CARDIAC RESPONSES TO EXERCISE IN CHILD DISTANCE RUNNERS

Cardiovascular responses to exercise in trained Endurance child athlet es have been largely unexplored. Doppler echocardiography was utilized to compare cardiac variables during progressive upright cycle exercis e to exhaustion in trained male prepubertal distance runners (n = 8) a nd untrained control boys (n = 14). Athletes demonstrated a greater ma ximal stroke index and cardiac index. Stroke volume rose progressively with increasing workloads in the runners but remained stable beyond l ow intensities in the non-athletes. No significant differences in stro ke volume were observed between the two groups at rest. This contrasts with the greater resting stroke volumes typically seen in adult endur ance athletes compared to non-athletes. Likewise, values for maximal s troke index were less in the child runners than those typically seen i n trained adults. This study demonstrated that the stroke volume respo nse to exercise differs in boy runners compared to non-athletes. The f indings also suggest quantitative differences in such responses betwee n prepubertal and young adult athletes.