The Relationship Between Motor Control of Lower Limb Muscles and EMGT During Incremental Pedaling Exercise

The present study investigated the change in motor control of lower limb muscles during the incremental cycling exercise by evaluating motor modules extracted from electromyography (EMG) measured before and after electromyography threshold (EMGT). 10 male cyclists performed 10 minutes of continuous incremental pedaling exercise. Cadence and exercise intensity were 90 rpm and 110 W at the start of the exercise, adding 10 W every 30 seconds, respectively. During the exercise, we measured 9 lower limb muscles’ EMG. Then we performed non-negative matrix factorization on EMG matrix to extract the motor modules and cluster analysis using EMG reconstruction accuracy vectors, which indicate the feature quantities of each module set, to evaluate the similarity among module sets extracted from different exercise intensities. As a result, at the exercise intensities above EMGT, the new motor module that is not mobilized below EMGT was activated. The EMG reconstruction accuracy vectors were distributed to different clusters whose borderline was fixed up bordering on EMGT. The above indicates that the rapid increase of EMG amplitude, which is the landmark of EMGT, may result from the change in motor control of lower limb muscles.