Alpha-1 adrenergic vasoconstriction during dynamic leg exercise is diminished in younger individuals, though the extent of this exercise-induced "sympatholysis" in the elderly remains uncertain. Thus, in nine young (25 ± 1 yrs) and six older (72 ± 2 yrs) healthy volunteers, we evaluated changes in leg blood flow (ultrasound Doppler) during blood flow-adjusted intra-arterial infusion of phenylephrine (PE, a selective alpha-1 adrenergic agonist) at rest and during knee-extensor leg exercise at 20, 40, and 60% of maximal work rate (WR_max). To probe the potential contributors to exercise-induced changes in alpha-1 adrenergic receptor sensitivity, exercising leg O₂ consumption (VO₂) and lactate efflux were also evaluated (n = 10). At rest, the PE-induced vasoconstriction (i.e. decrease in leg blood flow) was diminished in older (-37 ± 3%) compared to young (-54 ± 4%) subjects. During exercise, alpha-1 adrenergic vasoconstriction in the active leg decreased in both groups. However, compared to young, older subjects maintained a greater vasoconstrictor response to PE at 40% WR_max (-14 ± 3%, older; -7 ± 2%, young) and 60% WR_max (-11 ± 3%, older; -4 ± 3%, young). It is possible that this observation may be attributed to lower absolute work rates in the older group, because for a similar absolute work rate (10W) and leg VO₂ (0.36 L/min), vasoconstriction to PE was not different between groups (-14 ± 3%; older; -17 ± 5%, young). Together, these data challenge the concept of reduced sympatholysis in the elderly, suggesting instead that the inhibition of alpha-1 adrenergic vasoconstriction in the exercising tissue is associated with work performed and therefore more closely related to the rate of oxidative metabolism.