Exercise\u00a0does more than strengthen muscles; it also rewires the brain.\u00a0In a study publishing\u00a0February 12\u00a0in the Cell Press journal\u00a0Neuron, researchers reveal\u00a0that\u00a0the lasting gain in endurance from repeated exercise-such as the ability to run farther and faster over time-involves\u00a0changes in brain activity\u00a0that help muscles and hearts to become stronger.\u00a0<\/p>\n
A lot of people say they feel\u00a0sharper\u00a0and their minds are clearer after exercise. So\u00a0we wanted to understand what happens in the brain after exercise and how those changes influence the effects of exercise.”\u00a0<\/p>\n
J. Nicholas\u00a0Betley,\u00a0corresponding author, University of Pennsylvania<\/p>\n
In their experiments,\u00a0Betley\u00a0and his colleagues\u00a0noticed that mice had increased brain activity after\u00a0running on the treadmill, especially in the nerve cells\u00a0located\u00a0in their ventromedial hypothalamus (VMH). This brain region plays\u00a0an important role\u00a0in how the body uses energy, including regulating body weight and blood sugar.\u00a0<\/p>\n
By\u00a0monitoring\u00a0neural activity in\u00a0mice, the team found that\u00a0a specific group of nerve cells\u00a0in the VMH, called\u00a0steroidogenic factor-1 (SF1) neurons,\u00a0became active\u00a0when\u00a0the animals\u00a0ran on a treadmill. These neurons also\u00a0stayed\u00a0active for at least an hour after\u00a0the mice\u00a0finished running.\u00a0<\/p>\n
After\u00a0daily\u00a0exercise\u00a0for two\u00a0weeks,\u00a0these\u00a0mice\u00a0showed\u00a0improvement\u00a0in endurance. They\u00a0were able to run faster and longer before\u00a0becoming\u00a0exhausted.\u00a0When\u00a0researchers looked at the\u00a0mice’s\u00a0brains, they\u00a0saw\u00a0that\u00a0more SF1 neurons\u00a0in mice\u00a0became active,\u00a0and the\u00a0activity levels were\u00a0significantly higher\u00a0than at\u00a0the beginning of training.\u00a0<\/p>\n
When the team blocked\u00a0SF1\u00a0neuron\u00a0activity\u00a0and prevented them from sending signals\u00a0to the rest of the brain, these animals got tired quickly\u00a0and showed no\u00a0improvements in endurance over the two-week\u00a0training period.\u00a0<\/p>\n
To the\u00a0researchers’\u00a0surprise,\u00a0blocking\u00a0SF1 neurons only after exercise\u00a0also prevented endurance gains\u00a0even though the neurons functioned normally during exercise itself.\u00a0This result suggests\u00a0the\u00a0important role\u00a0for SF1 activity after exercise.\u00a0<\/p>\n
“When we lift weights, we think we are just building\u00a0muscle,” says\u00a0Betley.\u00a0“It turns out we might be building up our brain when we exercise.”\u00a0<\/p>\n
While the underlying mechanism\u00a0remains\u00a0unclear,\u00a0Betley\u00a0says\u00a0that\u00a0active SF1\u00a0neurons\u00a0post-exercise may help the body recover faster by using glucose stored in the body more efficiently. This may allow other parts of the body-like the muscle, lungs,\u00a0and heart-to adapt\u00a0more quickly\u00a0to harder workouts.\u00a0<\/p>\n
Betley\u00a0hopes that this research could one day help older people or people recovering from stroke stay active while also\u00a0benefiting\u00a0athletes and younger people recovering from injury.\u00a0<\/p>\n
“This study opens the door\u00a0for understanding\u00a0how we can get more out of exercise,”\u00a0he\u00a0says.\u00a0“If we can shorten the timeline and help people see benefits sooner, it may encourage them to keep exercising.”\u00a0<\/p>\n
This work was supported by\u00a0the University of Pennsylvania, the National Institutes of\u00a0Health, the National Science Foundation, the National Research Foundation of Korea, the Rhode Island Institutional Development Award, the Rhode Island Foundation,\u00a0and Providence College.\u00a0<\/p>\n
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