Healthy Aging Glossary

The reduced sensitivity of aging muscle tissue to the anabolic (muscle-building) signals triggered by protein intake and exercise. Older adults require greater amounts of dietary protein — particularly leucine — and a stronger exercise stimulus to achieve the same muscle protein synthesis response as younger adults. This is a key reason why protein targets and training intensity both need to be higher after 40.

The progressive, age-related loss of skeletal muscle mass, strength, and function. Sarcopenia begins as early as the 30s, accelerates after 60, and is a primary driver of frailty, falls, and functional decline in older adults. It is not inevitable — resistance training and adequate protein intake are the two most evidence-supported interventions.

The maximum rate at which the body can consume oxygen during intense exercise. VO2 max is considered one of the strongest predictors of all-cause mortality and cardiovascular health. It declines approximately 10% per decade with age but responds well to aerobic training — even in older adults. Higher VO2 max is associated with longer healthspan.