BETA-ENDORPHIN AND ADRENOCORTICOTROPIN AFTER INCREMENTAL EXERCISE ANDMARATHON RUNNING - FEMALE RESPONSES

Investigations of exercise-induced increases in beta-endorphin, adreno corticotropic hormone (ACTH) and cortisol concentration have been carr ied out mainly in men. Data concerning the female reaction are sparse and less clear. In a comparison between incremental exercise and marat hon running 14 experienced female marathon runners volunteered to run to exhaustion according to an incremental treadmill protocol. They ran a marathon 4 weeks later. Blood was analysed for beta-endorphin, ACTH and cortisol concentration immediately prior to the laboratory treadm ill test, 3, 30 and 60 min later, as well as prior to the marathon, af ter 60 min and 120 min of running and 3, 30 min, and 24 h after comple tion of the run. At each blood collection, lactate concentration, hear t frequency and perceived exertion were determined. The mean marathon running time was 3.22 h. Baseline concentrations for beta-endorphin of 22 pmol . l(-1) before the marathon and 19 pmol . l(-1) before the tr eadmill exercise increased 1.4-fold 30 min after the marathon and 1.9- fold after the treadmill exercise; for ACTH the baseline of 4.7 and 4. 0 pmol . l(-1) was increased by 8.3- and 10.3-fold, respectively. Cort isol concentration rose exponentially from a baseline 17 mu g . dl(-1) and peaked at 2.2-fold 30 min after the run, when the maximal concent ration also had been reached after the treadmill test, increasing 1.3- fold from a baseline of 21 mu g . dl(-1). The maximal values for corti sol concentration after both exercises differed from each other, while the maxima of ACTH and beta-endorphin concentrations were similar. Th e ACTH and beta-endorphin concentration declined more slowly during th e recovery after the marathon than after the treadmill. Cortisol conce ntration was below baseline 24 h later. In comparison with men studied earlier, female marathon runners showed higher baseline concentration s and lesser increases in beta-endorphin and lower baseline concentrat ions and larger increases in ACTH concentration after both types of ex ercise. The delayed decrease in concentration of the hormones after th e marathon was similar in male and female runners.