maximal oxygen consumption (VO2 max)

Introduction

VO2 max is dependent upon maximum cardiac output, the ability of the lungs to oxygenate blood pumped by the heart & O2 extraction by skeletal muscle.

The capacity of oxygen transport system

cardiac output (CO) x arterial-venous O2 difference

VO2 max declines with age in sedentary individuals, about 1%/year (40% between the ages of 30 & 70). Training increases VO2 max by increasing cardiac output & O2 extraction by skeletal muscle, but does not diminish the rate of decline.

The decline in VO2 max with age is largely a result of a decline in:

• forced expiratory volume in 1 second (FEV1)
• maximum heart rate
• ability of skeletal muscle to metabolize oxygen

The rate of decline may be slightly slower in women than in men; No means of slowing the rate of decline is known.

It has been predicted that the deline in VO2 max with age will intersect the minimal oxygen consumption necessary to avoid hypoxia at an age of ~115 years, roughly the maximum life span of humans.