Effect of long-term intense swimming training on the upper body peak oxygen uptake of prepubertal girls

Abstract

The purpose of the present investigation was to determine the effect of a long-term intense swimming programme on the aerobic potential of prepubertal girls. Five girls [GS, aged 9.3 (SD 0.5) years] participated in a 10-month intense training period. The girls trained on average 10–12 h · week⁻¹, approximately 1 h-1.5 h twice a day, 5 days each week. Nine girls [CG aged 9.3 (SD 0.4) years] who were engaged in various activities (on average 1–4 h · week⁻¹, but not in sports involving upper body muscle mass, served as the control group. All the children completed, on a special swim bench, an incremental maximal exercise prior to (pretest) and after (post-test) the swimming programme. Biometric parameters and the peak oxygen uptake ($\dot V{\text{O}}_{{\text{2peak}}}$) were determined using the same procedure at the pre- and post-test sessions. There was no significant difference between the two groups for any of the variables at the beginning of the study. The biometric characteristics remained similar at the post-test session, indicating that intense swimming training early in life has no influence on the physical growth of prepubertal children. The $\dot V{\text{O}}_{\text{2}}$ peak expressed in absolute values, however, increased over a year in GS and CG by 38% and 13%, respectively. The improvement in CG $\dot V{\text{O}}_{{\text{2peak}}}$ was related to normal growth and development while that of GS was much higher (P<0.01) than would have been expected due to growth factors alone. The reason for such an improvement could be attributed to an increase in the stroke volume and/or in the difference of the arteriovenous concentration of oxygen since the maximal O₂ pulse was different between CG and GS only at the post-test. Moreover, it increased after 10 months only in GS (Δ maximal O₂ pulse: GS 1.09, P < 0.01; CG 0.27 NS, ml · beat⁻¹). Thus, the results of this study show that physiological adaptations can occur in prepubertal children as a consequence of intense physical training.