The purpose of the present study was to investigate the relationship between muscle fatigue and hormonal responses in maximal repetitive sprinting. Ten active male Sprinters performed a maximal intensity sprint exercise session (10 x 50m with four minute recoveries). Blood samples were taken at rest and before and after the exercise session to measure circulating hormonal and lactate (LA) concentrations. The maximal isometric voluntary contraction force (MVC) of the knee extensor muscles and average electromyographic (aEMGmax) activity were determined before and immediately after the exercise session. The running velocity in the last sprint of the exercise session decreased (1.7% (SD 0.8), p<0.01) compared to the velocity of the fastest sprint. The LA peak value immediately after the session was 13.8/mmol (SD 2.1). MVC decreased (7.7% (SD 5.2), p<0.001) after the session, but there were no changes in aEMGmax. Those individuals who had the strongest decline in MVC also had the highest increases in circulating noradrenaline and growth hormone (r=-0.77, p<0.01 and r=-0.75, p<0.05). The noradrenaline and adrenaline concentration increases correlated with the growth hormone increase (r=0.83, p<0.01 and r=0.80, p<0.01) and the noradrenaline increase correlated also with the cortisol increase (r=0.69, p<0.05). The results of the present study suggest a role for local metabolic factors in mediating parallel both the sympathoadrenal and pituitary secretion in this type of lactic exercise.
© Copyright 2005 Journal of Human Movement Studies. Teviot-Kimpton. Veröffentlicht von Teviot Scientific Publications. Alle Rechte vorbehalten.