µm2) whereas the number of myonuclei per fiber remained stable (3.4±0.4 and 3.9±0.5, pre and post respectively). The nuclear domain size was thereby decreased by ~40% (from 1255 to 722 µm2). There were only minor changes in type I muscle fiber CSA, myonuclei content and domain size.

    Conclusion: in line with previous findings from animal studies, the present case study shows that the number of myonuclei per fiber is maintained and the domain size is reduced in human skeletal muscle after immobilization induced atrophy.

  • 7.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.
    Petré, Henrik
    Swedish School of Sport and Health Sciences, GIH.
    Löfving, Pontus
    Swedish School of Sport and Health Sciences, GIH.
    Överdriven oro för kombinationsträning2015In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, no 1, p. 8-13Article in journal (Other academic)
    Abstract [sv]

    Många som vill öka sin muskelmassa och styrka undviker uthållighetsträning. En vanlig åsikt är nämligen att man inte bör kombinera styrke ochuthållighetsträning. Den uppfattningen har däremot inget stöd i den senaste forskningen.

  • 8.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Nya forskningsrön kan ge bättre träningsmetoder2013In: Svensk Idrottsforskning: Organ för Centrum för Idrottsforskning, ISSN 1103-4629, Vol. 22, no 1, p. 41-44Article in journal (Other academic)
    Abstract [sv]

    Det finns många uppfattningar om hur man bäst förbättrar konditionen. Ofta förlitar idrottare sig mer på beprövad erfarenhet än på vetenskapen. Men under de senaste åren har idrottsforskningen, med hjälp av molekylärbiologisk teknik, gjort framsteg i hur man kan effektivisera sin träning genom kosten och sättet att träna.

  • 9.
    Psilander, Niklas
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Wang, Li
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Westergren, Jens
    Tonkonogi, Michail
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Mitochondrial gene expression in elite cyclists: effects of high-intensity interval exercise.2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 110, no 3, p. 597-606Article in journal (Refereed)
    Abstract [en]

    Little is known about the effect of training on genetic markers for mitochondrial biogenesis in elite athletes. We tested the hypothesis that low-volume sprint interval exercise (SIE) would be as effective as high-volume interval exercise (IE). Ten male cyclists competing on national elite level (W (max) 403 ± 13 W, VO(2peak) 68 ± 1 mL kg(-1) min(-1)) performed two interval exercise protocols: 7 × 30-s "all-out" bouts (SIE) and 3 × 20-min bouts at ~87% of VO(2peak) (IE). During IE, the work was eightfold larger (1,095 ± 43 vs. 135 ± 5 kJ) and the exercise duration 17 times longer (60 vs. 3.5 min) than during SIE. Muscle samples were taken before and 3 h after exercise. The mRNA of upstream markers of mitochondrial biogenesis [peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1α), PGC-1α-related coactivator (PRC) and peroxisome proliferator-activated receptor δ (PPARδ)] increased to the same extent after SIE and IE (6-, 1.5- and 1.5-fold increase, respectively). Of the downstream targets of PGC-1α, mitochondrial transcription factor A (Tfam) increased only after SIE and was significantly different from that after IE (P < 0.05), whereas others increased to the same extent (pyruvate dehydrogenase kinase, PDK4) or was unchanged (nuclear respiratory factor 2, NRF2). We conclude that upstream genetic markers of mitochondrial biogenesis increase in a similar way in elite athletes after one exercise session of SIE and IE. However, since the volume and duration of work was considerably lower during SIE and since Tfam, the downstream target of PGC-1α, increased only after SIE, we conclude that SIE might be a time-efficient training strategy for highly trained individuals.

  • 10. Wang, Li
    et al.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Blomstrand, Eva
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Eva Blomstrand's research group.
    Mascher, Henrik
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Resistance exercise enhances the molecular signaling of mitochondrial biogenesis induced by endurance exercise in human skeletal muscle.2011In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 111, no 5, p. 1335-1344Article in journal (Refereed)
    Abstract [en]

    Combining endurance and strength training (concurrent training) may change the adaptation compared with single mode training. However, the site of interaction and the mechanisms are unclear. We have investigated the hypothesis that molecular signaling of mitochondrial biogenesis after endurance exercise is impaired by resistance exercise. Ten healthy subjects performed either only endurance exercise (E: 1h cycling at ~65% of VO(2max)) or endurance exercise followed by resistance exercise (ER: 1h cycling + 6 sets of leg press at 70-80% of 1 repetition maximum) in a randomized cross-over design. Muscle biopsies were obtained before and after exercise (1 and 3h Post cycling). The mRNA of genes related to mitochondrial biogenesis (PGC-1α, PRC) and substrate regulation (PDK4) increased after both E and ER, but the mRNA levels were about 2-fold higher after ER (P<0.01). Phosphorylation of proteins involved in the signaling cascade of protein synthesis (mTOR, S6K1 and eEF2) was altered after ER but not after E. Moreover, ER induced a larger increase in mRNA of genes associated with positive mTOR signaling (cMyc and Rheb). Phosphorylation of AMPK, ACC and Akt increased similarly at 1h Post (P<0.01) after both types of exercise. Contrary to our hypothesis, the results demonstrate that resistance exercise, performed after endurance exercise, amplifies the adaptive signaling response of mitochondrial biogenesis compared with single-mode endurance exercise. The mechanism may relate to a crosstalk between signaling pathways mediated by mTOR. The results suggest that concurrent training may be beneficial for the adaptation of muscle oxidative capacity.

  • 11.
    Wang, Li
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Psilander, Niklas
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Tonkonogi, Michail
    Ding, Shuzhe
    Sahlin, Kent
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Research group for Mitokondriell funktion och metabolisk kontroll.
    Similar expression of oxidative genes after interval and continuous exercise.2009In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 41, no 12, p. 2136-44Article in journal (Refereed)
    Abstract [en]

    PURPOSE: There is a debate whether interval or traditional endurance training is the most effective stimulus of mitochondrial biogenesis. Here, we compared the effects of acute interval exercise (IE) or continuous exercise (CE) on the muscle messenger RNA (mRNA) content for several genes involved in mitochondrial biogenesis and lipid metabolism. METHODS: Nine sedentary subjects cycled for 90 min with two protocols: CE (at 67% VO2max) and IE (12 s at 120% and 18 s at 20% of VO2max). The duration of exercise and work performed with CE and IE was identical. Muscle biopsies were taken before and 3 h after exercise. RESULTS: There were no significant differences between the two exercise protocols in the increases in VO2 and HR, the reduction in muscle glycogen (35%-40% with both protocols) or the changes in blood metabolites (lactate, glucose, and fatty acids). The mRNA content for major regulators of mitochondrial biogenesis [peroxisome proliferator-activated receptor (PPAR) gamma coactivator 1alpha (PGC-1alpha), PGC-1-related coactivator, PPARbeta/delta] and of lipid metabolism [pyruvate dehydrogenase kinase isozyme 4 (PDK4)] increased after exercise, but there was no significant difference between IE and CE. However, the mRNA content for several downstream targets of PGC-1alpha increased significantly only after CE, and mRNA content for nuclear respiratory factor 2 was significantly higher after CE (P < 0.025 vs IE). CONCLUSIONS: The present findings demonstrate that, when the duration of exercise and work performed is the same, IE and CE influence the transcription of genes involved in oxidative metabolism in a similar manner.

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