Effects of training resumption on conduit arterial diameter in elite rowers
Background: Exercise training is a known stimulus for arteriogenesis, but it is unclear whether elite athletes, who exhibit increased conduit vessel diameter at rest, experience further structural vascular adaptations as a result of intense exercise training. Methods: Cross-sectional comparisons were performed between elite rowers (N = 17), following a respite from training, and eight untrained age- and gender-matched controls to assess the effects of long-term exercise on vessel structure. To determine the impact of the resumption of intensive exercise training on conduit artery structure, measures were repeated following 3 and 6 months of training in the athletes; the controls remained inactive. Conduit vessel structure was assessed, using high-resolution B-mode ultrasound, as brachial artery diameter at rest (BADr) and in response to 5-min (BAD5) and 10-min (BAD10) periods of forearm cuff ischemia. Shear rate profiles were also analyzed following cuff deflation at all time points. Results: At entry, all measures of BAD were greater (all P < 0.05) in the athletes relative to controls (athletes vs controls; BADr 4.47 ± 0.10 vs 3.84 ± 0.22 mm; BAD 5 4.70 ± 0.10 vs 4.05 ± 0.36 mm, and BAD10 4.93 ± 0.10 vs 4.07 ± 0.25 mm). Resumption of exercise training caused a further increase in brachial artery diameters in the athletes at 3 months (BADr, 4.71 ± 0.10 mm, P < 0.01; BAD5 4.94 ± 0.10 mm, P < 0.05; BAD10 5.12 ± 0.10 mm, P < 0.001), which were maintained, but not further increased, after 6 months of training. Conclusions: Athletes exhibit enhanced conduit artery diameters at rest and in response to vasodilator stimuli. Despite this long-term training effect on arterial structure, resumption of training further enhances diameter, an effect that occurs within 3 months.