title: Muscle activation during low- versus high-load resistance training in well-trained men.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Health Sciences, Program of Exercise Science, CUNY Lehman College, Bronx, NY, USA, brad@workout911.com.
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Schoenfeld
authors.forename: Bret
authors.initials: B
authors.lastname: Contreras
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Willardson
authors.forename: Fabio
authors.initials: F
authors.lastname: Fontana
authors.forename: Gul
authors.initials: G
authors.lastname: Tiryaki-Sonmez
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult
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