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Salier Eriksson, J., Ekblom, B., Kallings, L., Hemmingsson, E., Andersson, G., Wallin, P., . . . Ekblom Bak, E. (2020). Active commuting in Swedish workers between 1998 and 2015 - trends, characteristics and cardiovascular disease risk.. Scandinavian Journal of Medicine and Science in Sports, 30(2)
Open this publication in new window or tab >>Active commuting in Swedish workers between 1998 and 2015 - trends, characteristics and cardiovascular disease risk.
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2020 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 30, no 2Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Trend analyses of active commuting and potential variations in trends and association with cardiovascular disease (CVD) risk within sub-groups are unknown.

OBJECTIVES: To a) describe trends in active commuting between 1998 to 2015 and b) to study the association between different amounts of active commuting and the incidence risk of CVD in a large sample of Swedish workers, and analyses of potential variations across sub-groups of socio-demographics, physical activity and BMI.

METHODS: A total of 318,309 participants (47% women, 18-74 years) who participated in a nationwide occupational health service screening between 1998 and 2015 were included. Commuting habits were self-reported, and data on first-time CVD events were derived from national registers.

RESULTS: Self-reported passive commuters decreased between 1998 and 2015 (64% to 56%), transferring to an increase in mainly moderate/high-dose active commuters (12% to 19%). Changes were seen in all subgroups. The characteristics and life-style habits of the typical passive and active commuter changed little over the study period. Low- and moderate/high-dose active commuters had significantly decreased risks for a first time CVD during follow-up. This was accentuated in men, middle-aged and in participants with light physical work situations, irregular exercise habits, being overweight/obese and with low fitness.

CONCLUSION: Increases in active commuting were observed between 1998 and 2015, however still leaving a majority who do not actively commute. As active commuting, regardless dose, is associated with a lower CVD risk, encouraging more people to actively commute may provide an easily accessible and time-efficient possibility to increase physical activity and health in the general population.

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
Keywords
active commuting, cardiovascular disease, cycling, physical activity, trends, walking, working population
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5889 (URN)10.1111/sms.13581 (DOI)000499749900001 ()31631386 (PubMedID)
Projects
HPI-gruppen
Available from: 2019-10-28 Created: 2019-10-28 Last updated: 2020-01-28Bibliographically approved
Moberg, M., Lindholm, M. E., Reitzner, S. M., Ekblom, B., Sundberg, C.-J. & Psilander, N. (2020). Exercise Induces Different Molecular Responses in Trained and Untrained Human Muscle.. Medicine & Science in Sports & Exercise
Open this publication in new window or tab >>Exercise Induces Different Molecular Responses in Trained and Untrained Human Muscle.
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2020 (English)In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315Article in journal (Refereed) Epub ahead of print
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.

Place, publisher, year, edition, pages
Wolters Kluwer, 2020
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-6079 (URN)10.1249/MSS.0000000000002310 (DOI)32079914 (PubMedID)
Available from: 2020-03-16 Created: 2020-03-16 Last updated: 2020-03-16Bibliographically approved
Horwath, O., Apro, W., Moberg, M., Godhe, M., Helge, T., Ekblom, M., . . . Ekblom, B. (2020). Fiber type-specific hypertrophy and increased capillarization in skeletal muscle following testosterone administration of young women.. Journal of applied physiology
Open this publication in new window or tab >>Fiber type-specific hypertrophy and increased capillarization in skeletal muscle following testosterone administration of young women.
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2020 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601Article in journal (Refereed) Epub ahead of print
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.

Place, publisher, year, edition, pages
American Physiological Society, 2020
Keywords
androgens, capillarization, myonuclear domain, myonuclei, satellite cells
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-6096 (URN)10.1152/japplphysiol.00893.2019 (DOI)32191598 (PubMedID)
Available from: 2020-03-24 Created: 2020-03-24 Last updated: 2020-03-26Bibliographically approved
Eftestøl, E., Psilander, N., Cumming, K. T., Juvkam, I., Ekblom, M., Sunding, K., . . . Gundersen, K. (2020). Muscle memory: Are myonuclei ever lost? [Letter to the editor]. Journal of applied physiology, 128, 456-457
Open this publication in new window or tab >>Muscle memory: Are myonuclei ever lost?
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2020 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 128, p. 456-457Article in journal, Letter (Other academic) Published
Place, publisher, year, edition, pages
American Physiological Society, 2020
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5982 (URN)10.1152/japplphysiol.00761.2019 (DOI)31854249 (PubMedID)
Available from: 2020-01-07 Created: 2020-01-07 Last updated: 2020-02-24Bibliographically approved
Godhe, M., Helge, T., Mattsson, C. M., Ekblom, Ö. & Ekblom, B. (2020). Physiological Factors of Importance for Load Carriage in Experienced and Inexperienced Men and Women.. Military medicine, Article ID usaa050.
Open this publication in new window or tab >>Physiological Factors of Importance for Load Carriage in Experienced and Inexperienced Men and Women.
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2020 (English)In: Military medicine, ISSN 0026-4075, E-ISSN 1930-613X, article id usaa050Article in journal (Refereed) Epub ahead of print
Abstract [en]

INTRODUCTION: The ability to carry heavy loads is an important and necessary task during numerous outdoor activities and especially in military operations. The aim of this study was to investigate factors associated with load-carrying ability in men and women with and without extensive load-carrying experience.

MATERIALS AND METHODS: The energy expenditure during carrying no load, 20, 35, and 50 kg at 2 walking speeds, 3 and 5 km h-1, was studied in 36 healthy participants, 19 men (30 ± 6 years, 82.5 ± 7.0 kg) and 17 women (29 ± 6 years, 66.1 ± 8.9 kg), experienced (>5 years) in carrying heavy loads (n = 16, 8 women) or with minor or no such experience (n = 20, 9 women). A standard backpack filled with weights to according carry load was used during the walks. Anthropometric data, leg muscle strength, as well as trunk muscle endurance and muscle fiber distribution of the thigh, were also obtained. Extra Load Index (ELI)-the oxygen uptake (VO2) during total load over unloaded walking-was used as a proxy for load-carrying ability at 20, 35, and 50 kg (ELI20, ELI35, and ELI50, respectively). In addition to analyzing factors of importance for the ELI values, we also conducted mediator analyses using sex and long-term carrying experience as causal variables for ELI as the outcome value. The study was approved by the Regional Ethics Committee in Stockholm, Sweden.

RESULTS: For the lowest load (20 kg), ELI20, was correlated with body mass but no other factors. Walking with 35 and 50 kg load at 5 km h-1 body mass, body height, leg muscle strength, and absolute VO2max were correlated, while relative VO2max, trunk muscle endurance, and leg muscle fiber distribution were not correlated to ELI35 and ELI50.ELI50 at 5 km h-1 differed between the sexes. This difference was only mediated by the difference in body mass. Neither muscle fiber distribution, leg muscle strength, trunk muscle endurance, and body height nor did absolute or relative VO2max explain the difference.Participants with long-term experience of heavy load carrying had significant lower ELI20 and ELI50 values than those with minor or no experience, but none of the above studied factors could explain this difference.

CONCLUSION: The study showed that body mass, without sex differences, and experience of carrying heavy loads are the dominant factors for the ability to carry heavy loads. Even though the effect of experience alludes to the need for extensive carrying training, no causality can be proven. Load carry training intervention studies is suggested for future investigations.

Place, publisher, year, edition, pages
Oxford University Press, 2020
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-6148 (URN)10.1093/milmed/usaa050 (DOI)32248224 (PubMedID)
Available from: 2020-04-08 Created: 2020-04-08 Last updated: 2020-04-08Bibliographically approved
Blom, V., Kallings, L., Ekblom, B., Wallin, P., Andersson, G., Hemmingsson, E., . . . Ekblom Bak, E. (2020). Self-Reported General Health, Overall and Work-Related Stress, Loneliness, and Sleeping Problems in 335,625 Swedish Adults from 2000 to 2016.. International Journal of Environmental Research and Public Health, 17(2), Article ID E511.
Open this publication in new window or tab >>Self-Reported General Health, Overall and Work-Related Stress, Loneliness, and Sleeping Problems in 335,625 Swedish Adults from 2000 to 2016.
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2020 (English)In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 17, no 2, article id E511Article in journal (Refereed) Published
Abstract [en]

The prevalence of poor health, in particular stress-related mental ill-health, is increasing over time and birth cohorts. As rapid societal changes have occurred in the last decade and still are occurring, there is an interest in investigating the trends in health-related factors. The aim of the present study was to investigate trends in self-reported general health, overall stress, work-related stress, feelings of loneliness, and sleeping problems in 335,625 Swedish adults across categories of gender, geographic regions, length of education, and age from 2000 to 2016. On population level, sleeping problems and poor general health have increased markedly and significantly, while experiences of work stress decreased between 2000 and 2016 (p < 0.05). Overall stress and level of loneliness were unchanged (p > 0.05). The risk of having ≥3 symptoms (any of poor or very poor general health, often or very often perceived overall stress, loneliness, or sleeping problems) has increased significantly from 2000 to 2016 (ß = 1034 (1027-1040)). This increase was significantly higher in young (ß = 1052 (1038-1065)) and individuals with lower education (ß = 1056 (1037-1076)) compared to older and high length of education.

Place, publisher, year, edition, pages
MDPI, 2020
Keywords
loneliness, public health, self-reported health, sleeping problems, stress, working population
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-6007 (URN)10.3390/ijerph17020511 (DOI)000516827400132 ()31947519 (PubMedID)
Projects
HPI-gruppen
Available from: 2020-01-28 Created: 2020-01-28 Last updated: 2020-04-08
Nilsson, L., Flockhart, M., Apro, W., Ekblom, B. & Larsen, F. J. (2019). Biphasic relationship between training load and glucose tolerance. In: : . Paper presented at Cell Symposia, Exercise Metabolism. May 5-7 2019, Sitges Spain.
Open this publication in new window or tab >>Biphasic relationship between training load and glucose tolerance
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2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [sv]

Biphasic relationship between training load and glucose tolerance

Nilsson, L, Flockhart M, Bergman K, Apro W, Ekblom B, Larsen FJ

 

There is a well-established construct regarding the positive effects of exercise on glucose tolerance and insulin sensitivity, as well as muscle glycogen storage. In insulin resistance, physical activity is an essential part of the treatment. However, the optimal dose is unknown. Reduced muscular glycogen stores, resulting from exercise, should stimulate an increased uptake of blood glucose. In this study we investigated the relation between training load, glucose tolerance and insulin sensitivity during three weeks of increasing interval training. Three times during the intervention, oral glucose tests were conducted to investigate the rate of glucose uptake. We found a biphasic dose-response relationship between training load and glucose tolerance, where an excessive training load led to a paradoxical reduction in glucose tolerance and impaired insulin release despite an unchanged amount of muscle glycogen. In light of these results, an upper limit of physical exercise exist where the negative effects overpowers the positive.

National Category
Cell Biology
Research subject
Medicine/Technology; Medicine/Technology; Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5933 (URN)
Conference
Cell Symposia, Exercise Metabolism. May 5-7 2019, Sitges Spain
Funder
Swedish National Centre for Research in Sports
Available from: 2019-11-29 Created: 2019-11-29 Last updated: 2019-12-09Bibliographically approved
Metaxas, T., Mandroukas, A., Michailidis, Y., Koutlianos, N., Christoulas, K. & Ekblom, B. (2019). Correlation of Fiber-Type Composition and Sprint Performance in Youth Soccer Players.. Journal of Strength and Conditioning Research, 33(10), 2629-1634
Open this publication in new window or tab >>Correlation of Fiber-Type Composition and Sprint Performance in Youth Soccer Players.
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2019 (English)In: Journal of Strength and Conditioning Research, ISSN 1064-8011, E-ISSN 1533-4287, Vol. 33, no 10, p. 2629-1634Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to examine the correlation between muscle fiber type and sprint performance in elite young soccer players of different age groups of the same team. Twenty-eight young players participated in this study (group U15, n = 8; group U13, n = 9; and group U11, n = 11). Anthropometric assessments, acceleration (10 m), and Bangsbo modified sprint test (30 m) were performed. Muscle biopsies were obtained from the vastus lateralis, and after that, fiber-type composition was determined by immunohistochemistry. No significant correlations were found between the sprint test and muscle fiber distribution for the groups U13 and U11 (p > 0.05). Also, no correlations were found between cross-sectional areas in the types of fibers with the sprint test in all groups (p > 0.05). A positive correlation was found between type I fibers and the performance in the acceleration test (10 m) (r = 0.77, p < 0.05) was found only in group U15 and a negative correlation between type IIA fibers and the performance in the acceleration test (10 m) (r = -0.89, p < 0.05). The correlations were observed only in group U15, which may indicate that the duration and the intensity of the soccer systematic training can affect the plasticity of the muscle fibers. Specific soccer training in youth is one of the factors that can affect fiber-type plasticity. The specific training programs and status of U15 are more intensive, and the exercises are oriented more to improve physical fitness.

Place, publisher, year, edition, pages
Wolters Kluwer, 2019
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5859 (URN)10.1519/JSC.0000000000003320 (DOI)000505956100007 ()31403577 (PubMedID)
Available from: 2019-09-26 Created: 2019-09-26 Last updated: 2020-01-16Bibliographically approved
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
Flockhart, M., Nilsson, L., Apro, W., Ekblom, B. & Larsen, F. J. (2019). Dose-response relationship between exercise load and mitochondrial function. In: : . Paper presented at Cell Symposia: Exercise Metabolism, May 5-7 2019, Sitges Spain.
Open this publication in new window or tab >>Dose-response relationship between exercise load and mitochondrial function
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2019 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Dose-response relationship between exercise load and mitochondrial function

Flockhart M, Nilsson L, Bergman K, Apro W, Ekblom B, Larsen FJ

A dose-dependent relationship exists between exercise load and muscular adaptation. Mitochondria adapt to the increased ATP-demand by alterations in mass and/or quality. How mitochondrial mass and quality changes as a function of exercise load is not well investigated and we have previously found mitochondrial dysfunction after short-term intensive exercise. We therefore aimed to study mitochondrial function by altering exercise load during a three week interval training regimen to understand the dose-response relationship between exercise load and mitochondrial function. We took four muscle biopsies throughout the study, and as expected, mitochondrial function was positively affected during the first two weeks. After the third week, a dramatic mitochondrial dysfunction was evident as mitochondrial intrinsic respiration was reduced by 26% despite a 32% increase in mitochondrial yield. We hereby present evidence of a striking exercise-induced reduction in mitochondrial function after a period of very intense interval training.

National Category
Cell Biology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5932 (URN)
Conference
Cell Symposia: Exercise Metabolism, May 5-7 2019, Sitges Spain
Funder
Swedish National Centre for Research in Sports
Available from: 2019-11-29 Created: 2019-11-29 Last updated: 2019-12-09Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4030-5437

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