The influence of physical and mental training on plasma beta-endorphin level and pain perception after intensive physical exercise
Oktedalen, O.; Solberg, E.E.; Haugen, A.H.; Opstad, P.K.
Stress and Health 17(2): 121-127
ISSN/ISBN: 1532-3005 DOI: 10.1002/smi.892
The intention of the study was to investigate a possible correlation between increase in circulating blood level of beta-endorphin and decrease in pain perception after short-term intensive physical exercise. In addition, we wanted to see if plasma beta-endorphin level and pain perception were influenced by regular physical or mental training and if there was any difference in response between trained and untrained subjects. Twenty physically trained males were studied before and after a 6-month intervention period while practising regular physical endurance training. Eleven of them were randomized to perform daily additional mental training (ACEM mediation). Nine untrained males served as control subjects and were investigated only at baseline. All participants were tested for maximum oxygen uptake (VO2 max) during treadmill exercise, and pain perception measured by an ischaemic pain test was performed just before and after VO2 max. Blood samples analysed for beta-endorphin were drawn before and after the tests. There was a substantial decrease of 47 per cent (p < 0.005) in basal plasma beta-endorphin level after the intervention. The plasma beta-endorphin level increased two-fold (p < 0.01) in response to the VO2 max test. The subjects experienced post-exercise hypoalgesia (p < 0.001), but there was no correlation between the exercise-associated opioid hyperendemia and the hypoalgesia. No difference was found between trained and untrained subjects regarding the circulating blood level of beta-endorphin or the exercise-induced hypoalgesia. Practising regular meditation had no influence on beta-endorphin level or pain tolerance level. Peripheral beta-endorphin level and pain perception are modulated by intensive physical exercise and by regular physical, but not by mental training. It could be speculated that the observed initial high basal level of beta-endorphin is due to pre-experimental stress and tension.