Everyone knows that exercise is good for you, but what type of training helps most, especially when you’re older – say over 65? A Mayo Clinic study says it’s high-intensity aerobic exercise, which can reverse some cellular aspects of aging. The findings appear in Cell Metabolism.Mayo researchers compared high-intensity interval training, resistance training and combined training. All training types improved lean body mass and insulin sensitivity, but only high-intensity and combined training improved aerobic capacity and mitochondrial function for skeletal muscle. Decline in mitochondrial content and function are common in older adults.