A study in the journal Nature Communications indicates that exercise can help can improve the cells in muscles. This happens by renewing mitochrondria, the part of cells that turn foods into energy. The study found exercise causes “mitophagy”,” a process where damaged mitochrondria are removed following stress. The removal of the bad mitorchrondria keeps skeletal muscle strong. Workouts on a treadmill activated two types of enzymes that led to mitophagy, researchers found. Without one of the enzymes, Ulk1, mitophagy was inhibited.