Article

The purpose of this study was to compare the acute neuromuscular fatigue during
dynamic maximal strength and hypertrophic loadings, known to cause different
adaptations underlying strength gain during training. Thirteen healthy, untrained
males performed two leg press loadings, one week apart, consisting of 15 sets of
1 repetition maximum (MAX) and 5 sets of 10 repetition maximums (HYP). Concentric
load and muscle activity, electromyography (EMG) amplitude and median frequency,
was assessed throughout each set. Additionally, maximal bilateral isometric force
and muscle activity was assessed pre-, mid-, and up to 30 min post-loading.
Concentric load during MAX was decreased after set 10 (P<0.05), while the load
was maintained throughout HYP. Both loadings caused large reductions in maximal
isometric force (MAX=-30+/-6.4% vs. HYP=-48+/-9.7%, P<0.001). The decreased
concentric and isometric strength during MAX loading was accompanied by reduced
EMG amplitude (P<0.05). Conversely, hypertrophic loading caused decreased median
frequency only during isometric contractions (P<0.01). During concentric
contractions, EMG amplitude increased and median frequency decreased in HYP
(P<0.01). Our results indicate reduced neural drive during MAX loading and more
complex changes in muscle activity during HYP loading.
CI - Copyright (c) 2011 Elsevier Ltd. All rights reserved.

Langue : ANGLAIS