Endothelial sensitivity to exercise-induced shear rate in older adults: effect of biological sex and acute folic acid consumption.

Endothelial sensitivity to exercise-induced shear rate did not differ between postmenopausal females and age-matched males during the placebo condition.

• Females: 0.102 ± 0.055%·s-1; Males: 0.091 ± 0.061%·s-1 (P = 0.603)
• 17 postmenopausal females (66 ± 8 yr) and 14 males (66 ± 6 yr) participated
• Endothelial sensitivity was quantified as the slope of the linear regression between brachial artery dilation (% change from baseline) and shear rate
• Double-blind randomized crossover study design was used

Acute folic acid consumption did not improve endothelial sensitivity to exercise-induced shear rate in postmenopausal females.

• Placebo: 0.102 ± 0.055%·s-1 vs. folic acid: 0.099 ± 0.062%·s-1 (P = 0.887)
• A dose of 5 mg of folic acid was consumed acutely
• Study used a double-blind crossover design with placebo and folic acid conditions

Acute folic acid consumption did not improve endothelial sensitivity to exercise-induced shear rate in older males.

• Placebo: 0.091 ± 0.061%·s-1 vs. folic acid: 0.102 ± 0.083%·s-1 (P = 0.697)
• 14 males aged 66 ± 6 yr participated
• A dose of 5 mg of folic acid was consumed acutely

Handgrip exercise at multiple intensities was used to induce graded increases in shear rate for assessing endothelial sensitivity.

• Participants performed handgrip exercise at 20%, 40%, 60%, and 80% of maximal voluntary contraction
• Brachial artery diameter and blood velocity were measured continuously using high-resolution ultrasound
• Data were analyzed using edge-detection software

A reduced endothelial sensitivity to exercise-induced shear rate may not contribute to the inconsistent effect of aerobic exercise interventions on brachial artery flow-mediated dilation in healthy postmenopausal females.

• The authors had hypothesized that endothelial sensitivity to exercise-induced shear rate would be reduced in postmenopausal females compared to males
• Results were contrary to this hypothesis, with no significant sex difference observed (P = 0.603)
• The authors note that aerobic exercise interventions improve peripheral endothelial function in healthy older males but this effect is inconsistently observed in healthy postmenopausal females