If you want to make your partner's knees wobble, make sure that yours don't. "Sex is like any physical activity. If your body isn't prepared, you run the risk of straining yourself," says Louis Maharam, M.D., president of the New York chapter of the American College of Sports Medicine, and author of The Healthy Back. "If you're only looking to give an erotic massage, not much physical preparation is necessary. But if you're going for sexual acrobatics, you need to condition the relevant muscles." Here are his pointers to getting a bedroom-ready body.

Triceps: Strong triceps are essential for anyone supporting their body weight—like a man when he is over his partner, or a woman when she's facing towards the mattress. Recommended exercises: triceps extensions, triceps bench dips.

Biceps: This muscle group is particularly important for a woman during intercourse if she wants to hold on while in the upright position. Recommended exercise: arm curls.

Back: A flexible back can enhance sexual activity for either partner because it allows you to arch easily. If you need a little extra support while lying down, place a roll of paper towels under the crook of your lower back. Recommended exercise: lower back stretches (for example laying down on your back and bringing your knees to your chest).

Quadriceps and Glutes: A man's quads stabilize his body during sex in the upright position, while strong glutes help facilitate his movements. Recommended exercise: angled leg press.

And the final component of a "sexually strong" body: cardiovascular fitness. The more aerobically fit you are the more stamina you'll have.