In search of a challenge for her buffest triathlete clients, Wendy Larkin, a personal trainer with Crunch Fitness in San Francisco, created this seaside workout that strengthens, tones, and zaps 300 calories in 30 minutes:

· Warm up with 50 jumping jacks in dry sand.

· Sprint barefoot from shoreline into sea until you're waist-deep. Sprint back. Repeat 10 times.

· Return to dry sand for 20 walking lunges.

· Head back into water with a beach ball. Hold ball between the knees and swim with arms only: 30 strokes freestyle, 30 strokes backstroke, 30 strokes breaststroke.

· Repeat steps 1 through 3 until half-hour is up.

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