Background and aims Severely preterm birth is associated with low physical activity and cardiorespiratory fitness. We studied the association of gestational age across its full range with physical activity (self-reported) and cardiorespiratory fitness in adolescence.
Methods Of the 16-year-old members of the population-based Northern Finland Birth Cohort 1986, 6675 singletons with no major physical disability reported the amount of light, brisk and commuting physical activity outside school hours and 4706 completed a submaximal cycle ergometer test for the assessment of cardiorespiratory fitness. Physical activity was summarised as metabolic equivalent hours (METhours) per week and peak oxygen uptake relative to body weight (ml/kg/min) calculated by heart rate responses. To assess the effect of gestational age on the outcomes, the adequate data were analysed by multiple linear regression.
Results There was an inverse U-shaped association between gestational age and physical activity such that adolescents born at both ends of the full range of gestational age undertook less physical activity than others (Figure). These adolescents also seemed to have low cardiorespiratory fitness; however only the linear inverse trend was statistically significant (Figure), suggesting low fitness in those born later gestational ages.
Conclusion Our results are consistent with previous findings of low levels of physical activity in adolescents born severely preterm. We found no evidence of low physical activity and fitness among adolescents born less preterm. Our results also suggest lower physical activity and fitness among adolescents born at later gestational ages; this was post hoc and requires replication.