Exercise: her options. (Editorial).

While data accumulate supporting benefits of exercise, the United States population has a growing problem: its collective body mass index (BMI). In 2000, the majority (56%) of US adults had a BMI[less than or equal to]25 kg/[m.sup.2] ("overweight"), and 19.8% were obese (BMI [less than or equal to]30 kg/[m.sup.2] The prevalence of obesity has risen rapidly, increasing 61% since 1991.(2) In the same interval, the rate of combined obesity and diabetes more than doubled, increasing to 2.9%.(1) Besides an obvious reduction in the risk for obesity, exercise is associated with a lower likelihood of type 2 diabetes (3) and many other benefits, including some that are unique for women.

Recommendations by the American College of Sports Medicine (ACSM) for frequent and regular exercise are echoed by the Centers for Disease Control and Prevention and the American Heart Association. The ACSM recommends moderate intensity aerobic exercise most (if not all) days of the week, including resistance training twice weekly. Although this may sound prohibitive, the daily goal of expending 150 kcal in 30 to 40 minutes can be accomplished cumulatively, including such activities as brisk walking.(4)

The cardiovascular benefits of regular exercise include increased HDL level (5] and lower blood pressure.(6) Although data are inadequate to determine whether exercise affects the risk of breast, endometrial, or ovarian cancer, regular exercise does reduce the risk of colon cancer. Combined with the associated reduction in risk for diabetes, regular exercise thus contributes to a reduction in mortality rate from 40 per 10,000 woman-years in relatively inactive women to 9 per 10,000 woman-years in the women who are most active.(7) Beyond prolonging life-span, exercise also is associated with several mental health benefits, including mental performance, concentration, self-esteem, self-confidence, sleep quality and mood. (8)

In addition to these general benefits of exercise, some unique benefits exist for females. Remarkably, female high school students who participate in sanctioned sports activities have lower rates of pregnancy, drug abuse, and depression; female student athletes also have higher self-esteem scores and are more likely to graduate from high school than non-athlete peers.(8) Young women who exercise regularly may benefit from an amelioration of symptoms related to the menstrual cycle, including a decrease in pain, anxiety, fatigue, and depression.(8) These benefits come at no cost in performance; athletic performance is not affected by the menstrual cycle or hormone therapy, including oral contraceptives. However, when pursued to the extreme, exercise can lead to menstrual dysfunction. The term female athlete triad refers to the combination of exercise-induced amenorrhea, a restricted training diet, and osteoporosis, which doubles the risk for stress fracture. After eliminating other potential causes for amenorr hea, the female athlete triad can be treated with a low-dose combination contraceptive agent.

Women who exercise regularly generally can continue their habits during an uncomplicated pregnancy, with the bonus of specific additional benefits, including improved exercise potential (measured as a 10% increase in maximal oxygen consumption during the third trimester). (9) Subjectively, women who exercise during pregnancy report improved pain tolerance, a shorter postpartum recovery, and a better self-image. In a study of exercise during pregnancy, active women have shown 25% lower total weight gain and less than half the fat mass gain of sedentary control subjects.(10) However, exercise during pregnancy has not proven to shorten labor or increase the likelihood of vaginal delivery.

These benefits of exercise during pregnancy accumulate without any clinically significant associated maternal or fetal risk. Although moderate exercise may acutely increase the frequency of uterine contractions in women with term pregnancies," exercise during pregnancy does not increase the risk for miscarriage, preterm labor, or premature rupture of membranes.(12) Conversely, lack of exercise may increase the risk for pregnancy complications. In an observational study correcting for pregnancy complications, exercise three times per week was only one third as common in women who were delivered of low-birthweight (<1,500 g) fetuses as compared with women who had babies of normal birthweight. (13) Maternal exercise leads to an increase in the fetal heart rate; the magnitude increases with advancing gestational age, exercise intensity, and exercise duration, but generally stays within the normal range (<160/mm) and returns to the pre-exercise range within minutes after cessation of maternal exercise. (14) Mater nal exercise does not increase the incidence of non-reassuring fetal heart rate decelerations. (11) The small reduction in birthweight after maternal exercise (mean, 240 g) includes a decrease in fat percentage at birth (15% vs 10%) and beneficially leads to a lower weight and fat content at 5 years of age. (15) Five-year follow-up after pregnancies including maternal exercise also shows no negative impact on neonatal mental or psychomotor development. (15)

The benefits of exercise extend to menopausal women. Exercise in older women is associated with a reduction in the number of falls, improved mental health, reduced cardiovascular disease, improved glucose tolerance, and reduced painful symptoms of arthritis. (16) Although physical activity is necessary for maintaining normal skeletal development, muscle strength, and joint structure and function, it remains unclear whether physical activity can reduce the rate of bone loss in postmenopausal women in the absence of estrogen replacement therapy. (17)

Regular exercise clearly has diverse benefits for women of all ages. The failure of medical professionals to promote exercise to patients is highlighted by the fact that only one in six overweight patients has been advised by a health care provider to lose weight. (1) Primary care providers for women are already accustomed to the application of strategies for disease screening and prevention. In the same fashion, they need to set a good example by exercising regularly; even more importantly, however, they should individually discuss with each female patient the potential benefits exercise might provide.

Steven R. Allen, MD

Department of Obstetrics and Gynecology 

Scott & White Memorial Hospital and Clinic

2401 S 31st St

Temple, TX 76508

(1.) Mokdad AH, Bowman BA, Ford ES, et al: The continuing epidemics of obesity and diabetes in the United States. JAMA 2001; 286:1195-1200

References

(2.) Mokdad AH, Serdula MK, Dietz WI-I, et al: The spread of the obesity epidemic in the United States, 1991-1998. JAMA 1999; 282:1519-1522

(3.) Hu FB, Manson JE, Stampfer MJ, et al: Diet, lifestyle, and the risk of type 2 diabetes mellitus in women. N Engl J Med 2001; 345:790-797

(4.) Pollack ML, Gaesser GA, Butcher JD, et al: American College of Sports Medicine Position Stand: the recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness and flexibility in healthy adults. Med Sci Sports Exerc 1998; 30:975

(5.) Leon AS, Sanchez OA: Response of blood lipids to exercise training alone or combined with dietary intervention. Med Sci Sports Exerc 2001; 33:S502-S515

(6.) Mensink GBM, Ziese T, Kok FJ: Benefits of leisure-time physical activity on the cardiovascular risk profile at older age. Int J Epidemiol 1999;28:659-666

(7.) Blair SN, Kohl HW III, Paffenbarger RS Jr, et al: Physical fitness and all-cause mortality: a prospective study of healthy men and women. JAMA 1989;262:2395-2401

(8.) Tanji JL: The benefits of exercise for women, Clin Sports Med 2000; 19:175-185

(9.) Avery MD, Leon AS, Kopher RA Effects of a partially home-based exercise program for women with gestational diabetes. Obstet Gynecol 1997;89:10-15

(10.) Clapp JF III, Kiess W: Effects of pregnancy and exercise on concentrations of the metabolic markers tumor necrosis factor alpha and leptin. Am J Obstet Gynecol 2000; 182:300-306

(11.) Spinnewijn WEM, Lotgering FK, Struijk PC, etal: Fetal heart rate and uterine contractility during maternal exercise at term. Am J Obstet Gynecol 1996; 174:43-48

(12.) Clapp JF III: The effect of continuing regular endurance exercise on the physiologic adaptations to pregnancy and pregnancy outcome. Am J Sports Med 1996; 24:S28-S29

(13.) Schramm WF, Stockbauer JW, Hoffman HJ: Exercise, employment, other daily activities, and adverse pregnancy outcomes. Am J Epidemiol 1996; 143:211-218

(14.) Clapp JF III, Little KD, Capeless EL: Fetal heart rate response to sustained recreational exercise. Am J Obstet Gynecol 1993; 168:198-206

(15.) Clapp III JF: Morphometric and neurodevelopmental outcome at age five years of the offspring of women who continued to exercise regularly throughout pregnancy. J Pediatr 1996; 129:856-863

(16.) Curl WW: Aging and exercise: are they compatible in women? Clin Orthop 2000;372:151-158

(17.) Physical Activity and Health: Report of the Surgeon General, 1999. http://www.cdc.gov/nccdphp/sgr/sgr.htm