A study published in the Journal of Manipulative and Physiological Therapeutics (June 1992; 15(5):279–285) examined the effects of chiropractic care on dysmenorrhea. The study included 45 women with primary dysmenorrhea who were randomly assigned to one of two groups. Twenty-four women received spinal adjustments, defined as high-velocity, short-lever thrusts intended to restore joint motion, while 21 women in the control group received a sham manipulation that mimicked the positioning of an adjustment but involved only a light thrust to the base of the sacrum. Women who received the actual spinal manipulation reported an immediate reduction in pain and distress compared with those in the placebo group.