Similar performance fatigability and neuromuscular responses following sustained bilateral tasks above and below critical force

Men Exhibit Greater Pain Pressure Thresholds and Times to Task Failure but Not Performance Fatigability Following Self-Paced Exercise

“…It is important to note that the current protocol required participants to maintain a defined level of exertion, not effort. It has previously been shown that in order to maintain a constant level of exertion, individuals must continuously reduce force production, which typically exhibits a curvilinear pattern across time in men and women (Keller et al., 2021; Keller, Housh, Hill, et al., 2018; Keller et al., 2019a; Keller, Housh, Hill, et al., 2020). Hutchinson and Tenenbaum (2019) highlighted the significance of differentiating effort from exertion such that exertion has been related to sensations of pain and/or discomfort, whereas effort is a cognitive feeling of work associated with voluntary actions.…”

“…The experimental visit of interest here took place at least 24 hours after the initial familiarization visit. We have previously published non-overlapping data collected under the same application for ethical review (Garrett et al., 2021; Keller et al., 2021; Keller, Housh, Anders, et al., 2020). The University Institutional Review Board for Human Subjects approved the study (IRB Approval #: 20190619436EP), and all participants completed a health history questionnaire and gave signed, written informed consent prior to any testing.…”

Comparison of Inter- and Intra-Individual Neuromuscular Patterns of Responses During Moderate-Load Bilateral Leg Extension Exercise

“…More recently, investigators have examined the neuromuscular responses of the right and left limbs to compare the inter-and intra-individual and composite responses during fatiguing bilateral muscle actions. 5,6,8,9 During the performance of maximal, bilateral, isokinetic muscle actions of the leg extensors performed at 180° s -1 , authors reported no difference in the time course or onset of fatigue-induced changes in neuromuscular responses (EMG and MMG, AMP and MFP) between the right and left limbs. 5,6,9 When examining the composite (i.e., mean of all subjects) response for EMG and MMG, AMP and MPF for both right and left limbs, investigators have reported consistency in the direction (i.e., positive or negative) of fatigue-induced changes in the neuromuscular responses between right and left limbs, as well as the same pattern (i.e., linear, quadratic, or no relationship) and direction for 25%, 9 50%, 8 and 75% 6,8 of the signals in the composite data.…”

“…5,6,8,9 During the performance of maximal, bilateral, isokinetic muscle actions of the leg extensors performed at 180° s -1 , authors reported no difference in the time course or onset of fatigue-induced changes in neuromuscular responses (EMG and MMG, AMP and MFP) between the right and left limbs. 5,6,9 When examining the composite (i.e., mean of all subjects) response for EMG and MMG, AMP and MPF for both right and left limbs, investigators have reported consistency in the direction (i.e., positive or negative) of fatigue-induced changes in the neuromuscular responses between right and left limbs, as well as the same pattern (i.e., linear, quadratic, or no relationship) and direction for 25%, 9 50%, 8 and 75% 6,8 of the signals in the composite data. Further, a range from 0% to 92% of individual subjects demonstrated the same pattern and direction of response for the EMG and MMG signals as the composite response for the right and left limbs.…”

“…Typically, investigators have reported increases in EMG and MMG AMP and decreases in EMG and MMG MPF over time during fatiguing isokinetic, isometric, and dynamic constant external resistance (DCER) muscle actions. 5,6,7,8 These responses indicate there are increases in muscle excitation and motor unit recruitment and decreases in the motor unit action potential conduction velocity and the motor unit firing rate to maintain force production during the fatiguing task.…”