Adolescent Cardiorespiratory Fitness and Future Work Ability

Abstract

Importance: Although research indicates that low fitness in youth is associated with a higher risk of chronic disability in men, the association of fitness in adolescence with work ability in working men and women remains unknown.

Objective: To examine the associations of adolescent health-related physical fitness with future work ability.

Design, setting, and participants: This 45-year observational cohort study, conducted in Finland, examined the direct and indirect longitudinal associations of objectively measured health-related fitness in adolescence (in 1976) with self-reported work ability and sickness absence in early middle age (in 2001) and the Work Ability Index in late middle age (in 2021). A countrywide stratified random baseline sample included fitness measurements for cardiorespiratory fitness (CRF) (running 1.5 km for girls and 2 km for boys), musculoskeletal fitness (MF; standing broad jump and sit-ups for both sexes, pull-ups for boys, and flexed-arm hang for girls), and height and weight, from which body mass index (BMI) was calculated. Structural equation modeling-based path analysis, adjusted for age and sex at baseline and for educational level, work-related physical strain, and leisure-time physical activity in late middle age, was conducted. Data analysis was performed from January to July 2023.

Main outcomes and measures: Self-reported work ability was measured with structured questions in early middle age and with the validated Work Ability Index in late middle age.

Results: The final sample from longitudinal analyses (1207 individuals; 579 [48%] male individuals) consisted of participants with fitness measurement from age 12 to 19 years, and work ability assessment from age 37 to 44 years and/or age 57 to 64 years. Higher adolescent CRF was associated with higher work ability (839 participants; β = 0.12; 95% CI, 0.01 to 0.22; P = .03) and lower sickness absence (834 participants; β = -0.07; 95% CI, -0.12 to -0.02; P = .004) in early middle age and, indirectly, mediated by work ability in early middle age, with a higher work ability at the end of working age (603 participants; β = 0.04; 95% CI, 0.001 to 0.08; P = .04). The results remained consistent in both sexes and after adjustment for the confounders. Neither MF nor BMI was associated with work ability (MF, 1192 participants; β = -0.07; 95% CI, -0.17 to 0.03; BMI, 1207 participants, β = 0.09; 95% CI, -0.004 to 0.19) or sickness absence (MF, 1185 participants, β = 0.02; 95% CI, -0.03 to 0.06; BMI, 1202 participants, β = -0.03; 95% CI, -0.09 to 0.03) in early middle age or with late middle age work ability, mediated by work ability in early middle age (MF, 603 participants, β = -0.02; 95% CI, -0.06 to 0.01; BMI, 603 participants, β = 0.03; 95% CI, -0.004 to 0.07).

Conclusions and relevance: These findings suggest that low CRF in youth is associated with poor work ability at the middle and end of working life, which highlights the informative and prognostic value of CRF assessment early in youth. Enhancing CRF in the first decades of life might contribute to better work capacity and productivity in the labor force, which would have implications for health, quality of life, society, and the economy.

Figure 1.. Data Structure of the Study

The path model used in this study analyzed all the associations of at least 1 exposure in baseline (1976) with at least 1 outcome in the first (2001) and/or the second (2021) follow-up. Because of the possibility of participating in 1976 and 2021 without participating in 2001, the missing data are not cumulative. The numbers for a particular association analyzed are presented in eTable 1 in Supplement 1. BMI indicates body mass index; CRF, cardiorespiratory fitness; MF, musculoskeletal fitness; WAE, Work Ability Estimate; WAI, Work Ability Index.

Figure 2.. Path Diagram

Diagram shows statistically significant (P < .05) standardized regression coefficients (straight arrow), correlations (curved arrow), and SEs (in parentheses). Absence 2001 refers to absenteeism due to sickness or injury in 2001. Strain 2021 refers to work-related physical strain in 2021. Education 2021 refers to education level in 2021. BMI indicates body mass index; CRF, cardiorespiratory fitness; LTPA, leisure-time physical activity; MF, musculoskeletal fitness; WAE, work ability estimate; WAI, Work Ability Index. ^aRefers to an inverted (multiplied by −1) version of the variable decreased work ability and overall functioning due to health impairment in 2001.