If you are an experienced swimmer and have access to a pool then swimming is a great alternative to running. You’ll get a whole body workout and easily elevate your heart rate with minimal stress on the legs. Some less experienced swimmers get frustrated with stroke or breathing technique and may prefer deep water running or swim aids.
For those who have gotten injured as they increase their mileage, supplementing your running program with swimming can improve your running times without the additional impact. Research conducted by the Milwaukee Heart Institute compared supplemental swimming to supplemental running. Participants increased their normal training by 10%, either more running or more swimming. After eight weeks both groups improved their 2 mile run times, although the run group was slightly faster.