age-associated changes in metabolism

Introduction

Metabolic rate declines with age

Physiology

• lean body mass. excluding bone, accounts for majority of energy expenditure with age
• lean body mass declines with age
• thus metabolic rate declines with age
• maximal oxygen consumption declines with age
  • VO2 max declines with age in sedentary individuals, ~ 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

More general terms

• age-related physiological changes

Additional terms

• maximal oxygen consumption (VO2 max)
• metabolism