INFLUENCE OF AGING AND EXERCISE TRAINING ON THE INCREASE IN OXYGEN-UPTAKE AS A FUNCTION OF THE INCREASE IN WORK RATE

Background: The increase in oxygen uptake as a function of the increas e in work rate (DELTAVo2/DELTAWR) is an index of oxygen delivery to wo rking muscles. As the effect of both aging and exercise training on DE LTAVo2/DELTAWR had not been investigated previously, we conducted this study. Methods: Ten elderly (mean age, 65.7 +/- 4.1 years) and seven young (mean age, 23.0 +/- 2.1 years) healthy untrained men underwent a cardiopulmonary exercise test with breath-by-breath monitoring of car diorespiratory variables and continuously increased work rate protocol before and after 3 to 5 months of moderate-intensity exercise trainin g. The DELTAVo2/DELTAWR was verified by linear regression analysis of data acquired at the workloads between 30 W and the midpoint between a naerobic threshold and peak exercise. A profile analysis was performed , and P < 0.05 was considered statistically significant. Results: Befo re exercise training, DELTAVo2/DELTAWR was significantly lower in the elderly than in the young men (9.3 +/- 1.2 mL/W vs 10.3 +/- 0.4 mL/W). Exercise training increased peak Vo2 to a similar extent in young and elderly men (18.0 +/- 6.7% and 21.7 +/- 18.9%), whereas the differenc e in DELTAVo2/DELTAWR observed in the sedentary state was no longer fo und (10.3 +/- 0.3 mL/W vs 11.4 +/- mL/W), suggesting that this relatio n was a sensitive variable discriminating exercise training effect in the elderly. Conclusions: We found that DELTAVo2/DELTAWR was lower in elderly than in young healthy untrained men. Moderate-intensity exerci se training significantly increased DELTAVo2/DELTAWR in elderly but no t in young men and eliminated the difference in DELTAVo2/DELTAWR betwe en elderly and young men.