A strong back is something to be grateful for, MarieMarie. A couple of my friends damaged their backs playing sports: at age 30 they started getting probs that don't usually turn up until you're 70. Very unfair as they were the guys who had made the effort to stay fit.
Traditionally respected sports can do a lot more damage than good. From the obvious boxing and American football down to triathlon and basket ball, despite what ill-informed badgering coaches might tell you, these are not healthy occupations.