Physiologic responses of men 49 to 65 years of age to endurance training

A study was made of the effects of training for 30 minutes, three days a week for 20 weeks on certain physiologic measures of sedentary men between 49 and 65 years of age. Twenty-two subjects volunteered for the experimental group, and 8 others for the control group. Exercise sessions were conducted on a quarter-mile track and consisted of continuous bouts of walking and jogging. The average daily energy expenditures progressed from 228 to 365 kilocalories between weeks 4 and 20. For the same period, average exercise heart rates (HRs) progressed from 149 beats/minute (83 per cent maximum HR) to 155 beats/minute (91 per cent maximum HR). The experimental group showed significant increases in maximum oxygen intake (VO2 max) from 2.47 to 2.90 liters/minute (18 per cent) and in maximum pulmonary ventilation (VE max) from 105 to 121 liters/minute (BTPS), and decreases in resting HR, diastolic blood pressure, body weight, skinfold fat, and abdominal girth. Serum cholesterol and triglyceride levels and heart volume remained unchanged. The control subjects showed no significant changes. Regression analysis, with use of age as a covariate, showed a small but significant inverse relationship with changes in VO2 max. It was concluded that men of the 49-65 age group respond favorably to endurance exercise and show a magnitude of change similar to that found in previous investigations of similar design with younger subjects.

[Training methods suggested for the preservation of health and physical fitness of the dentist and his auxiliaries. 1. Heart and circulation training]

The performance of the cardiovascular system may be improved by endurance training. To avoid injuries due to overexertion, it is necessary to test regularly the individual physical capacity by appropriate methods. A practice-tried program of running exercises ensures, when taken consistently, a steady improvement of the cardiovascular fitness.

Comparison of self-selected recovery methods on lactic acid removal rates

The purpose of this study was to compare lactic acid removal rates during three modes of recovery from a standardized exercise bout. Each subject (N = 6) completed a 1 mile run (92.2 +/- 3.7% Vo2max). Thereafter, lactic acid removal rates were compared in the runners at each of three different modes of recovery: a) rest; b) a self-selected, continuous jogging pace (free-jogging); and c) completely uncontrolled recovery (free-intermittent) normally practiced by athletes. Venous blood samples were taken immediately after the mile run and every 5 min thereafter for 20 min. Data were expressed relative to the initial post-exercise blood sample (100%). Lactic acid removal was significantly faster during the free-jogging recovery than during the free-intermittent and the resting recoveries (P less than 0.001). Removal rates during the free-intermittent recovery were significantly faster than during the resting recovery (P less than 0.001). The results indicated that nearly optimal lactic acid removal rates were attained during the free-jogging recovery.

Cardiac limitation to maximal oxygen transport and changes in components after jogging across the US

Observations were made before and 3-5 days after prolonged endurance jogging an average of 42 miles/day, 6 days/wk for 2.5 mo by a young male adult who voluntarily initiated a run across the United States. Both arterial PO2 and lactic acid increased. In each instance, the first limitation in circulatory delivery of oxygen was a plateau in stroke volume and cardiac output. Afterward, pulse deficit and systemic arterial pressure fell with exercise and heart rate accelerated. Although there was no change in oxygen transport (Q X CAO2), a reduction in stroke volume was exactly balanced by a rise in arterial oxygen content. Vital capacity, residual volume, and total lung capacity and diffusion capacity for carbon monoxide, hematocrit, and red cell mass increased, while plasma volume diminished and heart size and total blood volume were unchanged.