Hormonal Response to Incremental and Continuous Exercise in Cyclists with Left Ventricle Hypertrophy

The aim of this study was to assess the effects of incremental and continuous exercise on the concentration of insulin-like growth factor-1 (IGF-1), growth hormone (GH), testosterone (T), and cortisol (C), as well as to investigate whether increased cardiac dimensions in cyclists were related to changes in these hormones and cardiac biomarkers. The study included 30 elite cyclists divided into two groups, i.e., athletes with left ventricle hypertrophy (a LVH group), and a control group (CG) without LVH. The study protocol included performance of a standard incremental exercise (IncEx) test to measure athletes’ maximum power (Pmax), maximum oxygen uptake (VO2max), and lactate threshold (LAT). The IncEx test results were then used to determine the intensity of the continuous exercise (ConEx) test which was performed after the 1-week washout period. Cyclists with LVH and without LVH did not differ in resting hormone concentrations and cardiac biomarkers levels. There was a significant effect of exercise on serum IGF-1 levels (p < 0.05) in the LVH group and a combined effect of the type of exercise and LVH on IGF-1 (p < 0.05). Cyclists with LVH demonstrated higher post exercise T levels recorded in response to exercise compared to the CG (p < 0.01). Significantly higher serum T levels were observed in response to ConEx compared to IncEx in the LVH group and the CG (p < 0.05 and p < 0.05, respectively). In the LVH group, a significant positive correlation between the post-exercise T/C ratio and left ventricular mass index was observed (r = 0.98, p < 0.01). There were no effects of heart hypertrophy on cardiac standard biomarkers. Incremental and continuous exercise caused a marked increase in steroid hormone concentrations and moderate strengthening of insulin growth factors effects. Regular incremental exercise seems to induce beneficial cardiac adaptations via significant increases in the concentration of anabolic factors compared to the same training mode yet with constant exercise intensity.