Human Forearm Muscle Metabolism during Exercise: V. Quantitative Aspects of Glucose Uptake and Lactate Production during Prolonged Exercise

Abstract

In 6 subjects brachial artery blood flow and concentrations of glucose and lactate were determined in arterial (a) and deep venous blood (dv) at rest and during forearm exercise at 10 kpm/min. During the initial 2–3 minutes of exercise the a—dv glucose difference approached zero and became negative. On continued exercise a rapid increase in the a—dv glucose difference was seen, and after 10 minutes' exercise forearm muscle glucose uptake was more than 15 times the resting level. Glucose uptake showed a further rise during the remainder of the exercise period; the mean value recorded after 60 minutes' exercise was approximately 35 times the uptake at rest. The maximum lactate production was measured during the initial phase of exercise and proved to be approximately 130 times the resting level. Lactate production gradually diminished during the rest of the exercise period.

Key Words:

• Exercise
• forearm
• glucose
• lactate
• metabolism
• muscle
• quantitative