Sound Traditional and Nontraditional Prepartum Exercise for Good Health

Pregnancy is a time of joyful expectation. The mother wants to do everything in her power to ensure a safe delivery and a healthy baby. One of the key questions for the safety of exercise during pregnancy has been: does the selective redistribution of blood flow during regular or prolonged exercise in pregnancy interfere with the transport of oxygen, carbon dioxide, and nutrients? The indirect evidence does not support this concern [1]. In fact, research has shown that regular exercise during pregnancy provides health and fitness benefits to both the mother and the child [2].

Conventional exercise for women has most notably been aerobic exercise. Resistance training, while still considered a traditional exercise, has historically been male dominated. This trend has changed dramatically. Today we see more and more women engaging in resistance training, even during pregnancy. Most probably, water exercise, yoga, and Pilates would not be considered traditional exercise in the United States (US), especially not as a form of resistance training. Yet all of these movement patterns are a form of resistance training. Yoga and Pilates use body weight, or small props such as balls and bands to increase resistance. Water exercise uses the weight of the water for resistance.

For the sake of discussion in this paper, traditional exercise will be referred to as aerobic exercise and resistance training using weights. Nontraditional exercise will be referred to as yoga, water exercise, and Pilates.

A thorough clinical evaluation of each pregnant woman should be conducted before an exercise program is recommended. Minimally, the Canadian Society for Exercise Physiology Physical Activity Readiness Questionnaire, termed the PARmed-X for Pregnancy should be used for health screening for pregnant women https://www.csep.ca/CMFiles/ publications/parq/parmed-xpreg.pdf [3]. The examining physician as well as the pregnant female should be well aware of the absolute and relative contraindications to exercise as well as indications to terminate exercise. The American College of Obstetricians and Gynecologists (ACOG) have outlined these conditions in their ACOG Committee Opinion 267 [2]. Absolute means that exercise should not be initiated until this condition is controlled or abated and relative means that a decision should be made by the healthcare team regarding the cost benefit ratio. For example, will more good be gained from exercising than not exercising during the pregnancy for both the mother’s wellbeing and that of the fetus? Table 1 lists the absolute contraindications with an (A) following the condition, a (R) following the relative contraindication, and a (T) following the condition for terminate exercise (Table 1).

Table 1: Absolute (A), Relative (R), and Reason to Terminate Exercise (T) from the American College of Obstetricians and Gynecologists.

In 1985, certified aerobics instructors were trained not to allow pregnant women to exceed a heart rate (HR) of 140 beats per minute during exercise [2]. Today the professional community of certified instructors understands that HR is not a valid tool to use during pregnancy to monitor intensity. Historically, duration of the exercise was also expected to be monitored closely; ACOG recommended no more than 15 min of continuous exercise due to issues with thermoregulation. It is true that hyperthermia is a concern given that both exercise and pregnancy raise the metabolic rate. Furthermore, it can be considered a teratogenic effect for the mother’s core temperature to rise above 102.6 F, especially in the first trimester [4]. However, these concerns about the teratogenic effect of high core body temperatures in the early first trimester have not been demonstrated in studies of exercising women [5]. Therefore, a maximal duration of 15 min is not advocated in 2016 unless there are warning signs of hyperthermia. In 2002, the ACOG promoted moderate exercise during pregnancy, suggesting that exercise may play an important role in the prevention and management of gestational diabetes mellitus, particularly in morbidly obese women (BMI> 33) [2]. In the 2002 updated guidelines, the ACOG even encouraged sedentary women to begin exercising in the absence of medical contraindications after a thorough evaluation with their physician. In 2003, the Joint SOGC/CSEP Clinical Practice Guidelines stated that in uncomplicated pregnancies, women with or without a previously sedentary lifestyle should be encouraged to participate in aerobic and strength conditioning exercises as part of a healthy lifestyle [6]. They further advocated that women and their caregivers should consider the risks of not participating in exercise during pregnancy, including the loss of muscular and cardiovascular fitness etc.

While there are many physiological changes, gravid women who exercise during their pregnancy need to be aware of the increase in energy requirements. Women should increase their caloric intake by 300 kcal per day per fetus after the 13th week of pregnancy [7]. Exercise activities must also be compensated for with increased caloric intake. The combined energy requirements of pregnancy and exercise coupled with poor weight gain may lead to fetal growth restriction [1]. At the other end of the spectrum, we have obesity during pregnancy, which also brings about additional complications. Regardless of which way the pendulum swings, prepartum women should work with a nutritionist and exercise physiologist as well as their primary care physician to ensure that they are adjusting their caloric needs appropriately to meet their changing physiology and active lifestyle patterns. Additional physiological changes that occur during pregnancy are highlighted (Table 2).

Table 2: Physiological Changes during Pregnancy

Exercise prescription for aerobic exercise during pregnancy

There is sufficient evidence to support 30 min of moderate aerobic conditioning on most if not all days of the week during uncomplicated pregnancies [1-3,6]. Given the variability in target heart rates during pregnancy, it is advisable to use another means to monitor intensity such as: (1) the talk test; (2) the compendium of physical activity chart with metabolic equivalents [(METS)]; or (3) the Borg Rating of Perceived Exertion Scale (RPE) [1,8]. As the talk test name implies, a woman is exercising at a moderate level if she can maintain a conversation during exercise. Moderate exercise is defined as 3-5 METS which means that a woman is exercising 3-5 times above her resting metabolic rate [3]. Table 3 highlights some common MET categories for low, moderate and vigorous exercise. An RPE of 12 to 14 (light to somewhat hard) on the 6-20 Borg scales indicates a feeling of moderate exercise. The Borg Scale accounts for an individual’s fitness level. Perceived Exertion matches how hard an individual feels they are working with numbers from 6 to 20; thus, it is relative to fitness levels (Table 3).

Table 3: Metabolic Equivalents (MET) Values for Physical Activity Levels

Previously sedentary women’s exercise progression should follow a gradual progression of up to 30 min a day beginning with 15 min a day 3 times a week. Reasonable goals for women who were previously active would be to maintain a good fitness level without trying to reach peak fitness or train for an athletic competition. Elite athletes who continue to train during pregnancy should work under the supervision of their obstetric care provider with knowledge of the impact of strenuous exercise on maternal and fetal outcomes [6]. A summary of recommendations for aerobic exercise during pregnancy can be found (Table 4).

Table 4: Summary of Recommendations for Aerobic Exercise During Pregnancy.

Exercise prescription for resistance training during exercise

While there is less evidence on strength-conditioning and resistance training (RT) using weights in pregnancy, it seems that appropriate RT provides an enhanced level of muscular fitness. Enhanced muscular fitness may help compensate for the postural adjustments that typically occur during pregnancy [9,10]. Nonetheless, the recommendation from the ACOG [2] is that exercise in the supine position should be avoided whenever possible because of the relative obstruction of venous return and, therefore deceased cardiac output and orthostatic hypertension, especially after the first trimester. Furthermore, heavy lifting during pregnancy is never appropriate since it may expose the joints, connective tissue, and skeletal structures of a gravid woman to excessive forces [11].

All RT exercises should be performed in a slow and controlled manner. An intensity of 9 (very light) to 14 (somewhat hard) or moderate exertion on the RPE scale would be appropriate for RT during pregnancy. RT on machines is preferred to free-weights because machines can be more easily controlled and require less skill [11]. RT should occur every other day with one day of rest between sessions.

One to three sets is appropriate depending on the exercise and the stage of pregnancy. An exercise set consisting of at least 12-15 repetitions without undue fatigue is recommended for the lower body and 10-12 repetitions for the upper body for the desired goal [11]. If the prepartum female cannot perform the desired number of repetitions initially, she should start with fewer repetitions and build up to the desired number before adding additional weight. Increased recovery time between sets may be needed with fewer repetitions and less weight as time of pregnancy increases. Prepartum women interested in resistance conditioning are encouraged to read, Fit to Deliver, an exercise program for you and your baby [11] (Table 5). Table 5 summarizes guidelines for RT during pregnancy.

Table 5: Recommendations Regarding Resistance Training during Pregnancy

Yoga during pregnancy

Even though yoga has been classified as a non-traditional exercise in the US, yoga is an ancient tradition designed to bring balance and health to the physical, mental, emotional, and spiritual domains of an individual [12]. This ancient discipline is often represented metaphorically as a tree consisting of eight ‘‘limbs’’ or aspects: Yama (universal ethics), Niyama (self-discipline), Asana (physical postures), Pranayama (breath control), Pratyahara (control of the senses), Dharana (concentration), Dyana (meditation), and Samadhi (bliss or transcendent meditative awareness) [13]. In contrast to other branches of yoga, the type known as Hatha focuses on the body and fitness [14]. Indeed, what most people refer to as simply "yoga" is hatha yoga, the most popular type practiced in the West [13,14].

While there is little research on the effects of yoga on pregnancy, yoga has been shown to produce significant health benefits in other healthy and clinical populations. Many of the clinical effects would be beneficial for conditions associated with pregnancy, such as gestational diabetes, hyper or hypotension, and an increased resting and exercising HR. Therefore, the statements made in this paper on Yoga are based on following the recommended exercise guidelines for prepartum women from leading experts in the field and published research on other clinical populations regarding the physiological effects of yoga on these conditions [2,3,6]. While some of these changes during pregnancy are to be expected given the additional demands of carrying a fetus, the endocrine system of pregnant women undergoes significant changes Adrenocorticotropic hormone [15]. The stimulation of the pituitary adrenal axis during pregnancy raises the production of Adrenocorticotropic hormone (ACTH). This is associated with an increase of total and free cortisol [16]. Yoga is associated with rapid stress reduction and anxiolysis, significant decreases in heart rate, systolic and diastolic blood pressure, as well as increases heart rate variability (HRV) [17-20]. Data also shows that yoga decreases levels of salivary cortisol, blood glucose as well as plasma renin levels, and 24- hour urine norepinephrine and epinephrine levels [18,19,21,22]. Many of the postures in yoga would have to be adapted to avoid compromised positions and to stay within the guidelines promoted by experts in the field [1,2,6].

With a professional background as a Registered Yoga Teacher (RYT^®) instructor and American College of Sports Medicine Certified Program Director and Clinical Exercise Physiologist, the author chose suitable postures in yoga for prepartum women or adapted postures in yoga. The Sanskrit term for the asana as well as the English translation with suggested modifications in posture are listed in Table 6. The author also thinks that the affirmations that are taught with the asanas in Ananda Yoga for Higher Awareness would be beneficial during pregnancy if the gravid female was inclined to spiritual inspirations of this nature. The affirmations could easily be changed to affirmations related to increased health and well-being during pregnancy. The affirmation should be stated softly by the yoga instructor at the beginning of the asana or during the asana and then silently repeated by the yoga participant if desired. There is no published research to support the spiritual inspirations during the asana for pregnant women nor a plethora of research to support or not support yoga during pregnancy. Caution must always be practiced and the guidelines for resistance training must be applied a stated in Table 5 (Table 6).

Table 6: Sample Yoga Asanas for Gravid Women without Contraindications to Exercise During Pregnancy with Uplifting Affirmations from Ananda Yoga

Pilates during pregnancy

Similar to yoga, the statements made in this paper on Pilates are based on following the recommended guidelines for prepartum exercise from leading experts in the field and the knowledge and background of the author in exercise physiology [2,3,6]. The author also holds a certification from the American Council of Exercise as a group exercise leader. Because so many of the postures in Pilates are executed while reclining in a recumbent position and this position should be avoided during exercise as much as possible, Pilates does not lend itself easily as a viable movement form during pregnancy [2]. Albeit, the exercises could be changed to a side lying plane on the floor, and sitting postures on a chair could be used to strengthen the back muscles. It would require advanced knowledge and a manipulation of many of the postures on the part of the Pilates instructor for the exercises to be considered safe. A further concern is that the ability to perform abdominal exercise may be impeded by the development of diastasis recti and associated abdominal muscle weakening [23].

Nevertheless the positions in Pilates could be adapted for gravid women as long as the guidelines for resistance training were applied (Table 5). Nordahl et al. [11] has a chapter on balance training in her book that illustrates exercises using balls and bands. While the word Pilates is not used, these exercises are very similar to the movement patterns in Pilates. The breath control used in Pilates could easily be adapted for these exercises.

Water exercise during pregnancy

Water aerobics has been viewed as more of an aerobic conditioning exercise rather than a resistance training tool. However, water exercise is a viable form of resistance conditioning during pregnancy. Exercising in water has many physiological benefits for gravid women [1]. The major effect of immersion is a redistribution of extravascular fluid resulting in an increase in blood volume and centripetal shift [24]. Water exercise is highly recommended as a form of resistance training during pregnancy barring no contraindications to exercise [2].

Providing that there are no contraindications to exercise during pregnancy, the gravid female should be encouraged to perform both moderate aerobic conditioning activities as well as reasonableresistance training activities [2]. These activities can be chosen from traditional and non-traditional exercise as defined in this paper. These activities should be chosen in consultation with the obstetric physician and health care team. Pregnant women should be knowledgeable of the changes that occur during pregnancy and why certain exercises should be avoided. An excerpt taken from the Active Female, co-authored with Cardona Gonzales and Álvarez Carnero, summarizes exercise recommendations during pregnancy very nicely.

The pregnant woman should be monitored closely to adjust training loads as a function of body mass, blood markers and the fetus developmental changes. Individual prescriptions should be based on assessing energy requirements and capacity as tight as possible. A flow networking must be established between gynecologist, nutritionist and exercise physiologist in order to maximize benefits to both the fetus and the mother. The first aim of exercise program must be to guarantee the safety of the mother and fetus more than performance or esthetic outcomes during pregnancy and after-delivery [15].