Tillin, N. A., Pain, M. T., & Folland, J. P. (2012). Training for maximal vs. explosive strength elicits distinct neuromuscular adaptations. Presentation 596 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

"Maximal and explosive force production (peak and slope of the force-time curve, respectively) are distinct components of neuromuscular strength that are both influenced by the level of agonist activation. However, training for maximal strength may elicit distinct neural adaptations to those elicited when training for explosive strength, but this hypothesis has not previously been tested."

This study compared the neuromuscular adaptations in untrained males to training for maximal (N = 9) vs. explosive strength (N = 10). Both groups performed four sets of 10 isometric knee extensions, four times a week for four weeks. In each contraction, the maximal-strength group was instructed to contract to 75% of maximal voluntary force (MVF) and hold for three seconds, whilst the explosive-strength group was instructed to push as fast and hard as possible for ~one second. Pre- and post-training measurements included recording MVF (greatest force of three maximal voluntary contractions) and force at 50, 100, and 150 ms from force onset during the same explosive contractions as those performed in training by the explosive-strength group. To assess agonist activation, EMG of the three superficial quadriceps was recorded at MVF and between 0-50, 50-100, and 100-150 ms during the explosive contractions. EMG variables were normalized to a maximal M-wave elicited via supramaximal stimulation of the femoral nerve, and averaged across the three muscles.

Maximal voluntary force increased in both groups, being significantly greater in the maximal-strength group. Explosive force at all time points increased in the explosive-strength group by 13-54%, but was unchanged in the maximal-strength group.

Implication. The two forms of strength training elicited very different neuromuscular adaptations. The traditional inference of transfer of gains from one form of training to the other was not exhibited in this investigation. For different modalities of strength training the Principle of Specificity reigns.

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