Neuromuscular Responses at Acute Altitude Exposure during Fatiguing Dynamic Exercise of the Biceps Brachii
BACKGROUND: The capacity to do work is greatly affected by high altitude exposure. Larger muscle groups of the lower body and exercises primarily aerobic in nature have been well investigated at high altitude. The present study examined acute altitude exposure on the number of repetitions to failure and electromyographic (EMG) repetition duration (Time), EMG root mean square (RMS) and EMG mean power frequency (MPF) during dynamic constant external resistance (DCER) exercise of the biceps brachii. METHODS: Thirteen subjects performed two sets of fatiguing DCER arm curl repetitions to failure at 70% of their one repetition maximum (1RM) obtained at 1067 m, in simulated normobaric elevations of 1067m, 2438m, and 3810m. Electromyography of the biceps brachii was analyzed for EMG Time, EMG RMS, and EMG MPF. Repetitions were selected as 25%, 50%, 75% and 100% of total repetitions completed. RESULTS: There was no significant three-way (altitude x set x percent of repetitions to failure) or two-way (altitude x set or percent of repetitions to failure) interaction for any variable. The number of repetitions to failure significantly decreased from (mean ± SEM) 18.2 ± 1.4 to 9.5 ± 1.0 with each set. In addition, EMG Time increased (25% < 50% < 75% < 100%), EMG RMS decreased (50% > 75% > 100%), and EMG MPF decreased (75% > 100%) as a result of fatiguing exercise. DISCUSSION: The changes in biceps brachii EMG variables indicated exercise caused myoelectric manifestations of fatigue, however, acute altitude exposure had no additional influence on rate of fatigue development or neuromuscular parameters.
Jenkins, Jasmin Renee, "Neuromuscular Responses at Acute Altitude Exposure during Fatiguing Dynamic Exercise of the Biceps Brachii" (2020). ETD Collection for University of Texas, El Paso. AAI27999092.