Pregnancy and exercise - exercise programs for pregnant women

American Fitness, Sept-Oct, 1993 by Lauri J. Reimer-Mihailov

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All American Fitness CEU Corner[TM] articles are written by approved continuing education providers following AFAA Standards in Guidelines. "Pregnancy and Exercise" is written by Lauri J. Reimer-Mihailov, an AFAA certification specialist, prenatal exercise consultant at Saint John's Hospital and Health Center in Santa Monica, California and owner of Body Physics studio in Log Angeles. She is also mother of 21-month-old Erika. AFAA certified instructors are invited to submit manuscript queries to the AFAA Board, c/o American Fitness. American Fitness is seeking scholarly articles regarding fitness assessment, leadership, specialty practices, management, exercise research and critiques are trends.

Should a woman exercise during her pregnancy? Yes, if she follows certain guidelines. Guidelines for a prenatal exercise program should take into consideration the woman's initial fitness level and the physiological changes taking place in her body.

Making exercise part of a daily or weekly routine is valuable not only for the duration of pregnancy, but also in preparation for labor and delivery by increasing strength, flexibility, endurance and stamina. Many woman who exercise regularly before they become pregnant find they are able to stick with exercise routines with little or no discomfort.

Studies show active women who continued to exercise throughout pregnancy gained slightly less weight and had 16% fewer Cesarean sections. James Clapp, M.D., professor of reproductive biology at Case Western Reserve in Cleveland, Ohio, conducted several studies with pregnant women. His findings showed fit women had less complications such as meconium in the amniotic fluid, abnormal drops in fetal heart rate or core entanglement. Animal studies suggest specific effects of uterine blood flow on a fetus. Due to ethical limits, there is a lack of conclusive research in humans. Thus, exercise standards for pregnant women have been defined conservatively.

The ideal prenatal exercise program offers variety, such as walking, swimming, modified aerobic dance and calisthenics, stretching, cycling, prenatal yoga, etc. Personal preferences help keep women motivated to continue exercise throughout pregnancy. The American College of Obstetricians and Gynecologists (ACOG) recommends intuition and common sense when prescribing prenatal exercise. No single program will meet the needs of all pregnant women.

Physical activity during pregnancy must be approached with particular caution during the first trimester. Some evidence suggests sustained elevation in the mother's body temperature during this time is associated with a greater incidence of defects in the baby's central nervous system. The development of the nervous system, brain and spinal cord begins during the earliest part of the first timester when many women do not even know they're pregnant. Because of the lack of conclusive research, women are advised to avoid elevated body temperatures during the first trimester and sustain a conservative appproach to exercise throughout pregnancy.

Since the first trimester is when hormones cause physiological changes in the woman's body, fatique and nausea can limit physical activities. By the fourth month, risk of miscarriage is lower and energy level usually returns. This is often the time to begin a prenatal exercise program.

Factors and Fluctuations During Pregnancy

During pregnancy there is a continuous fluctuation of hormones in the body. The influence of these hormones, particularly relaxin, estrogen, progesterone and elastin, begin to soften connective tissue creating laxity in the ligaments and joint instability. This makes the joints more susceptible to injury during exercise.

The woman's center of gravity changes as breast size increase and the uterus expands to accommodate the growing fetus. Increased spine curvature also causes added strain on the back, particularly in the third trimester.

Sustaining vigorous exercise over 15 minutes many compromise blood flow to the uterus, placenta and fetus due to increased flow to ot'er working muscles and the skin. During normal pregnancy, blood volume increases 30 to 50% to protect against decreased blood flow to the baby. However, target heart rates should be kept 25 to 30% lower than usual, or approximately 140 bpm for no more than 15 minutes.