Fear of movement is associated with corticomotor depression in response to acute experimental muscle pain.

Acute musculoskeletal pain is associated with reductions in corticomotor output that persists even after pain resolves. Factors that contribute to corticomotor depression following acute pain are unknown. This study examined whether psychological factors, including pain catastrophising, kinesiophobia, and implicit theories of pain, were associated with corticomotor depression following acute experimental muscle pain. Forty-two healthy individuals participated. Participants completed three questionnaires: Pain Catastrophising Scale, Tampa Scale of Kinesiophobia, and Implicit Theories of Pain Scale. Acute pain was induced into the right extensor carpi radialis brevis (ECRB) muscle by injection of hypertonic saline. Corticomotor depression was assessed as a reduction in motor-evoked potentials measured from ECRB muscle in response to transcranial magnetic stimulation before, immediately after, and at 10, 20, and 30 min following pain resolution. Corticomotor depression was present at each time point relative to baseline (p < 0.001). Higher levels of kinesiophobia were associated with less corticomotor depression 10-min post pain resolution (r = 0.32, p = 0.03), but not at any other time point (p > 0.11). When corticomotor depression was compared between individuals with 'high' and 'low' kinesiophobia, a similar relationship was observed: Individuals with high compared to low kinesiophobia displayed less corticomotor depression immediately after (p = 0.02) and 10 min post pain (p = 0.02), but not at 20 or 30 min (p = 0.05 for both). No relationship was observed with any other psychological variable (p > 0.15). These data provide preliminary support for a relationship between pain-related fear of movement and corticomotor depression in response to acute pain. These findings may have implications for clinical musculoskeletal pain disorders.