I m an active 67 year old female and had an episode over a month ago where I suddenly had a cramp, spasm like pain that had me unable to walk any distance without discomfort. Not typical for me. I do pilates group reformer three times a week but am careful not to over do or hyperextend my joints/muscles, etc. Someone told me it was because of pilates...that the core work I was doing...maybe I was compensating with my hip flexors and that was shortening my muscles. I ve laid off pilates for about 3 weeks now and tried to stretch. Still have cramp pain in front groin when I overdo. I haven t seen a doc yet. Using Aleve which helps.