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Time Course of Postactivation Potentiation During Intermittent Submaximal Fatiguing Contractions in Endurance- and Power-Trained Athletes

Morana, Claire; Perrey, Stéphane

Journal of Strength & Conditioning Research: August 2009 - Volume 23 - Issue 5 - pp 1456-1464
doi: 10.1519/JSC.0b013e3181a518f1
Original Research

Morana, C and Perrey, S. Time course of postactivation potentiation during intermittent submaximal fatiguing contrations in endurance- and power-trained athletes. J Strength Cond Res 23(5): 1456-1464, 2009-This study aimed to measure time course of postactivation potentiation during intermittent submaximal fatiguing isometric contractions in 2 groups of subjects with different physical training history. Fifteen men subjects (8 endurance-trained athletes [END] and 7 power-trained athletes [POW]) performed a 10-minute intermittent (5-second contraction, 5-second rest) knee extension exercise at 50% of their maximal voluntary isometric contraction. Mechanical (peak twitch torque, Pt) and electrophysiological (M-wave) responses following electrical stimulation of the femoral nerve were measured at rest and every 10 s throughout exercise. Vastus lateralis (VL) muscle activity (root mean square, RMS) was recorded during each contraction, and the RMS/M ratio was calculated. A significant increase in Pt (+52%, p < 0.01) was observed in both groups during the first minute of the exercise. Thereafter Pt decreased dramatically (p < 0.05) in POW whereas it remained above baseline values in END until the end of exercise. The VL RMS/M ratio increased from 7 minutes of exercise for the entire population of subjects, but showed a tendency toward greater and earlier increase in POW. Our study showed the effectiveness of an intermittent submaximal preconditioning protocol to induce similar potentiation (5-10 repetitions of 5-second submaximal contraction at 50% MVC of knee-extensors) for 2 groups of trained-individuals with different muscular profiles (END vs. POW). The enhanced fatigue resistance of endurance athletes allows the potentiating effect to prevail longer over the fatigue effect during all the 10-minute exercise. The proposed conditioning protocol (moderate-intensity, short-duration intermittent exercise) as an interesting alternative compared to MVC is adequate to warm all athletes and increase sports performance.

Faculty of Sport Sciences, EA 2991 Motor Efficiency and Deficiency Laboratory, Montpellier, France

Address correspondence to Dr. Stephane Perrey, stephane.perrey@univ-montp1.fr.

© 2009 National Strength and Conditioning Association