Similarities between exercise-induced hypoalgesia and conditioned pain modulation in humans.
Pain inhibitory mechanisms are often assessed by paradigms of exercise-induced hypoalgesia (EIH) and conditioned pain modulation (CPM). In this study it was hypothesized that the spatial and temporal manifestations of EIH and CPM were comparable. The participants were 80 healthy subjects (40 females), between 18 and 65 years of age in this randomized, repeated-measures cross-over trial that involved data collection on 2 different days. CPM was assessed by 2 different cold pressor tests (hand and foot). EIH was assessed by 2 intensities of aerobic bicycling exercises and 2 intensities of isometric muscle contraction exercises (arm and leg). Pressure pain thresholds (PPTs) were recorded before, during, after, and 15 minutes after conditioning/exercise at sites local to and remote from the extremity used for cold pressor stimulation and exercise. PPTs increased at local as well as at remote sites during both cold pressor tests and after all of the exercise conditions except low-intensity bicycling. EIH after bicycling was higher in women than in men. CPM and the EIH responses after isometric exercises were comparable in men and women and were not affected by age. The EIH response was larger in the exercising body part compared with nonexercising body parts for all exercise conditions. High-intensity exercise produced greater EIH responses than did low-intensity exercise. The change in PPTs during cold pressor tests and the change in PPTs after exercises were not correlated. The CPM response was not dominated by local manifestations, and the effect was seen only during the stimulation, whereas exercise had larger local manifestations, and the effects were also found after exercise.
Pain Center South, University Hospital Odense, Odense, Denmark Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
Henrik Bjarke
HB
Vaegter
Gitte
G
Handberg
Thomas
T
Graven-Nielsen
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D003080:Cold Temperature / Q000009:adverse effects; D003213:Conditioning, Psychological; D018592:Cross-Over Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation / Q000009:adverse effects; D011312:Pressure / Q000009:adverse effects; D013997:Time Factors; D055815:Young Adult
Conditioned pain modulation; Exercise-induced hypoalgesia; Experimental pain; Pressure-pain thresholds