Muscle activation during low- versus high-load resistance training in well-trained men

• Published in: European journal of applied physiology Vol. 114; no. 12; pp. 2491 - 2497
• Main Authors: Schoenfeld, Brad J., Contreras, Bret, Willardson, Jeffrey M., Fontana, Fabio, Tiryaki-Sonmez, Gul
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.12.2014; Springer Nature B.V
• Subjects: Biomechanical Phenomena - physiology; Biomedical and Life Sciences; Biomedicine; Electromyography; Human Physiology; Humans; Isometric Contraction - physiology; Male; Muscle contraction; Muscle, Skeletal - physiology; Muscles; Occupational Medicine/Industrial Medicine; Original Article; Physical training; Quadriceps muscle; Resistance Training - methods; Sports Medicine; Young Adult; Muscle recruitment; Light weights; Low-load resistance training; Momentary muscular failure
• ISSN: 1439-6319; 1439-6327; 1439-6327
• DOI: 10.1007/s00421-014-2976-9

Purpose It has been hypothesized that lifting light loads to muscular failure will activate the full spectrum of MUs and thus bring about muscular adaptations similar to high-load training. The purpose of this study was to investigate EMG activity during low- versus high-load training during performance of a multi-joint exercise by well-trained subjects. Methods Employing a within-subject design, 10 young, resistance-trained men performed sets of the leg press at different intensities of load: a high-load (HL) set at 75 % of 1-RM and a low-load (LL) set at 30 % of 1-RM. The order of performance of the exercises was counterbalanced between participants, so that half of the subjects performed LL first and the other half performed HL first, separated by 15 min rest. Surface electromyography (EMG) was used to assess mean and peak muscle activation of the vastus medialis, vastus lateralis, rectus femoris, and biceps femoris. Results Significant main effects for trials and muscles were found ( p  < 0.01). Significantly greater peak EMG activity was found during the HL set ( M  = 177.3, SD = 89.53) compared to the LL set ( M  = 137.73, SD = 95.35). Significantly greater mean EMG activity was found during the HL set ( M  = 63.7, SD = 37.23) compared to the LL set ( M  = 41.63, SD = 28.03). Conclusions Results indicate that training with a load of 30 % 1-RM to momentary muscular failure does not maximally activate the full motor unit pool of the quadriceps femoris and hamstrings during performance of multi-joint lower body exercise.