Effects of a situational interest-based rotational fitness training program on positive affect in university students

Background: To evaluate whether a 12-week situational interest-based rotational fitness program improved positive emotional states in university students, to compare module-specific effects, and to examine whether the intervention moderated the heart rate–emotion association. Methods: In this 2-arm randomized controlled trial, 560 freshmen from 10 Chinese universities were assigned to an experimental (n = 280) or control group (n = 280). The experimental group completed weekly 90-minute sessions covering strength, endurance, speed, and agility modules; controls received regular physical education. Positive emotional states were assessed using the positive well-being subscale of the Subjective Exercise Experiences Scale through ecological momentary assessment at 3 points per session, yielding over 14,000 observations. Linear mixed-effects models tested group, time, group × time, heart rate, and heart rate × group effects. Assessors and analysts were blinded. Ethical approval for the trial was granted by the Institutional Review Board of Capital University of Physical Education and Sports (2025A055). Results: Improvement was greater in the experimental group than in controls (EMM change: 1.843 vs 0.505; difference = 1.338, 95% confidence interval [CI]: 1.275–1.400, P < .001). At week 12, the raw between-group difference was 1.85 ( d = 2.23), and all group × week interactions from weeks 2 to 12 were significant. Heart rate positively predicted emotional states in controls ( B = 0.005, 95% CI: 0.003–0.007), but this association was attenuated in the experimental group (interaction B = −0.008, 95% CI: −0.011 to −0.005). Strength and agility showed significant improvements, while endurance produced consistently higher emotional states across assessment points. Heart rate moderation was significant for strength and endurance, but not speed or agility. Conclusion: The rotational program improved positive emotional states more than regular physical education, although effects varied by module. Strength showed the most robust benefit. The program also weakened, but did not eliminate, the heart rate–emotion association during more demanding activities.