Relationship between health-related quality of life and physical fitness in Norwegian adolescents

This cross-sectional study investigated the association between health-related quality of life (HRQoL), cardiorespiratory fitness (CRF) and muscular fitness in 14-year-old adolescents.Norwegian adolescents (N = 1985) carried out a 10-min running test to assess cardiorespiratory fitness and three different muscular fitness tests (handgrip, sit-ups, and standing broad jump) and answered the KIDSCREEN-27 questionnaire to provide HRQoL data. Linear-mixed effect models were applied to detect relationships among the variables.Running-test results were positively associated with higher scores in the following KIDSCREEN domains: physical well-being, psychological well-being, autonomy and parent relationships, and school environment (β = 0.01-0.04; p .01 for all). Performance in sit-ups test was positively associated with higher scores in three out of five KIDSCREEN domains: physical well-being (β = 0.31; p .001), social support and peers (β = 0.16; p = .023), and school environment scores (β = 0.19; p = .006). An inverse association was found between the handgrip test results and the score on psychological well-being domain (β = - 0.10; p = .013).The associations between HRQoL and physical fitness were trivial (abdominal strength and handgrip strength) to small (CRF) but confirmed that earlier findings from children also are applied to adolescents. Explosive strength in the lower body showed no association with HRQoL. Further research should investigate the direction of causality.Clinicaltrials.gov ID nr: NCT03817047. Registered 01/25/2019 'retrospectively registered'.