The guide

Why does VO2 max fall as you get older, and can you slow it?

By GyroscopeUpdated November 15, 202611 sources

Three things wear it down. Your top heart rate drops about 7 beats a decade whatever you do, your muscles pull less oxygen out of each beat’s worth of blood, and most of us get heavier and move less. Together that’s 3 to 6 percent a decade in your 20s and 30s and more than 20 percent a decade in your 70s. Training can’t stop the heart rate part, but it can win back most of the rest and hold you flat for years.

Isn’t it just getting old?

Most people picture aging as a gentle, even slope, the same little bit lost every year, and nothing to do about it.

Both halves of that are wrong. In the Baltimore Longitudinal Study of Aging, 810 healthy adults aged 21 to 87 had their VO2 max measured again and again over a median of 7.9 years. The fall was 3 to 6 percent a decade in the 20s and 30s and more than 20 percent a decade in the 70s and beyond, and from the 40s on men lost more than women. It happened in every quarter of the activity scale. The researchers also found that charts made by comparing young and old people at one moment, which is how most charts are made, paint a falsely gentle picture.

And the part you can’t change is smaller than it looks. When researchers took the loss apart, most of it turned out to be in places training reaches.

What actually wears down?

Your top heart rate. Maximum heart rate falls with age, about 0.7 beats a year by the formula 208 minus 0.7 times your age, built on 351 studies and 18,712 people. In the researchers’ own lab study it fell the same way whether people were active or not (Tanaka 2001). A slower top speed means less blood pumped at full effort, unless each beat pushes out more.

The oxygen in each beat. In the Baltimore study, top heart rate fell only 4 to 6 percent a decade and barely sped up. The bigger, faster loss was in the oxygen used per heartbeat, which fell in step with VO2 max. That number combines how much blood each beat pushes out and how much oxygen the muscles take from it.

Your muscles. The Dallas men below are the clearest case. At 50 their hearts pumped as much blood at full effort as they had at 20, because each beat pushed out 16 percent more to make up for a slower top rate. What they’d lost was in the muscles, which pulled 15 percent less oxygen out of every liter of blood, and the researchers found it accounted for the entire loss. Keeping your muscle as you age is strength.guide’s subject, and how fast you lose muscle is part of this story.

Weight and habits. VO2 max is per kilogram, so every pound you add lowers it with the same engine. And going without training costs a lot, fast. Seven endurance-trained people who stopped lost 7 percent in three weeks and 16 percent by eight (Coyle 1984), mostly because each heartbeat pushed out less blood.

Three weeks in bed against 30 birthdays

In 1966, five healthy 20-year-old men in Dallas volunteered for a study that sounds like a holiday. They spent three weeks in bed. Their fitness was measured before and after, and again after a spell of training.

Thirty years later, in 1996, researchers tracked down the same five men, now 50, and tested them again. Their weight had gone from 77 to 100 kg on average and their bodyfat from 14 to 28 percent, while their lean mass barely changed. Their VO2 max in liters a minute had fallen only 11 percent, from 3.30 to 2.90. Per kilogram it had fallen from 43 to 31, because they were carrying 23 more kilos.

The researchers wrote that three weeks of bed rest at 20 “had a more profound impact on physical work capacity than did 3 decades of aging.”

Then they put the men on six months of endurance training. Their VO2 max rose 14 percent, from 2.9 back to 3.3 liters a minute, the level they’d had at 20, and per kilogram from 31 to 36. The gain came from the muscles taking 10 percent more oxygen from the blood, while their hearts’ top output stayed about the same. None of them got back to the peak they’d reached after training at 20, so age left a mark. But all of the lost oxygen use came back in six months.

That’s a twist on the usual story. In young people, training raises VO2 max mainly by raising the heart’s output (Bassett and Howley, 2000). In these five middle-aged men, the muscle end of the chain did the recovering.

How fast does it fall, decade by decade?

On the US FRIEND chart, the middle falls about 13.5 percent, or 4 points, a decade. Each column is a different group of people, so it’s a snapshot of ages, and the Baltimore study says one person’s own slope starts gentler and ends steeper.

From the FRIEND 2022 treadmill tables, in ml/kg/min.

Can people in their 70s hold it?

The best answer comes from Trondheim, Norway. In the Generation 100 trial, 1,567 people aged 70 to 77 were assigned for five years to one of three things:

• Two sessions a week of 4-minute intervals at about 90 percent of their peak heart rate, about 16 on the 6 to 20 effort scale, after a 10-minute warm-up.
• Two sessions a week of 50 minutes of steady exercise at about 70 percent, about 13 on the scale.
• The national advice to stay active.

Based on earlier studies, the researchers expected VO2 max to fall by at least 3.5 ml/kg/min over five years. It didn’t fall in any of the three groups. The interval group ended 0.7 higher than the other two.

The limit is who signed up. They started at 28.6 on average, which puts the men near the 88th percentile for their age and the women in the top 10 percent, and 80 percent already reported medium or high activity. Holding steady is easier from a strong start. But it shows the slope isn’t fixed if you keep training.

Why does holding steady count as climbing?

Because the chart drops underneath you, a number that stays put moves you up. Here’s a man with a VO2 max of 42 who holds it for 20 years.

At 45: about the 73rd percentile, above average.

At 55: about the 87th percentile, high.

At 65: over the 90th percentile, top 10 percent.

His fitness age stays at 32 the whole time, while the people he’s compared with keep getting older.

The line where daily life gets hard

The physiologist R. J. Shephard looked at what falling fitness means late in life. Below about 18 ml/kg/min for men and 15 for women, he concluded, losing your independence seems likely, and most people reach that line at 80 to 85. On the US chart the middle for people in their 80s is 17.6 for men and 15.4 for women, which is right on it. He also found regular aerobic exercise can take 10 or more years off your biological age, and possibly keep you independent about that much longer.

Think of it as a savings account. The decline is a withdrawal you can’t stop, and it gets bigger every decade. The more you put in before 60, and the more you keep topping it up, the later you hit the bottom. The minimum VO2 max you want puts the line next to the stairs and the groceries.

What slows it?

1. Hard minutes, twice a week, for as long as you can. The Generation 100 interval group ended fittest, and in 28 trials of adults up to 45, intervals beat steady training by a little more in the older people. How to raise it has the session.
2. Steady cardio most days. It builds the base the hard sessions sit on, and it’s what most people can keep up for decades.
3. A steady weight. The Dallas men lost more to 23 kilos than to their hearts. Weight and VO2 max has the math.
4. No long breaks. Three weeks off costs about 7 percent in trained people. A week off for a cold costs very little.
5. Starting anyway. The Dallas men started at 50, and in the Cleveland Clinic study patients aged 70 and over in the fittest group had 0.71 times the risk of death of those in the high group, so gains kept counting late in life.

After 60 it’s too late goes through the evidence. If you’re starting from mostly sitting, read is it safe to push hard? first and walk for a few weeks before any hard session. lifespan.guide covers why we age more broadly.