Cardio or weights: what is best for your brain?

Whether you bounce out of bed pumped for a Saturday morning run or begrudgingly drag yourself to the gym, we all know a workout – chiefly the burst of whizzing endorphins that follow – does great things to our brain.

But different types of exercise can have specific benefits for brain health, recent research suggests. So what’s better – running marathons or pumping iron?

In Scientific Reports, a group of Swiss researchers discovered that lactate, a waste product of intense, aerobic exercise, triggers a molecular cascade that protects brain cells.

During acute brain trauma, such as a stroke or spinal cord injury, nerve cells start firing on overdrive in response to a brain chemical called glutamate. This results in so-called “excitotoxicity”, where calcium builds up inside nerve cells, and eventually kills them.

Lactate, which is produced in muscles and the brain when the body breaks down glucose, protects from this excitotoxicity.

Testing mouse nerve cells in petri dishes, the Swiss team discovered adding glutamate killed 65% of nerve cells – but when lactate was added, this death rate dropped to only 32%.

So what can exercise do for the brains of us who – touch wood – don’t end up with acute brain trauma?

Good news: endurance exercise can prompt new brain cells to grow, according to a Journal of Physiology paper earlier this month.

Finnish researchers investigated the effects of different types of exercise on rats – in particular, their hippocampus, a part of the brain important for learning.

After six to eight weeks of training, rats who ran on treadmills or running wheels produced two to three times more new nerve cells in the hippocampus than rats who didn’t exercise.

Other rats “weight-trained” – climbing up vertical ladders with pouches containing lead weights attached to their tails. Even though these rats were physically much stronger at the end of the experiment, they didn’t grow more hippocampal nerve cells than their no-exercise counterparts.

The researchers also tested the effects of “high-intensity interval training” – a workout trend sweeping gyms around the world, entailing short bursts of high-intensity anaerobic activity alternated by short, low-intensity recovery periods.

Where this interval training has been shown to improve cardiovascular fitness more efficiently than moderate endurance training, the effects on the brain in this study appear to be minimal.

Rats on the interval training grew a few more nerve cells in the hippocampus than rats who didn’t exercise, but not enough to be statistically significant. The reason, study author Miriam Nokia told The New York Times, could be that the stress of the high-intensity exercise reduces new brain cell formation.

But at the same time, she added, weight and interval exercise may encourage formation of new blood vessels or new connections between different parts of the brain.

So it appears variety is key to cover all brain health bases.

Power-lifters: consider adding some cardio between reps, and marathon runners, pick up a dumbbell every now and then.