MONDAY, Jan. 13, 2020 (HealthDay News) -- 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. 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...