Why VO2 max Declines with Age, and What to Do about It.

"Use it or lose it" also applies to the heart.

Getting older is inevitable, as are many of the declines in physical and cognitive function that occur as our bodies move forward in time. With age, our mental capacities sometimes suffer — though there is evidence that this can be prevented by maintaining social relationships, engaging in high-level cognitive activity, and finding meaning and purpose in our work and hobbies.

Perhaps more apparent than age-related cognitive decline is physical decline — which can take the form of slower walking speeds (just watch grandma), reduced overall muscle mass, decreased strength and power, and a loss of mitochondria.

Even when changes in fitness parameters aren’t outwardly visible, intrinsic changes to our tissues and organs cause a general decline in physical capabilities with age.

This doesn’t just happen to the “oldest of the old” nor is it unique to frail elderly individuals — it’s a general phenomenon that happens even in people who maintain an active lifestyle. Though admittedly, “active agers” fare a lot better than their sedentary

Although there is a general decline across all physiological systems with age, this decline may be delayed, or the steepness of the decline flattened out, by regularly engaging in physical activity like aerobic exercise and resistance training. 

“Use it or lose it” is a fitting adage for what happens to the human body at all stages of life, and particularly at old(er) ages.

Use it and lose it?

There is a general consensus that our maximal aerobic capacity or VO2 max — which is the maximal rate at which we can take up and use oxygen — undergoes a steep decline as we get older.

Up until about age 30, VO2 max increases a fair amount, assuming you’re physically active and not a couch potato. But around age 30-40, we begin to see a somewhat linear decline in our aerobic capacity each decade.

The importance here may be that the more you increase your VO2 max while you’re young, the higher “baseline” you’ll have once aerobic capacity inevitably begins to decline, giving yourself a bit of a head start on the cardiovascular decline and protecting yourself from other age-related cardiovascular changes.

Changes in peak VO2 with age (left) and percent change in VO2 per decade (right) in men and women. Source: Strait and Lakatta, 2013.

Can exercise prevent the decline in aerobic capacity with age?

Since exercise training can increase VO2 max, one would think that as long as one just keeps exercising at the same level throughout life, one should be able to maintain aerobic fitness levels. If this were the case, you’d theoretically never really “slow down” so long as you could also maintain your muscle mass, strength, and mitochondrial capacity to match your cardiovascular system.

It doesn’t take much observation to conclude that we can’t really maintain peak performance throughout life. Just watch the career trajectories of high-level and even amateur athletes, or even your own performance. Inevitably, we fail to produce the same fast times or gym numbers as we age despite maintaining a high level of training.

The fantasy of maintaining a youthful cardiovascular fitness throughout life may be just that — a fantasy. As it turns out there is a consistently observed and fairly linear decline in VO2 max throughout life no matter how active one is.

Data show that even among exercise-trained or physically-active older adults, VO2 max still declines. 

This is apparent in both men and women and individuals who are highly or even moderately active.

Rate of age-related decline in VO2 max in groups of endurance-trained, active, and sedentary women. Source: Fitzgerald 1997.

As you can see, the baseline of endurance-trained and active individuals is higher at any given age — when VO2 max begins to decline. So, at age 60 or 70, these people have a considerably higher aerobic fitness than their sedentary age-matched peers — and likely a much higher quality of life.

With the debate over whether or not VO2 max declines with age settled, it’s time to talk about why.