"Dumbbells are the most versatile piece of equipment you can own," says Rast. "You can do anything – squats, dead lifts, presses, rows – and work your body unilaterally. In sports, it's not often that we have two feet planted. Dumbbells give you the freedom to work one side of the body independent of the other." Rast recommends getting two sets: one that you can hold over your head with little strain for a minute and one that you can barely curl 10 times in a row. [$48; roguefitness.com]

DO THIS: 1. Push-up rows. Hold a dumbbell in each hand. Do a push-up, then a row (shown) on one and then the other arm. Repeat 10 times. 2. Dumbbell thrusters: Squat with weights at your shoulders. As you come up, thrust them above your head. Repeat 15 times.

Also try:
• Standing flies. With dumbbells at your waist, raise straight arms to shoulder height and then lower.
• Side lunges. Hold one dumbbell in both hands and step sideways.
• Twists. Seated with your feet in the air, hold one weight and twist left, then right.