People who exercise regularly burn more calories and have more muscle mass than those who are less active. Aerobic exercise, like brisk walking and swimming, burns calories, while strength training slows the inevitable muscle loss associated with aging, which helps boost metabolism. It’s often reported that aerobic and resistance exercise increase metabolism not only while you are exercising, but for several hours afterwards as well. This increase in metabolism is not sustained long-term, however. High-intensity resistance training may have the greatest effect on metabolic rate post exercise, but there are no studies linking the after effects of activity with significant weight loss.