Aerobic exercise training can reverse age-related peripheral circulatory changes in healthy older men

Background-The age-related decline in maximal oxygen consumption is attenua ted by habitual aerobic exercise. However, the relative effects of training on central and peripheral responses to exercise in older subjects are not known. The present study assessed the contribution of central and periphera l responses to the age-associated decline in peak oxygen consumption and co mpared the effect of exercise training in healthy older and younger subject s. Methods and Results-Ten older and 13 younger men underwent invasive measure ment of central and peripheral cardiovascular responses during an upright, staged cycle exercise test before and after a 3-month period of exercise tr aining with cycle ergometry. At baseline, cardiac output and AV oxygen diff erence during exercise were significantly lower in older subjects. With tra ining, the older and younger groups increased maximal oxygen consumption by 17.8% and 20.2% respectively. Peak cardiac output was unchanged in both gr oups. Systemic AV oxygen difference increased 14.4% in the older group and 14.3% in the younger group and accounted for changes in peak oxygen consump tion. Peak leg blood flow increased by 50% in older subjects, whereas the y ounger group showed no significant change. There was no change in peak leg oxygen extraction in the older group, but in the younger group, leg AV oxyg en difference increased by 15.4%. Conclusions-These findings suggest that the age-related decline in maximal oxygen consumption results from a reversible deconditioning effect on the d istribution of cardiac output to exercising muscle and an age-related reduc tion in cardiac output reserve.