Physical Activity During Pregnancy – Comprehensive Article10 min readReading Time: 7 minutes
Many women have questions about physical activity during pregnancy. Some questions might be whether it is good or not to exercise during pregnancy, what type of exercise that can be conducted and what frequency and intensity that are appropriate.
- All pregnant women should be recommended to perform aerobic (cardio) and muscle-strengthening physical activity as part of a healthy lifestyle.
- Regular exercise improves and maintains a good general condition during pregnancy and prepares the body for childbirth.
- Aerobic physical activity (cardio) should take place for a total of at least 150 minutes per week. The intensity should be moderate. For those who are previously physically active, the intensity may be higher.
- If you have an uncomplicated pregnancy, physical activity during pregnancy is harmless to the pregnant woman and the fetus and does not pose an increased risk of deviating pregnancy or childbirth outcomes.
- Physical activity along with other lifestyle interventions can prevent and treat certain pregnancy complications.
- Pelvic floor training during pregnancy can prevent and treat urinary leakage.
A more liberal view
The view of physical activity during pregnancy was for a long time directly negative. In recent decades, on the basis of scientific studies, the view of physical activity during pregnancy has become much more liberal.
Increase the chance of staying active after pregnancy
From a public health perspective, one of the benefits of women exercising regularly during pregnancy is that they are usually more likely to continue with some form of physical activity after giving birth too.
Exercise some caution
However, some caution must be considered. There is an increased risk of falling or getting hit in the belly performing some sports (eg. horseback riding, downhill skiing and rugby), hence these sports should be avoided. Also, a certain amount of women experience different pregnancy-related discomforts, problems and complications that must be taken into account. Always check with your doctor to get an “all clear”.
The pregnant body adapts
As a natural part of the pregnancy, the body adapts to meet the new physiological requirements. There’s an adaptation to the increased oxygen demand which is achieved through an increased depth of breathing, a higher heart rate and a greater stroke volume. The blood volume also gradually increases during pregnancy by approximately 40-50 percent. Both pregnancy itself and physical activity increase the metabolism and the body temperature.
A body temperature of more than 39.2 degrees Celsius (102,5 Fahrenheit) is believed to be teratogenic (which means it can cause birth defects) on the basis of animal studies during the first 3 months. However, pregnancy increases the ventilation and the skin circulation which help reduce the risk of an abnormally high body temperature (hyperthermia). However, it is important to have a good fluid supply and to avoid physical exercise in hot and humid climates.
During a normal pregnancy, there’s a state of hyperinsulinemia and an increasing insulin resistance. Due to continuous fetal and placental consumption of glucose, the pregnant woman is in, what could be described as, a kind of starvation mode. The level of starvation increases with the duration of pregnancy. An increased release of free fatty acids and ketones contributes to this, while there is an inability to increase gluconeogenesis sufficiently. The risk of low blood sugar (hypoglycaemia) can be avoided with appropriate calorie intake and by limiting the length of the workout to a maximum of 45 minutes at moderate intensity.
Vein Cava Compression
The capacity of the heart is affected by the position the pregnant woman is in. When lying on her back, from about the fourth month, the venous reflux (the blood flow going back to the heart) may be hindered by the growing uterus, so-called a vein cava compression. This leads to an increased risk of decreased stroke volume and a blood pressure drop, which is why many women should avoid physical exercise lying on their back after the 16th week of pregnancy.
Hormonal changes caused by pregnancy result in an increased joint mobility. The pregnancy-induced weight gain also leads to a greater burden on the skeleton, muscles, joints and ligaments. At the same time, the body’s center of gravity is shifted forward, meaning there’s more load on the back muscles. That in turn creates an increased compression in the lower back. Concurrently, the sway back is increasing hence it can be more difficult to keep the balance and there’s an increased risk of falling.
As the stomach grows, the distance between the straight abdominal muscles increases, called rectus diastasis. It’s believed that rectus diastasis in combination with the changed center of gravity forward can lead to reduced core stability.
The benefits, in addition to maintaining or increasing physical well-being, include less fatigue and reduced risk of extremity swelling and varicose veins. In addition, physically active pregnant women often experience less stress, anxiety, depression and sleep disorders and have decreased lower back pain.
Being overweight carries an increased risk of pregnancy diabetes and has been shown to be preventable and to some extent treated with physical activity along with a reduced caloric intake.
Birth Outcomes and Labour
There is no difference in birth outcomes or neonatal outcomes between women who have trained and those who have not trained during pregnancy. Regular physical activity during pregnancy does not affect the duration of active labor. Well-trained women adapt more quickly to the changes that pregnancy entails and generally feel better and have fewer complications.
Physical Activity, Length & Intensity
Physical activity may include leisure activities such as outdoor activities, strength training, sports, gardening, movement at work or at home, and active transport in everyday life walking and cycling.
1. Aerobic physical activity is recommended for a total of at least 150 minutes per week. The intensity should be moderate. For those who are already physically active before pregnancy, the intensity may be higher. The activity should be spread out on at least 3 of the week’s days.
2. In addition to exercise of the pelvic floor muscles, strength training should be performed at least twice a week with a focus on the body’s large muscle groups.
3. Prolonged sitting should be avoided. Regular short breaks (“leg stretchers”) with some form of muscle activity for a few minutes are recommended for those who have a sedentary work or sit a lot in their spare time.
A reasonable goal should be maintaining your fitness during pregnancy, and not to seek personal bests. It should be noted that many elite athletes have continued with hard training without complications and it’s considered ok as long as you are advised by an obstetrician.
Each workout should include a warm-up and a cool-down period. Pregnant women who have not previously been physically active should start off gradually with slightly shorter workouts, 3 times per week. Thereafter, a gradual increase up to 30–45 minutes 3 times per week. Supplement with additional aerobic physical activity to achieve at least 150 minutes per week. Although there is no “safe” upper limit for physical activity during pregnancy, women who have been exercising at a high intensity level before pregnancy should be able to continue with this, such as jogging and aerobics. However, it is important to know that a decline in performance is to be expected, as the pregnancy progresses.
Regarding cardio training, the general recommendations can be followed as long as you avoid excessive body heat (see above) for the first 3 months. Pregnant people should exercise in light clothing as well as adding extra fluid during and after exercise. High intensity activities in hot and humid climates should be avoided. All activities that include rhythmic and dynamic work with large muscle groups are recommended, such as fast walking, jogging, cycling, aerobics, step-up training, gymnastics and dance.
Alternatives for pelvic girdle pain and back problems
As a complement, exercises such as swimming and water gymnastics are excellent activities and especially suitable for women with pelvic girdle pain and back problems.
How to measure intensity the level
Since the heart rate is increased during pregnancy, the heart rate isn’t the best way to measure the intensity of a workout. Instead, the recommendation is to assess the intensity with either a so-called “talk test” or with the Borg-RPE scale®. A talk test assumes that a moderate intensity workout will allow for a normal conversation. Borg’s scale measures subjective effort between 6 (extremely light) and 20 (maximum strenuous). Although the scientific basis is somewhat deficient, the recommended level during pregnancy is usually set at 12-14 on the Borg scale, i.e. moderate intensity.
Strength training during pregnancy should focus on the pelvic floor, back and inner abdominal muscles, but exercise of the lower and upper extremities can also be added. As there’s a risk of a so-called vein cava compression (see vein cava compression above) it’s recommended that strength training of the inner abdominals be performed sitting, lying down on the side or standing after the 16th week of pregnancy.
Repetitions and sets
Generally, 7-8 exercises are recommended for the body’s larger muscle groups, with 8-12 repetitions in 1-3 sets.
Activation of pelvic floor muscles
Many have problems activating the pelvic floor muscles during exercise. Then it may be advisable to contact a physiotherapist to check that the exercises are performed correctly.
After childbirth, this can be even more difficult depending on the damage that has occurred to the musculature, supporting tissue and possibly nerve damage. It’s therefore an advantage to have learned the technique in advance.
Due to a generally increased mobility during pregnancy, it is important to make sure that stretching exercises are done with some caution. The muscle groups that have been used during cardio and strength training should be stretched, but specific mobility training is usually not necessary. The stretching exercises should be done at a slow pace maintaining the outer position for 10-30 seconds.
Pregnancy and, above all, childbirth are risk factors for developing urinary incontinence due to potential damage to the muscles, connective tissue and peripheral nerves.
Urinary incontinence for women varies between 32 and 64 percent. The most common form of urinary leakage is stress incontinence, i.e. involuntary urinary leakage when coughing, sneezing or being physically active.
10 RCT studies regarding exercise of the pelvic floor muscles for the purpose of prevention or as treatment of urinary leakage during pregnancy, found that pregnant women who did not have urinary leakage at the onset of pregnancy had a 30 percent lower risk of having urinary leakage.
Two large Norwegian RCT studies with pelvic floor training during pregnancy on a group of women both with and without urinary leakage at the start showed a significant reduction in the number of women with leakage. The conclusion from seven mixed studies (i.e. studies that included both women with and without urinary leakage) was that there was a significant effect of pelvic floor exercise during pregnancy for this group.
Starting pelvic floor training for women who have urinary leakage 3 months after delivery showed about 40 percent less risk of urinary leakage 12 months after birth.
Always consult with your doctor or midwife to get an all clear before starting a new workout routine.
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