Guidelines for Prenatal and Postpartum Resistance Training

Abstract

Resistance training can be a safe form of both prenatal and postnatal exercise with appropriate exercise selection and modification, safety considerations, and understanding of pregnancy and postpartum recovery. Clinicians, coaches, trainers, and pregnant and postpartum women themselves, should be made aware of common conditions that can impact exercise such as diastasis recti, prolapse, gestational diabetes, preeclampsia and pelvic floor dysfunction such as urinary incontinence. Prenatal modifications will be introduced broken down into trimesters and postpartum conditions and recovery will be discussed. This chapter will also discuss the positive impact resistance training can have on pregnant and postpartum women when it is performed utilizing general safety guidelines and contraindications are observed and respected.

1. Introduction

Historically, pregnant and postpartum women have been discouraged and even advised against partaking in physical activity for fear of harming or terminating their pregnancy [1]. With an explosion of research in prenatal and postpartum exercise in the last decade, not only has the myth that physical activity causes miscarriage been disproven, evidence to support prenatal and postpartum exercise as a contributing factor to improved maternal and fetal health has emerged [1, 2, 3, 4, 5, 6]. Adherence to guidelines for prenatal and postpartum exercise, including resistance training, can ensure safe and active pregnancies and restorative postpartum recoveries. Topics discussed in this chapter include benefits and recommendations for prenatal exercise, general medical conditions that impact prenatal physical activity, contraindications and modifications for prenatal and postpartum exercise, common postpartum conditions that impact exercise and guidelines for postpartum exercise.

2. Benefits of and recommendations for exercise during pregnancy

Prenatal exercise has a plethora of benefits for both pregnant women and the fetus(es) they carry. Exercise during pregnancy has been shown to increase the incidence of vaginal delivery as well as lower the incidence of cesarean delivery, excessive gestational weight gain, gestational diabetes, gestational hypertensive disorders, preterm birth, and lower birth weight [1, 2, 3, 4, 5, 6]. Additionally, prenatal exercise has a positive impact on healthy growth and improved cognition and intelligence of the baby after birth [3].

The American College of Obstetrics and Gynecology (ACOG) recommends 30 minutes of physical activity 5 days a week for pregnant women [1, 6, 7, 8, 9]. Pregnant women with uncomplicated pregnancies, or pregnancies free of medical conditions that are deemed unsafe by their obstetrician, are safe to engage in both resistance training and aerobic activities. Contraindications for prenatal exercise will be further discussed in Section 2.4. It is important to note that according to the CDC, only 15% of American women meet these recommendations for prenatal physical activity [1]. Identified barriers to prenatal exercise include lack of energy and becoming too uncomfortable especially in the third trimester in addition to lack of education in safe prenatal exercise practices [1, 10, 11]. Despite its safety, only 11% of pregnant women engage in resistance training during their pregnancy [4, 12]. Acute bouts of resistance exercise are consistently associated with increased feelings of energy and decreased feelings of fatigue in pregnant women during the second and third trimesters [11].

Historically, physical activity was deemed unsafe for pregnant women for fear that it would cause a miscarriage or have negative impact on the developing fetus [1, 6, 8]. This view could be largely attributed to the lack of understanding of the physiological maternal adaptations throughout the 40 weeks of pregnancy. Physiological maternal adaptations include 50% increase in plasma, 40% increase in red blood cell volume, 40% increase in cardiac output in the late second trimester that remains stable until delivery, 40–50% increase in renal blood flow starting at 6 weeks gestation, 35–50% increase in tidal volume, 5% increase and lung capacity, and 10–20% increase in oxygen consumption [8]. All of these adaptations demonstrate the ability of the pregnant body to accommodate the growing fetus while also maintaining physical activity.

2.1 Strenuous exercise during pregnancy

While physical activity is both safe and beneficial, there are consequences for strenuous activity (95–100% Vo₂max to the point of exhaustion) [8]. Such strenuous activity may result in elevated maternal sympathetic response, reduced maternal placental blood flow, elevated maternal lactic acid, reduced glucose delivery, lowered maternal pH, increased uterine contractility, and reduced fetal oxygen [8]. Therefore, it is not recommended that pregnant women perform repeated bouts of extremely strenuous exercises at 95–100% of their Vo₂max or continue long duration workouts at a high level of perceived effort [8].

Women who are considered “untrained” can safely exercise at a moderate intensity 70–75% of Vo₂max, while trained women can handle up to 85–90% of Vo₂max [8].

2.2 Prenatal general medical conditions and their impact on physical activity

Two common prenatal medical conditions that can impact a pregnant woman’s ability to continue safe exercise are gestational diabetes and preeclampsia [13, 14, 15]. These conditions can develop during pregnancy and should be carefully monitored by the pregnant woman’s primary care physician or obstetrician.

Gestational diabetes is impaired glucose intolerance that is diagnosed for the first time during pregnancy and is associated with other prenatal conditions such as preeclampsia, hypertension, preterm birth and higher incidence of induced labor and cesarean delivery [13, 14]. It occurs in 2–10% of pregnancies and does not have any symptoms. Healthcare providers routinely test for gestational diabetes around 24–28 weeks gestation. If diagnosed, the pregnant woman will be advised to check her blood sugar, modify her diet, and partake in physical activity.

Moderate-intensity exercise training during pregnancy is associated with a lower incidence of gestational diabetes and reduced maternal weight gain [3, 6, 13, 14]. Prenatal physical activity yields the best results in managing gestational diabetes and maternal weight gain when performed in a combination aerobic and resistance training. Additionally, the benefits of physical activity are greater when started in the first trimester [6].

Preeclampsia is a serious high blood pressure condition that develops during pregnancy usually after 20 weeks gestation. It occurs in 3–7% of pregnancies and is more commonly seen in 1st time mothers, mothers who are black or of African descent, and those with a history of high blood pressure or thyroid conditions [15]. Preeclampsia can develop without symptoms and can change suddenly and drastically so it is important to regularly monitor maternal blood pressure throughout pregnancy. This condition should be closely monitored by the pregnant woman’s healthcare provider and exercise may or may not be recommended depending on the severity of the condition. Blood pressure medication may be prescribed to lower pressure during pregnancy and preeclampsia usually resolves after birth.

2.3 Contraindications and warning signs to terminate prenatal exercise

ACOG outlines absolute contraindications to prenatal exercise that include; significant heart or lung disease, incompetent cervix, multiple gestations at risk for premature labour, persistent second or third trimester bleeding, placenta previa after twenty-six weeks, premature labour during this pregnancy, ruptured membranes, and pregnancy-induced hypertension [9]. All of these conditions pose significant risk to maternal and fetal health and therefore should be considered absolute contraindications for exercise unless otherwise determined by the pregnant woman’s obstetrician (Table 1).

Contraindications to prenatal exercise	Warning signs to stop prenatal exercise
Significant heart or lung disease Incompetent cervix Multiple gestations at risk for premature labor Persistent second or third trimester bleeding Placenta previa after twenty-six weeks Premature labor during this pregnancy Ruptured membranes Pregnancy-induced hypertension	Shortness of breath before exercising Dizziness Headache Chest pain Calf pain or swelling Vaginal bleeding Preterm labor Decreased fetal movement Amniotic fluid leakage Muscle weakness

Table 1.

Contraindications to and warning signs to stop prenatal exercise [9].

There are also environmental conditions that should be considered as they can have adverse impacts on prenatal exercise. Higher altitude creates challenges in handling exercise load for the pregnant woman and warrants caution. It is recommended that pregnant women stay in a more moderate heart rate zone, 50–60% max heart rate, for a shorter duration- about 20 min [8, 9]. Prenatal exercise in high temperatures can have adverse effects on maternal and fetal health. Because increased fetal heart rate correlates with higher maternal body temperatures, maternal body temperature, especially with strenuous exercise, should be closely monitored. Prolonged exercise of more than 45 min can result in elevated core maternal and fetal temperature and increased uterine contractions, leading to preterm labor [8].

While physical activity is safe for most pregnancies, there are definitive warning signs to terminate or cease prenatal exercise. Some warning signs are those that are applied to any person working out such as shortness of breath before exercising, dizziness, headache, chest pain, calf pain or swelling. Others are very specific to pregnancy; vaginal bleeding, preterm labor, decreased fetal movement, amniotic fluid leakage, muscle weakness. All of these symptoms should be treated as indicators that exercise should be stopped immediately and reported to the pregnant woman’s obstetrician [9].

3. Exercise modification for pregnant women

The 40 weeks of pregnancy are commonly broken down into three trimesters that serve as mile markers for both fetal development and maternal changes. In regards to prenatal exercise, the trimesters serve as general time frames for when modifications need to be made for safe exercise practice.

3.1 The first trimester

In general, women experiencing healthy, uncomplicated pregnancies do not require much exercise modification in the first trimester. For most women, the first trimester is marked by mild to extreme fatigue [11]. Scaling back on exercise volume to reduce fatigue can be a useful strategy until energy levels return in the second trimester. Nausea is also very common in the first trimester making maintenance of adequate nutrition and physical activity difficult.

3.2 The second trimester

Upon entering the second trimester, more exercise modifications are necessary to accommodate the expanding uterus and pregnant belly. Modifications are also necessary to help manage the development of diastasis recti and bearing down into the pelvic floor which can ultimately lead to pelvic organ prolapse.

Diastasis recti, or abdominal separation, is a normal and necessary adaptation for the pregnant body. As the uterus expands and the fetus grows, the two rectus abdominal muscles will separate to create more space. Diastasis recti also involves the thinning and stretching of the linea alba, or the connective tissue between the two rectus abdominal muscles [16, 17]. It is measured by both the width between the two separated rectus abdominis muscles and the degree of tissue thinning of the linea alba. Diastasis recti is prevalent in 33% of pregnant women at 21 weeks gestation and 100% of pregnant women at 35 weeks gestation [16]. While diastasis recti is necessary prenatal accommodation, it should be managed appropriately to limit the amount of separation and thinning.

Important considerations in limiting diastasis recti during pregnancy include posture, body awareness, and intra abdominal pressure management. Pregnant women should be coached on being more mindful of how they are carrying themselves and maintaining posture throughout the day. Pregnancy tends to invoke an anterior pelvic tilt, therefore placing additional stress on the anterior core and the separating rectus abdominis muscles and thinning linea alba [18]. Placing unnecessary pressure on these structures when getting up from the seated position or utilizing a “crunch” to sit up can also exacerbate diastasis recti.

Specific modifications that need to be made starting in the second trimester to help manage diastasis recti include removing front loading exercises from the pregnant woman’s workout routine. Front loading exercises include crunches, planks, pull-ups, push-ups, and leg lifts. Front loading exercises generate excessive intra abdominal pressure that presses on the linea alba and rectus abdominis muscles causing a more significant diastasis recti [19].

Pelvic organ prolapse, or more commonly referred to simply as prolapse, occurs when pelvic floor muscles and ligaments stretch and weaken and no longer provide enough support for the uterus. As a result, the uterus slips down into or protrudes out of the vagina [20]. The pelvic floor muscles and connective tissues are responsible for supporting pelvic organs such as the bowels and bladder and uterus and vagina in females. Additionally they provide the contractor mechanism for the anal canal, urethra, and vagina.

As a pregnancy progresses, the uterus expands and becomes heavier placing increased strain on the pelvic floor. If the pregnant woman exerts additional downward pressure into the pelvic floor such as excessive pushing to have a bowel movement or bracing and bearing down with lifting a heavy object, the pelvic floor tissue may not be able to withstand the pressure and prolapse can result. Prolapse can be avoided during pregnancy by properly managing intra abdominal pressure when lifting, removing front loading exercises from the workout routine, and consulting a healthcare provider if persistent constipation occurs during the pregnancy.

Another modification to consider upon entering the second trimester is performing exercises in the supine position. Extended time spent in the supine position can cause venous obstruction in some pregnant women [21, 22, 23]. The weight of the uterus and fetus can compress both the superior vena cava and the aorta while in the supine position. This can reduce blood flow to the uterus and make the pregnant woman feel dizzy, light headed, and possibly nauseous. Therefore it is recommended that pregnant women do not lie flat on their back after the first trimester but rather utilize an inclined position in lieu of the full supine position. Some modifications that can be made for exercises commonly performed in the supine position include; seated deadbugs, incline chest press, and being creative with the kneeling or half kneeling positions for different shoulder fly movements.

3.3 The third trimester

Further modifications are needed throughout the third trimester as the uterus expands, the fetus grows larger and heavier, abdominal separation increases, the pelvic floor undergoes more stress, hormones change to relax ligaments to prepare for delivery, movement becomes more challenging for the pregnant woman, and fatigue increases.

If the pregnant woman has been running throughout her pregnancy, she is welcome to continue to do so but it may be beneficial to phase out running as the stress it imposes on the pelvic floor may become more problematic as her due date approaches. Urinary incontinence, or the involuntary leaking of urine, becomes more likely in the third trimester. An estimated 37% of women experience urinary incontinence during pregnancy and it is most common in the third trimester [24]. Running and jumping will increase the incidence of urinary incontinence during pregnancy as it significantly increases the stress on the pelvic floor [2] which is already undergoing increased stress from the weight of the uterus and growing fetus. Other lower-impact modes of cardiovascular training should be considered to replace running such as walking, swimming, stairmaster, elliptical, upper body ergometer, etc.

There are six key pregnancy hormones that help regulate the female body to maintain a normal pregnancy. The six key hormones are human chorionic gonadotropin (hCG), progesterone, estrogen, prolactin, oxytocin, and relaxin. For the purposes of this chapter we will focus only on relaxin and its role during pregnancy as it has the most direct impact on exercise and resistance training.

Relaxin, a peptide hormone of the insulin-like growth factor family, has been associated with collagen remodeling. It is secreted by the corpus luteum in the ovary and by the placenta beginning around the 10th–12th week of pregnancy [25]. In addition to inhibiting uterine contractions to prevent preterm birth, relaxing blood vessels, increasing blood flow to the placenta and kidneys, and softening and lengthening the cervix during birth, relaxin relaxes the joints of the pelvis in preparation for delivery [25, 26]. It is believed that relaxin increases pelvic laxity, and predisposes separation of the pubic symphysis, by altering the structure of collagen [25].

Pelvic and sacroiliac joint (SIJ) pain are common complaints of pregnant women particularly in their third trimester and may be attributed to the changes in the pelvic region due to increased relaxin levels [25, 27, 28]. This will lead to a need for exercise modification to reduce pelvic and SIJ pain. Modification suggestions include decreasing or eliminating single leg exercises such as single leg deadlifts and decreasing exercises performed with wide legs such as plie squats. It is also recommended to increase glute and hamstring strength to help stabilize the pelvis.

Lastly, for women still engaging in resistance training in the third trimester are encouraged to continue pending that they feel comfortable and motivated to do so. Scaling back is also appropriate as the pregnant woman will be experiencing greater challenges with movement, discomfort, and lack of energy. General guidelines to help maintain resistance training include decreasing barbell lifts especially if she is experiencing difficulties navigating her large belly and maintaining balance, and utilizing free weights and bands as necessary.

3.4 Guidelines for prenatal resistance training

Resistance training is a safe mode of physical exercise for women experiencing uncomplicated pregnancies and have been cleared by their healthcare provider to do so [12, 13, 14, 29]. It can be beneficial in maintaining current strength, posture, and mood during pregnancy. When done properly, without creating excessive intra abdominal pressure or bearing down into the pelvic floor, it can prepare the body for labor and help maintain pelvic stability.

When designing a prenatal resistance training program, it is important to consider that not only does each woman experience pregnancy differently, it can also vary widely with each pregnancy in the same woman. This makes it exceedingly difficult to create an all-encompassing prenatal resistance training plan that is appropriate and realistic for all women and all pregnancies. Some women will be able to continue resistance training at a high level for their entire pregnancy. Some will feel the need to scale back almost immediately. While it varies widely, there are some concepts and components that can be applied to all prenatal resistance training.

Front loading exercise, as previously mentioned, should be removed from physical activity and lifting routines by the start of the second trimester. This will help decrease unnecessary pressure on the linea alba and pelvic floor to manage diastasis recti and prevent pelvic floor dysfunction and prolapse during pregnancy.

Equipment selection will also be an important consideration as pregnancy progresses. As the pregnant belly continues to grow, lifting a barbell may not be comfortable or safe- ensuring that there is adequate clearance from the belly while lifting and lowering the barbell will need to be a top priority to prevent dropping the bar on the pregnant belly [2]. Balance will also be altered as the pelvis tilts anteriorly and the pregnant belly expands 18]. It may not be advisable for some pregnant women experiencing balance changing to lift the barbell even if she is an experienced lifter. Proper monitoring of balance changes should be completed periodically to determine if specific equipment selections are safe. Dumbbells and resistance bands are safe alternatives to heavier equipment if balance issues are present [2].

The intensity of prenatal exercise will vary from woman to woman depending on her level of physical fitness before becoming pregnant and the goals she has in maintaining that fitness. The American College of Sports Medicine (ASCM) defines moderate exercise as d as exercise of 3–4 METS or any activity that is equivalent in difficulty to brisk walking without any reason to alter the recommendation for pregnant women [30]. It should be noted that the allowance for intensity for pregnant women wishing to maintain or progress physical fitness throughout pregnancy is increased without cause for safety concerns in uncomplicated pregnancies. The ACSM recommends that intensity should be 60–90% of maximal heart rate or 50–85% of either maximal oxygen uptake or heart rate reserve. The lower end of these ranges (60–70% of maximal heart rate or 50–60% of maximal oxygen uptake) appears to be appropriate for most pregnant women who did not engage in regular exercise before pregnancy, and the upper part of these ranges should be considered for those who wish to continue to maintain fitness during pregnancy [30].

ACOG recommends the use of ratings of perceived exertion (RPE) in addition to heart rate suggesting the use of Borg’s conventional 6–20-point scale, with 12–14 (a rating of 13 corresponds to a subjective rating of “somewhat hard”) identified as the RPE range to apply in pregnancy [30, 31]. Occasional higher intensity cardiovascular activities may be completed for short time periods, but time spent exceeding the RPE ranges of 5–7 should be limited as the increased pressure directly impacts the health of the pelvic floor [2]. Historically there was a prenatal maximum heart rate limit of 140 bpm that has since been discredited by ACOG. Observing this unsupported heart rate maximum is not necessary [32].

While no universal prenatal resistance training protocol currently exists due to the wide variability in previous lifting experience, pre-pregnancy physical fitness levels, and prenatal medical conditions, The ACSM does provide basic guidelines for safety measures. In general, the ACSM does not recommend using a one repetition maximum (1-RM) with pregnant women [31]. It is suggested that clinicians, coaches, and trainers use the Oddvar Holten diagram to make a 1-RM prediction to guide resistance training. For example, the clinician, coach or trainer, makes an estimation of the weight that can be lifted for 10–20 times; the number of repetitions that can be maximally performed is registered; the percentage of intensity can than be looked up in the Oddvar Holten diagram, seen in Figure 1, at the number of repetitions and 1RM can be computed by the formula as seen in Figure 2 [31].

Figure 1.

Oddvar Holten diagram.

Figure 2.

Formula. A: lifted weight; B: percentage of intensity.

The most important consideration for prenatal resistance training is determining if the pregnant woman is properly managing intra abdominal pressure and is not bearing down into the pelvic floor. Pregnant women who engage in prenatal resistance training should be educated on how to manage intra abdominal pressure by utilizing proper breathing and bracing technique rather than a breath-holding technique. Pregnant women should breathe through their lift without holding their breath or simulating a valsalva maneuver as it generates significant pressure in the abdomen [33]. This pressure also can go directly down into the pelvic floor leading to dysfunction or prolapse. It is estimated that 46% of women had some degree of prolapse at 36 week gestation [34], making it a common concern especially if continuing resistance training throughout pregnancy.

Generally, resistance training movement selections should be made with the intention of focusing on the outlined goals of the pregnant woman and with respect to her energy levels, nausea, and other common pregnancy symptoms. If the goal is to maintain a moderate level of physical activity during pregnancy, the focus of resistance training should be on postural endurance and endurance with full body movements. Resistance training should take place at least 2 days in a week with a selection of movements desired by the patient and clinician, coach, or trainer [2]. Movements that focus on pelvic stabilization such as squats and lunges, postural strength and endurance such as rows and flys, and work in the quadruped position such as bird dogs are all encouraged to be utilized in prenatal resistance training [2].

4. Postpartum recovery and common postpartum conditions

Before discussing postpartum exercise, it is important to have a solid understanding of the postpartum recovery process and common postpartum conditions that impact a woman’s return to exercise. No two postpartum experiences are alike and there are a plethora of different conditions that may or may not occur after every delivery. All of the following conditions should be carefully considered by the clinician, coach, or trainer and discussed thoroughly with the postpartum woman and her medical provider if necessary, before designing a postpartum exercise program.

Although commonly thought of as the space between the vagina and the anus, the female perineum is a diamond shaped structure spanning from the pubic symphysis and the coccyx. The perineum is essential for supporting the pelvic floor and when tearing occurs in childbirth, damage can be done to muscle, fascia, veins, arteries, and nerves housed in the perineum. Tears range in severity from a 1st degree tear (first layer of skin around the vagina) to 4th degree tear (extends from the vagina to the anus). A 2nd degree tear is most common and 85% of women experience some degree of tearing in a vaginal delivery [35]. Tearing can impact the perineum’s ability to support the pelvic floor and unresolved trauma can lead to urinary and fecal incontinence and prolapse [36]. This type of birth injury can have a direct impact on postpartum physical activity and should be a consideration for program design.

C-sections are performed when vaginal delivery is too risky for the pregnant woman or the fetus, when labor has become complicated or fails to progress, or can be elected through consultation with the patient and obstetrician. This surgery involves cutting through skin, fat, fascia, and the uterus. Abdominal muscles are separated, not cut.Incisions are generally 12–17 cm, or 4.5–6.5 inches and the resulting scar tissue can make the surrounding skin and fascia tight and restricted [37]. The scar can also be painful, tender, sensitive, or lacking in sensation. This will have an impact on the recovery and return to physical activity timeline. As a general rule, no physical activity should occur before the incision has closed and clearance from a healthcare provider has been obtained.

Arguably, the condition most commonly exacerbated by premature return to postpartum physical activity is prolapse. At six weeks postpartum, 83% of women have some degree of prolapse and at 7–11 weeks postpartum, 52% of women develop a new prolapse, or a prolapse that was not present at the 6 week checkup [38]. Resistance training and running can generate intra abdominal pressure that pushes directly down on the pelvic floor that creates or exacerbates prolapse [2]. Prolapse can be avoided by gradually progressing the training program and scaling back when symptoms dictate. Prolapse and its impact on physical activity is related to perineum tearing and resulting scar tissue, pelvic floor resting tone (how tight or loose the pelvic floor muscles are), and whether or not the woman experienced prolapse or pelvic floor dysfunction during pregnancy. All of these factors should be considered before returning to physical activity.

Postpartum women commonly experience urinary (and sometimes fecal) incontinence with physical activity [2, 39]. It is referred to as stress urinary incontinence and is the leaking of urine without an urge and is brought on by a stressor such as running or jumping. When the muscles of the pelvic floor are not strong enough to support the bladder and/or contract the muscles that tighten the opening of the urethra, urine may leak when a stressor is introduced. It is important to recognize that while urinary incontinence is common in postpartum women, it is not normal. It is a sign of pelvic floor dysfunction and needs to be rehabilitated as any other injury before physical activity begins or continues. Urinary leakage needs to be acknowledged as a symptom of dysfunction and a potential precursor to prolapse and a sign that running and resistance training may not be appropriate until proper pelvic floor rehabilitation has taken place [2]. Pelvic floor therapy is not recommended to pregnant or postpartum women as a standard of care in the United States, leaving women to self advocate for such treatment [2]. Informed clinicians, coaches, and trainers could be instrumental in recognizing these signs of pelvic floor dysfunction and recommending or referring a client or patient for pelvic floor therapy.

Diastasis recti, while a normal adaptation of pregnancy, needs to be rehabilitated and permitted to heal before strenuous physical activity occurs. Some natural healing of the linea alba and surrounding fascia does occur spontaneously in the early postpartum weeks [17]. An estimated 60% of postpartum women have a diastasis at 6 weeks postpartum which decreases to 32% of women at 12 weeks postpartum [16]. There are several factors that impact the severity of diastasis recti including genetic factors related to collagen and elastin, advanced maternal age, ethnicity, number of pregnancies carried to term, pregnancies with multiple fetuses, high birth weight, and maternal weight gain [8, 16, 19]. All of these factors can impact the amount of spontaneous healing that is possible in addition to postpartum hormonal changes that regulate tissue healing.

Postpartum hormones are responsible for maternal recovery but also prepare the woman’s body to produce breast milk. The four key postpartum hormones are estrogen, progesterone, oxytocin, and prolactin [40]. Relaxin is also a hormone produced in pregnancy that remains present in the postpartum body. For the purposes of this chapter, we will primarily focus on postpartum estrogen and relaxin levels as they have the greatest impact on physical activity.

Estrogen level dramatically drops to 10% of the prenatal value and reaches its lowest value by 7 days postpartum [40]. If the postpartum woman breastfeeds the newborn, estrogen levels will remain low until ceasing breastfeeding. The American Academy of Pediatrics recommends exclusive breastfeeding for the first 6 months and urges greater support for mothers to nurse until at least 1 year of age [41], so this could be a significant period of low estrogen. This has a profound effect on postpartum tissue healing as estrogen is directly linked to tissue healing [42]. Low levels of estrogen may delay perineal tearing and c-section incisions. Additionally, long term suppressed estrogen due to breastfeeding may delay the soft tissue healing of the linea alba in regards to diastasis recti healing.

Relaxin, the hormone responsible for relaxing the ligaments in the pelvis in preparation for delivery, remains present for 12 months after delivery and longer if breastfeeding [43]. This means that women who do choose to breastfeed will have the effect of relaxin; ligament relaxation and laxity, possible SIJ pain, and pelvic pain. There is also some evidence to suggest that increased levels of relaxin in postpartum women can delay healing of diastasis recti because relaxin is designed to increase soft tissue laxity [17, 43]. The linea alba serves as the anchor for the rectus abdominis and transverse abdominis and if its tissue integrity is compromised by relaxin, abdominal strengthening and healing of the diastasis recti may be delayed [17].

After delivery, the hormone prolactin will prompt milk production. If a woman chooses to breastfeed, levels of prolactin will rise and fall in proportion to nipple stimulation [40]. When a postpartum woman’s milk comes in, they can experience engorgement of the breasts which can range from uncomfortable to painful. Direct nursing or using a breast pump will relieve the engorgement. Breastfeeding continues on a supply and demand basis, meaning that the more the baby nurses (or the more milk that is pumped) the more the breasts will produce and if the baby nurses less (or less is pumped) then the supply will go down [41]. This process will fluctuate over the course of breastfeeding until weaning is initiated and eventually prolactin levels drop and milk ceases to be produced. For women who choose not to breastfeed or cannot breastfeed, prolactin levels usually return to normal around 7 days postpartum [40].

It is to be expected that new mothers will experience significant sleep loss and fatigue following the birth of their baby. Postpartum women experience disrupted sleep patterns that can lead to sleep disturbances and sleep deprivation. Common postpartum sleep patterns include lack of nocturnal sleep that is replaced by daytime sleep. Many women report that sleep disturbances continued well past the 3 month postpartum mark [44, 45]. Sleep disturbances and sleep deprivation are closely intertwined with depressive symptoms and postpartum depression. Postpartum depression is most common 3 weeks after delivery up until the 6 month mark but can present later as well [46, 47]. Women who experience miscarriage or stillbirth are at a higher risk of developing postpartum depression and those experiencing preterm delivery are at an increased risk for posttraumatic stress disorders [47].

4.1 The postpartum checkup

At six weeks postpartum, women are seen by their healthcare provider, usually the obstetrician’s office that oversaw the pregnancy, labor and delivery. At this postpartum checkup the provider will check the incision if a c-section was performed and the perineum will be checked if tearing occurred or stitches were used. The uterus will also be externally evaluated and the breasts will be examined. The provider will also do a general medical assessment in taking blood pressure, height, weight, and heart rate. The postpartum patient will also complete a survey to assess for postpartum depression.

Barring any major red flags, the postpartum woman is medically cleared to resume physical activity, usually with very little guidance as to where to begin or how to progress safely. Many women incorrectly assume they are ready to return to running and resistance training at this point. There are several reasons why returning to physical activity after giving birth needs to be done as a gradual progression including; perineum tears, c-section incisions, healing prolapse, urinary and fecal incontinence, healing diastasis recti, hormonal changes, breastfeeding and changes to the breasts, fatigue, and mental health considerations.

4.2 Postpartum exercise readiness guidelines

The first step in returning to postpartum exercise is gaining clearance from the obstetrician or healthcare provider. Even after a postpartum woman is cleared by her physician, it is highly recommended that clinicians, coaches, and trainers utilize a physical activity readiness questionnaire (PAR-Q) to identify contraindications for postpartum exercise. These questionnaires are completed by the patient before any physical activity begins. If contraindications for exercise are identified, the patient should be referred back to her physician to address any health concerns [2]. If no contraindications are identified, the postpartum conditions outlined in the previous section should be carefully considered while creating an exercise routine (Table 2).

What type of delivery did you have, vaginal or c-section? Are you breastfeeding? Did you have your postnatal check-up? Did your healthcare provider clear you for physical activity at your postnatal checkup? Currently or during pregnancy, have you suffered any of the following? Pubic symphysis dysfunction, sacroiliac joint dysfunction, or pelvic pain Tearing/episiotomy or problem with stitches Urinary or fecal incontinence C-section wound discomfort Diastasis recti (abdominal muscle separation) Prolapse Bleeding during or after exercise Gestational diabetes

Table 2.

Sample postpartum physical activity readiness questions [2].

Contraindications and signs that exercise should stop for postnatal exercise include; postpartum bleeding (lochia) changes color, heavier flow, or starts again after stopping, feelings of heaviness or bulging in the vagina, leaking urine during or after exercise, pelvic pain, bulging or doming of the abdomen during exercise or discomfort afterwards [48], increased fatigue, dizziness or lightheadedness, difficulty breathing, chest pain, and pain or discomfort around the c-section scar or perineum stitches if applicable.

5. Foundational postpartum physical activity timeline

While prenatal exercise is largely scaling back as the pregnancy progresses, postpartum exercise is the reverse process; exercise needs to be gradually and progressively implemented over time. Every postpartum woman recovers differently and recovery is dependent upon several factors including her labor and delivery experience, health before and after delivery, mental health concerns, postpartum support, and the health and wellbeing of her new baby and other children and family members. Therefore, it is difficult to assign specific physical activity milestones to all postpartum women. However there are safety precautions and logical sequencing of rehabilitation and return to physical activity that can be utilized to ensure safe postpartum exercise.

For the purpose of this textbook, a focus on resistance training will take persistence over details about all types of physical activity including cardiovascular exercise. Historically, it has been advised that postpartum women do absolutely no exercise or mobility work in the first 6 weeks after delivery with many healthcare professionals still insisting on this outdated practice. Then they would be cleared for all activity at the 6 week postpartum check-up leaving a very wide gap in physical activity readiness leading to pain or injury of postpartum women returning to exercise. Updated protocols for postpartum physical activity do include foundational movements that can be performed in the early postpartum weeks to encourage healing and better prepare women for a return to physical activity [2].

In the very early postpartum weeks, weeks 0–2, if a woman wants to engage in movements, mobilization and postural movements need to be the primary focus. Some examples can be encouraging anterior and posterior pelvic tilts for postural alignment and light standing open kinetic chain movements. In weeks 3–4 postpartum, women can initiate short duration (less than 15 min) walks as well movements such as transverse abdominis engagement and glute bridges. In weeks 5–6 postpartum, an increase in walking duration (less than 30 min) can be implemented as well as muscular activities such as standing and quadruped hip abduction and extension, double leg calf raises, as well as sit to stand movements [2]. The intensity of all movements during the first 6 weeks postpartum should be kept at an RPE of 0–2 [2].

Upon clearance at the 6 week postpartum checkup, postpartum women can progress to muscular strength tasks either with body weight or with additional weights if appropriate. These muscular strength tasks can include squats, single leg sit to stand, and single leg calf raises. It should be noted that most recent evidence suggests that impact exercises such as running and jumping should be postponed until weeks 8–10 postpartum. Before doing so, gradual dynamic movements should be progressed in the exercise routine and can include single leg calf raises, single leg hop down from a step, single leg hopping, and jumping in place [2]. It is recommended that RPE during tasks should be maintained under a 6 [2].

It is also highly recommended that every postpartum woman see a pelvic floor therapist at least once after delivery. After clearance from the healthcare provider at the 6 week checkup is an ideal time to seek pelvic floor therapy as they will be able to perform an internal examination. The pelvic floor therapist can determine if there are any contraindications to advancing further into exercise such as pelvic floor dysfunction or prolapse that could be made worse by more stressful physical activity [2].

Most recent evidence suggests that 13 weeks postpartum is a safe point to return to running and sport activity given that the postpartum woman has progressed throughout other stages of postpartum recovery and exercise without complication [2]. Resistance training can begin to safely progress into more sets, repetitions, or weight depending on the lifting experience of the postpartum woman and her recovery process thus far.

6. Guidelines for postpartum resistance training

Upon successful progression through foundational physical activity milestones, postpartum women are capable of returning to resistance training. It is recommended that clinicians, coaches, and trainers discuss specific goals and exercise expectations with their postpartum patients or clients so they design exercise plans that progress realistically in conjunction with their patient or clients needs and desires.

Recall that beginning in the second trimester, front loading exercises including crunches, planks, pull-ups, push-ups, and leg lifts, were removed from exercise routines. Progressive reintroduction of these movements can be accomplished safely if the postpartum woman is monitored and educated on abdominal doming or bulging, diastasis recti and intra abdominal pressure management.

Diastasis recti can be assessed very simply through self-examination by lying on the floor with knees bent and feet on the ground. Then, while performing a small crunch with head and shoulders off the ground, palpate the linea alba from distal sternum to the pubic bone noting tissue tension (or lack thereof) and also noting the distance between the two rectus abdominis muscles. When the distance between the two rectus abdominis muscles exceeds 2 finger widths there is considered to be a diastasis [19, 43]. Tissue tension is an important factor for determining severity of a diastasis as tissue integrity needs to be insured for proper biomechanical function. If a diastasis recti exists, front loading exercises in particular will need to be carefully prescribed and pressure management education will need to be administered. The clinician, coach, or trainer will need to watch for abdominal doming or bulging of the lower abdomen as it is an indicator that pressure is not being properly managed.

A common cause of abdominal doming or bulging in postpartum women is a lack of connection or firing of the transverse abdominis. These muscles are responsible for maintaining abdominal wall tension in order to stabilize the spine and the pelvis before movement of the limbs occurs [49]. Because the transverse abdominis muscles co-contract with the muscles of the pelvic floor [49, 50] and have altered firing patterns after pregnancy [49], it may take significant retraining to properly engage these muscles to restore a functioning core. Abdominal doming and bulging are an indicator that the transverse abdominis muscles may not be contracting or may not be contracting the proper sequence in relation to the rectus abdominis and oblique muscles [49]. Retraining the transverse abdominis is the first step in reintroducing front loading abdominal exercises to the postpartum woman.

Equipment selection and the amount of weight lifted are very important factors to consider when designing postpartum exercise plans. Equipment selection should follow a logical progression with a recommendation for starting with bodyweight exercises, followed by resistance band use, followed by hand weight or dumbbell incorporation, and working up to barbell introduction. The timeline for equipment progression will be dependent upon the postpartum woman’s lifting experience, comfort level in using each type of equipment, and overall recovery process. If she is breastfeeding, relaxin levels will remain elevated and can cause ligament laxity and possibly pelvic or SIJ pain even if she is an experienced weight lifter [51].

Equipment selection and weight lifted will have a significant impact on prolapse. Women who return to strenuous lifting too soon postpartum can be at an increased risk for developing prolapse [2]. Women with prolapse can still lift lighter loads if they are able to properly manage intra abdominal pressure and are not bearing down into the pelvic floor while lifting. Bearing down into the pelvic floor while lifting is an inappropriate but common strategy for attempting to stabilize the pelvis when there is a lack of strength or function in the core. Addressing diastasis recti if present will also encourage proper intra abdominal pressure management and provide strength and function to the core and pelvis and limit the need for other compensatory movements and strategies that can lead to prolapse.

Jumping and plyometrics are some of the last impact exercises that are introduced in postpartum exercise plans. High impact exercises such as jumping and plyometrics can reveal pelvic dysfunction in the form of urinary incontinence. Because these exercises place a high level of stress on the pelvic floor, postpartum women who had not experienced urinary incontinence before may experience it for the first time while attempting jumping or plyometrics [2]. Urinary incontinence should be recognized as a symptom of pelvic floor dysfunction and a referral to a pelvic floor therapist should be recommended. It is also a sign that the pelvic floor is not ready for such high impact and scaling back may be necessary.

To date, there is no evidence to support a definitive intensity maximum after the 13 week postpartum period without any RPE or heart rate restrictions outside of normal, age-appropriate ranges. The ACSM does suggest that training volume should progress gradually at 2–10% per week in direct relation to postpartum recovery progress and goals of the postpartum woman [2].

7. Conclusion

Considering all components of pregnancy and postpartum recovery is essential to planning and implementing resistance training into an exercise program. When done correctly, resistance training can be a safe form of exercise for pregnant and postpartum women and can enhance their pregnancy, supplement their postpartum recovery, and add to their quality of life.