Sex Differences in Neuromuscular Function after Repeated Eccentric Contractions of the Knee Extensor Muscles

Authors

Andrea Lee, University of British Columbia
Jake Baxter, University of Minnesota - Duluth
Claire Eischer, Michigan Technological University
Matt Gage, Michigan Technological University
Sandra K. Hunter, Marquette UniversityFollow
Tejin Yoon, Michigan Technological UniversityFollow

Document Type

Article

Language

eng

Publication Date

6-2017

Publisher

Springer

Source Publication

European Journal of Applied Physiology

Source ISSN

1439-6319

Abstract

Purpose

This study examined the mechanisms for force and power reduction during and up to 48 h after maximal eccentric contractions of the knee extensor muscles in young men and women.

Methods

13 men (22.8 ± 2.6 years) and 13 women (21.6 ± 2.2 years) performed 150 maximal effort eccentric contractions (5 sets of 30) with the knee extensor muscles at 60° s⁻¹. Maximal voluntary isometric contractions (MVIC) and maximal voluntary concentric contractions (MVCC) were performed before and after the 150 eccentric contractions. The MVCCs involved a set of two isokinetic contractions at 60° s⁻¹ and sets of isotonic contractions performed at seven different resistance loads (1 N m, 10, 20, 30, 40, 50, and 60% MVIC). Electrical stimulation was used during the MVICs and at rest to determine changes in voluntary activation and contractile properties.

Results

At baseline, men were stronger than women (MVIC: 276 ± 48 vs. 133 ± 37 N m) and more powerful (MVCC: 649 ± 77 vs. 346 ± 78 W). At termination of the eccentric contractions, voluntary activation, resting twitch amplitude, and peak power during concentric contractions at the seven loads and at 60° s⁻¹ decreased (P < 0.05) similarly in the men and women. At 48 h post-exercise, the MVIC torque, power (for loads ≥20–60% MVIC), and voluntary activation remained depressed (P < 0.05), but the resting twitch had returned to baseline (P > 0.05) with no sex differences.

Conclusion

Central mechanisms were primarily responsible for the depressed maximal force production up to 48 h after repeated eccentric contractions of the knee extensors and these mechanisms were similar in men and women.

Comments

European Journal of Applied Physiology, Vol. 117, No. 6 (June 2017): 1119-1130. DOI.

Recommended Citation

Lee, Andrea; Baxter, Jake; Eischer, Claire; Gage, Matt; Hunter, Sandra K.; and Yoon, Tejin, "Sex Differences in Neuromuscular Function after Repeated Eccentric Contractions of the Knee Extensor Muscles" (2017). Exercise Science Faculty Research and Publications. 111.
https://epublications.marquette.edu/exsci_fac/111