Exercise During Pregnancy – Guidelines

Our time can be confidently characterized as a time of craze for sports. And if once sport was, for the most part, the destiny of men, then now there is clear gender equality in this. In general, both men and women with equal healthy fanaticism approach training, nutrition, and lifestyle. However, there is a circumstance that can prevent only a woman from realizing her sporting ambitions. This is pregnancy. Public opinion negatively refers to the coexistence of the period of pregnancy and active sports, believing that exercise during pregnancy should be postponed to the postpartum period.

However, the medical community thinks very differently. Sport not only does not need to be excluded, it, on the contrary, must be added, adhering to certain restrictions.

Exercise During Pregnancy Recommendations

As an illustrative example, we can cite recommendations on physical activity and physical exercises during pregnancy and the postpartum period, developed by the American College of Obstetricians and Gynecologists, adopted by other countries of the world (German Obstetrics Practice Committee, Conclusion No. 804).

These recommendations are designed for medical professionals so that on this basis, they can prescribe specific activities related to physical activity based on the individual characteristics of the particular patient they are observing. Individualization is indispensable, and pregnancy can occur in different ways, and the loads can differ significantly (professional and amateur sports are a big difference).

Therefore, this article does not contain specific numbers of how many sets, repetitions, how much intensity you should do, although certain guidelines are given.

• Physical activity and exercise during pregnancy are associated with minimal risks and have been shown to benefit most women, although some modification of exercise may be necessary due to normal anatomical and physiological changes and fetal needs.
• Before recommending an exercise program, a thorough clinical evaluation must be performed to ensure that the patient has no medical reason to avoid exercise.
• Women with uncomplicated pregnancy should be encouraged to engage in aerobic and strength exercises before, during, and after pregnancy. (Women who usually had an intensive aerobic activity or who were physically active prior to pregnancy can continue this activity during pregnancy and the postpartum period. Observational studies of women who exercise during pregnancy have shown benefits such as lowering the risk of gestational sugar diabetes, cesarean section, and surgical vaginal delivery, as well as recovery time after childbirth. Physical activity can also be a significant factor in the prevention of depressive disorders in women in the postpartum period.)
• Obstetrician-gynecologists and other obstetric care providers should carefully evaluate women with medical or obstetric complications before giving advice on engaging in physical activity during pregnancy. Activity restriction should not be prescribed regularly as a treatment to reduce preterm labor.
• More research is needed to study the effect of exercise on pregnancy-specific conditions and outcomes, as well as to clarify further effective behavioral counseling methods and the optimal type, frequency, and intensity of exercise. Similar studies are needed to create a better evidence base regarding the effects of occupational, physical activity on maternal and fetal health.

Anatomical and physiological aspects of physical activity during pregnancy

Pregnancy leads to anatomical and physiological changes that should be considered when prescribing exercise. The most pronounced changes during pregnancy are weight gain and a shift in the severity point, which leads to progressive lordosis. These changes lead to increased efforts in the joints and spine during the performance of strength exercises. As a result, more than 60% of all pregnant women experience back pain.

Strengthening the muscles of the abdomen and back can minimize this risk. Blood volume, heart rate, stroke volume, and cardiac output normally increase during pregnancy, and systemic vascular resistance decreases. These hemodynamic changes establish the circulatory reserve necessary to maintain the pregnant woman and the fetus at rest and during exercise.

During pregnancy, deep respiratory changes also occur. Minute ventilation increases to 50%, primarily as a result of an increase in tidal volume. Due to the physiological decrease in the pulmonary reserve, the ability to anaerobic exercise is impaired, and the availability of oxygen for aerobic exercise and increased workload is constantly lagging.

Physiological respiratory alkalosis of pregnancy may not be sufficient to compensate for developing metabolic acidosis with intense physical exertion.

The decrease in subjective workload and maximum physical performance in pregnant women, especially those who are overweight or obese, limits their ability to engage in more intense physical activities.

Aerobic exercise during pregnancy has been shown to increase aerobic ability in pregnant women with normal and excess weight.

The reaction of the fetus to the physical activity of the mother

Most studies on fetal reactions to maternal physical activity have focused on changes in the fetal heart rate and birth weight. Studies have shown a minimal and moderate increase in fetal heart rate by 10-30 beats per minute compared to baseline during or after exercise.

Three meta-analyses concluded that differences in birth weight were minimal or absent in women who performed exercises during pregnancy compared to controls.

However, women who continued to intensively exercise during the third trimester were less likely to give birth to children weighing 200-400 g less than in the comparable control groups, although there was no increased risk of fetal growth restriction.

A cohort study that evaluated umbilical arterial blood flow, fetal heart rate, and biophysical profiles before and after strenuous exercise in the second trimester showed that 30 minutes of strenuous exercise were well tolerated by women and the fetus in active and inactive pregnant women.

For pregnant athletes, individual exercise protocols can be justified to determine if there is a threshold (an absolute level of intensity or duration, or both) beyond which fetal well-being can be compromised.

Individual Exercise Program

The principles for prescribing exercise to pregnant women are no different from the principles for prescribing exercise for the general population. Before recommending an exercise program, a thorough clinical evaluation must be performed to ensure that the patient has no medical reason to avoid exercise.

An exercise program that leads to the ultimate goal of moderate exercise intensity for at least 20-30 minutes a day on most or all days of the week should be developed with the patient and adjusted according to medical indications.

Pregnant women who have a sedentary lifestyle before pregnancy should follow the more gradual progression of exercise.

Although the upper level of safe exercise intensity has not been established, women who regularly exercise before pregnancy and who have an uncomplicated, healthy pregnancy should be able to participate in high-intensity exercise programs, such as jogging and aerobics, without any side effects.

High-intensity or prolonged physical activity over 45 minutes can lead to hypoglycemia; therefore, adequate calorie intake before exercise or limiting the intensity or duration of an exercise session is important to minimize this risk.

Long physical exercises should be performed in a thermoneutral environment or in controlled environmental conditions (air-conditioned rooms), and pregnant women should avoid prolonged exposure to heat and pay close attention to proper drinking regimen and high-calorie diet.

In studies of pregnant women engaged in physical exercises in which physical activity was self-sustaining under conditions of the controlled temperature, body temperature increased by less than 1.5 ° C for 30 minutes and remained within safe limits.

Although physical activity and dehydration during pregnancy were associated with a slight increase in uterine contractions, a systematic review and meta-analysis involving pregnant women of normal weight with a singleton uncomplicated pregnancy showed that loads of 35-90 minutes 3-4 times a week were not associated with increased risk of premature birth or with a decrease in the average gestational age at the time of birth.

Women with uncomplicated pregnancy should be encouraged to engage in aerobic and strength exercises before, during, and after pregnancy. Contact activities with a high risk of abdominal injury or imbalance should be avoided.

Scuba diving should be avoided during pregnancy because of the impossibility of fetal pulmonary circulation to filter the formation of vesicles.

Women living at sea level were able to tolerate physical activity at an altitude of up to 6,000 feet, which suggests that this altitude is safe during pregnancy.

Women living at high altitudes can safely exercise at altitudes above 6,000 feet.

In cases where women experience back pain, an exercise in water is a good alternative. There may be additional benefits of water exercises. A randomized controlled trial of a water exercise program during pregnancy, consisting of three 60-minute exercises, showed a high incidence of intact perineum after childbirth.

Exercise during pregnancy for obese people

Obese pregnant women should be encouraged to change towards a healthy lifestyle during pregnancy, which includes exercise and reasonable diets.

Women should start with low intensity, short-duration exercises, and gradually increase the duration or intensity of the exercises as they are capable.

In a recent study examining the effects of exercise on obese pregnant women, future mothers prescribed for exercise showed a moderate decrease in weight gain and no adverse outcomes.

For athletes

Intensive exercises in the third trimester appear to be safe for most healthy pregnancies. Further studies are needed to study the effects of intense exercise in the first and second trimesters and the intensity of exercise in excess of 90% of the maximum heart rate.

Competing athletes require frequent and careful monitoring because they tend to maintain a more intense workout schedule throughout their pregnancy and resume high-intensity workouts after giving birth earlier than other women. Such athletes should pay particular attention to avoid hyperthermia, maintain adequate hydration and calorie intake to prevent weight loss, which can adversely affect fetal growth.

An elite athlete can be defined as a whole as an athlete with several years of experience in a particular sport who successfully competed with other high-level participants and trains all year round at the peak of opportunities; an elite athlete usually trains at least 5 days a week, on average about 2 hours a day throughout the year.

In addition to aerobic training, elite athletes in most sports also practice resistance training (machines, weight training, bodyweight, rubber shock absorbers) to increase muscle strength and endurance, but this training was not considered a safe activity in the early training manuals during pregnancy due to potential trauma and a possible slowdown of the fetal heart activity as a result of Valsalva maneuvers.

Consequently, there is scarce literature on this subject. For elite athletes who want to continue strenuous activities during pregnancy, it is advisable to have a clear idea of ​​the risks, get approval from their healthcare providers, and consider reducing the burden of resistance compared to prepregnant states. Avoid activities with an increased risk of blunt injury (martial arts), and it is also important that a pregnant elite athlete avoid overheating when participating in intense training or competition.

Activity limitation guidelines for exercise during pregnancy

A number of reviews found that there was no reliable evidence for prescribing bed rest during pregnancy to prevent preterm birth and should not be recommended regularly.

Patients who are prescribed prolonged bed rest or limited physical activity are at risk of venous thromboembolism, bone demineralization, and deconditioning.

There are no studies confirming improved outcomes in women at risk of preterm birth who are required to restrict their activities, including bed rest, and there are numerous studies that confirm the adverse effects of restricting voluntary activities on mother and family, including negative psychosocial consequences.

Activity restriction should not be prescribed arbitrarily as a treatment to reduce preterm birth. In addition, there is no evidence that bed rest reduces the risk of developing preeclampsia and should not be recommended for the primary prevention of preeclampsia and its complications.

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