Sex-specific effect of aging on submaximal leg exercise hemodynamics in middle-aged and older adults

Abstract

The purpose of the study was to examine predictors of the leg hemodynamic response to exercise in middle- and older-aged men and women. Femoral artery blood flow (FBF), mean arterial pressure (MAP), and femoral vascular conductance (FVC, calculated as the quotient of FBF and MAP) were measured at rest and during 5 min of single knee-extensor exercise at ~10 W workload in healthy men (n = 31) and women (n = 32) (age 40-72 years). Age, menopausal status, maximal quadriceps strength, blood lipids, vitamin D levels, maximal oxygen uptake (VO(2max)), physical activity, blood pressure, estimated quadriceps muscle mass, and body mass index (BMI) were also assessed. The effect of age on FBF and FVC was negative and significant in men (r = -0.44 and -0.42 and p = 0.01 and 0.02, respectively) but was abolished by normalization to estimated quadriceps muscle (p = 0.18 and 0.73, respectively). There was no effect of age on leg hemodynamic responses to exercise in women (alone or normalized to quadriceps muscle), but menopausal status was a significant predictor of FVC and normalized FVC (p = 0.04 and 0.02, respectively). The multivariate model for exercising FVC in men (in order of strongest to weakest predictors) included quadriceps strength, BMI, resting FVC, age, and high-density lipoprotein cholesterol. The multivariate model for exercising FVC in women included quadriceps mass, systolic blood pressure, vitamin D, age, VO(2max), waist circumference, and physical activity score. These findings suggest that factors besides chronological age mediate exercising leg hemodynamics in middle-aged to older adults and that these factors are sex-specific.

Atorvastatin increases exercise leg blood flow in healthy adults

“…Finally, our results suggest that the improvement in exercise hemodynamics are independent of LDL reduction adding improved exercise leg hemodynamics to the potential pleiotropic effects of statins. Notably, the ~20–25% increase in leg exercise hyperemia observed in the current study is equivalent to the magnitude of impairment observed in older adults or patients with Type II diabetes and heart failure (4;5;16). Therefore, statins may also be an effective therapy for treating blunted exercise hyperemia.…”

“…Specifically, on the 3 rd pre-study and 2 nd post-study visits, subjects performed one, 5 minute bout of single-knee extension exercise at a cadence of 40 kicks/minute using the Biodex System 3 as previously described (16). Single knee extensor exercise is not limited by cardiac output and elicits less excitation of the sympathetic nervous system than two-legged exercise, and is thus effective for examining the leg vasodilatory response to exercise independent of central limitations and alterations (3).…”

“…Both FBF and FVC were normalized to the power generated during the entire kick cycle. We have previously established the within-subject coefficient of variation for exercising leg blood flow (normalized to power output) in this model as 4.9 ± 1.6 % (16). Thigh volume was estimated anthropometrically from thigh patellar-pubic length, skinfold thicknesses, and circumference (17).…”

Exercise-induced vasodilation is associated with menopause stage in healthy middle-aged women

“…However, most studies on aging and active leg blood flow in women have been limited to two age groups: young (20–30 years) and old (60–75 years) (Parker et al 2008 a , 2008 b ; Proctor et al 2003 a ). Parker et al (2011) recently provided evidence that leg blood flow and conductance during knee extensor exercise are influenced by menopausal status, independent of age, in middle-aged and older women. However, the exercise protocol used was limited to a single, light work intensity (~10 W), and no perimenopausal women were included and reproductive hormones were not measured.…”

“…Whereas leg hyperemia and vascular conductance are well preserved during submaximal exercise in older men that are neither endurance trained nor overly sedentary (Parker et al 2008 a ; Proctor et al 2003 b ), leg blood flow and vascular conductance responses during submaximal two-legged cycling (Proctor et al 2003 a ) and single-leg knee extensor exercise (Parker et al 2008 a , 2008 b ) are attenuated in older versus younger women. Although the mechanisms underlying these age-associated reductions in exercise hyperemia and vasodilation in women are unknown, evidence suggests that they may be related to menopausal status (Parker et al 2011). …”