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The Effect of Exercise on Pregnant Women
Pregnancy causes numerous anatomical and physiological changes to the body. Many of these changes are improved with regular exercise. Here is a brief rundown (without getting overly technical) of the changes your body is experiencing and an explanation as to why exercising during pregnancy is beneficial.
- Pregnancy causes an increase in blood volume, stroke volume, cardiac output, and heart rate (both resting and during exercise).
- During exercise there is less cardiac reserve so endurance and stamina are reduced.
- These changes cause exercise to feel harder than it did pre-pregnancy, and women may experience lightheadedness and dizziness due to decreased blood pressure.
- Exercise enhances the increase in blood volume by 10-15% as compared to non-exercising pregnant women, and the hearts of exercising pregnant women pump 30-50% more per beat than the hearts of non-exercising pregnant women.
- Pregnant women have increased resting oxygen consumption and improved gas exchange efficiency in the lungs.
- Exercise will feel harder due to getting short of breath more easily and increased respiratory rate.
- Exercise enhances these respiratory changes by improving gas transfer in tissues and increasing oxygen availability.
- Pregnancy and exercise can result in a 5-10% increase in aerobic capacity for up to a year following birth. Yes, you can come back faster and stronger!
- Pregnancy causes an increased metabolic rate, increased insulin resistance, increased fat utilization, and decreased maternal carbohydrate utilization.
- Pregnant women need to eat additional calories to support not only the pregnancy but also exercise. They also need to snack before a workout to prevent a drop in blood sugar.
- Exercise during pregnancy results in decreased fat accumulation, increased fat utilization for fuel (every endurance athlete’s dream!), and lessens the chance of developing gestational diabetes.
- Pregnancy causes an increase in body mass which results in greater heat production and an increase in body fat which means greater body insulation. The body dissipates this heat through its increased blood volume and increased ventilation rate, and through the skin’s extra surface area.
- Pregnant women need to drink extra water and avoid high heat and high humidity when exercising as prolonged heat exposure can lead to neural tube defects and preterm labor.
- Exercise increases the pregnant body’s sweat response mechanism to help with heat loss, and the increased blood volume built through exercise also helps reduce the body’s core temperature.
- The pregnant body experiences postural changes, a shift in the center of gravity, and increased joint mobility.
- Pregnant women are at increased risk for injury due to decreased balance and to decreased joint stability.
- Exercise improves the body’s ability to adapt to the these changes by increasing muscle strength and function.
Overall, the pregnant body experiences numerous changes to support the growing fetus. Exercise helps the body better adapt to these changes. If you have a healthy pregnancy with no complications, there is nothing more beneficial you can do to help your body and your baby than to continue to remain physically active.
Clapp JF. Exercising through Your Pregnancy. Omaha, NE: Addicus Books; 2012.
Hyatt G, Cram C. Prenatal and Postpartum Exercise Design. Tuscon, AZ: DSWFitness; 2003.