Award Date

May 2023

Degree Type


Degree Name

Master of Science (MS)


Kinesiology and Nutrition Sciences

First Committee Member

Brach Poston

Second Committee Member

Sharon Jalene

Third Committee Member

John Mercer

Fourth Committee Member

Jennifer Nash

Number of Pages



Fatigue is an exercise-induced reduction in muscle force generating capacity. Several studies have shown that some forms of non-invasive brain stimulation can increase the resistance to fatigue during sustained isometric contractions. The purpose was to determine the influence of transcranial alternating current stimulation (tACS) on the time to task failure (TTF) of a precision grip task in young adults. Twenty-two healthy young men and women participated in the study. The study utilized a randomized, double-blind, SHAM-controlled, within-subjects, crossover design. Each participant completed two experimental sessions (tACS, SHAM) with a 7-day washout period between sessions. Each session involved performance of a fatiguing isometric contraction with a precision grip with the right hand (index finger and thumb) simultaneous with either tACS or SHAM stimulation. tACS was applied to the left (dominant) primary motor cortex (M1) with a current strength of 1 mA and at a frequency of 70 Hz. Participants were instructed to match an isometric target force of 20% of maximum voluntary contraction (MVC) force for as long as possible until task failure. In addition, pre and post-MVCs were performed before and after the fatiguing contractions to quantify the magnitude of force decline due to fatigue. Accordingly, the primary dependent variables were TTF and MVC force decline as well as the average EMG activity, force error, and standard deviation (SD) of force during the fatiguing contractions. The results indicated that there were no significant differences in any of the primary dependent variables between the tACS and SHAM conditions (P value range: 0.105 - 0.973). These findings suggest that tACS applied using the electrode montage and stimulation parameters utilized in the current study does not increase TTF during fatiguing hand muscle contractions in young adults. Therefore, different tACS parameters may be needed to elicit improvements in fatigue resistance in young adults.



File Format


Degree Grantor

University of Nevada, Las Vegas




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