Swimming is also an aerobic form of exercise. We know that swimming exercise has an effect on insulin sensitivity, which leads to a lower risk of diabetes. It also improves other health concerns, such as blood pressure, and it's good for flexibility. Swimming is probably one of the best all-around exercises that can be done. The only thing it's not good for is building and protecting bone mass.
So swimming wouldn't be a good choice for reducing risk of osteoporosis?
There's just not enough resistance placed on the body by the water. For example, if you're running, you're going to be coming down on each leg with two to three times your body weight, so your spine has to develop the strength to counteract that amount of tension. So if you're a 100-pound woman who is running, each time you hit the ground with your foot, you're going to put 200 to 300 pounds' worth of stress on the back, whereas if you're swimming, you're going to put 10 to 20 pounds of stress at the most.
I would recommend that swimmers who want to add resistance to their workout supplement it with some form of strength exercise two days a week. They should particularly focus on exercises that will work the legs and the back in order to prevent fractures later in life. (People who already have osteoporosis should do strength training under the supervision of their physician.)
What are the benefits of water aerobics?
Water aerobics put a lot less stress on the knee and hip joints than running or many other aerobic activities. If you put people in the water, they don't have that pounding and compression on those joints, so they're able to exercise nearly pain-free.
