Four Years Longitudinal Follow-up Of Fitness During Childhood

Abstract

Both physical activity and physical fitness are related to health outcomes, the evolution indicators (inter-age correlations) of physical fitness and physical activity level from childhood to adolescence tend to be moderate. This suggests that even if physical activity increases the physical fitness level, inactivity is not the principal cause of being unfit. PURPOSE To analyze health related fitness values during childhood (11 - to 16-years) in relation to changes in physical activity level. METHODS One hundred and fifty eight children were monitored over a 4-year period. Twice a year, they performed six physical fitness tests: standing broad jump, 10*5 meter shuttle run, sit-and-reach, hand grip, number of sit-ups in 30 seconds, 20 meter shuttle run. Height was measured four times a year to assess age at peak height velocity. Physical activity was assessed with a self-administered questionnaire at baseline and at the end of the follow-up. The physical activity level was defined by the frequency and the time spent in moderate to vigorous physical activities. Two groups were constituted: regularly active and sedentary. RESULTS A multiple linear multilevel regression analysis was used to analyze the longitudinal relationships between changes in physical activity and physical fitness levels. Corrections were made for both time-dependent (time) and time-independent (sex) variables. Except for flexibility, boys' fitness performances increased more than the girl's ones. Positive and significant (p<0.05) regression coefficients were found with the regularly active for standing broad jump, 20-meter shuttle run, number of sit-ups, 10*5 meter shuttle run in both sexes and for the girls' sit-and-reach performance. Increasing and decreasing physical activity level was not associated with fitness performances for girls, except for flexibility. The boys who increased their physical activity level showed better performances in the 20-meter shuttle run test only. CONCLUSION The children who stayed the most active were the fittest, particularly for the girls. From childhood to adolescence, an increase or a decrease in physical activity does not seem to have a significant impact on physical fitness.