BackgroundExercise training induces cardiovascular changes that are both generalized and restricted to the microcirculation of the tissues more actively involved in the exercise itself. Whether the local effect of exercise extends to larger arteries is unknown, however.MethodsIn the right and left upper limb of 17 right-handed subjects performing an asymmetric training of the upper limbs (hammer throwers and baseball players) and 16 age-matched sedentary controls, we continuously measured radial artery diameter, distensibility and wall thickness by an echotracking and a beat-to-beat finger blood pressure device. Arterial distensibility was calculated by the arctangent model of Langewouters and expressed as continuous values from diastolic to systolic blood pressure. Measurements were made: (1) in baseline conditions; (2) after release from prolonged proximal ischaemia; and (3) after an increase in radial artery blood flow caused by a short (4 min) distal ischaemia to determine the endothelial involvement in the training-induced change in arterial distensibility.ResultsIn athletes the radial artery distensibility was markedly greater in the right than in the left arm, the latter showing values slightly greater than those seen in the two arms of sedentary subjects. In both arms and groups radial artery distensibility increased markedly after prolonged ischaemia, the between arm and group differences being preserved, however. The radial artery response to distal short ischaemia was, on the other hand, similar in the two arms of the athletes, although greater in these subjects than in the sedentary ones. Radial artery wall thickness was greater in the trained than in the untrained arm of athletes, both values being greater than in sedentary subjects.ConclusionsAsymmetrical training of the upper limbs is accompanied by a greater distensibility of the middle-sized arteries of the more trained side. This is not associated with asymmetrical changes in endothelial structure or function. It is associated with a greater wall thickness in the trained side, suggesting that, at least in part, a training-induced asymmetrical change in wall structure (possibly with a predominance of more distensible tissues such as elastine and smooth muscle) is responsible.