• Ashley Smith, Carrie Ritchie, Jacelle Warren, and Michele Sterling.
• School of Allied Health Sciences, Griffith University, Gold Coast.
• Clin J Pain. 2020 Aug 1; 36 (8): 601-611.

ObjectivesExercise-induced hypoalgesia (EIH) can be impaired in patients with chronic pain and may be dependent on exercise type. Factors predictive of EIH are not known. This study aimed to: (1) compare EIH in participants with chronic whiplash-associated disorders (WAD) to asymptomatic controls, (2) determine if EIH differs between aerobic and isometric exercise, (3) determine predictors of EIH.Materials And MethodsA pre-post study investigated the effect of single sessions of submaximal aerobic treadmill walking and isometric knee extension on EIH in 40 participants with chronic WAD and 30 controls. Pressure pain thresholds were measured at the hand, cervical spine, and tibialis anterior. Pain intensity, reported previous week physical activity, temporal summation, and conditioned pain modulation (CPM) were measured at baseline.ResultsParticipants with WAD demonstrated impaired EIH. Although, the WAD participants demonstrated a partial EIH response (EIH induced at the hand during exercise), no EIH response was found immediately after exercise. There was no difference in EIH between exercise types. In the WAD group, moderate physical activity levels predicted EIH at the hand and high physical activity levels predicted impaired EIH at the neck. More efficient CPM predicted EIH at the hand and less efficient CPM predicted impaired EIH at the neck. These associations were found for isometric exercise only.DiscussionIndividuals with chronic WAD have impaired EIH with both aerobic and isometric exercise. Higher levels of physical activity and less efficient CPM may be associated with impaired EIH. This may have implications for exercise prescription in this patient group.

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