Return to Running for Postpartum Elite and Subelite Athletes

Abstract

Context:

There is little evidence to guide elite athletes who desire returning to competition after giving birth to a child. Ultimately, this can result in decreased performance and increased risk of injury. This paper addresses aspects that must be considered when building and monitoring a return to running program for a postpartum elite or subelite athlete, including pelvic floor and core stability, progressive reloading of the musculoskeletal system, monitoring of nutritional parameters, and considerations for lactation.

Evidence Acquisition:

PubMed and CINAHL (Cumulative Index for Nursing and Allied Health Literature) were searched with the following search strategy: (extreme sports OR elite athletes OR running OR exercise) AND (breastfeeding OR lactation OR bone density OR fetal weight OR gestational weight gain OR postpartum or post-partum OR postnatal OR post-natal OR pregnancy OR childbirth). The following information is based on best available evidence and clinical experience.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

Due to the interplay between cardiovascular fitness, postpartum nutrition, lactation, and progressive reloading of the muscular and skeletal system, we propose a multimodal, multidisciplinary approach to safely and successfully allow an athlete to return to an elite level of competition.

Conclusion:

Return to running in the postpartum period is a highly individualized process that benefits from multidisciplinary, individualized care. This includes monitoring of nutrition, core and pelvic floor function, bone reloading, muscle and tendon reloading, and breastfeeding care when applicable.

Strengh of Recommendation Taxonomy (SORT):

C.

There is limited literature documenting a successful, stepwise return to run protocol for elite and subelite postpartum athletes. Unfortunately, this lack of guidance may result in athletes returning to activity at an inappropriate rate, which could lead to decreased performance or possible injury. In addition, athletes may feel pressured to follow a timeline that does not fit their experience secondary to external pressures. Ultimately, the process of return to run is dynamic and should be guided by the athlete’s goals. Through this manuscript, our goal is to approach postpartum return to sport in an individualized manner, allowing for an athlete to return when mentally, physically, and emotionally ready. Key components of the discussion are shown in Appendix 1 (available in the online version of this article).

Current evidence supports exercise for postpartum women. The American College of Obstetricians and Gynecologists (ACOG) recommendations support women returning to exercise postpartum when medically indicated. ³ There is literature suggesting many elite athletes return to their prepartum level of competition. ⁷ One of the major unknown questions, however, is when this return should be initiated. Currently, many practitioners and protocols recommend waiting a standard 6 to 12 weeks before initiating impact activity for all patients. However, we know that for a variety of reasons many elite athletes may consider returning sooner than this. ⁴¹ A 1993 case report on an athlete with the Olympic B level standard for the marathon demonstrated successful return to rigorous training within 4 weeks of delivery. ⁵⁸ A 2021 Systematic review also indicated elite athletes may return before 6 weeks postpartum. ⁴¹ To our knowledge, there is no high-quality evidence documenting that early return to activity for elite athletes leads to higher injury rates when done correctly. This may be multifactorial, including the simple dearth of literature in this area, external pressures to return, or the level of fitness maintained during pregnancy in elite athletes, which may aid in more rapid return to previous levels of competition and fitness. ⁴⁰ However, there is also no current evidence indicating a benefit to early introduction of high-level activity. As such, return to sport requires an active discussion of the athlete’s goals, medical needs, emotional and mental readiness to return. We feel this approach is more individualized and appropriate than recommending return for all postpartum athletes based on time alone.

With the multitude of musculoskeletal and biomechanical changes a body experiences throughout pregnancy and delivery, no 2 postpartum journeys are the same. Therefore, assessing each athlete’s history, goals and readiness is the imperative first step. After this, we recommend assessments by a multidisciplinary team to determine each athlete’s status before initiating exercise prescription. These assessments are best administered by qualified professionals in pelvic health physical therapy (PT), musculoskeletal PT, nutrition and others as needed, including lactation medicine if applicable. The team can then compose an optimal, individualized return plan that meets each athlete’s readiness and physical needs. Throughout the return process, optimal nutrition is critical to preventing injury and maintaining performance. This writing group consists of fellowship trained sports medicine physicians, a pelvic floor physical therapist, a sports medicine physical therapist, an obstetrician, and a certified lactation consultant.

PubMed and CINAHL (Cumulative Index for Nursing and Allied Health Literature) were searched with the following search strategy: (extreme sports OR elite athletes OR running OR exercise) AND (breastfeeding OR lactation OR bone density OR fetal weight OR gestational weight gain OR postpartum or post partum OR postnatal OR post natal OR pregnancy OR childbirth). The following information is based on best available evidence and clinical experience.

Discussion

Definition of Postpartum Period

The postpartum period refers to the time period beginning after delivery and ending when maternal physiology reverts to its nonpregnant state, often termed the “fourth trimester.” Evidence is inconsistent in defining the end of the postpartum period. ² Some authors define the end to be 12 months after delivery, while others define the end of the postpartum period as the cessation of lactation. ⁵⁶

Cesarean Disclaimer

The following discussion and proposition for return to running postpartum relates to patients after uncomplicated, singleton, nonoperative vaginal deliveries. Cesarean deliveries change the musculoskeletal milieu and the abdominal wall integrity. Forceps delivery has been associated with pelvic floor muscle injury and subsequent complications. ⁹ As such, we recommend close discussion with the operating provider and primary care team when counseling an athlete regarding return to running. Unfortunately, insufficient literature is present to guide clinicians on return to run protocols for mothers after operative deliveries.

Timing and Implementation by the Medical Team

Healthcare providers and athletes must understand the importance of gradual introduction and progression of activity. Furthermore, the medical team must be aware of external pressures (eg, marquee competitions) that an athlete may face as they build their training program. The medical team should consider all aspects of an athlete’s athletic career and long-term health as they devise and complete a plan to return to sport. We propose a broad outline, keeping in mind the need for individualized nuance along the way.

The first step is assessment for “red flag” symptoms that warrant evaluation by the athlete’s obstetrician before further activity. These include worsening bleeding, uterine or abdominal pain, and/or increased lochia with activity. We then recommend assessment and initiation of foundational concepts including nutrition and pelvic floor/core retraining. Assessment of energy availability is key to ongoing health, recovery, and exercise goals, with consideration of lactation demands if applicable. Pelvic floor and core retraining may be initiated as early as during pregnancy and is best guided by a pelvic floor physical therapist. Together, these concepts provide a critical foundation to moving forward in cross-training and impact activity progression. Once an athlete can walk and perform activities of daily living without significant discomfort, we believe the athlete may move to additional nonimpact cross-training activities and progress as tolerated.

An athlete may undergo medical evaluation at any point during this process, but we feel it is particularly important before initiating return to impact activity and running. Our detailed prerunning screening and evaluation is shown in Online Appendix 2, Tables A1 and A2. Based on results of this prerunning evaluation, additional referrals, testing, or treatments may be indicated and recommended.

If deemed medically appropriate, the athlete then advances into a progressive return to running program, ideally guided by a physical therapist. This return program is similar to those designed for return after lower extremity and/or pelvic bony stress injury. We have an institution-specific progression adopted from Hegedus et al ³⁴ that slowly replaces cross-training workouts with running and is included in Online Appendix 3. Strength and stability training can be completed simultaneously, and pelvic floor/core retraining continues as the athlete progresses in the program. A more detailed description of each of these program components are discussed below.

A Note on Relaxin

Relaxin is a peptide hormone belonging to the insulin superfamily with 3 forms. Relaxin-2 is the form produced in the corpus luteum, decidua, and placenta, and traditionally studied in pregnancy and postpartum subjects. It has collagenolytic effects and is often implicated in postpartum musculoskeletal dysfunction. Relaxin-2 peaks around 12 weeks gestation, with gradual decrease through the second trimester. It then remains stable until delivery.^26,32,46

Relaxin correlates with increased knee valgus, ³¹ though has conflicting correlation to knee joint laxity in current literature.^25,64 Dumas et al ²⁵ demonstrated increased knee joint laxity which peaked before the fifth month of pregnancy and remained stable throughout the rest of pregnancy before steadily decreasing in the postpartum period. However, Schauberger et al ⁶⁴ demonstrated steadily increasing knee joint laxity from prepartum to peak at 2 weeks postpartum. In rodent models, progesterone and relaxin were noted to have a strong correlation, and knee joint laxity was noted to increase with both concomitantly. In nulliparous athletes, Dragoo et al ²⁴ demonstrated higher serum relaxin concentrations in college athletes who sustained anterior cruciate ligament (ACL) tears than those who were not injured. However, this study seemingly obtained serum relaxin concentrations once at the beginning of the 4-year study, and did not publish monitoring changes to menstrual pattern or hormone concentrations after this point. This leaves the serum relaxin concentration and menstrual health status unknown at the actual time of injury, and therefore difficult to interpret.

Though widely believed in clinical practice, research to date has not demonstrated a significant association between pregnancy-related increased relaxin levels and pelvic floor dysfunction (PFD).^4,33 One study by Kristiansson et al ⁴³ actually demonstrated a higher serum relaxin concentration was correlated to a lower prevalence of pregnancy-related stress urinary incontinence.

In summary, the precise relationship between relaxin and risk of musculoskeletal dysfunction and injury remains unclear.

Pelvic Floor

One area of critical importance when returning to activity postpartum is the core and pelvic floor. The pelvic floor consists of muscles and connective tissue that work with the diaphragm and deep abdominal muscles to assist in postural stability. The pelvic floor also supports pelvic structures and helps to maintain bowel and bladder control as well as sexual function. ⁶¹ PFD describes a multitude of disorders involving the pelvic floor muscles, including, but not limited to, urinary and/or fecal incontinence, pelvic heaviness or pressure, sexual dysfunction, and lumbopelvic pain. ¹⁰

Previous authors have cited pregnancy and delivery-related changes to the pelvic floor as limitations to early return to activity, particularly with impact activity. ¹² Some authors advocate for a recovery period of up to 12 weeks before return to high impact activity. However, it should be noted at this time there is little evidence supporting this specific timepoint. ²³

Currently, both the International Olympic Committee and American College of Obstetricians and Gynecologists have position statements regarding exercise and risk of PFD. The IOC states “we identified no studies on how the timing of return to strenuous exercise or competitive sport affects pelvic floor in athletes.” ⁹ Similarly, ACOG states “exercise routines may be resumed gradually after pregnancy as soon as medically safe, depending on the mode of delivery, vaginal or cesarean, and the presence or absence of medical or surgical complications.” ¹ In 2021, a systematic review indicated “very low” certainty evidence that elite athletes return to activity early, and may have an increased risk of injury. ⁴¹ Nygaard et al ⁵³ studied the relationship of early (defined as 2-3 weeks postpartum) moderate-to-vigorous activity and pelvic floor outcomes at 1 year postpartum. They concluded that with the exception of vaginal support, “early postpartum moderate to vigorous physical activity was either protective or had no effect on other parameters of pelvic floor health.” Certainly, there are multiple variables involved in every pregnancy and delivery. Therefore, we again believe assessing each athlete’s function before initiating exercise prescription is more appropriate than recommendations based on time alone.

We recommend this evaluation be completed by a certified pelvic floor physical therapist as early as during pregnancy or as soon as desired postpartum. This evaluation includes assessment of red flag symptoms as mentioned earlier, as well as degree of PFD, presence of diastasis recti, neuromuscular control, alignment, and posture. The patient will then continue working on treatment of PFD, neuromuscular retraining, and core stability in an ongoing fashion as indicated throughout their postpartum return. We believe the presence of symptoms should not disqualify an athlete from continuation through the program but should prompt activity modification and close symptom monitoring.

Muscle/Tendon Reloading

Pregnancy and delivery have a significant effect on the muscles and tendons of the mother. ²¹ Tendons are specifically affected by fluid retention secondary to weight gain and hormonal changes. ⁷³ As stated in biomechanical literature, the gait and loading patterns of the lower extremity are changed with pregnancy. ²⁹ Some of these changes last into the postpartum period, which can affect metrics like knee loading patterns. ¹⁶ Furthermore, impaired neuromuscular control and recovery of core musculature may contribute to running injury risk in the postpartum athlete. ⁷⁴ This could present as dyscoordination of core or pelvic floor muscular activation, decreased gluteal muscular activation, and poor truncal rotation among others. ⁶⁷ These may, in turn, alter gait patterns, loading and landing mechanics, and contribute to injury risk. ³⁵ However, at this time there is limited evidence to report on clinical outcomes or specific musculotendinous injury risks associated with the postpartum period. DeQuervain’s tenosynovitis of the abductor pollicis longus and extensor pollicis brevis tendon is known to increase during pregnancy and the postpartum period, which may affect carrying angle of the upper extremity while running, or cross-training activities for runners during their return program. ⁵ There is little data on lower extremity tendinopathy during pregnancy or the postpartum period, though a rapid return to repetitive activity may increase tendinopathy at any stage. One case report of Achilles tendinopathy during pregnancy has been reported. ⁷⁵

Weight changes throughout pregnancy and the postpartum period also affect musculoskeletal load and biomechanics. ²⁹ This includes changes in center of gravity, gait, and force. One such area that has been studied is the foot. ⁶⁵ Segal et al ⁶⁰ demonstrated that arch drop and midfoot pronation during pregnancy was associated with a shift in tibiofemoral articulation. This could explain increased knee pain in the postpartum period. Regarding larger knee injuries, no data on ACL tears during pregnancy or postpartum period has been reported. One case series of ACL reconstruction during the peri-partum period demonstrated no adverse ACL surgical outcomes. ³⁹

Research is lacking on an optimal strengthening and tendon reloading program for elite level runners. As such, we propose the importance of a gradual, criterion-based approach to reloading. We believe it is imperative to focus on core and lumbar stabilization initially due to strength and motor control deficits of the lumbopelvic region postpartum. ⁷⁴ This is especially true for patients with hypermobility syndromes who rely on muscular control for stability. Previous literature has cited the importance of lumbar stabilization exercises alongside running form modification when guiding athletes.^73,74 Such exercises include work with breathing dynamics, transversus abdominus, pelvic floor, and multifidi musculature. An individualized approach for stabilization exercises has been effective in treating postpartum women with pelvic girdle discomfort. ⁷⁰

Further progression should then focus on muscle strengthening, neuromuscular control, proprioception, and muscle activation to counteract the changes of pregnancy and delivery. ⁷⁴ Once the athlete is able to adequately activate and stabilize core musculature, we recommend integrating activation and strengthening exercises for the extremities. This can be achieved with bodyweight strengthening followed by progression to free weight, then single leg, and plyometric. A sample progression was described previously in triathletes by Thein-Nissenbaum. ⁷³

Cardiovascular Cross-Training

An athlete may begin progressive cardiovascular stimulus through cross-training activities after initiating a strength and stabilization program. An elite athlete must be cognizant of the effects of any detraining period on musculature and cardiovascular fitness, which will require reconditioning time. ⁹ Many nonimpact activities may be employed, including cycling, swimming, and lower-body positive pressure treadmills (LBPPT). LBPPT such as the Alter G treadmill (AlterG, Inc) have been used as an effective tool to add training volume and may reduce time to return to run after injury.^36,72 It must be mentioned, however, that running on LBPPT alone will not increase cardiovascular fitness to the same degree as running with full body weight. ⁶

Timing of cardiovascular training is highly variable. For some elite athletes participating in intense high-volume training throughout pregnancy, rapid return to competitive athletics may be feasible.^27,40 In addition, VO₂max can return to prepregnancy level or higher after delivery due to increased blood volume and improved oxygen transport. ⁸ As with all training programs, a gradual approach is recommended when implementing cross-training activities.

Bone Reloading

Returning to activity requires the adaptation of multiple systems. Bone is one such system that is under constant remodeling and subject to acute and chronic changes in load. This remodeling is the sum of osteoblastic and osteoclastic activity and allows a firm tissue to remain plastic and adaptable. Factors influencing bone remodeling are wide-ranging and include medications, hormones, nutritional status, force vectors, vitamins, and minerals.^{13,19,20,37,55,76}

Pregnancy and the postpartum period have significant influence on bone remodeling. Though there is no defined consensus on clinical outcomes, and limited available data on injury risk, there are multiple changes known to affect bone density and quality throughout this period. These include relative inactivity, calcium homeostasis shifts toward fetal development, postural changes, changes in nutritional intake particularly in the first trimester, increased weightbearing, vitamin D deficiency, increased PTHrP, and lactation, among others.^42,63 During pregnancy, 2% to 3% of maternal calcium is released to the fetus, and despite several counterregulatory processes, there has been shown to be a decrease in measured bone mineral density immediately postpartum.^42,54,56 There have been cases of pubic rami, sacral, and vertebral injuries reported in postpartum athletes and nonathletes.^49,59,77 A recent systematic review on vertebral fractures noted a total of 173 cases of vertebral fracture between January 1, 1990 and December 1, 2020, more commonly among older, thinner women in their first pregnancy. However, this is the extent of the current evidence on bone injury risk for pregnant and postpartum patients. ⁵⁹

During lactation, 300 to 400 mg of calcium is transferred per day to a singleton infant through breastmilk. ⁴² In addition, lactation-associated amenorrhea results in low-estrogenic states and increases bone resorption during this time. ⁴⁷ There is again no consensus on the clinical significance of these changes, and lactation-associated decreases in bone mineral density have been shown to be recoverable.^62,63 Altogether pregnancy and postpartum are potentially vulnerable periods that need to be considered during any bone loading program.

When running in the postpartum period, it is important to balance the benefits of mechanical stress on the bone with athlete’s hormonal and nutritional state. ¹³ When all other factors are optimized, training load must be introduced in a gradual and progressive manner to allow for proper adaptation. This can be achieved successfully through a stepwise program monitoring acute and chronic load. To start, the athlete is ideally pain-free with walking and can demonstrate ability to walk, jump, and perform plyometrics without increasing vaginal heaviness, pressure, or incontinence. The symptomatic patient should return for pelvic health reassessment with modification of ongoing load progression as necessary. Key components of determining readiness to run are shown in Table A2 (Online Appendix 2).

Our institution then utilizes a formalized running progression adopted from Hegedus et al ³⁴ that slowly replaces cross-training workouts with running. The program is divided into 6 phases and takes into consideration internal and external workload while allowing the athlete to incorporate high-intensity interval training, tempo training, and recovery sessions into the typical training week. Specific details can be found in Online Appendix 3.

Nutritional Considerations

A key component to any training program is sound nutrition. This holds true for postpartum women and especially breastfeeding women. Previous research with female athlete triad and Relative Energy Deficiency in Sport (REDS) has offered guidance on nutritional needs for female athletes.^17,18,50,51 The goal of these recommendations is maintenance of optimal health and function, including reproductive and bone health. Low energy availability during the postpartum period places an athlete at increased risk of further compromised bone health, PFD, and cardiovascular endothelial dysfunction among others.^14,17,78

To estimate energy needs, energy availability is calculated as the difference between energy intake and energy output. Historically, a threshold of 45 kcal/kg fat free mass per day energy availability was used, above which patients maintain optimal physiologic function. ³⁸ However, more recently this is thought to be more individualized, with that specific threshold studied only in sedentary persons. ⁵⁰ Physically active mothers should be aware of their energy balance and consume enough calories to cover their expended calories on a daily basis. Working with a dietitian during this time of significant change may be beneficial.

Lactating athletes have an additional set of daily requirements. Breastmilk production requires calorie expenditure and, as mentioned previously, is known to extract calcium from the maternal system. Lactating athletes are estimated to require an additional 300 to 500 kcal per day for singleton infants. With risk of breastfeeding-associated transient osteopenia, it is of utmost importance for athletes to optimize all other bone health factors, including adequate calorie, calcium, and vitamin D intake, and appropriate bone loading patterns.^44,57,68

Hydration is another key component to any training. Breastfeeding requires additional hydration; however, this is highly individualized, and no specific amount is recommended. Drinking to satisfy thirst is sufficient for most mothers and athletes.

Calcium requirements change throughout adolescence and into early adulthood, reflecting time of peak bone mass accrual. Calcium intake has also been associated with risk of bone stress injuries, ⁵² and therefore should be a nutrient of focus for pregnant and postpartum patients. As discussed previously, bone mineral density changes during this time have not been shown to be associated with specific risk outcomes and have been shown to be transient. In addition, there is evidence that bone loss during lactation is not reduced by increased calcium intake.^44,57,69 Therefore, at this time there are no additional calcium intake requirements for pregnant or breastfeeding women. However, given potential variability in daily intake, proper attention should be paid to meeting daily requirements of 1300 mg per day for adolescents, and 1000 mg per day in mothers aged ≥19 years. This may be accomplished through dietary intake (ie, ~3 servings of dairy for adults and ~4 servings per day for adolescents), supplementation, or combination of both.

To summarize, all lactating athletes should have calorie intake of

• Adequate energy availability (including 300-500 kcal for lactation)

• 1000 mg calcium per day in patients ≥19 years ⁴⁸

• 1300 mg calcium per day in patients 14 to 18 years ⁴⁸

• Vitamin D as directed by serum 25-OH Vitamin D levels (goal >50 mg/mL)

• Hydration to thirst

Postpartum weight loss may be a goal of some parents, including athletes. While maintaining healthy intake as discussed above, this can be achieved if medically guided and for an appropriate goal. ²² Not all increases or decreases in caloric intake result in weight changes. Weight changes may also be related to noncaloric factors such as fluid shifts. In general, weight loss should be gradual and with constant attention to nutritional, vitamin, and mineral needs of mother and infant.

Other Considerations for Lactation

Breastfeeding is recommended worldwide by the World Health Organization (WHO) and American Academy of Pediatrics (AAP) for up to 2 years or beyond due to evidence of multiple benefits for both mother and baby. There is little evidence guiding elite-level athletes in successful breastfeeding during return to sport postpartum. Previous studies have highlighted common challenges elite athletes face in breastfeeding successfully during return to sport and throughout high-level training. One such challenge is lack of relevant, reliable breastfeeding resources for these athletes. ³⁰ Breastfeeding while training can add complexity in an athlete’s day but, with proper guidance, can be achieved successfully if this is the goal of the athlete.^28,71

One of athletes’ most common concerns is maintaining adequate breastmilk supply.^22,28,71 If consistent pumping/nursing schedules, hydration, and nutrition are maintained, there is little to no effect of activity on breastmilk production. ¹⁵ Some athletes may even experience an increase in supply during training. ⁴⁵ One key is meeting all the athlete’s caloric, nutrient, and hydration needs to cover both milk production and training expenditure. The second is maintaining the supply-and-demand system of milk production. The number of times each athlete needs to empty their breasts to maintain adequate milk supply varies by person; however, most need to maintain approximately 8 sessions per 24-hour day in the early weeks-to-months postpartum. Working with a lactation consultant can help determine each person’s storage capacity and therefore specific pumping/nursing requirements to maintain supply. Wearing constricting clothing such as sports bras for prolonged periods may also decrease supply, so it is optimal to remove these as soon after exercise as feasible. Many women also wonder about the logistics of feeding or pumping breastmilk while training. Practical tips for breastfeeding are shown in Table A3 (Online Appendix 2). Further details regarding successful breastfeeding during training is beyond the scope of this paper.

Limitations

There are several limitations to our manuscript. In general, return to sport is a highly individualized process. Recommendations from this guideline are limited to uncomplicated, nonoperative singleton vaginal deliveries. Therefore, the recommendations may not be generalizable to all postpartum female athletes attempting return to sport. Further, the recommendations outlined in this article specifically target athletes in the elite and subelite population and may not be fully generalizable to the sedentary person. Currently, there are limited tools to evaluate and monitor the athlete’s progress objectively, making the clinical decision-making process difficult. Therefore, we recommend longitudinal follow-up when feasible. Guidance for return to physical activity and sport for operative deliveries should be directed toward the athlete’s primary provider, obstetrician, and sports medicine team.^11,66

Conclusion

Ultimately, there is limited literature documenting guidance for return to subelite and elite level sport postpartum. Athletes may face significant pressures not only to perform but to return to their previous level of athletic competition. We recommend each athlete work with their medical team to specifically address each facet of return to physical activity including pelvic floor and core health, tendon loading, cardiovascular retraining, bone reloading, nutrition, and breastfeeding.