Should You Work Out While Pregnant?

Nov. 17, 2008— -- Does it make sense to stop or to start an exercise program during pregnancy?

While many women believe that they need to rest during pregnancy, other expectant moms swear by their exercise regime, as they feel it eases childbirth and helps them bounce back to a normal dress size after giving birth.

Who is right and who is wrong? And what are the implications of exercising -- or staying sedentary -- when you are pregnant?

Before we launch into considerations of an exercise program, there are few considerations about pregnancy that need to be understood.

During pregnancy, the female goes through hormonal changes that increase the levels of the hormones relaxin, elastin, estrogen and progesterone in their bodies. These hormones soften the connective tissue surrounding the joints, which is necessary to allow the female pelvic joint to expand to accommodate the baby as it passes through the pelvic inlet during birth. Yet, the weight-bearing joints such as the knees, ankles and hips are affected, too.

Additionally, the blood volume in a woman's body increases by as much as 30 percent to 50 percent. Because of this, the heart rate and cardiac output are elevated at rest. The resting heart rate may be elevated as much as 15 beats per minute during pregnancy.

As pregnancy progresses, the uterus increases in size and weight and therefore pulls the pelvis into a forward tilt, causing stress on the lumbar sacral ligament and lower back muscles. The abdominal muscles tend to stretch and weaken, while the lower back muscles tend to shorten, resulting in a sway back -- or lordotic -- posture.

The weight of the growing breasts tends to pull the shoulders into a forward position, resulting in a slouched posture of the upper back. The chest muscles shorten, while the upper back muscles stretch and weaken.

As the uterus grows, it stretches the abdominal muscles. This lengthening process causes the body to add functional units called sarcomeres to muscles, making them progressively longer. When combined with the action of the aforementioned hormones, this process relaxes the muscles throughout the pelvic girdle, all of which are important units for your core. Keep in mind that a long muscle is a weak muscle and a short muscle is a strong muscle.