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Modality-Specific Differences in Exercise-Induced Fatigability and Neuromuscular Function between Unilateral and Bilateral Isokinetic Muscle Actions

John Paul V Anders, University of Nebraska - Lincoln


Exercise-induced fatigability is modality-specific and characterized by a greater fatigability during unilateral (UL) than bilateral (BL) tasks. It has been hypothesized that interhemispheric inhibition (IHI) may reduce cortical activation during BL compared to UL tasks, resulting in a BL force production deficit. No studies, however, have examined the influence of IHI under fatiguing conditions. Thus, the purpose of this study was to compare exercise-induced fatigability and neuromuscular responses [electromyography (EMG) and mechanomyography (MMG) amplitude (AMP) and mean power frequency (MPF)] during fatiguing, UL, BL, ULBL and BLUL leg extensions. Eleven recreationally trained men (Mean±SD; age =20.8±1.7 years; weight =84.0±16.2 kg; height =179.3±7.2 cm) performed fatiguing tasks consisting of either 50 BL, 50 UL, 25 BL followed by 25 UL (BLUL), or 25 UL followed by 25 BL (ULBL) maximal, isokinetic leg extensions at 180°·s-1 in random order on separate days. For peak force, EMG AMP, EMG MPF, MMG AMP, and MMG MPF, every 5 of the 50 repetitions were averaged, normalized to the value at repetition 5, and examined with 4 (Condition [UL, BL, ULBL, BLUL]) × 10 (Repetition [5-50]) repeated measures ANOVAs. The results indicated significant interactions (p<0.001, η2p=0.293-0.370) for peak force, EMG AMP, MMG AMP, and MMG MPF. For peak force, fatigue occurred earlier for the UL and ULBL conditions than the BL and BLUL conditions. The EMG AMP increased only for the BL and BLUL conditions. The MMG AMP for the BL, UL, and BLUL conditions decreased. Only the BLUL condition exhibited increases in MMG MPF. For EMG MPF, there was a significant (p<0.001, η2p=0.182) decrease collapsed across condition. The findings demonstrated a greater exercise-induced fatigability for the UL versus the BL condition. The results suggested that there were no alterations in exercise-induced fatigability and neuromuscular function with IHI engagement in fatigued muscle during the ULBL condition, however, we were unable to determine if IHI disengagement in fatigued muscle during the BLUL condition affected these parameters.

Subject Area

Health sciences

Recommended Citation

Anders, John Paul V, "Modality-Specific Differences in Exercise-Induced Fatigability and Neuromuscular Function between Unilateral and Bilateral Isokinetic Muscle Actions" (2022). ETD collection for University of Nebraska-Lincoln. AAI29162365.