Effect of age on systolic time intervals at rest and during exercise on a bicycle ergometer

Measurements of systolic time intervals were obtained by simultaneous recordings of ECG and first derivative transthoracic electrical impedance curves, at rest in the supine and upright body positions and during exercise while sitting on a bicycle ergometer. The same schedule was applied to 70 normal males divided into 3 groups: 20 boys 11–14 years, 25 yound adults 20–30 years, and 25 middle-aged men 45–55 years.