Could exercise be replaced with a protein supplement?
For people such as the elderly, injured or physically challenged, getting enough exercise can be difficult. Help may be on its way, however, as new research indicates that an existing protein provides some of the key benefits of exercise.
Previous studies have already shown that a naturally-occurring protein known as Sestrin accumulates in the muscles after intense physical activity. Scientists from the University of Michigan therefore wanted to see if artificially upping an animal's Sestrin levels could produce the beneficial effects that are associated with the protein.
They started with three groups of Drosophila flies.
One group was normal, one group had been bred to lack the ability to produce Sestrin, and one had been altered to overexpress Sestrin. All three groups were physically trained for three weeks, on a sort of mini treadmill designed by colleagues at Detroit's Wayne State University.
When the insects' ability to run and fly for prolonged periods was subsequently tested, it was found that while the regular flies had improved, those lacking Sestrin had not. The flies that overexpressed the protein, however, experienced even more of an improvement than the regular flies – this was the case even when the Sestrin-boosted insects hadn't trained at all.
The protein may do more than just increase endurance, though.
When mice that were bred to lack Sestrin exercised, there were none of the expected improvements in aerobic capacity, respiration, and the ability to burn fat. And in a related study conducted at Spain's Pompeu Fabra University, Sestrin was found to keep immobilized muscles from atrophying – this finding could be particularly applicable to people who have an injured limb encased within a cast.
"We propose that Sestrin can coordinate these biological activities by turning on or off different metabolic pathways," says U Michigan's Prof. Jun Hee Lee, who co-led the study along with Asst. Prof. Myungjin Kim. "This kind of combined effect is important for producing exercise's effects."
The scientists are now further exploring the manner in which Sestrin is produced within the body, and are looking into the development of supplements containing the protein.
This isn't the first time we've heard about the possibility of "exercise in a pill." Previous studies have looked at utilizing a hormone known as irisin, a molecule called compound 14, a protein known as Rev-ErbAα, and a protein called myostatin.