BRINGING SCIENCE TO TREATMENT

Avoiding the pregnant pause in exercise and training

Although exercise is strongly encouraged throughout a normal pregnancy, high intensity training may pose risk to both mother and baby. With this in mind, Tracy Ward examines the current guidelines, and provides exercise suggestions for pregnant athletes seeking a rapid return to sport.

Current guidelines on exercise strongly support continued physical activity throughout pregnancy. However, there remains apprehension regarding potential adverse affects on mother and baby. This arises principally due to a lack of knowledge, incorrect adherence to guidelines, or as a result of various risk factors associated with some pregnancies.

In particular, there remains some confusion on which activities are safe, which can be completed during each trimester, and at which intensity level. Most studies and recommendations are also made for normal, healthy women without risk factors. They are NOT formulated around the needs of the fitness enthusiast/athlete, who often exceeds these recommendations and may require stricter education and/or monitoring to ensure both mother and baby remain in optimal health.

There are a multitude of factors to consider when advising on exercise in pregnancy. These include physiological changes, the baseline musculoskeletal conditions, and the psychological impact of these on the mother. Pregnancy is not a static event, but rather an ever changing process through which the mother experiences both physical and emotional changes as she progresses through the trimesters.

Overview of the changes during pregnancy

Pregnancy initiates numerous physiological, musculoskeletal, and psychological changes that onset almost immediately and continue to develop through the trimesters.

*Physiological changes

The cardiovascular system adapts to pregnancy, with an increased resting heart rate of 15-20 beats per minute, a stroke volume increase of 10%, and blood volume increase of up to 50%(1). As the fetus develops, the diaphragm rises upwards, and reduces the total lung capacity by 5%, as well as the residual volume by 20%(2). This can create arterial oxygen tension, meaning decreased oxygen uptake. To the athlete, it may feel a bit like training at high altitude. Symptoms may include shortness of breath or dizziness during usual training activities.

In the first trimester, a rise in maternal body temperature of more than 39 degrees Celsius can affect fetal neural tube development. Research shows that exercise at 60-70% of VO2max for up to 60 minutes, does not raise the core temperature more than 38 degrees Celsius(3). Thermoregulation gradually improves following the first trimester, and the risks are then reduced.

*Musculoskeletal changes

As the body shape adapts through pregnancy, the pelvis tilts anteriorly, giving an increased lumbar lordosis (lower back curve). This often overloads the groin muscles and weakens the gluteals posteriorly. These adaptations – in conjunction with the expanding bump – stretch and weaken the abdominal muscles. Collectively these adaptations place strain on the spine and pelvis.

Lower back pain and pelvic girdle pain are the two common musculoskeletal complaints arising in pregnancy. Pelvic girdle pain is described as pain surrounding the pelvis anywhere from the front to the back and to the buttock crease(4). Lower back pain affects approximately 50% of the general female population while around 20-45% complain of pelvic girdle pain(5). These figures are somewhat lower in female athletes at around 18% and 30% respectively(6)– most likely due to higher levels of strength and stability pre-conception. Furthermore, pelvic girdle pain risks are reportedly 14% lower in women who are used to high impact exercise 3-5 times per week, again suggesting their bodies can cope with the added strains(7). These findings positively suggest continued exercise for the pregnant athlete.

*Mental health

Anxiety and depression rates are often higher among pregnant women, which may be due to fears of giving birth, health of their child, and the future impact on their lifestyle and livelihood. These rates appear higher within the first and second trimesters with approximately one quarter of women suffering high anxiety levels(8). These emotions may be heightened in the athletic population as they consider the consequences of gestational weight gain, reduced fitness, and how training abilities can affect their careers. Mental health concerns during pregnancy can also lead to postnatal depression.

A recent study evaluated the mental health outcomes of exercising throughout pregnancy and found that those who did exercise regularly had significantly lower rates of depression at the end of the third trimester, and at six weeks postpartum(9) Given exercise appears to promote positive mental health during these stages, it can be argued that continued exercise may help prevent future postnatal depression (although further research is required). Exercise could also minimise the use of pharmaceutical intervention for depression and anxiety.

Recommendations for pregnant athletes

*Physiological

To monitor the cardiovascular status, pregnant athletes should measure their heart rate directly during exercise and ensure values stay within their safety zone. Although these should be calculated individually, guidelines suggest heart rate values within 145-160 beats per minute (bpm) for women aged 20-29 years, and 140-156bpm for those aged 30-39years(10). Scales to report perceived exertion like the Borg scale are not reliable in pregnancy and actual vitals signs should be measured. A subjective report of how the athlete feels may be influenced by the pressure to train and maintain fitness.

Monitor respiration to ensure that breathing remains within comfortable levels – ie the athlete can control their oxygen intake adequately. Exercising above 90% VO2max should be avoided during pregnancy(10). To measure this intensity correctly, 90% values can be predicted based on sub-maximal VO2max testing and extrapolating upwards using heart rate values obtained at lower intensities.

To combat undesirable thermoregulation issues, athletes should avoid extreme exercise in the first trimester that may raise their core temperature above 39 degrees C, including endurance or marathon running, or exercising in humid environments. Careful monitoring of raised temperature during exercise should prevent any risks.


 

Figure 1: Diagram detailing the 4 muscle groups that make up the ‘core’ (11)


Musculoskeletal

Addressing the plethora of musculoskeletal complaints will almost always begin with addressing the pelvic floor and core muscles (see figure 1).

  • Pelvic floor muscle activation– Current guidelines state pelvic floor muscle exercises should begin from as early as 10 weeks antenatally and should be completed at least four times per day(12). Activation is achieved by lifting the pelvic floor muscles from the back passage to the front and upwards, and holding for 10 repetitions of 10 seconds, as well as doing fast contractions for 10 repetitions.
  • Core muscle activation– Core muscle activation is the gentle contraction (20-30% inward contraction) of the lower abdominal muscles, found approximately two inches in from the anterior hip bones and an inch down. Activation should be held for 10 repetitions of 10 seconds. This should be introduced in a crook lying position, and progressed to different positions such as sitting, standing, 4-point kneeling and prone.

Once the pelvic floor and core muscles are correctly functioning, exercises can be included that will maintain strength and fitness (following the correct guidelines), and also exercises to target problems such as poor posture, low back pain, or pelvic girdle pain. Correcting the postural abnormalities may also alleviate low back pain. See table 1 below for a summary of exercises specific to each condition, and links to videos demonstrating how to complete them. All exercises advised here, as well as any weight training should commence following pelvic floor and core engagement.

Strength training guidelines

For those used to weight lifting prior to pregnancy, it is acceptable to continue lifting light to moderate weights provided there are no complications. Evidence actually suggests that continued exercise has a positive effect on the fetus as it learns to regulate its heart rate in response to stress, and newborn stress following birth is reduced in those women who exercise at 50% their pre-conception levels(13).

An athlete who wishes to perform heavy lifts must consider several factors. Firstly the excess load can pressurise the pelvic floor and lead to pelvic floor dysfunction and prolapse. Secondly, risks to the baby may occur during the valsalva manoeuvre, where blood pressure is elevated during straining. This causes increased intra-abdominal pressure, therefore causing a transient reduction in blood flow to the baby. This can also occur with vena cava compression in the supine position, therefore exercising this way should be avoided after the first trimester. Strenuous activity should be modified to avoid the valsalva manoeuvre.

Miscarriage in the first 13 weeks has been associated with heavy lifting of greater than 1000kg/day and a frequency of more than 10 lifts per day. Late miscarriage has been linked to a total weight lifted per day of more than 200kg, but there seems to be no association with the number of lifts(14). Athletes should limit the number of lifts within the first trimester and consider reducing the load in the second and third trimesters.


Table 1: A summary of exercises to address common musculoskeletal complaints during pregnancy

PostureLow back painPelvic girdle pain
Dumb waiterWall pelvic tiltsIsometric Clam
CleopatraCat/cowSwimming in four point kneeling
Pelvic tiltsButtock squeezesSquats with ball squeeze

The following section features videos demonstrating exercises that address several of the frequent complaints of pregnancy. Add these exercises in the early stages of pregnancy to whatever regular training regimen the athlete requires to prepare the body for the increased anterior load and prevent strain. Maintain through the latter stages (or initiate then if not begun sooner) to treat the aches and pains that come nearer to term.

Video 1: Posture

Video 2: Pelvic girdle pain

Video 3: Low back pain


Mental health

Mental health should be addressed from as early as the first trimester to ensure any anxieties and fears are conquered before escalation. Having realistic expectations in terms of the gestational weight gain, physiological adaptations, and exercise modifications from the beginning can prepare the athlete, thereby reducing reactions to unexpected occurrences. Should there be any cause for concern, gentle monitoring of the athlete for onset of eating disorders (as a reaction to weight gain), overtraining (for fear of falling behind or reduced fitness), and low mood (as a result of a combination of things) may be recommended. Medical intervention should be sought early to reduce the risk of postnatal depression later on.

What happens after birth?

Returning to exercise postnatally will depend on current fitness levels and type of exercise maintained through pregnancy. More importantly however, it will be based upon the type of birth and any complications endured throughout pregnancy and labour. Regardless of fitness levels, the body needs time to heal after birth, as well as readjust to the nine months of adaptations that have slowly occurred – eg with the reorganisation of internal organs, stretching of abdominal muscles and pelvic floor, and the general deconditioning of muscle groups.

Pelvic floor muscle dysfunction (PFMD) affects approximately 80% of women postnatally who undergo a vaginal delivery (15), with only around 35% being recovered at six months postpartum (16). This prevalence is similar in athletes compared to the general population, despite their increased fitness and strength. Indeed, research has even shown those who train in high-impact sports have reported stress incontinence even prior to giving birth(17).

Pelvic floor muscle retraining should commence as soon as possible after birth, once pain has subsided. PFMD has also been related to low back pain and pelvic girdle pain, therefore ideally these exercises should commence in the first trimester and be continued throughout pregnancy to minimise postpartum complications(18).

Those who achieve this are much less likely to report incontinence postnatally. Ensuring a good pelvic floor support is essential prior to any impact or strenuous activity. This is because the overload to the pelvic floor and increased intra-abdominal pressure could lead to worsened incontinence, vaginal or anal prolapse, and general feelings of pain, discomfort and weakness throughout the pelvis region, preventing future sporting progression. The time this takes to achieve will vary to each individual.

Women who have a caesarean section for delivery undergo the forced surgical splitting of their rectus abdominus muscles. This is associated with increased fatigue and low back pain. Pain management and wound healing must be therefore considered prior to returning to exercise. The abdominal muscles regain their tensile strength by around 51-59% at six weeks postpartum, and 73-93% by six months postpartum(19). This emphasises the longer duration of muscle healing and ability to regain core strength to support the body.

Regardless if a woman has a vaginal or surgical delivery, the core muscles are almost always affected with 66-100% of women suffering diastasic recti. Fifty-three percent of women still experience this stretching and splitting of the abdominal muscles for some time postpartum. The muscles must therefore be rehabilitated to ensure adequate trunk support before adding strenuous overload(20). Rehabilitation has occurred if the split is less than 2cms in all directions, with adequate tensile strength. The abdominals should be loaded in small range with low repetitions initially.

Once PFMD and core support have been re-established, further exercise should commence only when uterine bleeding has stopped and there are no other muscular or joint pains. Ligament laxity persists for up to six months (or longer if breast feeding), so exercise caution in stretching and end ranges of resisted movements. See table 2 for a summary of postnatal exercise recommendations.


Time scaleGuidelines
0-6 weeksPelvic floor muscles

Gentle core engagement

Walking
6-12 weeksPelvic floor muscles

Low impact exercises

Gentle aerobic exercise
12 weeks +Pelvic floor muscles

High intensity training

Moderate to high impact as able


Are you competition ready?

An athlete may be classed as fit to return to sports-specific training if:

  • There is no vaginal heaviness or bulging down.
  • There is no abdominal ‘doming’.
  • There are no other aches and pains.
  • The athlete has worked through a progressive programme of weight training, aerobic training, & sports-specific drills with no problems and achieved a level similar to that of pre-pregnancy.

In summary

Physiological changes with pregnancy consist of changes to the cardiovascular, respiratory and thermoregulatory systems. Guidelines suggest monitoring heart rates within the 140-160 bpm, not exceeding 70% VO2max, or temperatures above 39 degrees C. Musculoskeletal changes consist of postural adaptations and can cause low back pain and pelvic girdle pain. Correctly exercising pelvic floor and core muscles from the first trimester onwards can assist in alleviating these conditions, as well as reducing weights lifted and avoiding extreme strenuous activity. Realistic expectations, adherence to guidelines, and close monitoring of eating habits, weight, mood, and training ensures high level exercise is beneficial mentally and physically for both mother and child.

References

  1. Sports Med. 2010; 40(6): 493-507.
  2. Br J Sports Med. 2016; 50:571-589.
  3. Semin Perinatol. 1996; 20:315-327.
  4. Eur Spine J. 2007; 17: 794-819.
  5. Br J Sports Med. 2013; 47:515-520.
  6. Scand J Med Sci Sports. 2007; 17:480-487.
  7. Br J Sports Med. 2016; 50(13): 817-822.
  8. BMC Public Health. 2010; 10: 766.
  9. Br J Sports Med. 2018; 0:1-7. doi:10.1136/bjsports-2017-098926.
  10. Med Sci Sports Exerc. 2006; 38: 1389-1395.
  11. APPI Matwork one course manual.
  12. POGP. 2016.
  13. ACOG. 2009. No 267.
  14. Scand J Work Environ Health. 2013; 39: 335-342.
  15. Br J Obstet Gynaecol. 1990; 97: 770-779.
  16. Am J Obstet Gynaecol. 2009; 200: e1-7: 519.
  17. Br J Sports Med. 2015; 49: 196-199.
  18. NICE 2008. CG62.
  19. Curr Surg. 2005; 62: 220-225.
  20. Int Urogynecol J. 2007; 18: 321-328.
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