I have noticed that whenever I am feeling low going for a long swim lifts my mood. It has helped me through some fairly prolonged troubled patches in my life. I found that no matter how bad I was feeling, if I went for a swim, my mood would lift significantly about 2 to 3 hours after I had left the pool. The effect was clear and predictable. I always felt better, at least for a time. The effect would then last for 3 to 4 hours.
I believe that part of this is the effect of excercise on the brain, and would have perhaps been the same if I had gone for a run, but it seems to me that there is something extra that swimming does to the body.
I looked to see if I could find some research on the effect of swimming on mood, but although it may exist I couldn’t find any. All I have to go on is my own experience.
I have a regular weekly appointment to go swimming with a good friend of mine who suffers from a chronic physical condition, rheumatoid arthritis. She swims every day partly because it is the only form of excercise she can realistically do, and partly as a way of coping with the challenges of her illness. I always meet her, every week, for a long swim, no matter what else is going on in my life. There have been some bad times when it has seemed like the only thing I could rely on. We usually go to the local pool. There is an outdoor pool that is open from May to September so five months of the year we swim outside. We always have a coffee and a chat afterwards and that can be very therapeutic in itself as my friend is very calm and kind and wise, but I am sure there is something in the swim itself that is so helpful and healing.
Besides possible biochemical changes in the brain, swimming requires the alternating stretch and relaxation of skeletal muscles while simultaneously deep-breathing in a rhythmic pattern. These are key elements of many practices, from hatha yoga to progressive muscle relaxation, used to evoke the relaxation response. Because it is so rhythmic swimming lends itself easily to a meditation. As I am always trying to work on the smoothness and efficiency of my stroke I am very aware of my whole body and how I am using it. I often chant or even sing to myself as I am swimming.
Again I have nothing to prove it but I am sure that swimming strengthens the immune system. I swim at least one kilometre a week and have done regularly for the last six or seven years. I swim mainly front crawl and I swim quite strongly. Although I do very occasionally get colds, I find that they are over very quickly, just as they were when I was pregnant. The cold would come and go very quickly instead of dragging on for days or even weeks which was sometimes my experience before I started swimming so much.