Influence of Age on the Local Circulatory Adaptation to Leg Exercise

Abstract

Blood flow and oxygen uptake of the leg and release of lactate were studied in a group of 7 healthy well-trained 52–59-year-old men at rest and during bicycle exercise at work loads that were increased in steps to near maximal levels of work intensity. The results were compared with those for 7 healthy subjects 25–30 years of age studied previously (11). Blood flow to the leg rose in linear proportion to pulmonary oxygen uptake at submaximal work intensities but tended to level off at the heaviest work loads. The rise in leg blood flow during exercise was less in the middle-aged group and was largely compensated for by a larger arterial-femoral venous oxygen difference during exercise. Leg release of lactate rose approximately exponentially in relation to work load. No difference was observed between the two age groups with regard to arterial lactate or net release of lactate during exercise. It is concluded that blood flow to the leg in middle-aged men rises in a curvilinear manner in response to exercise of increasing intensity, and that leg circulation during exercise becomes relatively hypokinetic with age.

Key Words:

• Age
• hypokinetic circulation
• lactate
• leg blood flow
• mechanical efficiency
• oxygen uptake