Nine Weeks of Plyometric Training Improves Running Economy in Highly Trained Distance Runners

1745 PURPOSE: To investigate the effects of plyometric training on running economy (RE), 13 highly trained distance runners (VO2max 71.1 ± 6.0 ml.min−1.kg−1; training volume 107 ± 43 km.wk−1; 3 km performance time 8.5 ± 4.0 min) were assigned to either a plyometric training (n = 7) or control (n = 8) group for a 9 wk period. METHODS: The plyometric training consisted of 3×30 min sessions per week. RE was assessed in both groups during sub-maximal treadmill runs at 14, 16 and 18 km.h−1 for 4 min, prior to and after 5 and 9 wk of the intervention period. Oxygen consumption (VO2), ventilation (VE), respiratory exchange ratio, stride rate, heart rate (HR) and blood lactate concentration were determined during the final 60 s of each sub-maximal run. Maximal oxygen consumption (VO2max) was measured prior to and after 9 wk of the intervention. Strength and power characteristics were measured using jumping protocols on a portable, unidirectional ground reaction force plate at each time point and included jump height, average power, maximal rate of force development (RFD), time to reach RFD, maximal dynamic strength (MDS), time to reach MDS and take-off time. RESULTS: VO2 was significantly lower (4.1%, p = 0.02) at 18 km.h-1 in the plyometric training group compared with the control group. There were no significant differences in any of the cardiorespiratory measures or VO2max as a result of the plyometric training. The 9 wk plyometric training coincided with higher (15%, p = 0.11) mean average power during a five-jump plyometric test and a lower (14%, p = 0.09) mean time to reach MDS during a strength quality assessment test. CONCLUSION: Nine weeks of plyometric training improved RE in a group of highly trained distance runners and in the absence of any changes in cardiorespiratory measures suggests that this improvement was not likely the result of decreased oxygen cost associated with VE and HR nor a change in substrate use. This, together with the significant improvement found only at the higher running speed, suggests that a likely mechanism may lie with changes in the muscle and elastic tissue.