Before the American College of Obstetricians and Gynecologists put out its first set of prenatal exercise guidelines in 1985, physicians generally advised their pregnant patients to avoid all physical activity. While the guidelines made it clear that prenatal exercise could be beneficial, they were also restrictive, stating that pregnant women shouldn't raise their heart rates above 140 beats per minute or work out for more than 15 minutes at a time. Current advice is less restrictive, depending on your individual fitness level.
Fitness Level
Your preconception fitness level indicates the level of fitness you can maintain during pregnancy, as long as you and your developing baby remain healthy. If you exercise most days of the week at moderate intensity, for example, you should be able to continue working out at moderate intensity throughout your pregnancy, or until your body demands that you slow down. Likewise, if you’re an athlete, or are accustomed to regular high-intensity workouts, you may be able to continue your training program into your first trimester with few modifications, depending on the type of activity you engage in.
Rate of Perceived Exertion
Current ACOG guidelines advise pregnant women who exercise to work out at a comfortable level of intensity rather than at or below a specific heart rate. Consequently, Borg’s rate of perceived exertion, or RPE, serves as more accurate way for pregnant women to assess intensity. The RPE scale runs from 6 to 20, ranging from “no exertion” to “maximal exertion.” Guidelines advise pregnant exercisers to stay within the 12 to 15 range, or “very light” to “somewhat hard.” Working at level 15 on the scale, the level of intensity experienced by a well-conditioned woman corresponds to the intensity experienced by a less conditioned woman working at a lower level.
Precautions
Pregnancy is not the time to make fitness gains, unless you were previously sedentary. With a doctor's approval, sedentary women can improve their fitness during pregnancy by beginning slowly and gradually increasing the intensity and duration of their workouts -- as long as they remain comfortable. No matter what your preconception fitness level was, discuss your workout routine with your health care provider before you train while pregnant. Certain sports and activities aren’t recommended in any trimester, including those that pose a risk of abdominal trauma, such as soccer, downhill skiing or rock climbing. In early pregnancy, a blow to your abdomen could damage the placenta. Activities that are jarring, such as gymnastics or horseback riding, are also contraindicated.
Warning Signs
In the first trimester, you might experience nausea as a pregnancy symptom. If you feel nauseous after an intense workout, it’s possible that you’re experiencing a buildup of lactic acid in your stomach. If exercise-induced nausea doesn’t subside within an hour of your cooldown, call your health care provider. Dizziness, swollen calves and changes in body temperature that persist after cooling down are other reasons to call your physician. If you experience pain while exercising, your body is telling you to slow down or stop. Sharp, recurring pain in your abdomen or chest, vaginal bleeding or leakage and blurred vision are signals to stop exercising immediately. If you can’t reach your doctor, go to the emergency room.
References
- “Healthy Moms Perinatal Fitness Instructor Training Manual”; Sheila Watkins; 2007
- “Mayo Clinic Guide to a Healthy Pregnancy”; Roger W. Harms, Editor in Chief; 2004
- IDEA Health and Fitness Association; The Pregnant Athlete; Lisa Druxman
- Personal Power UK: The Pregnant Client and Exercise – 10 Myths and Facts
