Abstract 13104: Effect of Aging on Exercise Capacity in Non-obese Healthy Sedentary Humans
Background: Maximal aerobic exercise power declines with healthy aging as evidenced by a reduction in maximal oxygen uptake (VO2 max). A decrease in cardiac output and/or peripheral oxygen extraction may be related to this decline of VO2 max. However, when in the aging process these changes occur is unknown.
Methods: Seventy four healthy sedentary non-obese (BMI < 30 kg/m2) subjects (male 34, female 40, age from 25 to 77 yrs) were recruited from the Dallas Heart Study, a population based, random sample of individuals in the Dallas community. Subjects were highly screened for cardiovascular diseases and were stratified into 4 groups according to their age; G1: ≤ 35 yrs, (30±4 yrs; n= 13), G2: 36–50 yrs, (44±4 yrs; n=18), G3: 51–65 yrs, (58±4 yrs; n=24), G4: > 65 yrs, (70±3 yrs; n=19). Anthropometric parameters and cardiovascular responses to maximal exercise were evaluated in all subjects with non-invasive methods.
Results: There were no differences in gender, height, or lean body mass among the 4 groups, while body weight and percent body fat increased with age. VO2 max was lower in G4 than G1 (1.62±0.47 vs. 2.14±0.68 L/min, p < 0.05), however, no differences were observed in VO2 max among the other groups. When indexed to body mass, VO2 max was inversely correlated with the increasing age (Rsqr = 0.98, P<0.01). There were no differences in maximal cardiac output (G1; 13.3±3.8, G2; 13.1±2.9, G3; 13.2±2.9, G4; 14.7±4.6 L/min, p = 0.46) among the 4 groups. Maximal heart rate declined along with aging, and G4 had the largest maximal stroke volume (G1: 71±18, G2: 74±17, G3: 76.8±17, G4: 90±28 ml, p=0.036). Arterio-venous oxygen difference was lower in G4 compared with the younger age groups (G1: 16.2±3.0, G2: 15.4±2.1, G3: 15.3±2.4, G4: 11.3±2.6 vol%, p<0.001).
Conclusion: These results suggest that impairment of peripheral oxygen extraction in healthy sedentary aging seems to occur > 65 years of age. In contrast, maximal cardiac output is maintained with a decrease in maximal heart rate compensated for by an increase in maximal stroke volume even at age > 65.
- © 2010 by American Heart Association, Inc.