Objective To investigate the associations of muscular strength in adolescence with later disability pension (DP), across different body mass index (BMI) categories and in combination with aerobic fitness.
Method This prospective cohort study consisted of males aged 16–19 years, recruited from the Swedish military conscription register between 1969 and 1994. A total of 1 212 503 adolescents met all the inclusion criteria and were therefore included in the analyses. Knee extension, handgrip and elbow flexion strength and aerobic fitness (bicycle ergometer test) were measured during conscription. Causes of DP were retrieved from the Social Insurance Office between years 1971 and 2012 (average follow-up time: 29.6 years).
Results Knee extension strength in adolescence was inversely associated with men’s risk of obtaining DP due to all causes (HR 1.40, 95% CI 1.36 to 1.44 for lowest vs highest strength quintile). Thus, muscular weakness was associated with DP. The risk associated with low muscular strength differed between specific causes of DP and the strongest associations were found for psychiatric, nervous system and other causes (HRs between 1.47 and 1.90 for lowest vs highest quintile). Being strong was associated with lower DP risk across BMI categories and being unfit, weak and obese was associated with the highest DP risk (HR 3.70, 95% CI 2.99 to 4.58).
Conclusion There was a strong association between muscular weakness and disability. A combination of muscular weakness and low aerobic fitness was an especially important risk factor for disability. This adds weight to call for muscular strength and fitness enhancing exercise for adolescents in all BMI categories.
- aerobic fitness
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HH and PH contributed equally.
Contributors All authors contributed to data analyses and manuscript preparation. FBO was responsible for study design, contributed to data analysis and manuscript preparation.
Funding HH was supported by a grant from The Swedish Society of Medicine and the County Council of Östergötland, Sweden. PH was supported by grants from Henning and Johan Throne-Holst Foundation and the Strategic Research Area Health Care Science, Karolinska Institutet/Umeå University. FBO was supported by a visiting grant from Henning and Johan Throne-Holst Foundation. Additional support was obtained from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 667302; the University of Granada, Plan Propio de Investigación 2016, Excellence actions: Units of Excellence, Unit of Excellence on Exercise and Health (UCEES); the SAMID IIInetwork, RETICS, funded by the PN I+D+I 2017-2021 (Spain), ISCIII- Sub-Directorate General for Research Assessment and Promotion, the European Regional Development Fund (ERDF) (Ref. RD16/0022) and the EXERNET Research Network on Exercise and Health in Special Populations (DEP2005-00046/ACTI).
Competing interests None declared.
Ethics approval The Regional Ethics committee, Stockholm, Sweden.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement We do not have ethical approval to share the data. However, the data is from Swedish national registers and can be obtained from the relevant authorities for researchers who have ethical permission.