Beta-endorphin and adrenocorticotropic hormone production during marathon and incremental exercise

To evaluate the increases in concentration of beta-endorphin and adrenocorticotropic hormone (ACTH) 16 healthy athletes, well-trained for endurance exercise, volunteered for an exhausting incremental graded treadmill exercise and a marathon run. Maximum oxygen uptake was determined during the treadmill exercise. Venous blood samples were drawn before and after exercise, and at 30, 60 and 120 min during the recovery phase. For the marathon race venous blood was collected before, after 1 and 2 h of running and at the end, as well as at 0.5, 1, 2 and 24 h during the recovery phase. Lactate concentration, heart rate and perceived exertion were also determined at all points of blood collection. Both types of exercise led to significant increases in concentration of beta-endorphin and ACTH of similar magnitude, with beta-endorphin tending to be higher after the marathon run. The decrease of both was slower during the recovery from the marathon than after the incremental test. Concentrations of both hormones increased exponentially during the marathon run. Positive correlations between beta-endorphin and ACTH concentrations were determined at the end of both runs. It was found that incremental exhausting and prolonged exhausting endurance exercise such as marathon running induced an increase of similar magnitude in both beta-endorphin and ACTH concentration.