40 minutes of swimming with sprints

Tonight I did some intervals in the pool. I tried swiming as fast as I could for 25 meters and timed myself at 16 seconds. I did a couple more around 17 seconds. I believe swimming is an excellent way to improve aerobic fitness without the pounding. Swimming is going to become part of my base training. I also do some aqua jogging and various exercises such as high knees and butt kicks in the water.