Ask the Docs

Is Cardio Useless? Your Brain Says No

By Dr. Jonathan Chung

As of the timing of this post, I consider myself primarily a weightlifter when it comes to fitness. If you follow my social media posts on Instagram, Twitter, and Facebook you’ll mainly see photos and videos of squats, snatches, cleans, and other movements that involve heavy barbells.

A popular trend in fitness is to condemn forms of exercise called steady-state cardio, which is your classic endurance exercise like long distance running, rowing, cycling, etc. Critics will say steady-state cardio is ineffective for putting on muscle mass and strength as well as a negligible effect on weight loss so it should be discarded as a form of exercise.

All of those things are pretty accurate. Cardiovascular exercise has a marginal effect on strength and hypertrophy, and in the absence of diet no form of exercise really promotes weight loss. But this doesn’t mean that cardiovascular exercise is useless. The effect that cardiovascular exercise has on your brain can be life changing.

Cardio and Neurogenesis

Neurogenesis is a term that scientists use to describe the growth of new neurons. For decades it was a widely held belief that all of the brain cells you are born with are the ones that you will have forever. In more recent years, scientists have identified parts of the brain that do produce new brain cells on a regular basis……just a lot more slowly than something like your skin.

One particular region in the brain that is well known to undergo neurogenesis is called the hippocampus.

The hippocampus is a piece of our brain that is associated with the formation of memories and in learning. It’s been well established in rat studies that neurogenesis happens in this part of the brain, and exercise enhances this process. But that’s just a rat study. Does this actually happen in humans?

While we can’t put humans on a treadmill for 30 minutes and cut out their hippocampus, there are studies that imply that neurogenesis happens in humans after cardiovascular exercise too. These studies have showed that exercise improves memory scores, increases the size of the hippocampus, and produces higher amounts of brain derived neurotrophic factor which is the chemical compound associated with neurogenesis.

That’s pretty amazing stuff! This is the type of stuff that helps to explain why people that exercise regularly have a lower risk of dementia. It also helps us understand how exercise can help combat things like ADHD and other brain related disorders.

Does Weight Training Have the Same Impact?

Scientists who did the study on rat brains found that aerobic exercise had double the amount of neurogenesis as sedentary rats. They also found that rats who did resistance exercise had very little effect on the rat brains, even though the rats got physically stronger. 

Now we have to take that with a grain of salt because:

1. Rats aren’t people.
2. The way that the scientists “strength trained” the rats is by tying a weight on their tails and making them climb with it. Not a terribly good comparison to men and women who voluntarily lift weights recreationally.The biggest take away from this study is the way that aerobic exercise seems to pump up that brain derived neurotrophic factor which may be a key to making your brain grow and heal.

While the effects of weightlifting on neurogenesis hasn’t been studied yet, there is compelling evidence that suggests weight training is beneficial in people with early stages of memory loss. Resistance training has been shown to improve general cognitive performance, improve blood flow to memory areas of the brain, and save seniors with memory problems money.

All Exercise Is Beneficial

At the end of the day, all kinds of exercise is beneficial for different reasons. We have developed a stronger understanding for how cardio can benefit the brain, and there is data that shows that weight training also gives the brain a boost.

There’s no need to shame someone’s exercise of choice. There are so many people that don’t move at all, that anything that a person can do to be active and move regularly will provide them a substantial benefit.

Now if you’re a fitness junkie already, then taking a balanced approach and incorporating something you usually avoid is a great recipe to get the maximum benefits of exercise.

If you are someone that lifts weights 4 days a week without fail, then maybe taking a 2 mile run or row would be a great addition to your weekly regiment. If you run daily and never do strength, then you should definitely look into resistance training to supplement your cardiovascular fitness.

Your brain thrives on exposure to new things. Beyond some nice looking muscles and better heart health, the biggest benefit of exercise is making your brain better.