Cardiac Responses to Exercise in Child Distance Runners

Abstract

Cardiovascular responses to exercise in trained endurance child athletes have been largely unexplored. Doppler echocardiography was utilized to compare cardiac variables during progressive upright cycle exercise to exhaustion in trained male prepubertal distance runners (n = 8) and untrained control boys (n = 14). Athletes demonstrated a greater maximal stroke index and cardiac index. Stroke volume rose progressively with increasing workloads in the runners but remained stable beyond low intensities in the non-athletes. No significant differences in stroke volume were observed between the two groups at rest. This contrasts with the greater resting stroke volumes typically seen in adult endurance athletes compared to non-athletes. Likewise, values for maximal stroke index were less in the child runners than those typically seen in trained adults. This study demonstrated that the stroke volume response to exercise differs in boy runners compared to non-athletes. The findings also suggest quantitative differences in such responses between prepubertal and young adult athletes.

Myocardial Response to Incremental Exercise in Endurance‐Trained Athletes: Influence of Heart Rate, Contractility and the Frank‐Starling Effect

“…The SV reached a slight plateau at around 110-130 beats min _1 in both the supine and upright positions, but at maximal exercise there was another rise in SV (predominantly owing to changes in EDV). These findings are similar to those reported for the SV response during upright exercise in male prepubertal distance runners (Rowland et al 1998), endurance-trained men (Gledhill et al 1994;Krip et al 1997;Warburton et al 1999a), endurance-trained women (Wiebe et al 1999) and semi-supine exercise in endurancetrained men (Di Bello et al 1996).…”

Differences in Cardiac Parameters among Elite Rowers and Subelite Rowers

“…First, the relative biventricular chamber enlargement, RV systolic function enhancement, and maximally efficient late diastolic filling may be innate characteristics of ER that predate exercise training and thus provide a selective advantage to perform at the highest level of this sport. Although prior data from childhood high-performers does not suggest that innate cardiac phenotype dictates success at a young age (24,25,33,34,38), longitudinal studies characterizing cardiac structure from childhood through to the adulthood time of peak performance are needed to address this possibility. The second and more likely explanation is that the characteristic findings in ER may be a direct function of the amount of exercise training, both in the short-term and over cumulative years, to which these individuals are exposed.…”

Influence of training status and exercise modality on pulmonary O2 uptake kinetics in pubertal girls

“…A higher peak _ VO 2 in trained children is largely attributable to an enhanced peak cardiac output consequent solely to an enhanced stroke volume as peak heart rates do not differ. The mechanistic basis of the higher peak stroke volume in trained children remains equivocal, with evidence to suggest both morphological (Ayabakan et al 2006;Nottin et al 2004;Obert et al 2009;Rowland et al 2009) and/or functional (Rowland et al 1998) differences according to training status. In the current study, the trained swimmers' peak _ VO 2 was 21 and 28% higher than the untrained girls during cycle and upper body ergometry, respectively.…”