Teun Remmers

Relationship between PA enjoyment and PA in children | 45 swim, the average duration per day was 17.67 minutes (SD = 13.84). One may argue that seasonality influenced our results as a random error in the measurement of PA behavior. In the present study, 82.5% of the children were measured in spring or summer, and 17.5% in autumn. We tested the interaction of season (i.e. winter, autumn, spring and summer) in the relationship between association between PA enjoyment and PA behavior, and we found no statistically significant interaction. In total, 8.2% of the children in our sample had an alternative lifestyle. As these children may be exposed to alternative lifestyle patterns, the relationship between PA enjoyment and PA behavior may be different in these children. However, we found no evidence for a statistically significant interaction in this relationship. In the mean score and threshold for the median-split regarding PA enjoyment (see Table 1), one can see that this variable was negatively skewed. Therefore, dichotomy represented a limited contrast between children with normal/high- versus very high PA enjoyment. However, this study showed that even this small contrast was associated with impulsivity, gender differences, and ultimately PA behavior. Implications This study shows that a three-way interaction exists regarding PA enjoyment, impulsivity and gender in the relationship with PA behavior. As our limited sample size may have not resulted in statistical significance in all subgroups and all PA intensities, the strength of the regression coefficients in the present study may encourage researchers to investigate these interactions in future studies. Future studies are therefore stimulated to replicate the present study, using a larger sample with more variability in PA enjoyment. This is the first study that demonstrated moderating influences within the PA enjoyment – objective PA behavior relationship. Future interventions in public health practice should acknowledge that the cross-sectional relationship between PA enjoyment and objectively measured PA behavior remains uncertain and that gender and impulsivity may moderate this relationship. Based on the available evidence to date, the direct relationship between PA enjoyment and PA behavior remains questionable and not straightforward. The extent to which this stems from environmental constraints to perform PA, parental constraints or child personality constraints remains uncertain. This study however indicated that a personality trait (i.e. impulsivity) may play a role in this. Researchers are encouraged to replicate this study using a longitudinal design and focusing on potential moderating factors in this relationship. Acknowledgments We would like to thank the children and parents that participated in this part of the KOALA Birth Cohort Study. In addition, we would like to thank Lily Bogaards for her work on the Dutch translation and validation of the PACES. The present study was partially funded by the Netherlands Heart Foundation, grant number 2008 B112 to E.F.C. Sleddens. The authors declare that they have no competing interests.