Vægter, Henrik Bjarke1; Handberg, Gitte4; Graven-Nielsen, Thomas3
1 Department of Health Science and Technology, The Faculty of Medicine, Aalborg University, VBN2 Center for Sensory-Motor Interaction, The Faculty of Medicine, Aalborg University, VBN3 The Faculty of Medicine, Aalborg University, VBN4 unknown
Pain inhibitory mechanisms are often assessed by paradigms of exercise-induced hypoalgesia (EIH) and conditioned pain modulation (CPM). In this study it was hypothesised that the spatial and temporal manifestations of EIH and CPM were comparable. Eighty healthy subjects (40 females), between 18-65 years participated in this randomized repeated-measures crossover trial with data collection on two different days. CPM was assessed by two different cold pressor tests (hand,foot). EIH was assessed through two intensities of aerobic bicycling exercises and two intensities of isometric muscle contraction exercises (arm,leg). Pressure pain thresholds (PPTs) were recorded before, during, after, and 15 min after conditioning/exercise, at sites local and remote to the extremity used for cold pressor stimulation and exercise. PPTs increased at local as well as remote sites during both cold pressor tests and after all of the exercise conditions, except low intensity bicycling. EIH after bicycling was increased in women compared to men. CPM and the EIH response after isometric exercises were comparable in men and women and not affected by age. The EIH response was larger in the exercising body part compared with non-exercising body parts for all exercise conditions. High intensity exercise produced larger EIH response compared with low intensity exercise. The change in PPTs during cold pressor test and the change in PPTs after exercises were not correlated. The CPM response was not dominated by local manifestations and the effect was only seen during the stimulation, whereas exercise had larger local manifestations and the effects were also found after exercise.