Association between university aerobics course enrollment and changes in health-related physical fitness among college students: a retrospective cohort study

Background University aerobics is widely offered, but evidence comparing its real-world fitness outcomes with standard physical education (PE) using institutional records is limited. We examined whether enrollment in university aerobics was associated with greater 12-week improvement in health-related physical fitness than enrollment in standard PE and whether attendance was associated with fitness change. Methods This retrospective cohort study used PE, attendance, and fitness-testing records for 240 undergraduates (120 aerobics, 120 standard PE), randomly sampled at 30 students per class from eight existing class sections (four aerobics and four standard PE). Week-0 and week-12 post-session measurements of vital capacity, 50-m sprint, sit-and-reach, standing long jump, sex-specific endurance run, and BMI were used to construct a sex-standardized composite fitness z -score. Between-group differences were estimated using ANCOVA adjusted for baseline outcome value, sex, age, grade year, and baseline BMI (except for BMI), with class-cluster-robust standard errors; wild-cluster bootstrap and random-intercept models were used as sensitivity analyses. Complete-case analyses included 232 students (96.7%). Results The adjusted follow-up composite fitness score was 0.274 points higher in the aerobics group than in the standard PE group (cluster-robust 95% CI [0.225, 0.323]; d = 0.40). Cardiorespiratory endurance showed the largest secondary effect ( d = 0.38), whereas standing long jump ( d = 0.19), sit-and-reach ( d = 0.17), 50-m sprint ( d = −0.15), vital capacity ( d = 0.10), and BMI ( d = −0.08) showed small effects. Within the aerobics group, greater attendance was associated with greater composite fitness improvement ( β = 0.050 points/session, 95% CI [0.028, 0.073]), although residual confounding cannot be excluded. No significant interactions by sex or baseline fitness were identified. Conclusion Enrollment in the studied aerobics sections was associated with greater fitness improvement than enrollment in the available standard PE sections. Because course enrollment was non-randomized, only eight sections were available, the comparison condition was incompletely characterized, and relevant pre-exposure confounders were unavailable, the findings should be considered hypothesis-generating rather than causal.