Performance Fatigability and Neuromuscular Responses During and after One Set of Forearm Flexion Muscle Actions to Failure At 30% Versus 70% One-repetition Maximum in Men and Women

Authors

Tyler Joseph Neltner, University of Nebraska-LincolnFollow

First Advisor

Terry J. Housh

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Nutrition and Human Sciences

Date of this Version

7-2024

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Nutrition and Human Science (Exercise Physiology)

Under the supervision of Professor Terry J. Housh

Lincoln, Nebraska, August 2024

Comments

Copyright 2024, Tyler Joseph Neltner. Used by permission

Abstract

Previous studies have examined sex differences in performance fatigability during isometric, isokinetic and controlled dynamic constant external resistance (DCER) fatiguing tasks (FT), however, whether those sex differences remain during maximal intended velocity (MIV) DCER muscle actions remains unclear. The purpose of this study was to examine the sex-related differences in the time course of fatigue, neuromuscular responses, and coactivation from the ipsilateral and contralateral limbs during MIV DCER muscle actions to failure at low versus high relative loads, as well as performance fatigability from pre- to post-testing. Twenty-seven college-aged men (n = 14) and women (n = 13) completed one-repetition maximum (1RM) testing of both arms to determine the loads that would be used. The subjects then completed one of four FTs, in a random order, on separate days. The FTs include one set of repetitions to failure with both arms, using a load of 30% and 70% 1RM. Pre- and post-testing was conducted for each FT using forearm flexion and extension maximum voluntary isometric contractions (MVICs) and a DCER test at MIV. During each testing visit, electromyography (EMG) and mechanomyography were recorded from both arms. Repeated measures ANOVAs and t-tests with Bonferroni-corrections, when necessary, were used to analyze the data (alpha: p < 0.05). The results indicated that there were no sex differences in fatigability or neuromuscular responses between the men or women or between arms. There was, however, load-specific fatigability, with greater decreases in MVIC, peak force, velocity, and power for the 30% FTs compared to the 70% FTs. In addition, there was a greater decrease in EMG mean power frequency for the 30% FTs, which indicated a greater magnitude of peripheral fatigue. There were, however, no differences in EMG amplitude between loads, which indicated no differences in muscle excitation. Thus, MIV DCER muscle actions may be used to elicit adaptations from maximal muscle actions when higher loads are not possible.

Advisor: Terry J. Housh

Recommended Citation

Neltner, Tyler Joseph, "Performance Fatigability and Neuromuscular Responses During and after One Set of Forearm Flexion Muscle Actions to Failure At 30% Versus 70% One-repetition Maximum in Men and Women" (2024). Dissertations and Doctoral Documents from University of Nebraska-Lincoln, 2023–. 163.
https://digitalcommons.unl.edu/dissunl/163