Getting your workout in can also improve your sleep. In one study of 2,600 subjects, people who exercised at least 150 minutes a week reported a 65 percent improvement in sleep quality as well as better energy levels during the day, according to the National Sleep Foundation. And there's nothing more heavenly than a solid night of sleep (and nothing more rewarding after a tough workout during the day).
A new study from her lab shows that a 20-minute moderate workout has measurable effects on the immune system: Participants were asked to walk or jog on a treadmill, depending on their fitness level. They measured levels of TNF, an inflammatory marker, before and after the exercise, and found that there was a 5% reduction in the number of immune cells that produced the marker.
1. It strengthens the heart. The heart is a muscle. Like other muscles, its performance improves when it's regularly challenged by exercise. The heart responds to exercise by becoming stronger and more efficient. Strengthening the heart muscle can help ward off heart disease -- the leading cause of death in the United States, according to the U.S. Department of Health and Human Services -- even in early childhood.
FIT TIP: If you exercised on an empty or almost-empty stomach, you're probably feeling light-headed or even nauseated or headachy. Your immediate food fix: A high-carb nosh, like a banana or half a bagel, will refuel you and kick-start your recovery. And don't forget to drink plenty of water with your snack. Intense or long workouts can leave you dehydrated.
If you're ready to move on from classic Bulgarian split squats, Swan's amped-up variation gets your upper body in on the action for a true total-body exercise. "This combination move works your legs, butt, chest, back, arms, and core," she says. "And it not only hits all the major muscle groups—it also lets you work on balance." Give it a shot and you'll see why.