Abstract

The aims of this investigation were to determine the corticotrophin (ACTH) and endorphin (END) responses to a single bout of competitive swimming exercise and to examine the relationship between them. Plasma ACTH and ENDs concentrations were determined in 13 male swimmers at three time points: basal conditions, and before and after swimming competition (100 m freestyle). The results showed an END response to precompetition stress, since an increase in END plasma levels was observed (from 36.3±2.9 pg/ml assessed in basal conditions to 51.8±3.2 pg/ml, p≤0.01). However, ACTH plasma levels remained unchanged at this time-point (10.1±0.9 pg/ml and 10.9±1.2 pg/ml for basal conditions and precompetition respectively). After competitive swimming effort ACTH and END levels rose significantly, reaching values of 39.4±5.2 pg/ml and 128.6±18.1 pg/ml for ACTH and END, respectively, and showing statistical differences with precompetition (p≤0.001) and basal condition levels (p≤0.001). Significant correlations were found between ACTH and END levels both in precompetition (r=0.647; p≤0.05) and in postcompetition (r=0.725; p≤0.01). It is concluded that single bout of competitive swimming induces a psychological and physiological stress which stimulates the same pattern of response for ACTH and END.