Leg blood flow during submaximal cycle ergometry is not reduced in healthy older normally active men

Abstract

The purpose of the present study was to test the hypothesis that leg blood flow responses during submaximal cycle ergometry are reduced with age in healthy normally active men. Eleven younger (20-25 yr) and eight older (62-73 yr) normotensive, nonendurance-trained men performed both graded and constant-load bouts of leg cycling at the same absolute and relative [% of peak O(2) consumption (Vo(2 peak))] exercise intensities while leg blood flow (femoral vein thermodilution), mean arterial pressure (MAP; radial artery), cardiac output (acetylene rebreathing), blood O(2) content, and plasma catecholamines were measured. Leg blood flow responses at the same absolute submaximal power outputs (20-100 W) and at a fixed systemic O(2) demand (1.1 l/min) did not differ between groups (P = 0.14-0.19), despite lower absolute levels of cardiac output in the older men (P < 0.05). MAP at the same absolute power outputs was 8-12 mmHg higher (P < 0.05) in the older men, but calculated leg vascular conductance responses (leg blood flow/MAP) were identical in the two groups (P > 0.9). At the same relative intensity (60% Vo(2 peak)), leg norepinephrine spillover rates were approximately twofold higher in the older men (P = 0.38). Exercise-induced increases in leg arterial-venous O(2) difference were identical between groups (P > 0.9) because both arterial and venous O(2) contents were lower in the older vs. younger men. These results suggest that the ability to augment active limb blood flow and O(2) extraction during submaximal large muscle mass exercise is not impaired but is well preserved with age in healthy men who are normally active.

Peripheral Arterial Disease Assessment

“…Although age-related differences between Nl max and PAD can exaggerate differences in perfusion between these 2 groups, studies have demonstrated that active muscle perfusion remains intact in healthy older individuals. 75,76 In all subjects in this protocol, we observed a heterogenous pattern of limb perfusion after exercise consistent with previous investigators. 52,53,77 However, the pattern of perfusion heterogeneity we observed differed among some individuals, suggesting muscle groups being used to perform exercise on the ergometer were inconsistent, and this could have skewed our comparisons.…”

Calf muscle perfusion at peak exercise in peripheral arterial disease: Measurement by first‐pass contrast‐enhanced magnetic resonance imaging

“…While age-related differences between Nl max and PAD could exaggerate differences in perfusion between these two groups, studies have demonstrated that active muscle perfusion remains intact in healthy older individuals (35,36). In all subjects in this protocol, we ob- served a heterogenous pattern of limb perfusion following exercise consistent with previous investigators (14,29,37).…”

The Effects of Aging on Capillary Hemodynamics in Contracting Rat Spinotrapezius Muscle

“…Recently, Donato et al demonstrated that the difference in the leg Q & m response to exercise found between young and old subjects was a product of the response to the exercise stimulus itself, as opposed to variations in resting Q & m between age groups. Collectively, the results of the aforementioned studies are in conflict with other reports where no difference in Q & m was found between young and old subjects during forearm exercise (Jasperse et al, 1994) or dynamic leg exercise (Olive et al, 2002;Proctor et al, 2003b). Specifically, Olive et al (Olive et al, 2002) demonstrated that exercising Q & m is a function of physical activity patterns but not age differences.…”

“…In that investigation, 1 Hz contractions elicited no consistent increases in arteriolar diameter or V RBC in 24 month-old male Sprague-Dawley rats. In contrast, some studies have found no difference between Q & m to exercising limbs in young and old subjects (Jasperse et al, 1994;Olive et al, 2002;Proctor et al, 2003b). However, the current literature is certainly not definitive on this issue (Wahren et al, 1974;Proctor et al, 1998;Proctor et al, 2003a) with differences possibly related to the activity level of the population studied, the function of the active muscle(s), and/or the intensity of the exercise.…”