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Many people swim because it’s easy on the joints. While that’s a plus for skiers, the most slope-friendly aspect of swimming is that it tones all major-and many minor-muscle groups. And because it demands a wide range of motion, it can boost flexibility, especially in your neck, shoulders, torso and hips. Swim fast intervals for an anaerobic drill, or keep a steadier pace for an aerobic workout. If you’re a novice swimmer, take a lesson to learn the mechanics of a swim stroke: The better your technique, the better your workout will be.

What It Works shoulders, chest, triceps, biceps, upper back, lower back, abdominals, obliques, gluteals, hamstrings, quadriceps, calves-you get the idea

Insider’s Tip In a typical crawl stroke, about 70 percent of a swimmer’s propulsion comes from the upper body. To move the focus to your lower body, grab a kickboard and propel yourself solely with your legs. It won’t take long to feel the burn.