INFLUENCE OF GENDER AND MATURATION ON THE STROKE VOLUME RESPONSE TO EXERCISE IN CHILDREN

Abstract

The purpose of this study was to determine the influence of gender and stage of maturation on the stroke volume (SV) response to exercise in healthy children. Sixty boys and 61 girls aged 8–17 years were recruited. Stage of maturation was based on Tanner stages of public hair development. Children were classified as prepubertal (PRE, Tanner 1), peripubertal (PERI, Tanner 2 and 3) or pubertal (PUB, Tanner 4 and 5). Heart rate (ECG) and stroke volume (impedance cardiography) were measured continuously during supine and upright rest and during a progressive cycle exercise test to exhaustion. Oxygen consumption was measured throughout exercise. As expected, PUB children were (p < 0.01) older, taller, and heavier compared to PERI children who had higher values than PRE children. PRE and PERI girls were younger (p < 0.01) than PRE and PERI boys, respectively. Peak oxygen consumption relative to body weight did not change significantly with maturation in boys or girls, and only PUB boys had higher (p < 0.05) values than PUB girls. Relative to upright rest values, SV increased to 40% of peak VO2max in PRE, PERI and PUB girls, to 60% of peak VO2max in PRE and PERI boys, and to 90% of peak VO2max in PUB boys. The capacity to increase SV during exercise increased with maturation and at each stage of maturation boys increased SV more than girls (PRE 19% vs 13%; PERI 31% vs 26%; PUB 42% vs 31%). Only PUB boys increased SV significantly (p < 0.05) above supine resting levels during exercise. These data indicate that the capacity to increase SV during exercise is influenced by the stage of maturation and the gender of the child.