Regular exercise is now recommended for most pregnant women, but as the physiological changes of a pregnant woman are complex, great care is needed in screening and programming, says Liz Dene, Australian Institute of Fitness NSW Coach.
Despite the complexity of pregnancy, training a client throughout their pregnancy can be very rewarding, and the benefits of exercise can occur before, during and after pregnancy.
Over the past 20 years there has been a radical change in the attitude towards exercise during pregnancy. Thankfully we have moved on from the time when women were told to endure the discomforts of pregnancy.
Recent publications from the American College of Obstetricians and Gynaecologists (ACOG) provide new recommendations and guidelines for exercise and the postpartum period. For example, ACOG now recommends exercise for pregnant sedentary women and those with medical or obstetric complications, but only after medical evaluation and clearance. Until recently, we have been advised to only train clients who were previously exercising prior to pregnancy, yet the new directive is that all pregnant women without contraindications should be encouraged to participate in both aerobic and strength training.
Current ACOG guidelines recommend 30 minutes of exercise on most, if not all days of the week for women with uncomplicated pregnancies. The women should be well hydrated and perceive the exercise to be mild to moderate.
It is well understood that women who are fit have shorter labours with a significantly lower rate of caesarean sections (C-sections). More evidence is showing that women who begin regular moderate exercise in trimester 1 (T1) and continue throughout their pregnancy will also benefit.
Ensure your pregnant clients are appropriately screened with written permission to exercise from their doctor. It is important to confirm that your client is clear from any of the absolute contraindications (see below). The clients that fall into the ‘relative’ category will need to cleared and closely monitored by you and their specialist medical practitioner.
Table 1. Contraindications to Exercise in Pregnancy
|Absolute Contraindications||Relative Contraindications|
Source: ACOG Committee Opinion No. 267
There are many anatomical and physiological changes during pregnancy that have the potential to affect the musculoskeletal system at rest and during exercise. The most obvious of these is weight gain. The increased weight in pregnancy may significantly increase the forces across joints such as hips and knees by as much as 100 per cent during weight bearing exercise such as running. Such large forces may cause discomfort to normal joints and increase damage to arthritic or previously unstable joints.
Musculoskeletal changes occur and are extremely significant. These changes are referred to as ‘postural distortion patterns.’ Typically women develop lumbar lordosis, which contributes to the high prevalence (50 per cent) of low back pain. The pelvis often rotates more anteriorly due to the position and weight of the foetus. To compensate, the kyphotic curve may increase as well to counteract the increased lordotic curve. The cervical spine can then be affected as the shoulders become more rounded and the head will shift forward. The weight gain plus increased ligamentous laxity due to the rise in oestrogen and relaxing may result in increased pronation at the foot and ankle. All of this combined will ultimately affect the mechanics of the kinetic chain.
Therefore effective postural screening of all pregnant women is essential prior to exercise prescription.
Table 2. Postural Distortion Patterns
|Postural Distortion||Short/Tight Muscles||Long/Weak Muscles|
|Foot/Ankle||Feet externally rotated||Soleus/gastrocnemius||Anterior/posterior tibialis|
|Pronation at ankle||Soleus/gastrocnemius Peroneals||Anterior/posterior tibialis|
Hip external rotators
|Hips||Anterior pelvic tilt||Iliopsoas|
|Shoulders||Protracted shoulder girdle||Pectoralis major/minor|
|Deep cervical flexors|
Once you have recognised any postural imbalances it is recommended that you address these needs in the first trimester (T1) and effectively design a comprehensive training program that focuses on strength, stability and corrective techniques to overcome imbalances. Addressing these issues in T1 will help strengthen your client for the trimesters to follow.
Intensity is another area to be regulated when programming. Pregnancy induces profound alterations in maternal haemodynamics. Such changes include an increase in blood volume as well as cardiac output, and a decrease in systemic vascular resistance. By mid-pregnancy cardiac outputs are 30 to 50 per cent greater. These changes influence the intensity that can be tolerated.
Intensities can be measured in three different ways: modified heart rate zone, ‘talk test’ which indicates the exertion level through conversation; and perceived exertion according to the Borg scale. Your client’s stage of pregnancy will indicate which type of scale you use.
In T1 there is an increase in maternal heart rate at any given workload, but the rate of perceived exertion (RPE) will be decreased due to an underfilling of the cardiovascular system. This is also a protective mechanism, as weeks three to eight hold the greatest risk of foetal malformation due to heat shock on cell development. Therefore, keeping well within the target zone for this period is essential.
In the third trimester (T3) there is a decrease in maternal heart rate at any given workload; however, the RPE is increased due to returned heart rate reserve (HRR) and increased maternal weight. You will find most clients will find it difficult to keep up the exercise intensity as the pregnancy progresses.
Table 3. Modified Heart Rate Target Zones for Aerobic Exercise in Pregnancy
|Maternal age||Heart rate target zone (bpm)|
|< 20||140 – 155|
Source: Canadian Society for Exercise Physiology
Duration and Frequency of Exercise
The two major concerns of exercise duration is the effect on thermoregulation and energy balance. It is best to limit the duration to 30 minutes maximum, of course, depending on intensity. Another option is to accumulate activity to shorter periods such as 15-minute periods. This may prevent concerns of thermoregulation and energy imbalance during exercise. Also look at introducing multi-peak training as opposed to long sessions.
Table 4. F.I.T.T. Principle for Pregnancy
All exercise sessions follows these general training principles of frequency, intensity, time and type, F.I.T.T.
|Frequency||Most Days of the Week|
|Intensity||T1: 70% HRR|
T2: 70% HRR and RPE (12 14)
T3: 70% HRR, RPE (12 -14) and talk test’
|Time||30 minutes maximum at correct intensity for trimester|
|Type||Large muscles, continuous movement|
Type of Exercise
A mix of cardiovascular and resistance training is recommended as long as the appropriate screening has been conducted. Aerobic exercise can include activities that use large muscle groups in a continuous manner such as walking, stationary cycling, swimming, low impact aerobics, aqua fitness and resistance training. Avoid activities that could increase risk of falls such as skiing, or those that may result in excessive joint stress, such as jogging, tennis and other organised sports.
When designing resistance training program some of considerations to keep in mind are:
1. Address any specific weakness or instability during T1 since the client can move more easily.
2. Keep aware of imbalances whilst focusing on corrective exercise technique.
3. Strengthen the deep abdominal corset musculature. This will provide a stable based and help to alleviate musculoskeletal stresses later on.
4. Avoid the supine position after 16 weeks or any position where gravity is pushing down on the vena cava (e.g., shoulder bridge, recumbent cycling, bench incline of 30 per cent or lower).
5. Decrease rectus abdominus and dynamic oblique work after T1, especially if diastasis recti occurs (separation of the rectus, which occurs in more than 30 per cent of women). Focus on strengthening the deep abdominal muscles instead as these have a huge role to play in the birth and post labour recovery.
6. Overhead movements should be avoided especially during T3 due to possible decrease in blood flow to the baby and possible hypertension issues.
7. Be aware of ligamentous laxity due to increased level of oestrogen and relaxing. Design a program based on the initial assessment results. Watch for end range of movement and joint instability. Instability in the pelvis and tightness of the surrounding musculature can lead to such issues as sacroiliac joint pain and pubic symphysis instability. Avoid lower body unilateral work (lunges, one leg squats, high step ups and wide squats. Strengthen the gluteal complex and stabilise the pelvis through lateral tube walking. (Lateral tube walking is done by using band resistance consistent with your clients ability. Place the band around the ankles hip width apart, then step sideways keeping tension on the band).Always consult with the client’s practitioner and refer if the pain continues or worsens.
8. Keep intensity light, low weights, 12 to 15 repetitions of multiple muscles groups. Focus on corrective exercise techniques that strengthen the deep abdominal muscles. Machine weights are preferable over free weights.
9. Constantly assess the clients changing posture and modify the program accordingly.
Pregnancy should no longer be considered a state of confinement. Rather, pregnant women with uncomplicated pregnancies should be encouraged to continue to engage in exercise, keeping in mind that during weeks three to eight, the risk of foetal malformation due to heat shock is at its most highest.
Remember, the key objective is that your client has a healthy birth outcome. If you can assist in this in any way, such as their training, then you have helped to contribute to the amazing experience of life!