Peter,
In the old Yagya days, Brahma Baba (Lekhraj Kirpalani) used to take the children for walks to Baba's rock, there used to be a tennis court in the courtyard where the Tower of Peace stands now in Madhuban, and there is a badminton court outside one of the lodgings in Madhuban (Sukdham I think).
Sport is often seen as body consious, but if sport is fresh and good for the health and helps to relax, then it is good for the body which holds the Chariot. Sport is a way to energise your body elements and maintain a fresh mind. There is physical sports as well as less physical ones, so it is best to have the sports which do not exert too much pressure as it will cause tension, and also sports that become competitive will bring out competiveness in which someone will win and someone will lose. If one can humbly accept loss and well as a win, then it is fine for both parties. Otherwise egos will fly when a "winner takes all". Yoga is like a sport of the mind.
I often go swimmming, and also do many other exercises, to a lesser a degree than when I was younger. I enjoy sports with others and also I like it on my own (it's a bit like studying). Floating in the pool backwards and thinking about God is very pleasant, it's a nice feeling of floating but also of swimming in the Ocean.
However, if you feel pain, you should moderate your excercise and slowly build up your muscles and timing. In the Mahabarat story, Arjun has the concentration of being able to always hit the target with his archery skill and his pandav Brother Bheem had the strength and power but maintained softness. Physical pain will usually come with the process of aging anyway, but if you learn to know your own body then you will be able to acommodate it and control the pain. But you need not be attached to the body and accept the body you have been cherished with, so look after it well too. Feed it well too. Don't look at others when you do sports, enjoy it and feel free.
The aim of sports is not the target but the enjoyment.