Many women have difficulty climaxing during intercourse because of a lack of sufficient clitoral stimulation. (Several studies have reported that only 30 to 45 percent of women regularly climax during coitus.) The recommended cure for lack of orgasm is simple: self-help. Your girlfriend should teach herself to climax -- via vibrators, or shower massage units or her own hand. Then she should take that knowledge to bed with her. Dr. Mary Jane Gray, writing in Medical Aspects of Human Sexuality, reports that "apart from matters of technique, orgasm requires the trust which allows a complete loss of control. It may be that such loss of control is too much for a particular woman and that she pulls back from impending orgasm. She needs to recognize that the genital sensations of pleasure and pain can be very close together and learn to relax into them rather than to analyze them."

There may be another solution. Two researchers in Nebraska studied 281 women who were unable to experience orgasm during intercourse and found that they had poor vaginal muscles -- specifically, the pubococcygeus muscle, the one a woman clenches to control urination. The pubococcygeus muscle does not receive a lot of exercise in the normal state of affairs.

Isometrics (contracting the muscle for ten seconds at a time, several times a day) may remedy the problem. There's no explanation for the relation between fitness and fun, but if it gets results, who cares?