Exercise, hypoalgesia and blood pressure.
A number of studies have indicated that exercise is associated with alterations in pain perception. In general, investigators have typically found a hypoalgesic response (i.e. diminished pain perception) to occur during and following exercise. It is currently unclear why exercise alters pain perception but some research indicates that there is an interaction between pain modulatory and cardiovascular systems. Elevated resting blood pressure (BP), such as hypertension, has been associated with reduced sensitivity to noxious stimulation. In addition, acute elevations in BP (pharmacologically) have also been associated with alterations in pain perception. Exercise elevates BP due to the physiological demands of the activity, but only a limited amount of research has been conducted examining the interaction between exercise, hypoalgesia and BP. Results from this research indicate that exercise significantly alters cardiovascular responses, and these alterations appear to be associated with alterations in pain perception. However, the interaction between exercise, pain perception and BP has been primarily examined indirectly. The mechanisms underlying the interaction between BP and pain perception are currently not entirely understood. It has been suggested that endogenous opioids may be involved in the interaction between BP and pain perception; however, results appear to be equivocal in the human research that has been conducted in this area. It has also been suggested that baroreceptor activation may play a role in the interaction between BP and pain perception.