Age‐related decreases in basal limb blood flow in humans: time course, determinants and habitual exercise effects

Abstract

Basal whole‐limb blood flow is lower in older than in young healthy sedentary men due to a lower limb vascular conductance. In Study 1, we determined whether age‐associated reductions in basal whole‐leg (femoral artery) blood flow and vascular conductance are modulated by habitual physical activity by studying 89 healthy men aged 20‐35 or 55‐75 years (26 sedentary, 31 physically active and 32 endurance exercise trained). Femoral blood flow (duplex Doppler) and vascular conductance were ≈20‐30 % lower (P < 0.01) in the older men in all three physical activity groups. In Study 2, to determine the temporal pattern and relation to local metabolism and lean tissue mass of the age‐associated reductions in femoral blood flow, we studied 142 healthy men aged 18‐79 years. Femoral blood flow (r= ‐0.40) and vascular conductance (r= ‐0.51) were linearly and inversely related to age (both P < 0.001). Leg fat‐free mass (r= ‐0.48) and estimated leg oxygen consumption (r= ‐0.49) declined with advancing age (both P < 0.001), and were strongly and positively related (r= 0.75; P < 0.001). The age‐associated decline in femoral blood flow correlated with the corresponding reductions in leg fat‐free mass and estimated leg oxygen consumption (both r= 0.47; P < 0.001). We concluded that: (1) basal whole‐limb blood flow and vascular conductance decrease progressively with advancing age in healthy men; (2) reductions in both limb fat‐free mass and oxygen consumption are related to the decline in whole‐limb blood flow with age; and (3) habitual aerobic exercise does not appear to modulate the age‐related reductions in basal limb blood flow and vascular conductance.

Perfusion pressure and movement-induced hyperemia: evidence of limited vascular function and vasodilatory reserve with age

“…Healthy aging has previously been demonstrated to have deleterious effects on basal LBF and LVC (8,28). In agreement with these previous findings, the present investigation has documented that resting LBF and LVC in the old were ϳ30% and ϳ35% less than in the young, respectively, and this was independent of body posture.…”

Resistance exercise training improves age-related declines in leg vascular conductance and rejuvenates acute leg blood flow responses to feeding and exercise

“…In young healthy men RET reportedly increased peak limb vasodilatory capacity (26), which raises the possibility that decreased arteriolar tone could contribute to the increased capacity for higher LBF after RET. Thus decreased ␣-adrenergic tone [known to be elevated in older individuals (12,32)] and perhaps improved redistribution of LBF to working muscles (i.e., improved functional sympatholysis) are attractive possibilities to contribute to improvements in LBF and corresponding normalization of LVC in response to FEDEX.…”

Oxygen uptake kinetics for moderate exercise are speeded in older humans by prior heavy exercise

“…Although absolute HR and HR kinetics may not reflect the time course of blood flow changes to or within exercising muscle, a slower adaptation of HR may contribute to a slowed rate of increase of cardiac output [because stroke volume probably changes little from that seen during baseline cycling (ϳ15 W)], which in turn could result in a slower adaptation of blood flow to the muscle at exercise onset in the elderly. In addition, it has been shown recently that aging is associated with a greater femoral vascular resistance and reduced femoral vascular conductance (15,16), lower leg blood flow during dynamic exercise (28), increased sympathetic vasoconstrictor activity (15), and a reduced ability to shunt blood away from the splanchnic and renal circulations to muscle during exercise (19). Although it is not known whether the kinetics of blood flow redistribution within muscle at exercise onset are slowed with aging, these results suggest that the ability to redistribute blood flow to the active muscle units may be impaired in older adults.…”