Maximal and explosive strength training elicit distinct neuromuscular adaptations, specific to the training stimulus

Abstract

Purpose: To compare the effects of short-term maximal (MST) vs. explosive (EST) strength training on maximal and explosive force production, and assess the neural adaptations underpinning any training-specific functional changes.

Methods: Male participants completed either MST (n = 9) or EST (n = 10) for 4 weeks. In training participants were instructed to: contract as fast and hard as possible for ~1 s (EST); or contract progressively up to 75% maximal voluntary force (MVF) and hold for 3 s (MST). Pre- and post-training measurements included recording MVF during maximal voluntary contractions and explosive force at 50-ms intervals from force onset during explosive contractions. Neuromuscular activation was assessed by recording EMG RMS amplitude, normalised to a maximal M-wave and averaged across the three superficial heads of the quadriceps, at MVF and between 0-50, 0-100 and 0-150 ms during the explosive contractions.

Results: Improvements in MVF were significantly greater (P < 0.001) following MST (+21 ± 12%) than EST (+11 ± 7%), which appeared due to a twofold greater increase in EMG at MVF following MST. In contrast, early phase explosive force (at 100 ms) increased following EST (+16 ± 14%), but not MST, resulting in a time × group interaction effect (P = 0.03), which appeared due to a greater increase in EMG during the early phase (first 50 ms) of explosive contractions following EST (P = 0.052).

Conclusions: These results provide evidence for distinct neuromuscular adaptations after MST vs. EST that are specific to the training stimulus, and demonstrate the independent adaptability of maximal and explosive strength.