title: Neuromuscular Adaptations After 2 and 4 Weeks of 80% Versus 30% 1 Repetition Maximum Resistance Training to Failure.
abstract: Jenkins, NDM, Housh, TJ, Buckner, SL, Bergstrom, HC, Cochrane, KC, Hill, EC, Smith, CM, Schmidt, RJ, Johnson, GO, and Cramer, JT. Neuromuscular adaptations after 2 and 4 weeks of 80% versus 30% 1 repetition maximum resistance training to failure. J Strength Cond Res 30(8): 2174-2185, 2016-The purpose of this study was to investigate the hypertrophic, strength, and neuromuscular adaptations to 2 and 4 weeks of resistance training at 80 vs. 30% 1 repetition maximum (1RM) in untrained men. Fifteen untrained men (mean ± SD; age = 21.7 ± 2.4 years; weight = 84.7 ± 23.5 kg) were randomly assigned to either a high-load (n = 7) or low-load (n = 8) resistance training group and completed forearm flexion resistance training to failure 3 times per week for 4 weeks. Forearm flexor muscle thickness (MT) and echo intensity, maximal voluntary isometric (MVIC) and 1RM strength, and the electromyographic, mechanomyographic (MMG), and percent voluntary activation (%VA) responses at 10-100% of MVIC were determined at baseline, 2, and 4 weeks of training. The MT increased from baseline (2.9 ± 0.1 cm) to week 2 (3.0 ± 0.1 cm) and to week 4 (3.1 ± 0.1 cm) for the 80 and 30% 1RM groups. MVIC increased from week 2 (121.5 ± 19.1 Nm) to week 4 (138.6 ± 22.1 Nm) and 1RM increased from baseline (16.7 ± 1.6 kg) to weeks 2 and 4 (19.2 ± 1.9 and 20.5 ± 1.8 kg) in the 80% 1RM group only. The MMG amplitude at 80 and 90% MVIC decreased from baseline to week 4, and %VA increased at 20 and 30% MVIC for both groups. Resistance training to failure at 80 vs. 30% 1RM elicited similar muscle hypertrophy, but only 80% 1RM increased muscle strength. However, these disparate strength adaptations were difficult to explain with neuromuscular adaptations because they were subtle and similar for the 80 and 30% 1RM groups.
authors: 1Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska; 2Department of Health, Exercise Science, and Recreation Management, University of Mississippi, University, Mississippi; and 3Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky.
authors: Nathaniel D M
authors: ND
authors: Jenkins
authors: Terry J
authors: TJ
authors: Housh
authors: Samuel L
authors: SL
authors: Buckner
authors: Haley C
authors: HC
authors: Bergstrom
authors: Kristen C
authors: KC
authors: Cochrane
authors: Ethan C
authors: EC
authors: Hill
authors: Cory M
authors: CM
authors: Smith
authors: Richard J
authors: RJ
authors: Schmidt
authors: Glen O
authors: GO
authors: Johnson
authors: Joel T
authors: JT
authors: Cramer
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D004576:Electromyography; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult