Does students' self-determined motivation toward Physical Education influence the effectiveness of a fitness teaching unit? A cluster-randomized controlled trial and cluster analysis

Objective: The aim was to compare the effect of a Physical Education (PE)-based fitness teaching unit to improve cardiorespiratory fitness levels between students' motivational profiles toward PE in high-school students using cluster analysis. Method: One hundred and eighty-one high school students (final sample 165, 52.1% females; M-age = 12.9 +/- 0.9) from nine pre-established classes were cluster-randomly assigned into an experimental group (n = 120) and control group (n = 61). The experimental group performed a fitness teaching unit twice a week for nine weeks. Students' baseline of self-determined motivation toward PE was measured by the Spanish version of the Perceived Locus of Causality-II Scale. Cardiorespiratory fitness was measured before and after the intervention through the 20-m shuttle run test. Results: Based on a two-stage cluster analysis approach, four clusters were identified in both groups. Results showed that the experimental group students within the high self-determined motivational profiles toward PE (i.e., clusters 2 and 4) statistically significantly improved their cardiorespiratory fitness levels compared with the control group students in cluster 2 (i.e., those with moderate self-determined motivational profile toward PE) (p < 0.05; d = 0.37-0.48). However, statistically significant differences between the students with a moderate autonomous motivation profile toward PE (i.e., cluster 3 of the experimental group) and the control group students in clusters 2 and 3 were not found (p > 0.05). Conclusions: With the objective of increasing all students' cardiorespiratory fitness levels, PE teachers should encourage students' motivation toward PE applying specific motivational strategies during PE lessons.