Physiological variables during 10 years of endurance exercise.

The reported decline in Physical Working Capacity (PWC) max is from 9-15 percent during the ages of 45 to 55 years. The use of vigorous physical activity to prevent this decline and to possibly protect against fatal myocardial infarction has been suggested. The purpose of this study was to investigate the effect of an endurance type exercise program on the maximal PWC of middle-aged men during a 10 year span. Sixteen men, initially 32-56 years (M-44.6), were trained with running or swimming at an intensity above 60 percent of VO2 max during a 10 year period. The average weekly running distance was 15 miles (25 km). The criterion for PWC was directly measured VO2 using the Douglas Bag/Scholander technique. No changes were observed in body weight, resting heart rate (HR), or resting blood pressure (BP). Maximal HR declined 7 beats per minute in 10 years. Pulmonary ventilation (STPD) increased approximately 18 percent. Mean VO2 max was essentially unchanged, 3.376 and 3.303 1/min STPD. VO2 max related to body weight was 43.7 initially and 44.4 ml/min-kg after 10 years. It was concluded that the usual 9-15 percent decline in PWC or VO2 max from age 45 to 55 years can be forestalled by regular endurance exercise. The results may have implications for protecting against heart attacks.