Inconclusive prospective effects of physical activity and fitness: Simulated reanalyses of three studies using the cross-lagged panel model

Li et al., Dong et al., and Xu et al. reported statistically significant cross-lagged effects of initial scores on physical activity and fitness on subsequent scores on various outcomes, e.g., psychological resilience and cognitive control, and they concluded causal effects. However, in the present reanalyses of data simulated to resemble data used in the three evaluated studies we found contradictory increasing, decreasing, and null prospective effects, depending on the used model. In none of the six analyzed combinations of predictor and outcome variables did a meta-analytic aggregation of the prospective effects differ significantly from zero. Hence, we conclude that prospective cross-lagged effects reported by Li et al., Dong et al., and Xu et al. may have been spurious and that their conclusions of causality may have been premature. We recommend researchers to fit alternative models to their data and to juxtapose findings, e.g., through meta-analytic aggregation. If the juxtaposed finding does not differ significantly from zero caution is advised and conclusions of increasing or decreasing effects should probably be suspended.