Corollary discharges and perception of effort are dissociated during repeated sprints.

摘要

The thesis that perception of effort is independent of afferent feedback from skeletal muscles, heart, and lungs (3) during dynamic exercise challenges traditional views. It sustains that corollary discharges resulting from forwarding neural signals solely generate the sense of effort. However, results from studies involving repeated all-out sprints as exercise model raise some questions about this. Mean and peak power generated during 5- to 6-s sprints are decreased while performing 10-20 sprints interspersed by 10-30 s of passive rest (2, 4). This decrease in mechanical output is associated with significant decrease of surface electromyogram amplitude across the sprints (4), which can be linked to the motor neural drive. According to Marcora's thesis, the perception of effort should be progressively lower, because of the reduction in corollary discharges consequent to diminished muscle activation. It was not confirmed, as the perception of effort increased throughout the repeated sprints protocols (2). Therefore, other sensory cues must influence perception of effort, being multiple and dependent on the individual and task features. We are not precluding here the role of corollary discharges in determining the perception of effort increase during exercise, as during high-intensity continuous ones electromyogram amplitude increases linearly (1) with concomitant RPE increase (5). However, in certain tasks such as repeated sprints it does not seem to be main influence. In conclusion, more research is needed that adds to the understanding of physiological factors that modulate perception of effort in different tasks.