Exercise and physical activity have few risks and multiple rewards when it comes to (an uncomplicated) pregnancy. With exercise and pregnancy, one should keep in mind that it is NOT a time to focus on improving your physical fitness. The goal of a physical fitness and exercise program during pregnancy should be to ensure a good quality of health for the growth and development of the baby.
ACSM guidelines suggest a total of 150 minutes of moderate intensity exercise (level of difficulty equal to a brisk walk at 3 to 5 mph) and resistance exercise focusing on each major muscle group 3 days a week.
There are a handful of things that occur in the body during pregnancy (and exercise) that need to be taken into account and modifications to the program need to be addressed.
1. Weight Gain
As a woman increases her body weight during pregnancy, more stress is put on the joints by as much at 100% in the hips and knees during an activity like running. Alternative choices for cardiovascular exercise would include lower impact exercise (elliptical trainer, recumbent bike) or water-based activities (water aerobics, water jogging).
2. Laxity of the Joints
Two hormones (estrogen and relaxin) are released at higher levels to promote the relaxation of ligaments in the pelvis to prepare for birth. They are released in higher amounts during the first 14 weeks of the first trimester and at delivery. Avoid prolonged exercise that stretches or puts pressure/force on joints (running, tennis, over stretching).
3. Increase in Body Temperature
During pregnancy a woman burns more calories and generates more heat than when she was not pregnant. Because it only takes a few degrees to overheat (which can be dangerous for both mother and baby) it is important to monitor the duration and intensity of exercise and stick to climate-controlled (air conditioned) environments. Recommendations for cardiovascular exercise include sessions NO LONGER than 45 minutes and sessions of 15 to 20 minutes (adding up to 45 minutes) are recommended for women who are new to exercise during their pregnancy.
4. Energy Balance
During pregnancy a woman will increase her energy requirements by upwards of 3,000 calories per day in the second and third trimesters. If they are physically active they will need to increase the amount of food they eat to make up the difference to ensure the baby gets enough nourishment for healthy growth.
After the first trimester, lying down flat on your back (supine position) results in an obstruction in the blood returning to your heart. For this reason this position should be avoided as much as possible at rest and during activity. Examples of supine exercises include bench press, mat pilates (without modifications) and standard sit ups.
Prior to starting any exercise program be sure to check with your doctor and/or obstetrician to ensure you have a positive experience with exercise during your pregnancy. Stay tuned for future articles on programs post-pregnancy and ways to get your figure back after having a baby.