Effect of movement‐evoked and tonic experimental pain on muscle force production

Abstract

IntroductionWhen performing an exercise or a functional test, pain that is evoked by movement or muscle contraction could be a stronger stimulus for changing how individuals move compared to tonic pain. We investigated whether the decrease in muscle force production is larger when experimentally‐induced knee pain is directly associated to the torque produced (movement‐evoked) compared to a constant painful stimulation (tonic).MethodsTwenty‐one participants performed three isometric knee extension maximal voluntary contractions without pain (baseline), during pain, and after pain. Knee pain was induced using sinusoidal electrical stimuli at 10 Hz over the infrapatellar fat pad, applied continuously or modulated proportionally to the knee extension torque. Peak torque and contraction duration were averaged across repetitions and normalized to baseline.ResultsDuring tonic pain, participants reported lower pain intensity during the contraction than at rest (p < 0.001), whereas pain intensity increased with contraction during movement‐evoked pain (p < 0.001). Knee extension torque decreased during both pain conditions (p < 0.001), but a larger reduction was observed during movement‐evoked compared to tonic pain (p < 0.001). Participants produced torque for longer during tonic compared to movement‐evoked pain (p = 0.005).ConclusionOur results indicate that movement‐evoked pain was a more potent stimulus to reduce knee extension torque than tonic pain. The longer contraction time observed during tonic pain may be a result of a lower perceived pain intensity during muscle contraction. Overall, our results suggest different motor adaptation to tonic and movement‐evoked pain and support the notion that motor adaptation to pain is a purposeful strategy to limit pain. This mechanistic evidence suggests that individuals experiencing prevalently tonic or movement‐evoked pain may exhibit different motor adaptations, which may be important for exercise prescription.

Relationship between strength training and shoulder pain in male and female water polo players

“…Briefly, the greater the load of strength work, the greater the shoulder pain, which also negatively affects the perception of accumulated fatigue. A direct association has been observed between increased muscle force production and increased pain intensity ( Cabral et al, 2023 ). Besides, the accumulation of pain can increase the effort sense ( Hollander et al, 2008 ).…”

Moving in pain ‐ A preliminary study evaluating the immediate effects of experimental knee pain on locomotor biomechanics

“…A limitation of this method is habituation with repeated or constant stimulation [ 25 ], but it appears this can be mitigated in the short term by using low frequency sinusoids [ 21 , 24 , 26 ]. Two recent studies have demonstrated that these low frequency sinusoidal stimulation protocols can induce moderate knee pain along with observable neuromuscular and mechanical adaptions [ 24 , 27 ]. However, these studies were performed in static conditions (standing, seated), so it unknown if these findings extend to dynamic conditions like locomotion.…”