What exercises will help build strength for long-distance swimming?

The number one thing you can do is refine your stroke. The more efficient your technique, the less energy it's going to require to travel more distance in the water. Another way to think about it: If your stroke is inefficient, it takes you more energy to travel the same speed with more strokes.

Beyond that, you need strength and stability to maintain proper technique. Clearly, you need to train your whole body, but here are few keys to prevent pain and boost speed and endurance in the water:

- Rotational power If you use proper technique, your torso should rotate as you slice through the water. Improve rotational power with moves like rotational medicine ball throws.
- Shoulder protection Shoulder injuries are common for swimmers because of the overhead motion. To protect your shoulders, train the muscles that support your shoulder blades—your "scapular stabilizers"—with Ys and Ts, for example.
- Back, leg strength You pull yourself through the water with your back muscles and provide propulsion with your kick. Focus on both areas, including plenty of work for your glutes (butt muscles). Training your glutes will help cut down on soreness in the hamstrings and lower back since these two areas often overcompensate when the glutes are weak.

For more info, check out these articles:
Five Training Secrets for Triathletes
Four Keys to Better Swim Stroke
Pillar Strength

- Craig Friedman, Performance Specialist, Athletes' Performance