Meta-analysis of fitness outcomes from motivational physical activity interventions.

backgroundMotivational physical activity (PA) interventions are effective in increasing PA behavior among healthy adults; however, the impact of these interventions on cardiorespiratory fitness (CRF) has not yet been examined.

objectiveThe purpose of this meta-analysis is to quantitatively synthesize CRF outcomes of motivational PA interventions among healthy adults.

methodsComprehensive searching identified studies testing motivational PA interventions with CRF outcomes. Two independent coders extracted data. Data were synthesized using standardized mean difference effect sizes (ESs, d) under a random effects model. Heterogeneity was assessed, and moderator analyses were conducted using subgroup analyses and meta-regression.

resultsData were analyzed from 11,458 primary study subjects. The overall mean ES for CRF was 0.48 (p < .01), which corresponds to a difference in VO2 max of 2.5 mL/kg/min between treatment and control groups. Studies were significantly heterogeneous (Q = 133.29, p < .01). Significant moderators included age (β = -0.02, p = .01) and recommending endurance plus resistance exercises (d = 1.04) versus recommending only endurance exercise (d = 0.47). DISCUSSION: Motivational interventions designed to increase PA can improve CRF among healthy adults. Clinicians should recommend endurance and resistance exercise to improve CRF in this population. Future primary research should test interventions longitudinally and across more diverse populations. Although other moderators examined in this study did not show a significant effect on ES, the number of comparisons available for moderator analyses was small.