Adding core stability to this arm exercise will shape and tone the muscles in your midsection as well as the backs of your upper arms, called the triceps.
1. Hold a 5- to 10-pound dumbbell in each hand and lie on a full-length round roller. Place your hips and head on the roller (you can use a yoga block under your head if necessary). Put your feet flat on the floor, hip-width apart, toes and knees facing forward. Straighten your arms above your chest and press the ends of the dumbbells together.
2. Inhale, slowly lower the dumbbells until they're just above your forehead, pausing with your wrists at shoulder height. Then exhale, contracting the backs of your upper arms to reverse directions and move the dumbbells up to the start position. Do not "lock out" at the elbows. Hold for two seconds at the top of the lift and repeat until you have done 12 reps. Rest for 20 seconds and repeat for a total of three sets.
Karen Voight is the creator of a line of fitness DVDs, including "Sleek Essentials."