Cardiovascular adaptations to training may include changes in arterial distensibility, although studies involving sick and healthy individuals have yielded contradictory results. Moreover, despite the fact that endurance training frequently begins in childhood, its influence on arterial distensibility is less well characterised in children. This study was therefore to compare the upper limb pulse wave velocity (PWVUL) in highly trained prepubertal swimmers and age-matched moderately active counterparts, with that in swimmers and sedentary adults. The aim was to investigate the effects of maturation and training status on PWVUL in healthy individuals. PWVUL was evaluated by a dedicated continuous wave Doppler and photoplethysmography system. We calculated the pressure-corrected index of distensibility (Cp) which provides a measure of intrinsic structural compliance of the artery wall. PWVUL was significantly higher in highly trained child swimmers compared to moderately active ones (6.17+/-0.49 versus 5.20+/-0.38 ms(-1), P <0.05) even when mean arterial pressure was fixed as a covariate. Cp was significantly lower in child swimmers than in moderately active ones (0.15+/-0.03 versus 0.18+/-0.04, P <0.05 respectively) whereas Cp was not significantly different in either adult group. The PWVUL and Cp values of child swimmers were similar to those of adults.
Conclusion: Our results confirmed an increase in pulse wave velocity with maturation implying that compliance decreases with age. An unexpected result was that swimming training performed in children over a long period led to an increase in upper limb pulse wave velocity. This change, concerning the upper limbs which are strongly involved in swimming, may be related to enhanced smooth muscle content of the arterial wall, possibly due to intermittent elevations in arterial blood pressure during repetitive swimming exercise sessions. Whether adaptations to intensive swimming training are accompanied by alterations of the cardiovascular system in prepubertal children is an important question to be dealt with in further studies.