PURPOSE This study aimed to investigate the effects of a 10-week complex training program on physical fitness and running performance in male marathon club members aged 20–30 years. METHODS Thirty participants were recruited and randomly assigned to either a training group (TR) or a control group (CON). Following participant dropout, data from 14 participants in the TR and 13 in the CON were included in the final analysis. Participants in the TR completed complex training sessions lasting 60 minutes per session, twice per week, for 10 weeks, whereas the CON maintained their usual lifestyle patterns. Dependent variables—including body composition, physical fitness, and running performance—were measured pre- and post-intervention. Comparisons were made between groups and across time points using a two-way repeated measures ANOVA. RESULTS 1) Physical fitness: Squat 1RM, trap bar deadlift 1RM, and countermovement jump performance increased significantly in the TR; 2) Regarding running performance, drop jump and reactive strength index increased significantly in the TR; and 3) Running performance: time to exhaustion decreased significantly in the CON, whereas it was maintained in the TR, suggesting a protective effect of the complex training program. CONCLUSIONS The 10-week complex training program positively affected muscular strength, power, elastic utilization ability, and endurance (time to exhaustion) in male marathon club members. However, its effects were limited with respect to running efficiency, fatigue resistance, and rate of force development. Future studies should consider adjusting training intensity and volume and diversifying exercises to develop more effective programs for enhancing running performance.
