Date of Award
Doctor of Philosophy
Low cardiorespiratory fitness in the elderly is due to aging and to inactivity. Factors which limit performance of aerobic exercise and which influence the response to physical training were examined in a sample (n = 224) of elderly males (age 62 yrs). Subjects were randomly assigned to a training or control group. Maximum oxygen uptake (VO2max), pulmonary function and body composition were determined at entry (T1) and one year later (T2). Exercise testing included a continuous, incremental test (Stage I) and a discontinuous test with three steady state, submaximal loads on a motor driven treadmill. Cardiac output was estimated with the non-invasive Fick method. During the study year control group members were free to pursue their normal activities. The training group exercised (walk/jog) for thirty minutes at approximately 70 percent of the heart rate reserve. Supervised training sessions were available thrice weekly.;Results of repeated determinations indicated that maximal oxygen consumption was reliably and reproducibly measured. After one year VO2max was significantly higher in the training group with respect to baseline (13.2%) and control values. The large range of responses to training was related more strongly to whether the exercise test was fatigue or symptom limited than to training intensity or frequency. Neither cardiac output nor the difference between arterial and venous oxygen contents increased significantly with training. Systolic blood pressure was significantly lower at final testing in both the control and activity groups. The response to training was smaller in subjects with poor pulmonary function.;Submaximal and maximal responses to training were different. Only a moderate correlation between change in VO2max and training induced bradycardia was observed. The ventilation threshold was not significantly altered by training which induced a significant increase in VO2max.;Maximum aerobic capacity may be influenced by pulmonary function in the elderly. Training can effect substantial increases in capacity but the magnitude of the effect is difficult to predict. The change in maximal oxygen consumption may not be reflected in a submaximal measure such as ventilation threshold. Increased VO2max may be due to a combination of increased cardiac output and oxygen extraction.
Thomas, Scott Gordon, "Physiological Determinants Of Aerobic Function In Elderly Males" (1985). Digitized Theses. 1471.