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How weightlifting changes the brain

The study finds that weight training, accomplished in rodents with ladders and tiny, taped-on weights, can reduce or even reverse aspects of age-related memory loss

Gretchen Reynolds | NYT 

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Weight training may have benefits for brain health, at least in rats. When rats lift weights, they gain strength and also change the cellular environment inside their brains, improving their ability to think, according to a notable new study of resistance training, rodents and the workings of their minds.

The study finds that weight training, accomplished in rodents with ladders and tiny, taped-on weights, can reduce or even reverse aspects of age-related memory loss. The finding may have important brain-health implications for those of us who are not literal rats.

Most of us discover in middle age, to our chagrin, that brains change with age and thinking skills dip. Familiar names, words and the current location of our house keys begin to elude us.

But a wealth of helpful past research indicates that regular aerobic exercise, such as walking or jogging, can prop up memory and cognition. In these studies, which have involved people and animals, aerobic exercise generally increases the number of new neurons created in the brain’s memory center and also reduces inflammation. Unchecked, inflammation in the brain may contribute to the development of dementia and other neurodegenerative conditions.

Far less has been known, though, about whether and how resistance training affects the brain. A few studies with older people have linked weight training to improved cognition, but the studies have been small and the linkages tenuous. While researchers know that lifting weights builds muscle, it is not yet clear how, at a molecular level, it would affect the cells and functions of the brain.

So, for the new study, which was published this month in the Journal of Applied Physiology, Taylor Kelty, a PhD candidate at the University of Missouri in Columbia, began to consider rats and ladders. He and his collaborators knew that to closely study brain changes related to resistance training, they would need to induce animals to lift weights. But how?

Kelty’s solution, a modification of methods used in some earlier studies, involved a 100-centimeter-long ladder (a little over three feet) and bags of weighted pellets gently taped to the rats’ rear ends. The animals received a Froot Loop when they reached the top of the ladder and soon started climbing willingly, even without rewards. After several weeks, the climbers showed increased muscle mass, indicating that the activity was effective weight training.

Next, to test the training’s brain effects, Mr Kelty and his colleagues injected a separate group of animals with a substance known to induce inflammation in the brain, creating a rodent form of mild cognitive impairment or early dementia.

Half of these rats then began a weekly program of weight training. As the climbing became easier, the mass of the pellets in their bags was increased, just as people progressively add to the weight they lift at gyms.

After five weeks, all of the animals, including an untouched control group, were loosed individually into a brightly lit maze with a single, darkened chamber. Rodents gravitate toward dark places and during repeated visits to the maze, the animals would be expected to learn the location and aim for that chamber.

But their success differed. In the first few tests, the control animals were fastest and most accurate, and the rodents with mild cognitive impairments faltered. With a little practice, though, the weight-trained animals, despite their induced cognitive impairments, caught up to and in some cases surpassed the speed and accuracy of the controls. The weight training had “effectively restored” their ability to think, Kelty says.

The untrained animals with mild cognitive impairments, meanwhile, continued to lag far behind the others in their ability to find and recall the chamber.

© 2019 The New York Times News Service

First Published: Sat, July 27 2019. 22:39 IST