Exercise and arterial adaptation in humans: uncoupling localized and systemic effects

Previous studies have established effects of exercise training on arterial wall thickness, remodeling, and function in humans, but the extent to which these changes are locally or systemically mediated is unclear. We examined the brachial arteries of the dominant (D) and nondominant (ND) upper limbs of elite racquet sportsmen and compared them to those of matched healthy inactive controls. Carotid and superficial femoral artery responses were also assessed in both groups. High-resolution duplex ultrasound was used to examine resting diameter, wall thickness, peak diameter, and blood flow. We found larger resting arterial diameter in the preferred arm of the athletes (4.9 ± 0.5 mm) relative to their nonpreferred arm (4.3 ± 0.4 mm, P < 0.05) and both arms of control subjects (D: 4.1 ± 0.4 mm; ND: 4.0 ± 0.4, P < 0.05). Similar limb-specific differences were also evident in brachial artery dilator capacity (5.5 ± 0.5 vs. 4.8 ± 0.4, 4.8 ± 0.6, and 4.8 ± 0.6 mm, respectively; P < 0.05) following glyceryl trinitrate administration and peak blood flow (1,118 ± 326 vs. 732 ± 320, 737 ± 219, and 698 ± 174 ml/min, respectively; P < 0.05) following ischemic handgrip exercise. In contrast, athletes demonstrated consistently lower wall thickness in carotid (509 ± 55 μm), brachial (D: 239 ± 100 μm; ND: 234 ± 133 μm), and femoral (D: 479 ± 38 μm; ND: 479 ± 42 μm) arteries compared with control subjects (carotid: 618 ± 74 μm; brachial D: 516 ± 100 μm; ND: 539 ± 129 μm; femoral D: 634 ± 155 μm; ND: 589 ± 112 μm; all P < 0.05 vs. athletes), with no differences between the limbs of either group. These data suggest that localized effects of exercise are evident in the remodeling of arterial size, whereas arterial wall thickness appears to be affected by systemic factors.