Changes in biceps and triceps brachii electromyography during wingate anaerobic tests at different intensities

Introduction The Wingate Anaerobic Test (WAnT) is a cycling protocol used to assess maximal power, with metrics like velocity, power, and muscle activity (EMG) helping to evaluate performance and motor activation. EMG can reveal differences in motor drive between limbs, including bilateral deficits. There is currently a gap in the research on the different activation strategies employed by the biceps and triceps brachii during a WAnT. Objectives This study had two main objectives: 1) quantify the influence that arm dominance, unilateral or bilateral arm cycling, fatigue, WAnT resistance intensity, or crank position have on EMG amplitude of the biceps and triceps brachii; 2) assess whether there is evidence to support a bilateral EMG deficit during arm cycling. Methods In this quasi-randomized study, 12 participants performed a series of 30s WAnTs with a resistance of 3, 4, and 5% of body mass (BM) unilaterally with their dominant and non-dominant, and bilaterally with both arms with 24-48h between each session (1 familiarization, 3 experimental). Surface EMG from the biceps and triceps brachii was recorded during each WAnT. Metrics for arm dominance, laterality, intensity, crank position, and fatigue were used to determine what had the greatest effect on the normalized mean EMG amplitude for the biceps and triceps brachii. Results Crank position (6 o’clock/12 o’clock), (p<0.001, p<0.001), intensity (3%, 4%, 5%) (p<0.001, p<0.001), and arm (dominant/non dominant) (p<0.001, p<0.001) had a significant effect on EMG for the biceps and triceps brachii, respectively. WAnT section (beginning, middle, end) was only significant for the biceps brachii (p=0.022). There were significant intensity * arm (p<0.001, p<0.001), and crank position * arm (p<0.001, p<0.001) interactions, for biceps and triceps brachii, respectively, whereas intensity * crank position (p=0.019) and crank position * WAnT section (p=<0.001) were significant for the biceps brachii. Conclusions This study found that average muscle activity during a fatiguing arm cycling task varied with crank position, resistance, and whether the task was performed unilaterally or bilaterally. This variance of EMG activity for each of the aforementioned aspects, specifically when comparing between bilateral and unilateral trials suggests that there are different recruitment strategies used, depending on which arm is used for a given task. Future research could explore how these differences in individual motor unit recruitment, including bilateral deficits or facilitations, are influenced by factors like sex, training status, and task intensity, and assess their relationship to performance measures.