Flow-mediated dilation and exercise-induced hyperaemia in highly trained athletes: comparison of the upper and lower limb vasculature.

AIM: The main purpose of the present study was to assess whether similar vascular adaptive changes could be obtained by long-term intensive training involving predominantly either the lower or the upper limb musculature.
METHODS: In 11 cyclists (C), 10 swimmers (S) and 10 sedentary controls (Sed), duplex Doppler ultrasonography was used to measure post-occlusion endothelium-dependent flow-mediated dilation (FMD), endothelium-independent, glycerine trinitrate-induced dilation (GTND) and exercise-induced blood flow changes in the arm (axillary artery) and leg (superficial femoral artery). Limb-specific exercise was achieved by one elbow-flexion or one leg-extension maximal exercise test, thereby allowing assessment of upper and lower limb muscle perfusion, vascular conductance and vasodilatory capacity of resistance vessels during effort.
RESULTS: C and S exhibited vascular remodelling associated with improved FMD and GTND in the predominantly trained limbs compared to Sed. Both showed greater muscle perfusion and vascular conductance than Sed during isolated exercise involving the predominantly trained musculature. C showed also higher FMD in the brachial artery and greater peak muscle perfusion and conductance in the non-exercising muscles, whereas S presented only enhanced FMD in the superficial femoral artery.
CONCLUSION: Therefore, in the upper as well as in the lower limb vasculature, repetitive exposure to increased shear stress over a long-term period results in improved FMD of large conduit arteries as well as greater vasodilatory capacity during isolated exercise in the predominantly trained muscles. Long-term training involving predominantly the lower limbs also results in enhanced vascular reactivity in upper limb conduit and resistance vessels.