In the future, could exercise's benefits come in a pill?

A protein may be able to give immobile people the benefits of exercise.
A protein may be able to give immobile people the benefits of exercise.

The benefits of exercise are well-known, but what if you're not able to take a brisk walk or endure a punishing workout?

Luckily for you, scientists have identified a protein they think might one day help prevent muscle decline in seniors and people who are immobile.

'Fly treadmill'

Sestrin, the protein, accumulates naturally in muscle after exercise. The researchers decided to find out more about its link to exercise by conducting experiments in flies and mice.

They created a type of "fly treadmill" and trained the flies for three weeks. They then compared the running and flying ability of normal flies and flies bred to lack the ability to make Sestrin.

"Flies can usually run around four to six hours at this point and the normal flies' abilities improved over that period. The flies without Sestrin did not improve with exercise," said study author Jun Hee Lee.

Lee is a professor in the department of molecular and integrative physiology at the University of Michigan.

The researchers also found that triggering overexpression of Sestrin in the muscles of normal flies and maximising their Sestrin levels gave those flies greater abilities than the trained flies, even without exercise.

Improved endurance is just one of the benefits of Sestrin. Experiments with mice showed that those without the protein did not gain the improved aerobic capacity, improved respiration and fat-burning typically associated with exercise.

Prevent muscle wasting

"We propose that Sestrin can coordinate these biological activities by turning on or off different metabolic pathways," Lee said in a university news release. "This kind of combined effect is important for producing exercise's effects."

Further investigation showed that Sestrin can also help prevent wasting of muscle that's immobilised, such as when a limb is in a cast for a long time.

This "highlights that Sestrin alone is sufficient to produce many benefits of physical movement and exercise," Lee said.

That suggests that Sestrin could help combat muscle-wasting due to ageing and other causes without the need for exercise.

However, animal findings don't always translate to humans and much more research is needed before that might be possible, according to the study authors.

For example, they still don't know how exercise triggers Sestrin production.

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