STEROID AND PITUITARY-HORMONE RESPONSES TO ROWING - RELATIVE SIGNIFICANCE OF EXERCISE INTENSITY AND DURATION AND PERFORMANCE-LEVEL

To analyse the relative significance of exercise intensity and duratio n as well as of performance capacity, hormone changes were recorded in 16 male rowers in two experiments separated by a year. The test exerc ises consisted of 7-min (at the supramaximal intensity) and 40-min row ing (at the level of the anaerobic threshold) on a rowing apparatus. I n addition, somatotropin and cortisol responses were estimated in rowi ng for 8 x 2000 m in 14 rowers of national class. All three tests caus ed significant increases in somatotropin and cortisol concentrations i n the blood. Follitropin concentrations were elevated in the 7-min exe rcise test in the second experiment and in the 40-min exercise test in both experiments. Lutropin and progesterone concentrations increased during the more prolonged exercise in the first experiment. No common change was found in testosterone concentrations. Cortisol and somatotr opin responses to the 40-min rowing test at anaerobic threshold were m ore pronounced than to the 7-min exercise test at supramaximal intensi ty. When the rowers achieved a national class level of performance (th e second experiment) the hormone responses to 7-min supramaximal exerc ise were increased. During the 8 x 2000-m rowing test cortisol but not somatotropin concentration increased to an extremely high level in th e rowers of national class. It is concluded that in strenuous exercise cortisol and somatotropin responses were triggered by the exercise in tensity threshold. The exact magnitude of the response would seem to h ave depended on additional stimuli caused by exercise duration and on possibility of mobilizing hormone reserves.