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Ekblom Bak, E., Ekblom, Ö., Andersson, G., Wallin, P., Söderling, J., Hemmingsson, E. & Ekblom, B. (2019). Decline in cardiorespiratory fitness in the Swedish working force between 1995 and 2017.. Scandinavian Journal of Medicine and Science in Sports, 29(2), 232-239
Open this publication in new window or tab >>Decline in cardiorespiratory fitness in the Swedish working force between 1995 and 2017.
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2019 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 29, no 2, p. 232-239Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Long-term trend analyses of cardiorespiratory fitness (VO2 max) in the general population are limited.

OBJECTIVES: To describe trends in VO2 max from 1995 to 2017 in the Swedish working force and to study developments across categories of sex, age, education, and geographic regions.

METHODS: 354.277 participants (44% women, 18-74 years) who participated in a nationwide occupational health service screening between 1995 and 2017 were included. Changes in standardized mean values of absolute (L·min-1 ) and relative (ml·min-1 ·kg-1 ) VO2 max, and the proportion with low (<32) relative VO2 max are reported. VO2 max was estimated using a submaximal cycle test.

RESULTS: Absolute VO2 max decreased by -6.7% (-0.19 L·min-1 ) in the total population. Relative VO2 max decreased by -10.8% (-4.2 ml·min-1 ·kg-1 ) with approximately one-third explained by a simultaneous increase in body mass. Decreases in absolute fitness were more pronounced in men vs. women (8.7% vs. 5.3%), in younger vs. older (6.5% vs 2.3%), in short (11.4%) vs. long (4.5%) education, and in rural vs. urban regions (6.5% vs 3.5%), all p<0.001. The proportions with low VO2 max increased from 27% to 46% (p<0.001).

CONCLUSION: Between 1995 and 2017, there was a steady and pronounced decline in mean cardiorespiratory fitness in Swedish adults. Male gender, young age, short education and living in a rural area were predictive of greater reductions. The proportion with low cardiorespiratory fitness almost doubled. Given the strong associations between cardiorespiratory fitness and multiple morbidities and mortality, preventing further decreases is a clear public health priority, especially for vulnerable groups. This article is protected by copyright. All rights reserved.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
Maximal oxygen consumption, VO2max, aerobic capacity, population, secular trend
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5460 (URN)10.1111/sms.13328 (DOI)30351472 (PubMedID)
Projects
HPI-gruppen
Available from: 2018-10-31 Created: 2018-10-31 Last updated: 2019-01-18Bibliographically approved
Cardinale, D. A., Larsen, F. J., Jensen-Urstad, M., Rullman, E., Søndergaard, H., Morales-Alamo, D., . . . Boushel, R. (2019). Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: role of mitochondrial oxygen affinity.. Acta Physiologica, 225(1), Article ID e13110.
Open this publication in new window or tab >>Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: role of mitochondrial oxygen affinity.
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2019 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 225, no 1, article id e13110Article in journal (Refereed) Published
Abstract [en]

AIM:We examined the Fick components together with mitochondrial O2 affinity (p50mito ) in defining O2 extraction and O2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER).

METHODS:Seven individuals performed two incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and two on a one-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibers and muscle mass measured with magnetic resonance imaging in relation to peak leg O2 delivery.

RESULTS:The ex vivo p50mito increased from 0.06±0.02 to 0.17±0.04 kPa with varying substrate supply and O2 flux rates from 9.84±2.91 to 16.34±4.07 pmol O2 ·s-1 ·μg-1 respectively. O2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O2 delivery, and lower mitochondrial excess capacity. There was a significant relationship between O2 extraction and mitochondrial excess capacity and p50mito that was unrelated to blood flow and mean transit time.

CONCLUSION:O2 extraction varies with mitochondrial respiration rate, p50mito and O2 delivery. Mitochondrial excess capacity maintains a low p50mito which enhances O2 diffusion from microvessels to mitochondria during exercise. This article is protected by copyright. All rights reserved.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
Keywords
OXPHOS, VO2max, Fick method, hyperoxia, mitochondrial p50, muscle O2 diffusion, thermodilution technique
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5287 (URN)10.1111/apha.13110 (DOI)000454605500006 ()29863764 (PubMedID)
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2019-01-18Bibliographically approved
Ivarsson, N., Mattsson, C. M., Cheng, A. J., Bruton, J. D., Ekblom, B., Lanner, J. T. & Westerblad, H. (2019). SR Ca2+ leak in skeletal muscle fibers acts as an intracellular signal to increase fatigue resistance.. The Journal of General Physiology, Article ID jgp.201812152.
Open this publication in new window or tab >>SR Ca2+ leak in skeletal muscle fibers acts as an intracellular signal to increase fatigue resistance.
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2019 (English)In: The Journal of General Physiology, ISSN 0022-1295, E-ISSN 1540-7748, article id jgp.201812152Article in journal (Refereed) Epub ahead of print
Abstract [en]

Effective practices to improve skeletal muscle fatigue resistance are crucial for athletes as well as patients with dysfunctional muscles. To this end, it is important to identify the cellular signaling pathway that triggers mitochondrial biogenesis and thereby increases oxidative capacity and fatigue resistance in skeletal muscle fibers. Here, we test the hypothesis that the stress induced in skeletal muscle fibers by endurance exercise causes a reduction in the association of FK506-binding protein 12 (FKBP12) with ryanodine receptor 1 (RYR1). This will result in a mild Ca2+ leak from the sarcoplasmic reticulum (SR), which could trigger mitochondrial biogenesis and improved fatigue resistance. After giving mice access to an in-cage running wheel for three weeks, we observed decreased FKBP12 association to RYR1, increased baseline [Ca2+]i, and signaling associated with greater mitochondrial biogenesis in muscle, including PGC1α1. After six weeks of voluntary running, FKBP12 association is normalized, baseline [Ca2+]i returned to values below that of nonrunning controls, and signaling for increased mitochondrial biogenesis was no longer present. The adaptations toward improved endurance exercise performance that were observed with training could be mimicked by pharmacological agents that destabilize RYR1 and thereby induce a modest Ca2+ leak. We conclude that a mild RYR1 SR Ca2+ leak is a key trigger for the signaling pathway that increases muscle fatigue resistance.

Place, publisher, year, edition, pages
Rockefeller University Press, 2019
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5547 (URN)10.1085/jgp.201812152 (DOI)30635368 (PubMedID)
Available from: 2019-01-16 Created: 2019-01-16 Last updated: 2019-01-16Bibliographically approved
Cardinale, D. A. & Ekblom, B. (2018). Hyperoxia for performance and training.. Journal of Sports Sciences (13), 1515-1522
Open this publication in new window or tab >>Hyperoxia for performance and training.
2018 (English)In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, no 13, p. 1515-1522Article in journal (Refereed) Published
Abstract [en]

Recent technological developments have made it possible to use hyperoxia as an enhancement aid during training. Athletes wearing a mask can breathe a higher fraction of oxygen from a stationary or portable apparatus while exercising. A large body of evidence indicates that the oxygen transport capacity, lactate metabolism, power output and work tolerance (endurance) are improved when breathing hyperoxia. The physiological mechanisms underlying these performance improvements, although still not fully elucidated, are based on higher oxygen delivery and reduced central fatigue. Although much is known about the acute effects of hyperoxia, the effect of hyperoxic-supplemented endurance training on performance and the mechanisms beneath training adaptations are not very well understood, especially in well-trained endurance athletes. The few studies on the physiological effects of hyperoxia training have been conducted with conflicting results, discussed in this paper. Potential detrimental effects have not yet been shown experimentally and warrant further investigation.

Keywords
Hyperoxia, endurance training, oxygen transport
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5068 (URN)10.1080/02640414.2017.1398893 (DOI)000428863700013 ()29115912 (PubMedID)
Available from: 2017-11-16 Created: 2017-11-16 Last updated: 2018-05-25Bibliographically approved
Ekblom Bak, E., Ekblom, Ö., Andersson, G., Wallin, P. & Ekblom, B. (2018). Physical Education and Leisure-Time Physical Activity in Youth Are Both Important for Adulthood Activity, Physical Performance, and Health.. Journal of Physical Activity and Health, 15(9), 661-670
Open this publication in new window or tab >>Physical Education and Leisure-Time Physical Activity in Youth Are Both Important for Adulthood Activity, Physical Performance, and Health.
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2018 (English)In: Journal of Physical Activity and Health, ISSN 1543-3080, E-ISSN 1543-5474, Vol. 15, no 9, p. 661-670Article in journal (Refereed) Published
Abstract [en]

Background: The importance of youth physical activity (PA) for adulthood PA, performance, and health was retrospectively evaluated. Methods: A total of 258,146 participants (49% women), aged 19–70, with a first-time health-profile assessment between 1982 and 2015, provided self-reported data on current perceived health, PA, lifestyle, and physical education class participation, and PA outside school hours before age 20. Data on anthropometrics, blood pressure, and estimated maximal oxygen consumption (VO2max) were obtained. Results: Women participating in physical education class, compared with those who did not, had significantly lower OR (range: 0.81–0.87) for perceiving poor overall health, general obesity, and high diastolic blood pressure after adjustment for potential confounders, and increased OR (range: 1.17–1.23) for exercising regularly and a normal/high VO2max in adulthood. For men, the ORs were significantly lower (range: 0.66–0.86) for poor perceived overall health, general, and abdominal obesity. These associations were seen for participants up to 70 years. Increased PA outside school hours revealed even stronger beneficial associations. In joint analyses, both youth and current PA were important for lower OR of poor health and being obese in adulthood. Conclusions: Physical education class participation and additional PA after school hours were both important for perceived health, PA, VO2max, and metabolic health in adulthood up to 70 years.

Keywords
VO2max, adolescent, epidemiology, physical fitness, public health
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5253 (URN)10.1123/jpah.2017-0083 (DOI)000441442900004 ()29706117 (PubMedID)
Projects
HPI-gruppen
Available from: 2018-05-15 Created: 2018-05-15 Last updated: 2018-09-04Bibliographically approved
Cardinale, D. A., Larsen, F. J., Schiffer, T. A., Morales-Alamo, D., Ekblom, B., Calbet, J. A., . . . Boushel, R. (2018). Superior Intrinsic Mitochondrial Respiration in Women Than in Men.. Frontiers in Physiology, 9, Article ID 1133.
Open this publication in new window or tab >>Superior Intrinsic Mitochondrial Respiration in Women Than in Men.
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2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, article id 1133Article in journal (Refereed) Published
Abstract [en]

Sexual dimorphism is apparent in humans, however, to date no studies have investigated mitochondrial function focusing on intrinsic mitochondrial respiration (i.e., mitochondrial respiration for a given amount of mitochondrial protein) and mitochondrial oxygen affinity (p50mito) in relation to biological sex in human. A skeletal muscle biopsy was donated by nine active women, and ten men matched for maximal oxygen consumption (VO2max) and by nine endurance trained men. Intrinsic mitochondrial respiration, assessed in isolated mitochondria, was higher in women compared to men when activating complex I (CIP) and complex I+II (CI+IIP) (p < 0.05), and was similar to trained men (CIP, p = 0.053; CI+IIP, p = 0.066). Proton leak and p50mito were higher in women compared to men independent of VO2max. In conclusion, significant novel differences in mitochondrial oxidative function, intrinsic mitochondrial respiration and p50mito exist between women and men. These findings may represent an adaptation in the oxygen cascade in women to optimize muscle oxygen uptake to compensate for a lower oxygen delivery during exercise.

Keywords
OXPHOS, endurance performance, mitochondria, mitochondrial function, sexual dimorphism, skeletal muscle
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5407 (URN)10.3389/fphys.2018.01133 (DOI)000441955000001 ()30174617 (PubMedID)
Available from: 2018-09-04 Created: 2018-09-04 Last updated: 2018-10-17Bibliographically approved
Psilander, N., Kristoffer, T. C., Engström, B., Ekblom, B. & Raastad, T. (2017). Retention of myonuclei after grave atrophy in human skeletal muscle, a case study. In: Acta Physiologica Volume 219, Issue S710 February 2017: . Paper presented at Annual Meeting of the Scandinavian Physiological Society, Oslo, August 26th – 28th, 2016. (pp. 14-43). , 219
Open this publication in new window or tab >>Retention of myonuclei after grave atrophy in human skeletal muscle, a case study
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2017 (English)In: Acta Physiologica Volume 219, Issue S710 February 2017, 2017, Vol. 219, p. 14-43Conference paper, Oral presentation with published abstract (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.

Keywords
Myonuclei, atrophy, human, skeletal muscle
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4645 (URN)10.1111/apha.12841 (DOI)000393916600057 ()
Conference
Annual Meeting of the Scandinavian Physiological Society, Oslo, August 26th – 28th, 2016.
Funder
Swedish National Centre for Research in Sports
Available from: 2016-11-22 Created: 2016-11-22 Last updated: 2018-01-17Bibliographically approved
Ekblom, B. (2017). The muscle biopsy technique: Historical and methodological considerations.. Scandinavian Journal of Medicine and Science in Sports, 27(5), 458-461
Open this publication in new window or tab >>The muscle biopsy technique: Historical and methodological considerations.
2017 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 27, no 5, p. 458-461Article, review/survey (Refereed) Published
Abstract [en]

The muscle biopsy method is an important tool for clinical and scientific work. In this study, the two most used instruments, the Bergström needle and the Well-Blakesley conchotome, are described. The technique of using those instruments, risks, and other considerations are discussed. Finally, a few consequences and the error of the method for determining muscle fiber type, fiber area, substrates, and metabolites are presented.

Keywords
Bergström needle; Well-Blakesley conchotome; consequences; methodological error
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4700 (URN)10.1111/sms.12808 (DOI)000398783800001 ()28033689 (PubMedID)
Available from: 2017-01-11 Created: 2017-01-11 Last updated: 2018-01-13Bibliographically approved
Godhe, M., Helge, T., Mattsson, C. M. & Ekblom, B. (2016). Att bära tungt - en fysiologisk analys: Kvinnor: Rapport 8..
Open this publication in new window or tab >>Att bära tungt - en fysiologisk analys: Kvinnor: Rapport 8.
2016 (Swedish)Report (Other academic)
Abstract [sv]

Sjutton kvinnliga vältränade försökspersoner, åtta stycken med vana att bära tungt och nio stycken utan sådan vana, genomförde gång på löpband och mjukt underlag i hastigheterna 3 och 5 km/tim med bärvikter i ryggsäck på 20, 35 och 50 kg.Mjukt underlag i form av blå gymnastikmattor, indikerande gång i lätt terräng, ökade energiomsättningen under både hastigheterna mellan 10 och 15 %, jämfört med hårt underlag (löpband) med en grads lutning. Energiomsättningen ökade i genomsnitt lika mycket med ökad hastighet som med ökad bärvikt. Den individuella variationen vid en given bärvikt och hastighet är mycket stor. Beroende på bärvikt och hastighet kan energiomsättningen variera med 100 %. Dessa stora variationer i energiomsättning bör uppmärksammas vid beräkning av energitilldelning via kosten vid längre militära operationer.Energiomsättningen vid tyngsta belastningen – 50 kilo bärvikt och hastigheten 5 km/tim – belastade försökspersonerna på i genomsnitt 57 % av maximal syreupptagningsförmåga. I individuella fall var belastningen 72 % av maximal syreupptagningsförmåga. Dessa höga belastningar är oacceptabelt höga för transporter under längre tid och kan vara en orsak till belastningsskador.Förmågan att bära tungt sammanfaller med ökad kroppsvikt och benmuskelstyrka. Bärförmåga för mindre vikter, högst 35 kg, sammanfaller inte med någon av ovanstående faktorer. Således, för tyngre bärvikter vid förflyttningar bör selektion av soldater ske enligt de uppmätta parametrarna, medan vad gäller lättare vikter föreligger inte samma selektionskriterier.En slutsats från resultaten av denna undersökning är den ursprungliga uttagningen till tunga arbetsuppgifter inom försvaret bör genomföras med tunga arbetsbelastningar, motsvarande de i denna undersökning. I kommande rapport sammanfattas studierna på män och kvinnors bärförmåga, likheter och olikheter mellan könen, möjliga selektionskriterier samt rekommendationer med utgångspunkt från genomförda undersökningar och resultat från olika andra undersökningar.

Publisher
p. 30
Keywords
Energiutgift, tunga arbetsuppgifter, fysiskt stridsvärde, soldater
National Category
Occupational Health and Environmental Health Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4593 (URN)
Projects
Militärmedicinsk forskning
Available from: 2016-09-28 Created: 2016-09-28 Last updated: 2018-01-10Bibliographically approved
Schiffer, T. A., Peleli, M., Sundqvist, M. L., Ekblom, B., Lundberg, J. O., Weitzberg, E. & Larsen, F. J. (2016). Control of Human Energy Expenditure by Cytochrome C Oxidase Subunit IV-2.. American Journal of Physiology - Cell Physiology, 311(3), C452-C461
Open this publication in new window or tab >>Control of Human Energy Expenditure by Cytochrome C Oxidase Subunit IV-2.
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2016 (English)In: American Journal of Physiology - Cell Physiology, ISSN 0363-6143, E-ISSN 1522-1563, Vol. 311, no 3, p. C452-C461Article in journal (Refereed) Published
Abstract [en]

Resting metabolic rate (RMR) in human shows pronounced individual variations, but the underlying molecular mechanism remains elusive. Cytochrome C oxidase (COX) plays a key role in control of metabolic rate and recent studies of the subunit 4 isoform 2 (COX IV-2) indicate involvement in the cellular response to hypoxia and oxidative stress. We evaluated whether the COX subunit IV isoform composition may explain the pronounced individual variations in resting metabolic rate (RMR). RMR was determined in healthy humans by indirect calorimetry and correlated to levels of COX IV-2 and COX IV-1 in Vastus Lateralis. Over expression and knock down of the COX IV isoforms were performed in primary myotubes followed by evaluation of the cell respiration and production of reactive oxygen species. Here we show that COX IV-2 protein is constitutively expressed in human skeletal muscle and strongly correlated to RMR. Primary human myotubes overexpressing COX IV-2 displayed markedly (>60%) lower respiration, reduced (>50%) cellular H2O2 production, higher resistance towards both oxidative stress and severe hypoxia compared to control cells. These results suggest an important role of isoform COX IV-2 in the control of energy expenditure, hypoxic tolerance and mitochondrial ROS homeostasis in humans.

National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4521 (URN)10.1152/ajpcell.00099.2016 (DOI)000384749700010 ()27486093 (PubMedID)
Available from: 2016-08-08 Created: 2016-08-08 Last updated: 2018-01-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4030-5437

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