Most adults in the USA aren't meeting the federal physical activity recommendations for both aerobic exercise and muscle-strengthening activity, according to government statistics out today. About 79% of adults don't meet the physical activity guidelines that advise getting at least 2½ hours a week of moderate-intensity aerobic activity such as brisk walking, or one hour and 15 minutes a week of vigorous-intensity aerobic activity, such as jogging. Plus, the guidelines recommend that adults do muscle-strengthening activities, such as push-ups, sit-ups or exercise using resistance bands or weights. These activities should involve all major muscle groups and be done on two or more days a week, the guidelines say.