Pregnancy Strength Training

Is it safe to engage in strength training during pregnancy? Does it have any beneficial effects? These are common questions asked by newly pregnant women. Fortunately, this article aims to put your mind at rest. Remaining physically active during pregnancy is highly beneficial and is recommended by many healthcare professionals. Nonetheless, there are some exceptions and limitations, which we will explore in detail.

Overview

Many pregnant women experience fatigue and low energy levels during pregnancy, which could be attributed to sleep disturbances, medical conditions, or reduced physical activity. This fatigue not only reduces their quality of life but also creates a negative experience of pregnancy.¹ Some studies have shown that fatigue levels can serve as a predictive marker for cesarean deliveries.² However, engaging in regular exercise can improve mood and fatigue states in pregnant women.

Furthermore, recent studies have found additional benefits associated with regular exercise during pregnancy.³ For example, increasing muscular strength and fitness can help improve posture and balance, reduce lower back pain, and prepare for the physical intensity of labour. Moderate strength training, in particular, has been found to be very safe in pregnancy.⁴ 

However, it is important to consult your doctor first, as women with specific conditions might be advised to avoid strength training. If permitted to exercise, it's advisable to consult a qualified fitness instructor or personal trainer to help you design a training program suited to your needs and circumstances.⁵ 

Benefits of strength training during pregnancy

Improved muscle strength and tone

The first benefit of strength training during pregnancy is that it increases muscle strength and tone. During pregnancy, the metabolism of fats, carbohydrates, and proteins changes, causing increases in fat deposits around the body, as well as overall body mass.⁵ However, regular strength training can increase muscle mass and reduce excess body fat.⁶ In addition, resistance training tones up the muscles, which can improve body composition and image. Many women report feeling unattractive, fat, and unhappy with their appearance during pregnancy.⁷ However, pregnant women who exercise regularly have a positive body image and respond to pregnancy-related changes in their bodies.⁸

Enhanced posture and balance

A common complication during pregnancy is lower back pain, which can interfere with day-to-day life and disturb sleep. This pain is usually caused by an alteration in the lumbar lordotic curvature, or the natural curve in the lower back region of the spine. Additionally, this can cause a change in the mother’s centre of gravity. Together, these two alterations apply a lot of stress to the lower back muscles. However, research has shown that exercises aimed at improving strength in the back and core, thereby strengthening the postural trunk muscles, are very beneficial in treating lower back pain. In addition, targeting these muscles can improve overall posture and balance.⁸ 

Better weight management and control

Weight gain is a natural part of pregnancy. However, excessive weight gain can lead to serious consequences, making it important to keep your weight under control.⁹ Additionally, research has shown that excessive weight gain during pregnancy can contribute to higher postpartum weight. Therefore, pregnant women are advised to exercise regularly, as it helps in controlling weight gain and avoiding any related issues.¹⁰ 

Reduced risk of gestational diabetes and preeclampsia

Gestational diabetes is a common complication of labour that can affect up to 10% of pregnant women.⁸ The condition is characterised by reduced insulin production, leading to abnormally high blood sugar levels. There is no distinct cause, though it has been linked to hormonal and metabolic changes that can occur during pregnancy, as well as excessive weight gain. Gestational diabetes can cause various problems for both mother and baby, but fortunately, it can be controlled if detected early.¹¹ Remaining physically active during pregnancy reduces the risk of developing gestational diabetes significantly.⁸ In addition, strength training has been shown to reduce the need for insulin therapy, which is a common treatment for gestational diabetes.¹² 

Preeclampsia, a disorder associated with pregnancy, results in high blood pressure, protein in the urine, kidney damage, and other organ injuries, posing serious, sometimes fatal complications for both the mother and baby.¹³ Regular exercises during pregnancy have beneficial effects on disease progression, with the risk of developing preeclampsia decreasing as exercise volume increases. For example, one study demonstrated that light exercises led to a 24% reduction in preeclampsia incidence, whereas vigorous physical activity reduced the occurrence by 54%.¹⁴

Increased energy levels and improved mood

Pregnancy can lead to sleep disturbances and overall fatigue, which are associated with reduced quality of life and mood. Some medications have been used as a means of combating fatigue, but these are often avoided due to their potentially harmful effects on the foetus. However, recent research shows that regular strength exercise during pregnancy is associated with increased energy and decreased fatigue. In addition, physical activity can improve mood and overall quality of life.¹ 

Preparing for pregnancy strength training

Strength training during pregnancy has many benefits, yet it is important to consult a healthcare provider before starting any exercise regimen. Several contraindications to exercise during pregnancy have been identified:⁸

• Hemodynamically significant heart disease/maternal cardiac arrhythmia
• Restrictive lung disease/chronic bronchitis
• Incompetent cervix
• Multiple gestations at risk for premature labour
• Persistent vaginal bleeding
• Placenta previa after 26 weeks of pregnancy
• Premature labour
• Membrane rupture
• Preeclampsia/hypertension due to pregnancy (+poorly controlled hypertension)
• Severe anaemia
• Type 1 diabetes that is poorly controlled
• Underweight
• Sedentary lifestyle before pregnancy
• Intrauterine growth restriction during pregnancy
• Orthopaedic restrictions
• Seizure disorder or hyperthyroidism that is poorly controlled

If the mother does not suffer from any of these contraindications, a customised strength training program can be developed, preferably with the help of an educated prenatal fitness trainer. The program should focus on building and maintaining a reasonable fitness level without pushing it to the extreme. Many factors can influence the type and intensity of activity that is best suited, such as the mother’s pre-pregnancy fitness levels. For example, athletes who become pregnant can sustain a much higher exercise intensity than women who lived relatively sedentary lives before pregnancy.⁸ In addition, the type and intensity of physical activity will change as the pregnancy progresses.

Designing a pregnancy strength training program

Just like any physical exercise, it is important to include a proper warm-up and cool-down in the training routine. This will reduce muscle soreness, improve overall recovery, and prevent injury. It is recommended to warm up and cool down for at least 5-10 minutes.¹⁵ 

Many types of strength training are considered safe to start or continue during pregnancy, including free weights, cable machines, and more. However, it is advisable to avoid high-intensity plyometrics, Olympic lifting, and overhead-type movements as they could cause lumbar stress. Further, in later stages of pregnancy, some movements such as deadlifts and push-ups should also be avoided, as they create too much compression in the belly. 

Various training splits have been approved for exercise during pregnancy. In general, engaging in strength training with a full-body program three times a week seems to allow for good recovery. In addition, it is recommended to have at least one day of rest between training days. It is also advisable to use lower weights than those used pre-pregnancy to avoid overloading the joints and creating unnecessary stress.⁵

In addition to strength training, it is advisable to participate in aerobic exercises during pregnancy to improve overall cardiorespiratory fitness. This can include activities like walking, running, swimming, rowing, and more, as long as they do not pose a risk of falling. Contact sports such as basketball or boxing are not recommended.

Safe strength training exercises for pregnancy

Upper body exercises

• Dumbbell/resistance band arm exercises: Resistance bands are a convenient way to strengthen the upper body muscles and carry relatively low risk. Moreover, light dumbbells are great for increasing upper body strength with exercises such as lateral raises, bicep curls, and chest presses
• Seated rows and lat pulldowns: These exercises are both cable machine-based and target the back muscles. They will improve posture, and the machines can be used throughout the entire pregnancy as long as they do not involve a pad pressing against the belly⁸

Lower body exercises

• Squats/lunges: Walking lunges are not recommended because they increase the risk of pelvic floor injury. Squats and static lunges, however, target lower body muscles and improve overall leg strength. It is important to maintain correct form during these exercises, as bad form will cause dangerous lumbar stress¹⁶
• Leg press: By changing your foot placement, you can target multiple muscles in the lower body with the leg press machine. It is also much less technically demanding than squats, reducing the risk of injury

Core exercises

• Pelvic floor exercises: Pelvic floor muscle training can treat or prevent urinary incontinence, which is a very common effect of pregnancy. Simply put, this condition involves unintentional and uncontrollable leakage of urine. Kegel exercises are a very safe and effective way of strengthening the pelvic floor muscles¹⁷
• Modified plank variations: Core strengthening through plank exercise improves posture and helps during labour. Static core exercises such as planks put less pressure on the spine than dynamic ones, such as crunches¹⁸ 

Stretching for flexibility and relaxation

Stretching exercises and yoga offer a beneficial effect on perinatal depression and reduce stress and anxiety. Maintaining flexibility can also help in accommodating the physiological changes that occur during pregnancy and reduce any associated pain or discomfort. When performing stretching exercises, ensure they are performed in a slow and controlled manner, and avoid overstretching to prevent injury.¹⁷ 

Safety considerations and precautions

As aforementioned earlier, it is important to avoid any exercises that put pressure and stress on the abdomen or lower back, as they could pose risks to the baby. Additionally, monitoring your heart rate and breathing during training will ensure that the exercise intensity remains at the appropriate level and that you are not overexerting yourself. The ideal zone of perceived exertion rate falls between 12-14 on a scale from 6-20, which is classified as “somewhat hard” exercise.¹⁸

Proper hydration is important during exercise, particularly during pregnancy. Maternal hyperthermia is a condition where the foetus can be harmed if the mother is exposed to significant increases in body temperature. While exercise typically doesn't commonly induce this condition, staying properly hydrated throughout training will further reduce this risk.⁸ 

Several warning signs have been identified that may indicate exercise during pregnancy is detrimental rather than beneficial. These include:

• Vaginal bleeding
• Regular painful contractions
• Leaking of the amniotic fluid (a slightly yellow fluid)
• Dizziness
• Headaches
• Chest pain
• Muscle weaknesses causing reduced balance
• Calf pain/swelling
• Dyspnoea, shortness of breath

If you are experiencing any of these signs, it is advisable to stop exercising. In addition, it is important to listen to your body and reduce the program intensity when necessary.¹⁷

FAQ

Is strength training harmful to the baby?

Strength training, if performed according to the instructions of a qualified fitness trainer, is not harmful to the baby. In addition, engaging in exercise during pregnancy can potentially lead to an easier and safer delivery with fewer complications.⁵ Inactivity and obesity have been linked to chronic diseases and premature mortality of the foetus, further underscoring that exercise is not detrimental to the baby.⁸ 

Does strength training increase the risk of premature labour/miscarriage?

No link has been established between exercise and premature labour or miscarriage. This remains true even for exercise at a higher intensity than what is typically recommended. For example, in one study, pregnant women who were physically active before and during their pregnancy did not exhibit a significant difference in birth defect rates compared to previously sedentary women who remained inactive during pregnancy. Moreover, it is unlikely that exercise during pregnancy increases the risk of miscarriage, but it may be a concern for women with the aforementioned conditions.¹⁸

Debunking the notion of “eating for two” during pregnancy

A common misconception about pregnancy is the idea of “eating for two”, suggesting that when pregnant, a woman should double her nutritional intake. However, this is a myth that can potentially lead to pregnancy complications if taken seriously. Overeating during pregnancy can result in excessive weight gain, leading to various negative outcomes, such as gestational diabetes, hypertension, and other complications during labour and delivery. Instead, it is advisable to consult your healthcare provider regarding any necessary adjustments to your nutritional intake, typically amounting to no more than an additional 400 calories.¹⁹

Summary

Remaining physically active during pregnancy has many benefits for both mother and baby. Strength training, in particular, enhances muscular strength and tone, improves overall posture and balance, reduces the risk of excessive weight gain and associated complications, and improves overall mood and quality of life. However, it is important to listen to your body, adjust training intensity accordingly, and avoid any exercises discouraged during pregnancy. In addition, always consult your healthcare provider first to ensure there are no risks associated with physical activity during your pregnancy. Seeking professional help to create a personalised training program will also ensure a safe approach to strength training during pregnancy.