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Muscle activation during three sets to failure at 80 vs. 30% 1RM resistance exercise.
Eur J Appl Physiol. 2015 Nov; 115(11):2335-47.EJ

Abstract

PURPOSE

The purpose of this study was to investigate electromyographic amplitude (EMG AMP), EMG mean power frequency (MPF), exercise volume (VOL), total work and muscle activation (iEMG), and time under concentric load (TUCL) during, and muscle cross-sectional area (mCSA) before and after 3 sets to failure at 80 vs. 30 % 1RM resistance exercise.

METHODS

Nine men (mean ± SD, age 21.0 ± 2.4 years, resistance training week(-1) 6.0 ± 3.7 h) and 9 women (age 22.8 ± 3.8 years, resistance training week(-1) 3.4 ± 3.5 h) completed 1RM testing, followed by 2 experimental sessions during which they completed 3 sets to failure of leg extension exercise at 80 or 30 % 1RM. EMG signals were collected to quantify EMG AMP and MPF during the initial, middle, and last repetition of each set. Ultrasound was used to assess mCSA pre- and post-exercise, and VOL, total work, iEMG, and TUCL were calculated.

RESULTS

EMG AMP remained greater at 80 % than 30 % 1RM across all reps and sets, despite increasing 74 and 147 % across reps at 80 and 30 % 1RM, respectively. EMG MPF decreased across reps at 80 and 30 % 1RM, but decreased more and was lower for the last reps at 30 than 80 % 1RM (71.6 vs. 78.1 % MVIC). mCSA increased more from pre- to post-exercise for 30 % (20.2-24.1 cm(2)) than 80 % 1RM (20.3-22.8 cm(2)). VOL, total work, iEMG and TUCL were greater for 30 % than 80 % 1RM.

CONCLUSION

Muscle activation was greater at 80 % 1RM. However, differences in volume, metabolic byproduct accumulation, and muscle swelling may help explain the unexpected adaptations in hypertrophy vs. strength observed in previous studies.

Authors+Show Affiliations

Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Kinesiology and Health Promotion, 221 Seaton Building, University of Kentucky, Lexington, KY, 40506-0219, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA.Department of Nutrition and Health Sciences, Room 211, Ruth Leverton Hall, University of Nebraska-Lincoln, Lincoln, NE, 68583-0806, USA. jcramer@unl.edu.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

26159316

Citation

Jenkins, Nathaniel D M., et al. "Muscle Activation During Three Sets to Failure at 80 Vs. 30% 1RM Resistance Exercise." European Journal of Applied Physiology, vol. 115, no. 11, 2015, pp. 2335-47.
Jenkins ND, Housh TJ, Bergstrom HC, et al. Muscle activation during three sets to failure at 80 vs. 30% 1RM resistance exercise. Eur J Appl Physiol. 2015;115(11):2335-47.
Jenkins, N. D., Housh, T. J., Bergstrom, H. C., Cochrane, K. C., Hill, E. C., Smith, C. M., Johnson, G. O., Schmidt, R. J., & Cramer, J. T. (2015). Muscle activation during three sets to failure at 80 vs. 30% 1RM resistance exercise. European Journal of Applied Physiology, 115(11), 2335-47. https://doi.org/10.1007/s00421-015-3214-9
Jenkins ND, et al. Muscle Activation During Three Sets to Failure at 80 Vs. 30% 1RM Resistance Exercise. Eur J Appl Physiol. 2015;115(11):2335-47. PubMed PMID: 26159316.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Muscle activation during three sets to failure at 80 vs. 30% 1RM resistance exercise. AU - Jenkins,Nathaniel D M, AU - Housh,Terry J, AU - Bergstrom,Haley C, AU - Cochrane,Kristen C, AU - Hill,Ethan C, AU - Smith,Cory M, AU - Johnson,Glen O, AU - Schmidt,Richard J, AU - Cramer,Joel T, Y1 - 2015/07/10/ PY - 2015/04/16/received PY - 2015/06/28/accepted PY - 2015/7/11/entrez PY - 2015/7/15/pubmed PY - 2016/8/4/medline KW - Electromyography KW - Exercise volume KW - Muscle fatigue KW - Muscle size KW - Resistance training intensity KW - Skeletal muscle SP - 2335 EP - 47 JF - European journal of applied physiology JO - Eur. J. Appl. Physiol. VL - 115 IS - 11 N2 - PURPOSE: The purpose of this study was to investigate electromyographic amplitude (EMG AMP), EMG mean power frequency (MPF), exercise volume (VOL), total work and muscle activation (iEMG), and time under concentric load (TUCL) during, and muscle cross-sectional area (mCSA) before and after 3 sets to failure at 80 vs. 30 % 1RM resistance exercise. METHODS: Nine men (mean ± SD, age 21.0 ± 2.4 years, resistance training week(-1) 6.0 ± 3.7 h) and 9 women (age 22.8 ± 3.8 years, resistance training week(-1) 3.4 ± 3.5 h) completed 1RM testing, followed by 2 experimental sessions during which they completed 3 sets to failure of leg extension exercise at 80 or 30 % 1RM. EMG signals were collected to quantify EMG AMP and MPF during the initial, middle, and last repetition of each set. Ultrasound was used to assess mCSA pre- and post-exercise, and VOL, total work, iEMG, and TUCL were calculated. RESULTS: EMG AMP remained greater at 80 % than 30 % 1RM across all reps and sets, despite increasing 74 and 147 % across reps at 80 and 30 % 1RM, respectively. EMG MPF decreased across reps at 80 and 30 % 1RM, but decreased more and was lower for the last reps at 30 than 80 % 1RM (71.6 vs. 78.1 % MVIC). mCSA increased more from pre- to post-exercise for 30 % (20.2-24.1 cm(2)) than 80 % 1RM (20.3-22.8 cm(2)). VOL, total work, iEMG and TUCL were greater for 30 % than 80 % 1RM. CONCLUSION: Muscle activation was greater at 80 % 1RM. However, differences in volume, metabolic byproduct accumulation, and muscle swelling may help explain the unexpected adaptations in hypertrophy vs. strength observed in previous studies. SN - 1439-6327 UR - https://www.unboundmedicine.com/medline/citation/26159316/Muscle_activation_during_three_sets_to_failure_at_80_vs__30_1RM_resistance_exercise_ L2 - https://dx.doi.org/10.1007/s00421-015-3214-9 DB - PRIME DP - Unbound Medicine ER -