HYPOTHALAMO-PITUITARY-ADRENOCORTICAL RESPONSE AFTER PROLONGED AND INTENSIVE TRAINING AND COMPETITION PERIODS:

807 To evaluate training-related alterations in the hypothalamo-pituitary-adrenocortical system as a possible indicator of overtraining and regeneration, we performed CRH stimulation tests in 7 junior amateur cyclists (age 17±1 yrs, height 179±2 cm, body mass 64±5 kg, VO2max 56±7 ml*kg⁁−1*min⁁−1) after a synchronisation cycle of 2 weeks (B; median 435 km*wk⁁−1, 50%ROC 226-561) following a hard and long-lasting training/competition season of 8 month, after 2 weeks of to 52 % reduced cycling volume (I), and after 3 more weeks of to 42 % reduced training (F) compared to B, respectively. Baseline resting ACTH (median 4.8 pmol × l⁁−1, 50%ROC 2.9-6.0) and cortisol levels (median 257 mmol × 1⁁−1, 50%ROC 229-441) were in the normal range with an appropriate release in the CRH stimulated pituitary-adrenal function test. After the first 2 weeks of only slight training reduction (I), cortisol release was only ∼50 % by over 70 % CRH release on an in total elevated level of these hormones. Only when the training volume was further reduced for 3 more weeks (F), ACTH and cortisol resting levels and release returned to similar values as at baseline. In conclusion, the organism seems to react to overload, which was also reflected by a reduced or stagnating performance in graded cycle ergometer tests and 10-km outdoor time trials, with hyposensitivity of target organs as a protection against possible damage. The duration necessary for recovery after prolonged and intensive training/competition periods should be rather more than 2 weeks than less with only low-intensity, low-volume activities.