Discussion
elbow flexion exercise
This is the first study to compare sEMG amplitudes in traditional free weight exercise with EO and VR using electromagnetic technology. The results indicated clear evidence of differences in sEMG amplitude across multiple muscles and conditions during elbow flexion exercise. Where these differences were observed, however, magnitudes were generally modest between conditions (< 10%) and therefore unlikely to be practically meaningful. Consistent with our hypothesis, the electromagnetic technology produced similar sEMG amplitudes compared to free weights. Contrary to our initial hypothesis, however, the EO condition did not produce greater sEMG amplitude on the eccentric actions compared to the other conditions, and VR training did not produce greater sEMG amplitude on the concentric actions at any of the studied angles compared to the other conditions. What follows is a discussion of the specific findings and their potential practical implications for performance.In general, sEMG amplitude changed across joint angles irrespective of condition. Consistent with previous research, sEMG amplitude was higher during concentric vs eccentric actions for all conditionsIn regard to specific muscles, sEMG amplitude was modestly higher in all electromagnetic conditions compared to the DB for the anterior deltoid on the concentric action. This finding was observed across all joint angles and is consistent with previous research using a cable-based apparatus versus a selectorized machine for elbow flexion exerciseFor the biceps brachii, sEMG amplitude was generally similar across conditions concentrically. Amplitude for the DB and VR were slightly higher than for ELECTRO and EO (< 5%), and unlikely of practical significance. DB and EO produced the highest amplitudes eccentrically, but the magnitude of differences between all conditions was likely trivial (< 5%). As mentioned above, the DB produced a distinct pattern whereby biceps brachii sEMG amplitude remained relatively constant during the initial lowering phase, and then sharply declined at 50°. A similar pattern of amplitude across joint angles has been reported previously during elbow flexion with a dumbbellFor the brachioradialis, the DB produced higher amplitudes both concentrically and eccentrically, with the greatest differences occurring between 50 and 110° of elbow flexion. Concentrically, the differences between conditions were likely of trivial consequence (< 5%). However, eccentrically amplitudes for the DB likely exceeded those of ELECTRO and VR by ~ 5% but < 10%. The findings suggest that the DB evokes slightly greater muscle excitation to the brachioradialis compared to the electromagnetic device conditions, more so during the eccentric actions. However, the magnitude of differences between conditions are relatively modest and of questionable practical significance.Only a few previous studies have compared sEMG amplitude in EO versus traditional modes of training with combined concentric/eccentric actions. Sarto et al.In regard to VR, multiple studies have investigated amplitudes using bands and chains versus traditional training modalitiesThe present study had several limitations that must be acknowledged. First, our findings are specific to a young, resistance-trained population and cannot necessarily be extrapolated to other populations including youth, untrained, and older individuals. Second, the advanced training methods investigated herein are specific to a computer algorithm applied under electromagnetic conditions. Thus, results cannot necessarily be extrapolated to other forms of variable resistance and eccentric overload. Third, the findings are specific to isolated elbow flexion exercise and thus cannot necessarily be generalized to multi-joint movements or exercises for other joints/muscles. Finally and importantly, although sEMG is frequently used to predict muscular adaptations over longitudinal resistance training programs, and some evidence suggests a potential association between sEMG amplitudes and changes in muscle cross-sectional area