Exercise-induced muscle soreness impairs the efficiency of proprioceptive integration and body representation processing.

Delayed-onset muscle soreness (DOMS), occurring 24-72 h postexercise, is characterized by pain and decreased force production. Recent evidence suggests DOMS may result from damage to muscle spindle afferents rather than to muscle fibers. We hypothesized that this type of disruption impairs the central integration of proprioceptive inputs, reducing the efficiency of body-related motor imagery. In a controlled study, young sports science students were assigned to a DOMS group (n = 47)-induced by whole body eccentric exercises-or a control group (n = 47). All participants then performed mental rotation tasks; for the DOMS group, this assessment took place 48 h postexercise. The stimuli took the form of body images (arms and legs), and there was also a control condition involving nonbody images (the number "2"). Response times and accuracy were measured. Accuracy in motor imagery tasks was unaffected by DOMS, indicating preserved body representations. However, participants with DOMS responded more slowly than control participants to the arm images (trend, P = 0.06; 1,189.3 ± 51.1 ms vs. 1,044.7 ± 42.7 ms, respectively) and leg images (P = 0.03; 1,280.2 ± 65.5 ms vs. 1,121.5 ± 42.3 ms, respectively), whereas no significant difference was observed for the number images (P = 0.55; 792.9 ± 29.5 ms vs. 831.2 ± 25.7 ms, respectively). This selective slowing suggests that DOMS transiently reduces the efficiency, but not the accuracy, of proprioceptive-motor integration. These results suggest that acute muscle soreness imposes a measurable computational cost on the sensorimotor system, requiring participants to mobilize time-consuming internal models to maintain representational accuracy in the face of peripheral proprioceptive noise.NEW & NOTEWORTHY This study demonstrates that exercise-induced muscle soreness selectively impairs the efficiency of proprioceptive integration during body-related motor imagery, but without affecting global cognitive performance. By revealing how temporary peripheral disturbances alter internal sensorimotor representations, these findings provide new insights into the neural mechanisms of sensorimotor integration. This work highlights the functional consequences of acute muscle soreness for motor planning and offers a framework for understanding how the nervous system adapts to temporary proprioceptive disruption.