Oladosu FA, et al. - This study was undertaken to assess if involuntary abdominal muscle activity precedes spontaneous episodes of menstrual cramping pain in dysmenorrheic women and if naproxen administration affects abdominal muscle activity. Researchers recorded abdominal electromyography activity from women with severe dysmenorrheic and healthy controls and suggested abdominal muscle activity to contribute to cramping pain in primary dysmenorrhea, but this is resolvable with naproxen. Widespread pain sensitivity (lower pressure pain thresholds) was observed among dysmenorrheic patients without cramp-associated abdominal muscle activity and these patients were also more tended to have a chronic pain diagnosis, suggesting their cramps are linked to changes in central pain processes. Outcomes there support the hypothesis that multiple distinct mechanisms may contribute to dysmenorrhea.