maximal oxygen consumption (VO2 max)

Introduction

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

• VO2 max may be described as the capacity of oxygen transport system
  • cardiac output (CO) x arterial-venous O2 difference

Pathology

• 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 in VO2 max with age 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 decline 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.