Cadore, E. L., Conceicao, M., Izquierdo, M., Wilhelm, E. N., Liedtke, G. V., Pinto, R. S., Gonzalez-Isal, M., Schneider, C. D., Ferrari, R., Goltz, F. R., Bottaro, M, & Kruel, L. F. (2014). Acute effects of strength and plyometric training on performance and cardiorespiratory responses during endurance exercise. Medicine & Science in Sports & Exercise, 46(5), Supplement abstract number 927.

This study investigated the acute effects of two strength-training protocols on the time to exhaustion and cardiorespiratory variables during endurance exercise in young males (N = 13). The hypertrophic strength-training protocol comprised six sets of eight squats at 75% of maximal dynamic strength. The plyometric strength-training protocol comprised six sets of eight countermovement jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion (time-to-exhaustion). Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters (EMG) were assessed.

After both resistance-training protocols, significant decreases were observed in the maximum voluntary contraction (both 14%) and rate of force development (10-11%), whereas no changes were observed in the EMG parameters. Oxygen uptake (VO2) and heart rate were not significantly different among the groups. However, the time-to-exhaustion was significantly better in the endurance-training group when compared to the two strength-training protocol groups.

Implication. Hypertrophic and plyometric strength-training sessions performed prior to endurance training may similarly impair the neuromuscular system and the time to exhaustion during high-intensity endurance exercise. In addition, despite the acute endurance performance impairment, the two strength-training protocols did not influence the average VO2 values or heart rates during the exercise.

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