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Muscular strength in male adolescents and premature death: cohort study of one million participants

BMJ 2012; 345 doi: http://dx.doi.org/10.1136/bmj.e7279 (Published 20 November 2012) Cite this as: BMJ 2012;345:e7279
  1. Francisco B Ortega, research associate123,
  2. Karri Silventoinen, research associate4,
  3. Per Tynelius, statistician5,
  4. Finn Rasmussen, professor5
  1. 1Department of Physical Education and Sport, School of Sport Sciences, University of Granada, Granada, Spain
  2. 2Department of Biosciences and Nutrition at NOVUM, Karolinska Institutet, Huddinge, Stockholm, Sweden
  3. 3Department of Medical Physiology, School of Medicine, University of Granada
  4. 4Population Research Unit, Department of Social Research, University of Helsinki, Helsinki, Finland
  5. 5Child and Adolescent Public Health Epidemiology Group, Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to: F Rasmussen Finn.Rasmussen{at}ki.se
  • Accepted 19 October 2012

Abstract

Objectives To explore the extent to which muscular strength in adolescence is associated with all cause and cause specific premature mortality (<55 years).

Design Prospective cohort study.

Setting Sweden.

Participants 1 142 599 Swedish male adolescents aged 16-19 years were followed over a period of 24 years.

Main outcome measures Baseline examinations included knee extension, handgrip, and elbow flexion strength tests, as well as measures of diastolic and systolic blood pressure and body mass index. Cox regression was used to estimate hazard ratios for mortality according to muscular strength categories (tenths).

Results During a median follow-up period of 24 years, 26 145 participants died. Suicide was a more frequent cause of death in young adulthood (22.3%) than was cardiovascular diseases (7.8%) or cancer (14.9%). High muscular strength in adolescence, as assessed by knee extension and handgrip tests, was associated with a 20-35% lower risk of premature mortality due to any cause or cardiovascular disease, independently of body mass index or blood pressure; no association was observed with mortality due to cancer. Stronger adolescents had a 20-30% lower risk of death from suicide and were 15-65% less likely to have any psychiatric diagnosis (such as schizophrenia and mood disorders). Adolescents in the lowest tenth of muscular strength showed by far the highest risk of mortality for different causes. All cause mortality rates (per 100 000 person years) ranged between 122.3 and 86.9 for the weakest and strongest adolescents; corresponding figures were 9.5 and 5.6 for mortality due to cardiovascular diseases and 24.6 and 16.9 for mortality due to suicide.

Conclusions Low muscular strength in adolescents is an emerging risk factor for major causes of death in young adulthood, such as suicide and cardiovascular diseases. The effect size observed for all cause mortality was equivalent to that for well established risk factors such as elevated body mass index or blood pressure.

Footnotes

  • We are grateful to Jonatan R Ruiz, Manuel J Castillo, Michael Sjöström, and Steven Blair’s group for constructive scientific discussions. We are also indebted to Charlotte Goodrose-Flores for the English revision.

  • Contributors: FR was responsible for the concept and design of the study. FR and PT acquired the data. PT created the dataset, and FBO did the statistical analysis and prepared the first draft of the manuscript. All authors were involved in further analysis and interpretation of data, drafting the manuscript, and critical revision of the manuscript for important intellectual content. They are all guarantors.

  • Funding: The study was supported by a grant to FR from the Swedish Research Council (grant 2007-5942). FBO was supported by grants from the Spanish Ministry of Science and Innovation (RYC-2011-09011). The funding bodies had no role in the preparation of this manuscript.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: the study was supported by a grant to FR from the Swedish Research Council, and FBO was supported by grants from the Spanish Ministry of Science and Innovation; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: The study was approved by the Ethical Review Board, Stockholm, Sweden.

  • Data sharing: No additional data available.

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