Caring for and Counseling the Peripartum Runner

Introduction

Evidence suggests as little as 15 minutes a day of aerobic exercise improves health outcomes and helps prevent and manage common chronic conditions such as hypertension, diabetes, and obesity. Running has only recently been studied in risk factor reduction for these health outcomes, and like general physical activity, relatively low doses (5–10 minutes) of lower intensity speeds (<6 mi/hour) have similar health and longevity benefits as the aforementioned low doses of physical activity. Running is a popular physical activity for both men and women, thus women may seek healthcare provider advice regarding the continuation of running throughout their pregnancies and for advice on return to running after delivery. Many women choose to continue running because it is part of their physical activity routine prior to conception and for their physical and mental health benefits. It is important for the sports medicine clinician to be aware of the evidence-based recommendations for counseling the peripartum runner, medical contraindications for exercise, and the diagnosis and evaluation of common MSK conditions unique to this population.

Recommendations for physical activity levels during pregnancy have drastically changed within one generation of women. Thirty years ago, low-intensity cardiovascular activity such as walking constituted the majority of physical activity habits considered safe for pregnant women. Historically, it was believed that maternal physical activity may negatively influence fetal development and therefore prescribing exercise during pregnancy was uncommon practice. Bed rest was previously prescribed even for management of edema and hypertension, conditions now widely understood to benefit from appropriate physical activity. Historically a maximum heart rate threshold of 140 beats per minute was recommended and then retracted in 1994 by the American College of Obstetricians and Gynecologists (ACOG). Evidence suggests many healthcare providers still recommend this now obsolete heart rate threshold, and as a result, many expectant women are afraid to exceed low to moderate intensity of exercise. To compound this problem, much of the exercise and pregnancy literature does not clearly define “moderate” or “vigorous” intensity exercise.

It was not until 2002 that ACOG exercise and pregnancy guidelines were revised to include that physical activity should be recommended for pregnant women because of the proven benefits for both maternal and fetal health outcomes. These recommendations were also extended to sedentary women. Furthermore, regular exercise is a protective factor against the deleterious effects of gestational diabetes on both maternal and fetal health.

Concerns for increased risk of preterm delivery associated with exercise during pregnancy still persist among patients, as well as providers, despite evidence to the contrary. Such perceptions have largely been associated with cultural and societal beliefs. Such beliefs align with the previously conservative guidelines that have been recently updated ; however, evidence suggests that providers who lack exercise prescription knowledge are also more likely to be conservative in their recommendations for exercise during pregnancy, and sometime tend not to recommend it at all.

Metaanalyses investigating exercise and pregnancy reveal no detriment to the developing fetus as a result of the mother's physical activity throughout gestation. On the contrary, numerous studies have demonstrated the deleterious effects of obesity and sedentary lifestyles on both maternal and fetal health outcomes.

To that end, many of these same studies suggest pregnancy is an ideal time to adopt positive lifestyle changes such as better weight management, improving dietary habits, and smoking cessation. Unlike during other stages of their lives, many women worldwide only receive regular, frequent medical care during pregnancy. A physical activity program consisting of both aerobic and resistance training during pregnancy can help to avoid excessive weight gain during pregnancy (also known as gestational obesity).

It is well documented in the literature that maternal gestational obesity is associated with increased risk of preeclampsia, gestational diabetes, increased musculoskeletal (MSK) pain, increased fatigue and slow labor progression, and maternal mortality. Gestational obesity has also been associated with increased risk of infection and difficulty breastfeeding as well as miscarriage and neonatal death. Despite such clear evidence suggesting weight management is an important factor in determining positive maternal and fetal health outcomes, research suggests providers are not encouraging previously sedentary and/or obese patients to increase physical activity. The relationship between gestational weight gain and fetal growth, birth weight, and long-term health of the fetus is well documented throughout the literature, and larger birth weight has been associated with greater risk for development of chronic diseases such as Type II diabetes and cardiovascular diseases in adulthood.

Maternal/Fetal Benefits of Physical Activity

There is insufficient evidence to suggest that continuing or even starting a low to moderate aerobic intensity physical activity such as running during a healthy, uncomplicated pregnancy is harmful to the mother or the fetus. ACOG recommends that running is safe for women during pregnancy who were regular runners before pregnancy. For women who would like to start running, but who did not run prior to pregnancy, it still is a safe exercise with an appropriately graded progression. The “talk test” for rate of perceived exertion can be helpful for pregnant women to scale their exercise intensity. As long as she can carry on a conversation, “talk but not sing,” during the exercise, she is likely exercising in the moderate-intensity aerobic zone.

Most literature on the maternal/fetal benefits of exercise is not specific to running but on exercise in general. There is emerging evidence to suggest exercise during pregnancy has benefits for maternal and fetal health outcomes. For instance, mouse model studies have demonstrated maternal exercise benefits including improved memory and cognition in offspring into their adulthood. Evidence also suggests maternal physical activity levels may positively influence physical activity levels of offspring. In a separate study, women were randomized to exercise 20 minutes, 3×/week at rating of perceived exertion (RPE) 6/10, or to remain sedentary starting in the second trimester. Within 12 days of birth, researchers determined that babies whose mothers had exercised had “more mature” brainwave processing response to audio sounds than babies whose moms did not exercise.

Contrary to folklore, exercise during pregnancy is not believed to have a negative influence on birth weight or rates of preterm delivery. Exercise during pregnancy has not been shown to negatively influence labor duration ( Fig. 22.1 ). Thus far, what little research has been conducted on expectant women suggests such exercise habits are in fact healthful, not harmful, and both mother and baby experience benefits as a result of the mother's physical activity levels.

Physiological, Endocrine, and Biomechanical Changes During Pregnancy

Safe participation in running while pregnant includes consideration of several key physiological changes that occur during gestation. First, joint laxity, as a result of elevated relaxin hormone levels, peaks after the first trimester and subsequently plateaus by the second trimester. Center of gravity is altered due to increased lumbar lordosis and anterior pelvic tilt as the pregnancy progresses ; thus activities such as snow skiing, cycling, and certain yoga poses should be practiced with caution as balance becomes progressively more challenging. Also, positional and postural changes alter blood flow to the developing fetus. Therefore, it is recommended that after the first trimester, prolonged supine exercises be avoided in order to maximize fetal blood flow ( Fig. 22.2 ).

Of the limited studies analyzing gait during pregnancy, it is suggested that maternal weight gain plays the most significant role in determining MSK adaptations. Wider step width is one gait adaptation which increases energy costs. Other gait cycle changes associated with pregnancy include a reduced stride length, a reduction in single limb support time, and increased ground contact time. Other biomechanical changes during pregnancy which can affect gait include varying degrees of anterior pelvic tilt which accentuates the increased lumbar lordosis as pregnancy progresses. Evidence suggests that these biomechanical adaptations create a cascade of related changes in neuromuscular firing patterns, including increased activation of hip extensors and abductors with a concomitant decrease in knee extensor activation; all of which may lead to increased stress on the MSK system and increase energy costs.