Influence of age, sex, and aerobic capacity on forearm and skin blood flow and vascular conductance.

This study investigated the influence of age, sex, and aerobic capacity on resting and peak forearm and cutaneous blood flow (FBF, CBF). We recruited 93 female and 129 male subjects (age range 16-76 years). FBF and CBF were assessed by plethysmography and laser-Doppler flowmetry, respectively. Peak FBF was obtained following 5 min forearm vascular occlusion and peak CBF in response to local skin heating of 42 degrees C. Blood pressure was measured manually and by Finapres. Maximal oxygen uptake (VO2max) was obtained from a treadmill exercise stress test. Age was associated with declines in resting FBF (y = -1.176 ln(x) + 6.6899, r(2) = 0.45) and peak FBF (y = -17.21 ln(x) + 93.843, r(2) = 0.53) (both p < 0.05). Peak CBF decreased with increasing age (y = -223.6 ln(x) + 1,102.9, r(2) = 0.34) (p < 0.05), but resting CBF was unchanged (p > 0.05). Males had higher resting and peak FBF than females (p < 0.05) and these variables were related to ageing better in males (y = -1.245 ln(x) + 7.188, r(2) = 0.71 and y = -18.53 ln(x) + 102.82, r(2) = 0.69) than in females (y = -1.149 ln(x) + 6.4307, r(2) = 0.38 and y = -16.59 ln(x) + 88.872, r(2) = 0.55). There were no sex differences in resting CBF (p > 0.05). Peak CBF was much better related to ageing in males than females (y = -276.1 ln(x) + 1,365.4, r(2) = 0.53 vs. y = -183.1 ln(x) + 907.86, r(2) = 0.28). VO2max decreased with advancing age and this decline was associated with the decline in peak FBF (y = -0.5933x + 10.91, r(2) = 0.36, p < 0.05) but not with peak CBF (p > 0.05). These results suggest that healthy ageing is associated with a curvilinear decline in resting and peak forearm and peak cutaneous vasodilator capacity, with males more severely affected than females. The data indicate that peak FBF is influenced by VO2max but peak CBF is not.