Summer should be a time of activity and fun, not stress. But for some, heading to the pool even just to swim some leisurely laps can be a source of discomfort. It’s long been documented that spondylolysis--a form of arthritis of the spine--is common among swimmers, and can be exacerbated by improper swimming technique, especially if you swim a lot. The butterfly and breaststroke in particular are known for causing other lower back problems in swimmers, according to Livestrong.com. If…