Exercise During Pregnancy
Introduction
According to Williamson (2019) during a pregnancy, a woman's body goes through several physiologic and hormonal changes that can affect several factors in her life, including exercise. However, according to Cooper & Yang (2023) exercise helps increase the maternal and fetal wellbeing of a pregnant woman. Past advice from medical professionals discouraged pregnant women from exercise, in fear of premature labor or low weight infants at birth. A more recent meta-analysis proved that aerobic and moderate-intensity resistance training 3-4 times a week was not associated with an increased risk of premature or low weight births. Additionally, exercise can help decrease low back pain, urinary incontinence, gestational diabetes, pelvic girdle pain, macrosomia, and several other uncomfortable side effects (Cooper & Yang, 2022). Williamson (2019) states that exercise can aid in increased oxygen to the maternal and fetal cells. As a result, this can improve stamina during pregnancy. Also, aerobic and resistance training can help reduce the length of labor and pain associated with pregnancy and delivery. Pregnant women go through three different trimesters during pregnancy, where they experience various changes to their bodies (Williamson, 2019). Therefore, developing a tailored and progressive exercise program will aid in a successful pregnancy for both the mother and fetus. For example, during the first trimester, rapid cell division and growth, along with extreme hormonal changes take place. This is a very vulnerable time for both the mother and the development of the fetus. These hormonal fluctuations cause women to feel nauseous and fatigued (Williamson, 2019). Brekke et al. (2019) states that exercise helps reduce nausea during pregnancy, and a sedentary lifestyle can actually progress sickness and nausea during pregnancy (Brekke et al., 2019). In regard to nutritional recommendations, Chandrika & Selvi (2019) discuss how magnesium can help eliminate nausea during pregnancy. A magnesium deficiency during pregnancy can cause nausea, fatigue, muscle weakness and loss of appetite. Severe side effects include pre-eclampsia (Chandrika & Selvi, 2019). Also, there is an increased amount of estrogen and progesterone being produced, causing breast tenderness (Williamson, 2019). This increase causes extreme discomfort during exercise, especially with activities such as walking or jogging. Due to the vulnerability and rapid cellular changes to the fetus and mother at this time, high intensity or vigorous exercise should be avoided (Williamson, 2019).
Williamson (2019) explains that during the second trimester, the placenta is fully functioning, and physiologic changes such as pigmentation changes and abdomen growth become apparent. While nausea and fatigue begin to subside, high levels of progesterone and estrogen can cause congestion and nose bleeds. Also, due to the growth of the fetus, enlargement of the abdomen, and production of relaxin, women can experience an altered center of balance, lack of stability, and back pain (Williamson, 2019). Obstetrics & Gynecology (2020) viewed a cohort study on the fetal response to strenuous exercise of 85% V02max during the second trimester. They saw that 30 minutes was well tolerated by both inactive and active females. However, every mother and fetus is different, so understanding the strenuous level of activity is essential to avoid harm (Obstetrics & Gynecology, 2020).
Finally, during the third trimester, additional pressure is placed on the external organs, due to the growth of the fetus. Excessive constipation and urination takes place, which can make exercise uncomfortable (Williamson, 2019). There are many respiratory and cardiovascular changes that decrease the women's cardiac output by 10-30%, increase pulse rate by 10-15 beats, and blood pressure fluctuates. There’s also increased oxygen and more efficient alveoli to ensure adequate oxygen delivery to the fetus. An increased metabolism during this time can predispose the woman to hypoglycemia because of the higher demand and utilization of glucose. Therefore, it is encouraged to avoid strenuous exercise and to consume 30-50 grams of carbohydrates. (Williamson, 2019). Obstetrics & Gynecology (2020) saw that females who performed strenuous exercise during their third trimester were associated with low weight infants of 200-400g less. However, for female athletes, strenuous activity during the third trimester appeared to be safe (Obstetrics & Gynecology, 2020).
Exercise Prescription
American College of Sports & Medicine suggests that pregnant women who are not experiencing any contraindications of pregnancy can continue their exercise routine. However, exercise testing is necessary when recommended by a medical professional. If the exercise professional (EP) choses to do exercise testing, submaximal exercise testing of less than 75% of heart rate reserve is safe in predicting maximum oxygen consumption (Williamson, 2019). Depending on the woman's level of activity before getting pregnant will also determine the appropriate exercise prescription for them. If the female was previously sedentary, exercise testing is mandatory for them (Williamson, 2019). Also, if women are experiencing any contraindications, such as severe anemia, chronic bronchitis, incompetent cervix, or persistent bleeding, medical clearance and exercise testing is mandatory (Williamson, 2019). Before beginning, depending on the females age and level of activity, the EP should determine an appropriate target heart rate for them. For example, if the EP is training a pregnant female who is 29 and sedentary, her target heart rate will be different from someone who is 32 and moderately active. However, due to the various changes in a woman's body, many times it is better to practice the borg scale, using rate-of-perceived-exertion when finding the correct heart rate (Williamson, 2019). More information on this subject is explained below.
Liguori et al. (2020) recommends 150 minutes of activity each week during pregnancy. Depending on the current level of fitness will determine how long each bout of exercise will be. If the female is currently sedentary, beginning with 20 minute sessions, and progressively working up to 30-60 minute sessions over time may be more feasible. The intensity will also depend on the female's current level of fitness. Sedentary women should begin with light intensity and progress to moderate intensity over time. However, if the female is already an athlete or has a current and consistent workout routine, she may continue with that intensity, as long as she has medical clearance and is not experiencing any contraindications (Liguori et al., 2020; Williamson, 2019). Amongst these 150 minutes every week, pregnant women should split their time between aerobic, resistance, and flexibility exercises. More details on this exercise prescription below.
The warmup
All workouts should begin with a 5-10 minute warmup, preparing the muscles that will be utilized during the preceding exercises. This should involve a low intensity, low impact aerobic activity, such as walking on the treadmill or cycling on a stationary bike. This will increase blood flow to the muscles and fluid to the joints (Williamson, 2019). If the client is experiencing any lower back pain, make sure to include some light hip opening stretches and mobility for the lower back. If it is severe, and a pool is accessible for the patient, light water aerobics may be a better option for them.
Aerobic Training
Mode
Aerobic exercise should include large muscle groups in a continuous motion. These exercises should include: aerobic dance, walking, hiking, cycling, water aerobics, and rowing (Artal et al., 2003; Williamson, 2019).
Intensity
A pregnant woman's heart rate should be kept at a moderate zone. Use the “talk test” when performing aerobic activity. The female should be able to carry a light conversation while exercising. An EP can also use the Borg scale from 6-20. A rate-of-perceived-exertion of 12-14 is considered moderate (Williamson, 2019). However, if the pregnant female was a frequent exerciser before getting pregnant and is not experiencing any contraindications, high intensity aerobic exercise can be performed, with no adverse effects (Artal et al., 2020). Additionally, if the female is currently sedentary, aerobic exercise should start at a light intensity and progress to moderate over time (Liguori, 2021).
Frequency & Time
If the female has been sedentary, begin with shorter aerobic sessions of 15 minutes a day, three days a week, and progress to 30 minutes over time. If the client is already active, aerobic sessions can last up to 60 minutes, considering her hydration and caloric intake, as well as the environmental conditions in the room. It is discouraged to perform in hot or humid weather, in fear of excess heat and harming the fetus (Williamson, 2019). The American College of Sports Medicine recommends a total of 150 minutes of moderate activity each week, which includes resistance and flexibility exercise (Liguori, 2021).
Resistance Training
Mode
During pregnancy, a woman's center of gravity and joint stability is altered, so beginning with machines, instead of free weights is the safer, more efficient method (Williamson, 2019). However, if the patient has had a previous resistance training routine and is not experiencing any contraindications, they can continue that routine, while avoiding heavy lifting, as this can cause blood pressure to rise and other adverse effects (Williamson, 2019). These types of exercises include the following:
Seated chest press
Seated row
Seated shoulder press
Bicep curl
Seated tricep extension
Seated pelvic tilt using a stability balance ball
Assisted squats
Kegel exercises: Kegel exercises can help prevent urinary incontinence and aid in delivery (Williamson, 2019). These exercises should be encouraged by the EP, but are preferably done in private.
Frequency & Time
2-3 days a week
30-60 or more minutes a week, depending on the patient's status
Intensity
Light-moderate load of 12-15 repetitions or moderate load of 8-12 repetitions.
2 sets of each exercise
Muscles to focus on
While women can engage in full body exercise, Clark et al. (2012) states that some primary muscles to focus on are the abdominal, back, and pelvic floor muscles. Engaging in this practice will aid in the labor process, reduce low back pain, and help with posture. They also recommend core stabilization training to improve pelvic floor strength, while also including flexibility to help with posture (Clark et al., 2012).
Technique
Exercises should be performed slowly and controlled without deep flexion and extension, due to the lack of joint stability. Encourage exhalation during concentric phase and inhalation during eccentric phase (Williamson, 2019).
Kegel exercises will help pelvic floor strength and prevent urinary incontinence (Williamson, 2019).
Avoid tight grips on the dumbbells or isometric exercises, because it can raise the blood pressure (Williamson, 2019).
Avoid performing sit ups throughout pregnancy (Williamson, 2019).
After the 16th week of pregnancy, avoid all supine and prone positions. Supine positions can decrease cardiac output, lower blood pressure and decrease oxygen flow to the fetus Clark et al., 2012; Williamson, 2019).
Avoid motionless standing, to prevent blood pooling (Williamson, 2019).
Flexibility
Flexibility should be performed daily, and also be included in the warm up and cool down of the workouts performed during the week. Yeo (2010) performed a study on prenatal stretching and autonomic responses. Yeo (2010) found that various stretching exercises enhanced autonomic responses and reduced the risk of preeclampsia. Some of these flexibility exercises include:
Side bending neck stretch
Neck rotation
Neck flexion/extension
Chin tuck
Arm across chest stretch
Forearm and hands stretch
Wrist extension
Seated side bend
Child's pose
Cat-cow
Hamstring stretch
Various groin stretches
(Yeo, 2010)
What & When to avoid exercise
Combat sports and sports with high agility and quickness should be avoided. These types of sports can result in falls and injury to the fetus and/or mother. Also, avoid high impact activities, such as running or jumping (Williamson,2019). Additionally, pregnant women have increased core body temperatures and increased metabolism. Humidity or extreme heat can harm the fetus (Williamson, 2019). It is always important to not exercise through extreme fatigue, especially during the third trimester (Williamson, 2019). Lastly, the EP should discontinue all exercise if the patient experiences shortness of breath, vaginal bleeding, dizziness, headache, chest pain, amniotic fluid leakage, decreased fetal movement, significant calf pain or muscle swelling (Williamson, 2019).
Postpartum
During postpartum, women can typically resume exercising 4-6 weeks after their delivery. If it was a cesarean birth, it is recommended to wait at least 8-10 weeks before resuming exercise. If the female was already active before labor, she can usually begin to exercise sooner (Williamson, 2019). Additionally, postpartum weight retention is a predictor for obesity later in life. However, prescribing the correct exercise program can improve aerobic fitness, psychological well being, insulin sensitivity, reduce fatigue and prevent future illnesses by avoiding postpartum weight retention (Makama et al., 2021; Roy, 2014). What's more, if the female is breast feeding, high-intensity exercises can increase the lactate levels in her milk, so breastfeeding or pumping should be done before exercising (Roy, 2014). Additionally, high intensity exercises should be avoided until the client has gradually worked up to this. Makama et al. (2021) states that breastfeeding can burn up to 500 calories a day, which can aid in weight loss. With that said, women should be consuming the correct amount of calories, in order to have energy for the exercises prescribed. Another factor to consider is the amount of relaxin that is produced during pregnancy. During postpartum, a woman's stability and balance can still be affected by the previous relaxin production, so exercises should be adjusted accordingly (Williamson, 2019).
References
Artal, R. (2003). Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period. British Journal of Sports Medicine, 37(1), 6–12. https://doi.org/10.1136/bjsm.37.1.6
Brekke, I., Richardsen, K. R., & Jenum, A. K. (2019). Sickness absence in pregnancy and sedentary behavior: A population-based cohort study from Norway. BMC Public Health, 19(1). https://doi.org/10.1186/s12889-018-6379-4
Chandrika, M. A., & Selvi, K. (2019). Significance of serum magnesium in pregnancy. World Journal of Pharmaceutical and Medical Research, 5(2), 129–132. https://doi.org/file:///C:/Users/shannon/Downloads/article_1548850355.pdf
Clark, M., Sutton, B. G., & Lucett, S. (2014). Nasm Essentials of Personal Fitness training. Jones & Bartlett Learning.
Cooper, D. B., & Yang, L. (2022). Pregnancy And Exercise. In StatPearls. StatPearls Publishing.
Liguori, G., Feito, Y., Fountaine, C., Roy, B., & American College of Sports Medicine. (2022). ACSM’s guidelines for exercise testing and prescription (11th ed.). Wolters Kluwer.
Makama, M., Skouteris, H., Moran, L. J., & Lim, S. (2021). Reducing postpartum weight retention: A review of the implementation challenges of postpartum lifestyle interventions. Journal of clinical medicine, 10(9), 1891. https://doi.org/10.3390/jcm10091891
Physical activity and exercise during pregnancy and the postpartum period. (2020). Obstetrics & Gynecology, 135(4). https://doi.org/10.1097/aog.0000000000003772
Roy, Brad A. Ph.D., FACSM, FACHE. (2014). Postpartum Exercise. ACSM's Health & Fitness Journal 18(6), 3-4. DOI: 10.1249/FIT.0000000000000071
Williamson, P. (2019). Exercise for special populations. Wolters Kluwer.
Yeo S. (2010). Prenatal stretching exercise and autonomic responses: preliminary data and a model for reducing preeclampsia. Journal of nursing scholarship : an official publication of Sigma Theta Tau International Honor Society of Nursing, 42(2), 113–121. https://doi.org/10.1111/j.1547-5069.2010.01344.x