What Happens to Endurance as You Age? | Hardworkout Magazine

Key takeaways

- VO2 max typically begins to decline gradually from around the age of 30, and the decrease is often estimated at around 5-10 per cent per decade.

- A falling maximum heart rate limits how much blood the heart can pump during maximal effort, which reduces the oxygen delivered to working muscles.

- Loss of muscle mass and reduced mitochondrial function make the muscles less efficient at using the oxygen the blood delivers.

- A physically active 50-year-old can have considerably better fitness than a minimally active 30-year-old, so age alone says little about a person's endurance.

- A 2022 study reports that well-trained male endurance athletes who maintained their training lost about 5-6.5 per cent of VO2 max per decade, while those who cut training volume declined more.

Perhaps you notice that your fitness is not as good as before, that the uphill climbs feel heavier, or that you cannot maintain the same pace on your runs as you used to.

But how much of the changes are due to the aging process itself? And how significant are training habits for how physical capacity develops throughout life?

Why does VO2 max decrease with age?

VO2 max describes the body's maximum ability to take up, transport, and utilize oxygen during physical activity.

From around the age of 30, VO2 max typically begins to gradually decline. The decrease is often estimated to be around 5-10 percent per decade, but varies significantly from person to person.

One important reason is that maximum heart rate decreases with age. When you exercise at high intensity, the heart increases both the pulse and the amount of blood it pumps to supply the muscles with oxygen. As maximum heart rate decreases, the heart's ability to increase blood supply during maximal effort also diminishes.

Additionally, the heart's ability to fill with blood between each heartbeat can change with age.

Overall, this can lead to the muscles receiving less oxygen when you train hard, which can make it more difficult to maintain the same intensity as before.

Do the muscles age differently from the heart?

It is not just the heart that affects endurance. The muscles must also be able to utilize the oxygen that is transported through the blood.

With increasing age, muscle mass can gradually decrease, while changes occur in the muscle fibers and the function of the mitochondria.

Mitochondria are found inside the muscle cells and use oxygen to produce energy. If the muscles have fewer mitochondria or if these function poorly, the ability to produce energy through aerobic metabolism may be reduced.

This can affect endurance, as the muscles become less efficient at utilizing the oxygen supplied. However, the extent of the changes also depends on how physically active you are.

How Does Activity Level Affect Fitness?

One of the reasons fitness declines with age is that many gradually become less physically active.

When training sessions become less frequent or the intensity lower, the heart and muscles receive less stimulation to maintain capacity. Over time, this can lead to a decline in fitness that is more significant than what can be explained by the aging process alone.

A physically active 50-year-old can therefore have significantly better fitness than a minimally active 30-year-old. Even though the younger person has an age advantage, they may not necessarily have the highest VO2 max.

The same applies to individuals of the same age. A 50-year-old who has trained for endurance regularly for many years may have significantly higher oxygen uptake than a peer who rarely trains.

Age alone does not indicate how good a person's fitness is. How active you have been throughout your life, and how much you train today, also has a significant impact.

How much can training counteract the decline?

Regular cardiovascular training can help you maintain a high oxygen uptake longer, even though capacity gradually changes with age.

A [2022 study](https://pmc.ncbi.nlm.nih.gov/articles/PMC9517884/) refers to research where well-trained male endurance athletes who maintained their training had a decline in VO2 max of about 5-6.5 percent per decade. Athletes who reduced their training volume experienced a greater decline.

To preserve fitness after the age of 40, it is therefore important to continue with training that challenges both the heart and the muscles. Easy sessions allow for maintaining a good training volume, while intervals with higher intensity can help preserve or improve maximum oxygen uptake.

Strength training is also useful because it helps preserve muscle mass and strength. This can make it easier to maintain physical capacity and continue with cardiovascular training as you get older.

Can you still improve your fitness if you start training in your 40s?

If you have previously been inactive, you can still achieve significant progress. Even though VO2 max typically declines with age, a person who starts training regularly in their 40s or 50s can achieve much better fitness than they had when they were younger.


Sources:

The Impact of Training on the Loss of Cardiorespiratory Fitness in Aging Masters Endurance Athletes – [National Library of Medicine (NIH)](https://pmc.ncbi.nlm.nih.gov/articles/PMC9517884/)