Training During Pregnancy: What You Need to Know

Welcome readers. Perhaps you are pregnant right now (congratulations!), perhaps you are considering getting pregnant one day, or perhaps your partner is/will be (bravo for doing your research!). In any case, I am glad you are here. At this moment I am 37 weeks + 3 days pregnant so you could say I’m pretty experienced. Oh wait, there is no such thing as being an experienced pregnant person. Every pregnancy is different and even subsequent pregnancies can be different for each woman. For this reason, we will turn to the research to see what we know, what we are learning, and what we still have no idea about when it comes to training during pregnancy. I may also throw a personal anecdote or two in there for colour. I hope you get a lot out of today’s article and if you do please let me know! Leave a comment or share this article with someone else who may be interested. Ok on with the content.

In today’s post we are going to cover a number of topics related to training during pregnancy. We will begin with a brief overview of the physiological changes experienced during pregnancy (spoiler alert: the female body is hella impressive), then we will discuss the current recommendations for exercising during pregnancy focusing on where the evidence is strong versus where we are still quite in the dark and finally we will cover some recommended resources to point you in the right direction during your marvellous journey into motherhood.

PHYSIOLOGICAL ADAPTATIONS DURING PREGNANCY

1) CARDIOVASCULAR

Changes to the cardiovascular system begin around week 5 (i.e. almost immediately after you pee on the stick). Towards the end of pregnancy, your cardiac output (aka the amount of blood pumped by your heart per minute) increases by about 40% mainly due to an increase in stroke volume (amount of blood pumped by your heart in one contraction) and an increase in heart rate (Geva, 1997). Resting heart rate increases 15-20 beats per minute (bpm) above pre-pregnancy values (Wolfe, 1989). In other words, your heart pumps more blood, more often during pregnancy than it did before. Now get this, before the baby gets large enough to physically impede the space your lungs have to breathe, your respiratory system also changes. Due to the flaring of your rib cage, your diaphragm raises about 4cm (Artal, 1991) resulting in an a slight increase in tidal volume (the amount of air you inhale with each breath) and oxygen consumption (amount of oxygen your body uses to create energy) (V02). Isn’t that insane? Your ribs get out of the way so your diaphragm can lift to ultimately give your lungs super powers to get more oxygen to your baby. Like…what?! So cool. Here is something even more crazy, when you are pregnant your body becomes more sensitive to carbon dioxide by creating a buffer to protect your baby from any acute elevations in maternal carbon dioxide levels! (Weissgerber, 2006).

2) MUSCULOSKELETAL

As pregnancy progresses, your centre of gravity will shift with your growing uterus possibly causing you to feel off balance (Wang, 1998). To avoid falling forward, we compensate with an increase in our anterior pelvic tilt and an exaggerated lumbar lordosis (Hartmann, 1999) (could explain why booty looks so good during pregnancy….but that is a theory we have yet to test). Hormonal changes induce laxity in our joints which may increase our risk of experiencing strains and sprains (Shephard, 2000).

3) METABOLIC

During pregnancy the protein content of your muscle tissue increases (yay!) while carbohydrates accumulate in your liver, muscles and placenta (carbo loading anyone?)(Barakat, 2015). Crazily enough, our muscles actually become more resistant to glucose freeing up more for baby (Buchanan, 1990; Lesser, 1994). Fat deposits become noticeable under the skin (hello cellulite!) especially around breasts and buttocks (Bonen, 1995). Hormonal changes increase water retention (Bonen, 1995), and as a most obvious sign of pregnancy, we gain weight. According to the American College of Obstetrics and Gynaecology (Obstet Gyencol, 2013) , recommendations for maternal weight gain are based on your BMI pre-pregnancy:

• Underweight (BMI <18.5) 28-40lbs

• Normal weight (BMI 18.5-24.9) 25-35lbs

• Overweight (BMI 25-29.9) 15-25lbs

• Obese (BMI >30) 11-20lbs

Ok so it’s lame to talk about weight gain, I agree. But it is helpful to know what the recommendations are to keep your ice cream cravings in check…..pregnancy is not eating for two after all (as much as we’d like it to be). But what are the energy requirements for pregnancy you ask? (Butte, 2005)

• First trimester: you’ll need an extra 90kcal/day

• Second trimester: + 287kcal/day

• Third trimester: + 466kcal/day (exciting eh?)

Remember, these are guidelines not necessarily hard and fast rules. Depending on your age, ethnicity, body mass pre-pregnancy, physical activity level and a host of other factors you may need more or less calories to sustain your pregnancy. As always, consult your health care provider for all of your pregnancy concerns.

Ok so we covered some incredible changes your body is undergoing physiologically. But what does that mean for training during pregnancy? Let’s take a look at the recently published 2019 Canadian Guidelines for Physical Activity During Pregnancy (Mottola, 2018).

CURRENT RECOMMENDATIONS ARE AS FOLLOWS:

Strong recommendation, high quality evidence:

• A variety of exercise should be incorporated including aerobic and resistance exercise, yoga and gentle stretching

Strong recommendation, moderate quality evidence:

• All women without contraindication should be active throughout pregnancy

• To achieve clinically meaningful health benefits and reductions in pregnancy complications pregnant women should accumulate 150 of moderate intensity physical activity each week

  • Exercise should be accumulated over a minimum of three days per week

Weak recommendation, low quality evidence:

• Pelvic floor muscle training may be performed daily to reduce the risk of urinary incontinence

Weak recommendation, very low quality evidence:

• Women who experience light-headedness, nausea, or dizziness when exercising on their back should modify their exercise to avoid the supine position

Just so we are clear. the difference between a strong vs a weak recommendation is as follows: a strong recommendation means most if not all pregnant women will be best served by following this recommendation whereas a weak recommendation means not all pregnant women will benefit from this recommendation and thus consultation with a healthcare provider is advised.

LET’S DIG INTO THESE RECOMMENDATIONS BIT MORE…

Compared with doing nothing, meeting the recommended 150min of moderate intensity physical activity per week was associated with meaningful reductions in risk of developing gestational diabetes, preeclampsia, and gestational high blood pressure (Davenport, 2018). Getting more than 150 minutes per week was associated with even greater benefit, meaning there is a dose-response relationship. HOWEVER, an upper ceiling was not determined so whether exercising far and above these recommendations is extra beneficial…well we just don’t know.

Interestingly, combining aerobic exercise with resistance training was more effective at improving health outcomes than aerobic exercise alone (Davenport, Ruchat et al 2018; Davenport, McCurdy 2018). Great news for those of us who don’t enjoy cardio! Although a dose-response relationship was observed between exercise intensity and decreasing odds of complications during pregnancy (Davenport, Ruchat, 2018; Davenport, Sobierajski, 2018; Davenport, Nagpal, 2018), no evidence was identified for exercising at intensity levels significantly over and above these recommendations to incur any additional benefit. Moderate intensity according to these guidelines is the equivalent of a jog (apparently you just run for an extended period of time?). The guidelines include recommended heart rate ranges to monitor exercise intensity. Although, if you don’t have access to a heart rate monitor, the talk test is recommended (aka you should be able to talk during the activity, if you can’t hold a conversation, it is likely too intense). I know what you’re thinking, this doesn’t really help athlete types interested in maxing out their CrossFit WOD or chasing down PRs on the track….take these recommendations for what they are, recommendations for the general pregnant population. We will get to the athletic pregnant population in a moment.

Included in these guidelines is the recommendation to engage in pelvic floor therapy for the prevention of urinary incontinence. If you missed my article on Pelvic Floor Therapy check it out here. In that article we discuss in detail the what, who, where, when and whatzit of pelvic floor therapy. With proper instruction (aka under the supervision of a pelvic floor therapist) pelvic floor therapy can reduce prenatal urinary incontinence by 50% and postnatal urinary incontinence by 35% (Davenport, Nagpal, 2018), however the recommendation was considered weak based on low-quality evidence.

As far as exercising on your back, the evidence is very low (Motola, Nagpal, 2018), and thus only a weak recommendation was made for women who feel symptomatic when exercising supine to avoid this position. As a blanket rule, exercise that puts your baby at risk for fetal trauma (impact sports like rugby, football etc. as well as sports that involved a danger of falling e.g. horseback riding, rock climbing etc.) are to be avoided. Diastasis recti (separation of your abdominal muscles) was briefly addressed. It is recommended that women experiencing abdominal separation seek physical therapy and avoid traditional abdominal strengthening exercises like sit ups.

As a general rule, exercising in excessive heat is recommended against. And if you experience and any of the following symptoms you should cease exercise immediately and seek the consult of your healthcare provider:

• Persistent, excessive shortness of breath, dizziness or faintness, that does not resolve on rest

• Severe chest pain

• Painful and strong uterine contractions

• Vaginal bleeding

• Rupture of membranes (your water breaks!)

SO YOU’RE AN ATHLETE…

In 2016 the International Olympic Committee put out a 5 part series summarizing the evidence for exercising during pregnancy for recreational and elite athletes. As a whole. there is a severe lack of evidence surrounding exercise during pregnancy in the athletic population (Bø, 2018; Mottola, Nagpal, 2018). We know very little about the impact of high-intensity and/or high volumes exercise on maternal and foetal outcomes. We also know very little about the effect of training during pregnancy on a woman’s ability to return to her competitive peak post-partum. Some good news though: If you regularly exercise at least at a moderate intensity through pregnancy you can expect your V02max to return to pre-pregnancy level or even slightly increase! Post-partum it is recommended that endurance activities be low-impact to reduce the strain on the pelvic floor, same goes with strength training, paying extra attention to the recovery of your pelvic floor is strongly recommended.

Not exactly the straightforward recommendation you were hoping for was it? The problem is, we just don’t have a lot of evidence on training during pregnancy in athletic women. So it’s not that heavy resistance training or high-intensity interval training is necessarily harmful to mom or baby it’s that we just don’t know! In fact, be weary of anyone who interprets this evidence to sell you a program or a solution. Is exercise important during pregnancy? Yes. Is it appropriate for almost every woman? Yes but the key word is almost because again, each pregnancy is unique and we really can’t generalize these recommendations to all pregnant women.

If you were a competitive power lifter, triathlete, or any manner of recreational to elite athlete pre-pregnancy you are going to have seek your own answers through the help of a dedicated health care team. As a rule, your body is unique and there is no “one size fits all” approach to training during pregnancy. The best thing you can do is to establish a support network of care providers who are familiar with your health history and can provide sound advice for optimizing both you and your baby’s health. Besides your primary obstetric care provider (whether that be your family doctor, OB, or midwife), you might want to consider adding one or all of the following to your healthcare roster: a pelvic floor therapist, a personal trainer/coach well versed in pre and postnatal training strategies, a chiropractor, osteopath, or naturopathic doctor (whose practices focus on women’s health), and perhaps even a doula for support during labour! This is YOUR pregnancy and YOUR baby, so build a team that makes you feel confident and in control of your pregnancy. One more smidge of advice, listen to your instincts! If you think a second opinion is needed, get one! You are the captain of this ship.

IN SUMMARY,

Exercise is strongly recommended during pregnancy. Combining aerobic exercise with resistance training has greater benefit than aerobic exercise alone. Incorporating yoga and/or flexibility training is important though you should take caution in over stretching lax joints. Seek the treatment of a pelvic floor therapist to make sure you are preparing your body for a healthy delivery and return to exercise post-partum. If you are hungry for more info, check out some of the references below. Also, I would recommend following these amazing women who are blazing the trail in pre and post natal training: Jessie Mundell, Brianna Battles, Haley Shevener, Julie Wiebe, Physio Detective.

If you are local to the Hamilton/Burlington area, I would highly recommend a visit to Ebb and Flow Wellness to see Jenny or Robyn for incredible pelvic floor therapy treatment. And if a doula is something you are interested I promise to share my experience with Oakville Family Birth and The Stork’s Nest doulas who have so far been nothing short of an amazing addition to our care team.

Thanks for stopping by. If you enjoyed today’s article please leave a comment or share with someone you care about.

Yours,

Coach P.

References

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2.  Wolfe LA, Ohtake PJ, Mottola MF, et al. Physiological interactions between pregnancy and aerobic exercise. Exerc Sport Sci Rev 1989;17:295–351.

3.  Artal R, Wiswell R, Drinkwater B. Exercise in pregnancy. Williams & Willkins, 1991

4.  Weissgerber TL, Wolfe LA, Hopkins WG, et al. Serial respiratory adaptations and an alternate hypothesis of respiratory control in human pregnancy. Respir Physiol Neurobiol 2006;153:39–53.

5.  Wang TW, Apgar BS. Exercise during pregnancy. Am Fam Physician 1998;57:1846–52, 57.

6.  Hartmann S, Bung P. Physical exercise during pregnancy—physiological considerations and recommendations. J Perinat Med 1999;27:204–15.

7.  Shephard RJ. Exercise and training in women, part I: influence of gender on exercise and training responses. Can J Appl Physiol 2000;25:19–34. doi:10.1139/h00-002

8.   Barakat R, Perales M, Garatachea N, et al. Exercise during pregnancy. A narrative review asking: what do we know?Br J Sports Med 2015;49:1377-1381.

9.   Buchanan TA, Metzger BE, Freinkel N, et al. Insulin sensitivity and B-cell responsiveness to glucose during late pregnancy in lean and moderately obese women with normal glucose tolerance or mild gestational diabetes. Am J Obstet Gynecol 1990;162:1008–14.

10.  Lesser KB, Carpenter MW. Metabolic changes associated with normal pregnancy and pregnancy complicated by diabetes mellitus. Semin Perinatol 1994;18:399–406.

11.  Bonen A, Campagna PD, Gilchrist L, et al. Substrate and hormonal responses during exercise classes at selected stages of pregnancy. Can J Appl Physiol 1995;20:440–51. doi:10.1139/h95-035

12.  Weight gain during pregnancy. Committee Opinion No. 548. American College of Obstetricians and Gynecologists. Obstet Gynecol 2013;121:210-2.

13.  Butte NF, King JC. Energy requirements during pregnancy and lactation. Public Health Nutr 2005;8:1010–27.

14.  Mottola MF, Davenport MH, Ruchat S, et al. 2019 Canadian guideline for physical activity throughout pregnancy. Br J Sports Med 2018;52:1339-1346

15.  Davenport MH, Ruchat S-M, Poitras VJ, et al. Prenatal exercise for the prevention of gestational diabetes mellitus and hypertensive disorders of pregnancy: a systematic review and meta-analysis. Br J Sports Med 2018;52:1367–75.

16.  Davenport MH, McCurdy AP, Mottola MF, et al. Impact of prenatal exercise on both prenatal and postnatal anxiety and depressive symptoms: a systematic review and meta-analysis. Br J Sports Med 2018;52:1376–85.

17. Davenport MH, Sobierajski F, Mottola MF, et al. Glucose response to acute and chronic exercise during pregnancy: a systematic review and meta-analysis. Br J Sports Med 2018;52:1357–66.

18.  Davenport MH, Nagpal T, Mottola MF, et al. Prenatal exercise (including but not limited to pelvic floor muscle training) and urinary incontinence during and following pregnancy: A systematic review and meta-analysis. Br J Sports Med 2018;52:1397–404

19.  Mottola MF, Nagpal TS, Begeginski R, et al. Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review. Br J Sports Med 2018 [Epub ahead of print].

20.  Bø K, Artal R, Barakat R, et al. Exercise and pregnancy in recreational and elite athletes: 20M16/2017 evidence summary from the IOC expert group meeting, Lausanne. Part 5. Recommendations for health professionals and active women. Br J Sports Med. doi:10.1136/ bjsports-2018-099351