Relative change (in %) in peak vasodilator (ΔFVC) responses to single forearm contractions at 10% (A), 20% (B), and 40% (C) MVC during α-adrenergic blockade via phentolamine compared with control conditions in YM, YW, OM, and OW. α-Adrenergic blockade substantially increased peak vasodilator responses in OM compared with YM at all contraction intensities. Moreover, the increases in peak vasodilator responses during α-adrenergic blockade were greater in OM compared with OW at 10% and 20% MVC. Conversely, YW had a greater increase in peak vasodilator responses during α-adrenergic blockade than YM at 20% and 40% MVC. *P < 0.05 vs. men within same age group; †P < 0.05, age-related difference within the same sex.