Neuromuscular Adaptations after 2 and 4 Weeks of 80% Versus 30% 1 Repetition Maximum Resistance Training to Failure

Nathaniel D.M. Jenkins, Terry J. Housh, Samuel L. Buckner, Haley C. Bergstrom, Kristen C. Cochrane, Ethan C. Hill, Cory M. Smith, Richard J. Schmidt, Glen O. Johnson, Joel T. Cramer

Research output: Contribution to journalArticle

33 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)2174-2185
Number of pages12
JournalJournal of strength and conditioning research
Volume30
Issue number8
DOIs
StatePublished - Aug 1 2016

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Keywords

  • electromyography
  • interpolated twitch
  • load
  • mechanomyography
  • muscle hypertrophy
  • muscle strength
  • resistance training intensity

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Jenkins, N. D. M., Housh, T. J., Buckner, S. L., Bergstrom, H. C., Cochrane, K. C., Hill, E. C., Smith, C. M., Schmidt, R. J., Johnson, G. O., & Cramer, J. T. (2016). Neuromuscular Adaptations after 2 and 4 Weeks of 80% Versus 30% 1 Repetition Maximum Resistance Training to Failure. Journal of strength and conditioning research, 30(8), 2174-2185. https://doi.org/10.1519/JSC.0000000000001308