Motivation
Low cardiopulmonary fitness (CPF) predicts future morbidity in adults. Participation in physical activity (PA), particularly moderate to vigorous physical activity (MVPA), can improve CPF but the impact of MVPA throughout adolescence on CPF in early adult life remains unclear and potential differences in this association between men and women have not previously been quantified. We investigate sex-differences in the impact of MVPA throughout adolescence on early adult CRF.
Methods
Participants enrolled in a UK birth cohort (The Avon Longitudinal Study of Parents and Children, ALSPAC) undertook measures of physical activity at 11, 13, 15 and 24 years (y) old using a hip-worn accelerometer. Time in MVPA (average minutes/day) was derived from accelerometer data at each time. Cumulative MVPA participation was calculated as a life-time average across all measurement time points. CPF (VO2max) was estimated from a Tecumseh step test at age 24. Ethical clearance for all procedures was granted by the ALSPAC Law and Ethics Committee and the Local Research Ethics Committee and all participants provided written and informed consent.
Structural equation modelling was used to compare associations between MVPA measured at each time and VO2max at age 24 within the same model and cumulative MVPA participation and VO2max. Direct and indirect effects of MVPA at each time point on VO2max are presented. The full information maximum likelihood method was used to account for missingness under the assumption of missing at random. Maternal socioeconomic group was included in models as a predictor of missing observations. Skewed data were log transformed. Analysis was sex-stratified.
Results
Participants who undertook the step test at 24 and had undertaken at least two PA measurements during adolescence were included in this analysis (n=1347 (476 men)). Cumulative MVPA was positively associated with VO2max in both men and women, but the association was slightly stronger for men (Table 1). In men, after adjustment for MVPA at each measurement time (direct effects), only MVPA at 24 remained strongly associated with VO2max at 24 (Table 1). In women, we observed strong direct effects of MVPA at age 13 and age 24 on VO2max at 24 (Table 1).
Conclusion
Cumulative MVPA participation throughout adolescence is an important determinant of CRF in early adulthood. These data also suggest that MVPA in early adolescence is an important determinant of early adult CPF in women independent from MVPA participation in early adulthood.
