Attenuation of cardiovascular adaptations to exercise in frail octogenarians

1 Section of Applied Physiology, 2 Division of Geriatrics and Nutritional Sciences, 3 Cardiovascular Division, and 4 Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110 Submitted 25 February 2003 ; accepted in final form 2 June 2003 To determine the mechanisms underlying increased aerobic power in response to exercise training in octogenarians, we studied mildly frail elderly men and women randomly assigned to an exercise group ( n = 22) who participated in a training program of 6 mo of physical therapy, strength training, and walking followed by 3 mo of more intense endurance exercise at 78% of peak heart rate or a control sedentary group ( n = 24). Peak O 2 consumption ( O 2 peak ) increased 14% in the exercise group ( P < 0.0001) but decreased slightly in controls. Training induced 14% increase ( P = 0.027) in peak exercise cardiac output ( ), determined via acetylene re-breathing, and no change in arteriovenous O 2 content difference. The increase in was mediated by increases in heart rate ( P = 0.009) and probably stroke volume ( P = 0.096). Left ventricular stroke work also increased significantly. In the men, the increase in O 2 peak was exclusively due to a large increase in peak (22%). In the women, the gain in O 2 peak was due to small increases in and O 2 extraction from skeletal muscles. Pulse pressure normalized for stroke volume and arterial elastance during peak effort did not change with training. Controls showed no changes. The results suggest that, although frail octogenarians have a diminished capacity for improvement in aerobic power in response to exercise training, this adaptation is mediated mostly by an increase in during peak effort. Furthermore, likely plays a greater role in the adaptive increase in O 2 peak in old men than old women. cardiovascular changes; exercise training; gender Address for reprint requests and other correspondence: A. A. Ehsani, Washington Univ. School of Medicine, 4566 Scott Ave., Campus Box 8113, St. Louis, MO 63110 (E-mail address: aehsani{at}im.wustl.edu ).