We all know exercise is important to be healthy, every doctor in the world would tell you so. Now, new research in the journal Nature Communications 1, we also know who to thank for. Sestrins, a protein family has been linked to the health benefits of exercise. Sestrins improve physical performance It was previously known that sestrins build up in the muscle after exercising, but their exact role was not fully understood. The researchers first used fruit flies (Drosophila Melanogaster) and they mutated the gen responsible for sestina production to see what happened. Later, they took flies to the gym. They put them in a rotating tube which would change direction every 15 seconds so they would need to fly up repeatedly. After 3 weeks, the control flies did develop muscle, in the sense that they improved their performance and could keep at it for longer. However, the sestrins mutants did not. This result points to an involvement of sestrins in the improvement after training. When they did the opposite, and produced flies that over expressed sestrins to a point they could not increase their production even after exercise, they saw that these flies were better performers without training than controls. Not surprisingly, exercise did not improve their performance since they were already at their top sestrin levels. That’s all good and fine, but flies are flies. What about mammals? They did produce a mutant knock-out mouse for sestrins, which could not produce any and saw that after regular training in their little mouse wheels, these mice could not burn fat, increase their aerobic capacity, or improve their respiration like normal mice do. Could we one day get all the benefits of exercise from the couch? These results show that this protein family is definitely linked to health benefits of exercise. However, it is unlikely that professional athletes will get antidoping agencies to approve a drug based on these proteins but it might be a good alternative to avoid muscle loss in the bedridden and/or old. Another problem to its use as a pharmacological target is the size of these proteins, and delivery to the muscle. These problems could be solved by targeting smaller molecules with act on sestrins and viral delivery but that still is a dream of a (not so near) future.