Quantification of Global Myoelectric Spatial Activations to Delineate Normal Hamstring Function at Progressive Running Speeds: A Technical Report

Abstract

Schlink, BR, Nordin, AD, Diekfuss, JA, and Myer, GD. Quantification of global myoelectric spatial activations to delineate normal hamstring function at progressive running speeds: A technical report. J Strength Cond Res 36(3): 867–870, 2022—Hamstring function is critical to maintain sport performance, and strain injuries to the biceps femoris muscle commonly force an athlete to withdraw from their sport while the muscle heals. Current mechanistic understanding of underlying injury and return-to-play (RTP) guidelines has limited prognostic value because of limitations in technology and nonfunctional assessment strategies to guide clinical care. Integrated structural and functional determinants and dynamic assessment methods are needed to guide advanced rehabilitation strategies for safe and rapid return to sport. A potential solution for assessment of hamstring function is high-density electromyography (EMG), which can noninvasively measure spatial muscle activity in dynamic environments. In this study, we demonstrated the utility of high-density EMG by measuring spatial myoelectric activity from the biceps femoris from a group of recreational athletes running at a range of speeds. The level of significance set for this study was p < 0.05. During the late swing phase of running, we observed increased EMG amplitudes in the central and distal portions of the muscle. There were no changes in this pattern of EMG activation across speed, suggesting that running speed does not affect the general neuromuscular recruitment in the biceps femoris. Applying these methods to athletes with hamstring strains may lead to a more complete understanding of muscle function during rehabilitation and adjunctively support current methods to enhance RTP decision-making.

Activity distribution among the hamstring muscles during high‐speed running: A descriptive multichannel surface EMG study

“…Hamstring muscle activity during high‐speed running was previously assessed with multichannel EMG for the biceps femoris long head and semitendinosus 23,25 . These two studies investigated primarily the effect of running speed on the amplitude of normalized muscle activity within each muscle 23,25 . One of these studies reported within hamstring muscle activity distribution as a sub‐analysis 25 .…”

“…23,25 These two studies investigated primarily the effect of running speed on the amplitude of normalized muscle activity within each muscle. 23,25 One of these studies reported within hamstring muscle activity distribution as a subanalysis. 25 In contrast to our findings, no differences were found among three regions within the biceps femoris long head and semitendinosus, when comparing muscle activity over a stride cycle during high-speed running.…”

“…25,27 Running speed seems to have an influence on both the amplitude and timing of muscle activity: Amplitude increases with increasing running speed, 25,28 and at near maximum running speed, peak activity of the biceps femoris long head compared to the semitendinosus is delayed. 28 While the amplitude of muscle activity within individual hamstring muscles can be heterogeneous, [23][24][25][26] it is unknown whether regional peaks of this amplitude within individual muscles occur at the same hip and knee joint angles. A better understanding of peak muscle activation patterns within and between hamstring muscles is required to provide more insight into the etiology of hamstring injuries.…”

“…It has previously been reported that activation patterns differ both within and between the biceps femoris long head and semitendinosus during high‐speed running and various exercises 23–26 . On average, peak muscle activity during high‐speed running occurs in the late‐swing phase, yet muscle activation patterns between hamstring muscles differ substantially between athletes 25,27 .…”

“…It has previously been reported that activation patterns differ both within and between the biceps femoris long head and semitendinosus during high-speed running and various exercises. [23][24][25][26] On average, peak muscle activity during high-speed running occurs in the late-swing phase, yet muscle activation patterns between hamstring muscles differ substantially between athletes. 25,27 Running speed seems to have an influence on both the amplitude and timing of muscle activity: Amplitude increases with increasing running speed, 25,28 and at near maximum running speed, peak activity of the biceps femoris long head compared to the semitendinosus is delayed.…”