High‐density electromyography activity in various hamstring exercises

Abstract

Proximal-distal differences in muscle activity are rarely considered when defining the activity level of hamstring muscles. The aim of this study was to determine the inter-muscular and proximal-distal electromyography (EMG) activity patterns of hamstring muscles during common hamstring exercises. Nineteen amateur athletes without a history of hamstring injury performed 9 exercises, while EMG activity was recorded along the biceps femoris long head (BFlh) and semitendinosus (ST) muscles using 15-channel high-density electromyography (HD-EMG) electrodes. EMG activity levels normalized to those of a maximal voluntary isometric contraction (%MVIC) were determined for the eccentric and concentric phase of each exercise and compared between different muscles and regions (proximal, middle, distal) within each muscle. Straight-knee bridge, upright hip extension, and leg curls exhibited the highest hamstrings activity in both the eccentric (40%-54%MVIC) and concentric phases (69%-85%MVIC). Hip extension was the only BF-dominant exercise (Cohen's d = 0.28 (eccentric) and 0.33 (concentric)). Within ST, lower distal than middle/proximal activity was found in the bent-knee bridge and leg curl exercises (d range = 0.53-1.20), which was not evident in other exercises. BFlh also displayed large regional differences across exercises (d range = 0.00-1.28). This study demonstrates that inter-muscular and proximal-distal activity patterns are exercise-dependent, and in some exercises are affected by the contraction mode. Knowledge of activity levels and relative activity of hamstring muscles in different exercises may assist exercise selection in hamstring injury management.

Late swing or early stance? A narrative review of hamstring injury mechanisms during high‐speed running

“…In comparison with the rest of the gait cycle, the magnitude of excitation in late swing has been reported as two to three times greater than during early swing and late stance, and the excitation during early stance is significantly greater than during late stance . In addition, studies of strength training exercises have demonstrated differences in proximal to distal regional excitation of the hamstring muscles during exercises such as the Nordic hamstring exercise, stiff‐leg deadlift, bent‐knee bridge, prone leg curl, and sliding leg curl . While differences in regional muscle excitation have not yet been investigated during high‐speed running, it is likely that this could provide further insight into muscle function and potential injury mechanisms, as injuries often primarily affect one region (the proximal musculo‐tendinous junction) …”

“…37 In addition, studies of strength training exercises have demonstrated differences in proximal to distal regional excitation of the hamstring muscles during exercises such as the Nordic hamstring exercise, stiff-leg deadlift, bent-knee bridge, prone leg curl, and sliding leg curl. [42][43][44][45] While differences in regional muscle excitation have not yet been investigated during high-speed running, it is likely that this could provide further insight into muscle function and potential injury mechanisms, as injuries often primarily affect one region (the proximal musculo-tendinous junction). 46…”

Eccentric Resistance Training in Youth: Perspectives for Long-Term Athletic Development

“…Despite this, as presented in Table 1, the use of eccentric muscle actions does not appear to place the youth athlete at greater risk of muscle damage than adults. Appropriate NHE prescription as well as other exercises that develop eccentric hamstrings strength [238][239][240] should be permissible in youth. Indeed, the NHE should form part of a holistic injury prevention program within youth to ensure that the hamstrings receive the specialist consideration that they require throughout youth [241].…”

Wireless Epidermal Electromyogram Sensing System

“…Furthermore, the noise they induce from the movement is severe, resulting in poor signal acquisition characteristics. For this reason, conventional EMG sensors require the application of foam tape or conductive gel to the adhesive surface of the devices to complement the adhesion property and signal acquisition performance of the skin to ensure the practical level of sensor capabilities [60][61][62][63][64][65]. One clear limitation of current technologies is the fact that the devices can only be used once, and not repeatedly.…”