Effects of a 6-mo endurance-training program on venous compliance and maximal lower body negative pressure in older men and women

Abstract

. Effects of a 6-mo endurance-training program on venous compliance and maximal lower body negative pressure in older men and women. J Appl Physiol 99: 1070 -1077, 2005. First published April 14, 2005 doi:10.1152/japplphysiol.01169.2004.-Aging and chronic exercise training influence leg venous compliance. Venous compliance affects responses to an orthostatic stress. The extent to which exercise training in a previously sedentary older population will affect venous compliance and tolerance to the simulated orthostatic stress of maximal lower body negative pressure (LBNP) is unknown. The purpose of this investigation is to determine the influence of a 6-mo endurance-training program on calf venous compliance and responses and tolerance to maximal LBNP in older men and women. Twenty participants (exercise group: n ϭ 10, 5 men, 5 women; control group: n ϭ 10, 6 men, 4 women; all Ͼ60 yr) underwent graded LBNP to presyncope or 4 min at Ϫ100 mmHg before and after a 6-mo endurance-training program. Utilizing venous occlusion plethysmography, calf venous compliance was determined in both groups using the first derivative of the pressure-volume relation during cuff pressure reduction before training, at 3 mo, and at the end of the training program. The exercise group improved their fitness with the 6-mo endurance-training program, whereas the control group did not change (14 Ϯ 3 vs. Ͻ1 Ϯ 2%; P Ͻ 0.05). LBNP tolerance did not differ between groups or across trials (P ϭ 0.47). Venous compliance was not different between groups or trials, either initially or after 3 mo of endurance training, but tended to be greater in the exercise group after 6 mo of training (P ϭ 0.08). These data suggest that a 6-mo endurance-training program may improve venous compliance without affecting tolerance to maximal LBNP in older participants. orthostatic tolerance; peripheral circulation; baroreceptor sensitivity DESPITE EXTENSIVE investigation, the effects of either cardiovascular fitness or age on orthostatic tolerance remain uncertain. In younger people, some cross-sectional investigations have shown that endurance-trained participants have lower tolerance to head-up tilt or lower body negative pressure (LBNP) (6, 27), whereas others have found no fitness-related differences in tolerance (10, 16). Longitudinal investigations have shown that exercise training has improved (5, 13), had no effect on orthostatic tolerance (4, 33), or diminished tolerance to head-up tilt (26) and LBNP (28,36).Much less attention has been given to the effects of exercise training on orthostatic tolerance in older adults. Aging has been associated with a higher incidence of orthostatic hypotension (21, 30), which might increase the risk of falls in this population. A greater predisposition to orthostatic hypotension as a result of endurance training in an older population would be undesirable. On the other hand, if endurance training improved blood pressure regulation, then it would further support the inclusion of this type of exercise training in current recomm...

Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women

“…data for restricted and normal are collapsed and combined) endurance training where venous congestion is increased following training with no decrement on tolerance to orthostatic stress (Hernandez and Franke 2005). What is clear is that further research is needed to investigate the exact mechanisms behind the increase in peak PO bf found following LLRT with blood flow restriction.…”

Decreased capillary filtration but maintained venous compliance in the lower limb of aging women

“…Calf venous compliance is reduced with age in men, which increases the possibility to resist an orthostatic challenge due to smaller reduction in thoracic blood volume and cardiac filling volumes (25,33,38,39,49), although this relationship has recently been challenged (18). The decreased venous compliance and capacitance are probably an effect of increased collage-to-elastin ratio as well as thickening of the venous walls, corresponding to the known structural changes and a decrease in arterial wall compliance with age (3, 9, 48).…”

“…Although both elderly and young women were of average physical fitness, the elderly women may still have been more unfit. Sedentary subjects have lower calf venous compliance, and this would work in favor of detecting a putative reduction in venous compliance with age in women (18,33). Another confounder might be differences in venous filling before LBNP, i.e., unstressed volume (V 0 ).…”

Cardiovascular regulation in women with vasovagal syncope : With special reference to the venous system

“…In the present findings, the impact of net fluid filtration was corrected for and Ccalf was evaluated with the new VWM which is able to produce a valid characterization of the whole pressure-volume and pressurecompliance relation. Other factors, such as physical activity and sympathetic tone, could influence the measurements of Ccalf (87,132). However, there were no differences in physical activity between the groups and although activation of the sympathetic system has been shown to lower unstressed venous volume, increased sympathetic activation does not appear to directly affect venous compliance (90,93).…”