How far you can run might be down to brain not brawn, study finds

A special cluster of nerve cells in the brain may be playing a key role in determining endurance gains, a new study in mice suggests.

Previous studies have shown that exercise not only boosts muscle performance but also rewires the brain. Anecdotally, people often report feeling sharper and their minds clearer after workouts.

But exactly how endurance training alters the brain is a topic of continued research.

Now, a new study reveals that mice had increased brain activity after running on a treadmill.

Researchers particularly found improved activity of nerve cells located in their ventromedial hypothalamus (VMH), which is located at the base of the brain and known to regulate how the body uses energy, including the management of body weight and blood sugar.

“We wanted to understand what happens in the brain after exercise and how those changes influence the effects of exercise,” explained Nicholas Betley, an author of the study published in the journal Neuron.

“When we lift weights, we think we are just building muscle. It turns out we might be building up our brain when we exercise,” Dr Betley said.

Scientists found that a specific group of nerve cells in the VMH, called steroidogenic factor-1 (SF1) neurons, became active when the animals ran on a treadmill.

These nerve cells also stayed active for at least an hour after the mice finished running, and following daily exercise for two weeks, the mice showed improvement in endurance. Mice ran faster and longer before becoming exhausted with more training.

These changes were also accompanied by more SF1 neurons in the mice becoming active, and the activity levels were significantly higher than at the beginning of training.

But when researchers blocked SF1 neurons, these animals got tired quickly and showed no improvements in endurance over the two-week training period.

Blocking SF1 neurons only after exercise also prevented endurance gains, even when the neurons functioned normally during exercise itself.

The findings, according to researchers, suggest the important role of SF1 activity after exercise.

Scientists suspect active SF1 neurons post-exercise help the body recover faster by using glucose stored in the body more efficiently.

However, the exact underlying mechanism remains unclear, researchers say.

“These results demonstrate that exercise-induced hypothalamic SF1 neuron activity is essential for the coordination of physiological improvements following exercise training,” they wrote.

“This study opens the door for understanding how we can get more out of exercise. If we can shorten the timeline and help people see benefits sooner, it may encourage them to keep exercising,” Dr Betley said.