The effects of plyometric versus resistance training on running economy and 5-km running time in middle-aged recreational runners.

The effects of plyometric training (PT) versus resistance training (RT) on running economy and performance are unclear, especially in middle-aged recreational runners. We examined (1) the efficacy of PT versus RT on running economy and performance in middle-aged recreational runners and (2) the relationships between the main training outcomes. Twenty middle-aged recreational runners were randomly allocated to a PT or RT group (n = 10/group). Training was conducted twice/week for 10 weeks combined with daily running. PT included the countermovement jump (CMJ), rebound jump, hurdle hop, and drop jump. RT consisted of leg press, leg curl, and calf raise with 50%-90% of one-repetition maximum (1RM). Before and after the intervention, 1RM of the three lifting tasks, CMJ and drop jump performances, oxygen cost at 8-12 km/h, and 5 km running time were assessed. PT enhanced 1RM of leg curl only (8.5% and p = 0.007), whereas RT increased 1RM of the three lifting tasks (19.0%-21.1% and p < 0.001). Both groups improved CMJ height (6.4%-8.3% and p = 0.016) and drop jump performance (height: 9.7%-19.4%, p = 0.005, height/contact time: 11.4%-26.3% and p = 0.009) and oxygen cost regardless of running velocity (2.0% and p = 0.001) without significant group differences. However, neither group changed the 5-km running time (p ≥ 0.259). A significant correlation was found between the changes in calf raise 1RM and oxygen cost (r = -0.477 and p = 0.046) but not between the other measured variables. These results suggest that for middle-aged recreational runners, PT and RT can similarly improve running economy albeit not necessarily the 5-km running time, and enhancing plantarflexion strength may particularly contribute to improving running economy.