Joanna Hess PT, DPT, PRC, WCS
Exercise in ever tightening spandex while making frequent public toilet stops, or binge on Netflix and cronuts? Pregnancy is a great equalizer. Not even Kate Middleton can escape the hormones that can cause pregnant women to suffer from mood swings, fatigue, nausea, and achiness. Those symptoms—and modern culture—frequently encourage pregnant women to decrease movement and everyday activities. However, there is resounding support in academic literature that recreational physical activity during pregnancy is beneficial to both mother and baby.
While the pregnant woman is best suited to monitor what is beneficial for her body and baby during pregnancy, adequate information to make that decision is not always readily available. Yet around 600 studies published between the mid-1980s and mid-1990s corroborate that exercise during pregnancy is not harmful by measure of fetal birth weight, mode of delivery, preterm delivery, Apgar scores, and acute fetal well-being (1-3). What’s more, the American College of Obstetricians and Gynecologists (4) removed the limitations for intense exercises back in 1985 (5) and a literature review showed that bed rest was not beneficial for pregnancy complications. Still, 95% of ob-gyns continue to prescribe activity restrictions to certain pregnant mothers (6).
Clearer guidelines are needed for how pregnant women can decrease injury while maintaining performance and the well-being of mother and baby. While running is only one mode of boosting fetal and maternal health, many women, especially here in New York, embrace it as a key part of their overall wellness. As a recreational runner myself, I was disappointed during my first pregnancy with the foggy information regarding how to run safely during pregnancy. I found myself as a self-case study, correlating the physiological and biomechanical pregnancy changes with a shift in running mechanics. At the third trimester, I had a suspicion that I should replace running with the elliptical and restorative yoga.
The scientific literature specific to running during pregnancy is extremely limited, and in its absence, I’ve used findings for “moderate to strenuous” physical activity, in addition to clinical knowledge of pregnancy related changes in the body and running patterns to develop the recommendations below. Recently, a group of researchers published a series of five papers and combined recent literature about higher level physical activity during pregnancy for application in appropriate populations (7-8).
Pregnancy and exercise:
Pregnancy may seem like a counter-intuitive time to start an exercise program. However, research shows that 150 minutes/week of moderate exercise (9) for inactive and relatively sedentary women, and moderate to strenuous exercise for active women, has strong health benefits for both fetus and mother. Moderate exercise is recognized as 5-6 on the Rate of Perceived Exertion (RPE), 40-59% HRR (Heart Rate Reserve = Heart rate max – Heart rate resting). Moderate to strenuous is described as 7-8 RPE, 60-84% HRR (1). So while growing a baby is not a good time to start a running program, it is a good time to increase an appropriate level of physical activity or continue an established running program. Some of the benefits of appropriately prescribed exercise are correlated to (10-16):
· Improved cardiovascular function
· Lower risk for gestational diabetes
· Improved strength and lean muscle mass
· Improved sense of wellbeing
· Improved sleep
· Decreased bone density loss
· Decreased physical discomfort – low back pain, pelvic girdle pain
· Healthier gestational weight gain, which protects against complications like cesarean delivery, hypertension, preeclampsia, and gestational diabetes
· Improved general healthy behaviors
· Improved psychological wellbeing – reduction in depression and anxiety, improved self-esteem, particularly for women who were previously inactive
· Improved ability of the placenta to deliver oxygen
· Increased amniotic fluid
· Healthier fetal birth weights that correlate to changes in leptin levels that continue to correlate with a healthier body fat and muscle ratio at the age of 5
· Increased gestational age
· Decreased rate of pregnancy complications, although one study showed higher use of physician assisted delivery (10)
· Faster delivery and decreased chance of Cesarean delivery in a setting that supports natural birth (11)
· Higher Apgar scores
· Lower fetal heart rate and increased fetal heart-rate variability
· Improved neonatal orientation
· Higher general intelligence and oral language skills at the age of 5
· Improved ability of baby to self-soothe after birth, (i.e. longer stretches of night sleep)
Strenuous activity is correlated to a higher rate of miscarriage during the implantation phase of pregnancy—about 20-23 days after the last menstrual cycle. Elevated body core temperature (above 103 degrees Fahrenheit), which can be caused by strenuous activities like marathon running or exercising in hot and humid weather, can increase the risk of fetal neural tube abnormalities during its development, 35-42 days after last menstrual period. Exercising for 60 minutes in a comfortable environment will not raise core temperature above 100 degrees Fahrenheit.
The pregnant woman’s heart rate should not exceed 90% of her maximal heart rate. Because of physiological changes, the pregnant runner will underestimate her heart rate based on the typical rate of perceived exertion or talk test. For this reason, the pregnant runner should modify the run intensity knowing that her heart is working harder than she perceives or wear a heart rate monitor using the HRmax = 220-age, unless she has access to laboratory equipment that can calculate HRmax without full exhaustion.
The American College of Obstetrics and Gynecology, (ACOG) has set absolute and relative contraindications to aerobic exercise during pregnancy (4).
· Hemodynamically significant heart disease
· Restrictive lung disease
· Incompetent cervix or cerclage
· Multiple gestation at risk of premature labor
· Persistent second or third trimester bleeding
· Placenta previa after 26 weeks of gestation
· Premature labor during the current pregnancy
· Ruptured membranes
· Preeclampsia or pregnancy-induced hypertension
· Severe anemia (different than mild anemia)
· Unevaluated maternal cardiac arrhythmia
· Chronic bronchitis
· Poorly controlled type 1 diabetes
· Extreme morbid obesity
· Extreme underweight (BMI <12)
· History of extremely sedentary lifestyle
· Intrauterine growth restriction in current pregnancy
· Poorly controlled hypertension
· Orthopedic limitations
· Poorly controlled seizure disorder
· Poorly controlled hyperthyroidism
· Heavy smoker
Low back and pelvic girdle pain/instability, knee/hip pain, pelvic heaviness, sharp pains in the pelvic floor, urinary leakage, and regular ankle sprains are all signs that it may be time to modify running as exercise. In the clinic, I am often asked about pelvic floor symptoms, particularly urinary leakage during pregnancy, and specifically with running.
I like to think of these warning signs as a force transfer problem—something in the system is not working well. For stress incontinence and pelvic heaviness, it’s the inability of the pelvic floor to generate enough force to keep things up against the up-chain forces of running (2.5x while accepting weight after the flight phase) and down-chain forces of steadily increasing body weight + baby’s weight (around 20% of pre-pregnancy weight). But post-partum is not as simple as the forces that are generated from running or the ability to do a Kegel. Elite athletes and non-exercisers have about the same rate of post-partum incontinence. However, postpartum symptoms are more likely if exercise also caused urinary leakage during pregnancy (16).
The pregnant body is a little more complicated:
It needs to taken into account, that the 10-fold increase of relaxin and progesterone that might be responsible for more instability as forces from the ground traveling up into the falling arches of the feet, adduction of the knee, internal rotation of the hip, through the pelvic floor and gapping of the sacroiliac joint. As the fetus and breasts grow, the body’s center of gravity shifts forward, the ribs flare, and the pelvis tilts forward. While the gluteus maximus and calf muscles are getting stronger to propel the pregnant body forward, the front of the body gains significantly more mass. When this happens, the front of the diaphragm and the front of the pelvic floor are positioned so more forces are going through the front of the pelvic floor than the back. This requires more support of the bladder through the pelvic floor. As the pelvis widens, foot step width increases in walking (17), but decreases in running during the single stance phase, requiring more pelvic control. In other words, the pregnant runner’s leg strength, particularly the hip stabilizing muscles, gluteus medius and minimus, need to be exponentially stronger than in the non-pregnant runner to account for additional weight, forward weight shift, and ligamentous laxity. I primarily talk about the deficit of the gluteus group because of what I see clinically, but depending on when the woman is experiencing pain or pelvic floor instability symptoms, other muscles may also need attention.
The usual period of pain experienced by pregnant runner’s initial strike to single stance, corresponds with the biomechanical gapping of the sacroiliac joint. Alleviating such issues will require force absorption and muscle activation through the quadriceps, medial hamstrings, calf muscles, tibialis anterior, TFL, adductor magnus, iliopsoas, and gluteus medius/minimus. Symptoms of lower extremity and lumbopelvic pain, pelvic heaviness, or sharp pains in the pelvic floor have similar biomechanical and physiological causes as urinary leakage. They should be treated in a similar manner whether controlling the upward and downward loads by:
· decreasing speed of running – correlated to double flight phase, which increases upward pressures
· decreasing vertical displacement
· landing with a midfoot strike to increase shock absorption (18)
· increasing arm swing/thoracic movement – dispersing upward forces and facilitating the respiratory and pelvic floor piston
· decreasing daily physical exertion that causes increased abdominal pressure
· increasing external support with (sacroiliac joint) SIJ belts or foot orthotics – decreasing the body’s instability
· improving dynamic single leg pelvic stability – star excursion
· maintaining hip flexor mobility – controlling forward pelvic tilt, movement throughout the day out of sitting posture, hip flexor stretches, shifting weight back through heels, diaphragmatic vs. back breathing
An orthopedic physical therapist specializing in pelvic floor dysfunction and in prenatal and postpartum care will be able to give more specific recommendations, since each woman’s symptoms are a little different.
Expected running changes in pregnancy:
For previous recreational to elite runners, about 70% will continue to run at some point in the pregnancy with only 1/3 continuing into the third trimester. They usually cut the running volume and intensity by 50% compared to non-pregnancy training. For those who stopped running during pregnancy, over half elected to do so because of self-monitoring symptoms of wellness, about one quarter stopped due to physician’s advice, and the remainder stopped for fear of a miscarriage. Whether choosing to continue or stop running during pregnancy, most women had returned to running by 2 months postpartum, and without negative impact on breastfeeding (19).
Speed will decline as instability increases, so that the body has less time with both feet off the ground. Ankle sprains may happen intermittently because of changes in foot position, possible increased swelling, and laxity in the ankle ligaments. Resting heart rate increases 15-20%. Breathing might be more labored during running because of increased sensitivity to carbon dioxide (particularly in early pregnancy) and decreased lung capacity/rib excursion (in late pregnancy). Pregnancy-related mild anemia, which decreases available blood oxygen, affects more than 40% of pregnant women and may show up as accelerated fatigue and increased respiratory rate during running. Be sure that fatigue is not related to severe anemia or hypothyroidism, particularly in persistent symptoms. The pregnant body will improve its ability to thermoregulate with increased sweating to dissipate more heat.
Clothes won’t fit like they once did, especially the spandex. Find some appropriately fitting, breathable, loose exercise clothing that does not excessively compress around the stomach. Urinary urgency and frequency are common limitations in running as the pregnancy progresses, which requires some planning and increased water intake.
Running during pregnancy presents an opportunity to do something overwhelmingly beneficial for both mother and baby, with the added incentive of tuning into the body’s remarkable capacities. While physical activity, running or otherwise, will look different during pregnancy, the goals are similar for a healthy lifestyle. Be kind to yourself—body, mind, and spirit. You and your baby will be thankful. Happy trails. Please leave any comments or questions here!
Joanna is currently taking new patients at our downtown office.
Phone: (212)- 267- 0240
1. Szymanski LM, Satin AJ. Exercise during pregnancy: fetal responses to current public health guidelines. Obstetrics and gynecology. 2012 Mar;119(3):603.
2. Physical Activity Guidelines Advisory Committee. Physical Guidelines Advisory Committee Report, 2008. Wasington, DC: U.S. Department of Health and Human Services: 2008.
3. Barakat R, Stirling JR, Lucia A. Does exercise training during pregnancy affect gestational age? A randomised controlled trial. British Journal of Sports Medicine. 2008 Aug 1;42(8):674-8.
4. American College of Obstetricians and Gynecologists. Physical activity and exercise during pregnancy and the postpartum period. Committee Opinion No. 650. Obstet Gynecol. 2015;126(6):e135-142.
5. Artal R, O’toole M. Guidelines of the American College of Obstetricians and Gynecologists for exercise during pregnancy and the postpartum period. British journal of sports medicine. 2003 Feb 1;37(1):6-12.
6. Bigelow C, Stone J. Bed rest in pregnancy. Mount Sinai Journal of Medicine: A Journal of Translational and Personalized Medicine. 2011 Mar 1;78(2):291-302.
7. Bø K, Artal R, Barakat R, Brown W, Davies GA, Dooley M, Evenson KR, Haakstad LA, Henriksson-Larsen K, Kayser B, Kinnunen TI. Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 1—exercise in women planning pregnancy and those who are pregnant. Br J Sports Med. 2016 May 1;50(10):571-89.
8. Bø K, Artal R, Barakat R, Brown W, Dooley M, Evenson KR, Haakstad LA, Larsen K, Kayser B, Kinnunen TI, Mottola MF. Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 2—the effect of exercise on the fetus, labour and birth. Br J Sports Med. 2016 Sep 22:bjsports-2016.
9. US Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. Department of Health and Human Services. Washington, DC: 2008.
10. Kuhrt K, Harmon M, Hezelgrave NL, Seed PT, Shennan AH. Is recreational running associated with earlier delivery and lower birth weight in women who continue to run during pregnancy? An international retrospective cohort study of running habits of 1293 female runners during pregnancy. BMJ open sport & exercise medicine. 2018 Mar 1;4(1):e000296.
11. Erdelyi GJ. Gynecology survey of female atheletes. J Sports Med Phys Fitness. 1962;2:174-179.
12. Prather H, Spitznagle T, Hunt D. Benefits of exercise during pregnancy. PM&R. 2012 Nov 1;4(11):845-50.[Ine
13. Hoeg TB. Baby on Board: Long Distance Running During Pregnancy – iRunFar.com [Internet]. iRunFar.com. 2017 [cited 2018May7]. Available from: https://www.irunfar.com/2017/12/baby-on-board-long-distance-running-during-pregnancy.html
14. Clapp JH, Capeless E. The VO2max of recreational atheletes before and after pregnancy. Med Sci Sports Exerci. 1991;23:1128-33
15. Gjestland K, Bø K, Owe KM, Eberhard-Gran M. Do pregnant women follow exercise guidelines? Prevalence data among 3482 women, and prediction of low-back pain, pelvic girdle pain and depression. Br J Sports Med. 2012 Aug 1:bjsports-2012.
16. Bø K, Sundgot‐Borgen J. Are former female elite athletes more likely to experience urinary incontinence later in life than non‐athletes?. Scandinavian journal of medicine & science in sports. 2010 Feb 1;20(1):100-4.
17. Gilleard WL. Trunk motion and gait characteristics of pregnant women when walking: report of a longitudinal study with a control group. BMC pregnancy and childbirth. 2013 Dec;13(1):71.
18. Nicola TL, Jewison DJ. The anatomy and biomechanics of running. Clinics in sports medicine. 2012 Apr 1;31(2):187-201.
19. Tenforde AS, Toth KE, Langen E, Fredericson M, Sainani KL. Running habits of competitive runners during pregnancy and breastfeeding. Sports health. 2015 Mar;7(2):172-6.