Sex differences in leg vasodilation during graded knee extensor exercise in young adults

Abstract

Limb vascular conductance responses to pharmacological and nonexercise vasodilator stimuli are generally augmented in women compared with men. In the present investigation, we tested the hypothesis that exercise-induced vasodilator responses are also greater in women than men. Sixteen women and 15 men (20-30 yr) with similar fitness and activity levels performed graded quadriceps exercise (supine, single-leg knee extensions, 40 contractions/min) to maximal exertion. Active limb hemodynamics (left common femoral artery diameter and volumetric blood flow), heart rate (ECG), and beat-to-beat mean arterial blood pressure (MAP; radial artery tonometry) were measured during each 3-min workload (4.8 and 8 W/stage for women and men, respectively). The hyperemic response to exercise (slope of femoral blood flow vs. workload) was greater (P < 0.01) in women as was femoral blood flow at workloads >15 W. The leg vasodilatory response to exercise (slope of calculated femoral vascular conductance vs. absolute workload) was also greater in women than in men (P < 0.01) because of the sex difference in hyperemia and the women's lower MAP ( approximately 10-15 mmHg) at all workloads (P < 0.05). The femoral artery dilated to a significantly greater extent in the women ( approximately 0.5 mm) than in the men ( approximately 0.1 mm) across all submaximal workloads. At maximal exertion, femoral vascular conductance was lower in the men (men, 18.0 +/- 0.6 ml.min(-1)xmmHg(-1); women, 22.6 +/- 1.4 mlxmin(-1)xmmHg(-1); P < 0.01). Collectively, these findings suggest that the vasodilatory response to dynamic leg exercise is greater in young women vs. men.

Fadiga muscular entre séries de exercícios isocinéticos em mulheres jovens

“…Uma possível explicação para este fato é a oclusão vascular proveniente de uma grande produção absoluta de força. A produção de força leva a uma maior pressão intramuscular e, consequentemente, a uma menor perfusão sanguínea (KENT-BRAUN et al, 2002;PARKER et al, 2007). Assim, os sujeitos mais fracos podem ter um melhor aporte de oxigênio e, com isso, utilizar a via oxidativa, mais resistente à fadiga muscular por um período de tempo mais longo.…”

“…Dentre eles destacam-se a diferença no sistema músculo esquelético, a morfologia e distribuição das fibras musculares, a ativação neural, a concentração de hormônios (STARON et al, 2000;PINCIVERO et al, 2001;ESBJÖRNSSON-LILJEDAHL et al, 2002;HUNTER et al, 2004b;WÜST et al, 2008).…”

“…As mulheres possuem mais fibras do tipo I e menos fibras do tipo II do que os homens (PINCIVERO et al, 2001). Staron et al (2000) ressaltaram não haver diferenças entre os gêneros na distribuição das fibras musculares na musculatura vasto lateral do quadríceps.…”

Commentary on Viewpoint: Exercise and cardiovascular risk reduction: Time to update the rationale for exercise?

“…Additionally, it is also important to note that there are gender differences in exercise hyperemia. Young women showed a greater increase in exercise hyperemia than young men (6). The extent to which NO-mediated vasodilation contributes to the gender difference in exercise hyperemia is a subject for future investigations.…”

<b>Postcontraction hyperemia after electrical stimulation: potential utility in rehabilitation of patients with upper extremity </b><b>paralysis </b>

“…Billinger et al (3) reported that single-limb exercise of the affected side in patients with post-stroke improved the blood flow in the femoral artery in the affected extremity. Finally, Parker et al (12) evaluated the sex difference in the vasodilatory response after a knee extension exercise and concluded that it was greater in young women compared with men. However, there had been no reported studies comparing postcontraction hyperemia between healthy control subjects and patients with upper extremity paralysis caused by upper motor neuron diseases.…”