The feds have unveiled their first-ever physical activity guidelines for kids—kind of a food guide pyramid for exercise that outlines a comprehensive set of recommendations about the types and amounts of physical activity that offer substantial health benefits. The "2008 Physical Activity Guidelines for Americans" (www.health.gov/PAGuidelines) says kids should have one hour or more of moderate or vigorous aerobic physical activity a day (like biking or running and sports such as soccer or basketball), including vigorous intensity physical movement (such as hiking or skateboarding) at least three days a week. Incorporating muscle-strengthening activities, such as rope climbing, sit-ups, and tug-of war, three days a week is also suggested, as are bone-strengthening pursuits, such as jumping rope, running, and skipping. These activities improve cardiorespiratory and muscular fitness in kids and teens, as well as bone health, and contribute to favorable body composition, say the guidelines by the U.S. Department of Health and Human Services.