Women can profit substantially from exercise during pregnancy. But exercise during pregnancy should be discussed with a woman’s physician. If she was actively engaged in exercise prior to pregnancy, she most likely will be allowed to continue. If she was not physically active and wishes to become active during pregnancy, she would be wise to discuss the risks and benefits with her physician. If medical clearance is granted, she should be directed to a trained exercise specialist who is qualified to prescribe exercise during pregnancy.
The American College of Obstetricians and Gynecologists (ACOG) has developed the following guidelines for exercise during pregnancy. Pregnant women should:
- Engage in aerobic exercise—walking is most often recommended— three times per week.
- Reduce the intensity of exercise as pregnancy progresses, and then shift from higher-impact weight-bearing activities such as jogging to lower-impact activities such as walking, and then non-weight-bearing activities such as swimming and stationary cycling.
- Avoid activities that place a high reliance on balance.
- Avoid exercises performed while lying on the back after the third month of pregnancy. This position encourages a shift in blood supply away from the uterus, which has potential, although unproven, consequences for the fetus.
- Avoid prolonged motionless standing.
- Avoid activities that significantly raise the core maternal body temperature.
- Be careful not to dehydrate while exercising.
Special Concerns for Women
Although males and females are physiologically similar in some ways, they have enough differences to affect physical performance. For example, the aerobic capacity of the average female is approximately 20 percent lower than that of the average male. The difference results from the following:
- A smaller heart size per unit of body mass
- Lower oxygen-carrying capacity because of 10 percent to 15 percent less hemoglobin (the oxygen-carrying component of red blood cells)
- Less muscle mass to supply the power to move their body weight
- More inactive fat tissue to move about
Because of their larger muscle mass, the average male is about 30 percent to 40 percent stronger than the average female. Strength is highly and positively correlated with physical performance.
Menstruation represents a significant difference between males and females. The response to menstruation among females is variable. Some women feel no different than usual, and others may experience abdominal and leg cramping, low-back pain, and mood swings. The female response to menstruation may affect physical performance markedly.
Despite the physiological differences between males and females, the responses to aerobic training are remarkably similar. On a percentage basis, the ability to deliver and extract oxygen is essentially the same in men and women. So too, are benefits such as fat loss, decreased heart rate, and increases in bone density. In addition, exercise training reduces many of the risk factors associated with the chronic diseases that are the leading causes of death in the United States. In summary, regular exercise is as important a lifestyle behavior for women as it is for men.
