Swimming for Runners

If I had to pick one supplementary activity that would help you the most as a runner, it would be swimming. Once you get your stroke down, swimming has many benefits: You can work hard enough to sustain a solid effort; it’s a great upper-body strengthener, it’s a nonimpact activity; and the kicking is terrific for loosening tight tendons and muscles in your feet, ankles, and legs.
The other great use of a pool for runners is water running. This activity is pretty straightforward: You head to the deep end of the pool, usually with a flotation device on, and start running in place. After a few times, it will feel pretty much like running on land. Water running is especially good for injured runners who don’t want to lose their land legs during a lay-off, as well as for cross-training runners who get injured beyond a certain level of mileage, but don’t like other activities. As with swimming, you have to work a little harder than you would on land to maintain the same heart rate. Many pools now offer water running classes.
The two main drawbacks to swimming are convenience and gauging effort. Finding a suitable pool (one that’s big enough to legitimately swim laps in) that isn’t too crowded and that has decent hours can be a real challenge. If you don’t have good technique, you’ll spend your swim flailing around rather than giving your heart a good workout. Even when you do become adept, comparing swimming to running takes a little extra math. Because you’re supported by the water, and because you stay so much cooler than when working out on land, your heart will beat about 15 fewer times per minute for the same effort. So you really have to keep at it to keep your pulse near what it is when you run. Kicking vigorously with your legs is a good way to do this.