Why is it important to exercise during your pregnancy?

When you are pregnant, there are many benefits for staying active, providing your pregnancy is progressing well and there are no restrictions which would stop you from exercising. Check with your Doctor or Midwife regarding these, but medical conditions that would general stop you from exercising include risk of premature labour, leaking of amniotic fluid, vaginal bleeding, high blood pressure and intra-uterine growth retardation (i.e. your baby not growing as expected for your dates).

Many women can enjoy an active pregnancy, exercising throughout, with Doctor's or Midwife's checks giving reassurance that there is no problem with continuing to exercise.

Moderate aerobic exercise is not hazardous to your unborn baby. Babies tend to be leaner however, in women who continue with exercising closer to maximal intensity levels.

There are many benefits to exercising regularly throughout your pregnancy. These include:

• Maintaining or increasing your fitness level will give you more energy to deal with pregnancy and labour (you can often 'cope' with labour better). You will also have more energy after the birth to look after your new baby. A minimum of 15 minutes of aerobic activity 3 or more times per week is needed to gain these benefits.
  
  
• Moderate regular exercise enhances the release of beta endorphins which can provide a sense of well being and decrease pain perception during pregnancy. This can lead to less lower back pain, headaches or round ligament pain (see increased ligament laxity and hormonal changes in Changes to your body affecting exercise performance to find out more about round ligament pain).
  
  According to one study, women who didn't exercise regularly had a 2.5% increase in endorphins with exercise, whereas women who exercised regularly over two months had a 57%, 79% then a 145% increase in endorphin release with exercise.
  
  
• Women who are fit will have a greater release of beta endorphins during their labour and therefore reduced pain perception in labour.
  
  
• Improved well being and self image during and after pregnancy.
  
  
• Reduced back pain due to more toned muscles to support the back and pelvic joints.
  
  
• Your muscles will be more toned which improves the benefits gained by your abdominal and pelvic floor muscle exercises, and means they will go back to normal more easily and quickly after the birth.
  
  
• Better muscle strength and coordination, which helps you to adjust more easily to your changing shape.
  
  
• Improved sleep patterns - more slow wave sleep with fit individuals.
  
  
• After birth you will have more energy to cope with the demands of motherhood.
  
  
• Exercising during and then after pregnancy will help you to return to your pre-pregnancy weight earlier and more easily after the birth.

For more information on the Do's and Don'ts of pregnancy exercise, ideal exercises during pregnancy and exercises to avoid during pregnancy, click HERE.

Top

The benefits of water exercise during pregnancy

• Body weight is supported during exercise. This places less stress on joints and ligaments than exercising on land, so there is less chance of joint injury.
  
  
• The weight of the uterus is supported, so women experience less abdominal heaviness when exercising in water, especially in the last few months of pregnancy.
  
  
• No detrimental effects known. Women can exercise right up to their due date, providing that medical check ups permit.
  
  
• The pressure of the water helps to improve venous blood flow, and this can help to reduce swelling in the lower limbs.
  
  
• Exercising in water can be relaxing and relieve pain.
  
  
• Can experience less muscle soreness than after exercising on land.

Top

Exercising during pregnancy: Baby reaps rich rewards!

Written by: J. Malcolm, mother of two.

Women who are physically active always try to keep exercising throughout their pregnancies, but is what's good for mum, good for the baby?

A study conducted at Case Western Reserve University in Cleveland, Ohio by Dr. James Clapp showed that mothers who exercise during their pregnancy may reduce the amount of body fat in their babies. A team of researchers recorded body and developmental measurements among children of 20 women who exercised at a level greater than 55% of their maximum aerobic capacity for 30 minutes per session, three times a week. Those measurements were then compared to children of 20 women who voluntarily stopped all exercise, except walking throughout their pregnancies.

At birth, the children of the women who exercised weighed less and had less body fat than the children in the 'control' group. This trend lasted until both groups of children were 5 years old. The children from the exercise group were not only leaner, they scored higher in tests of general intelligence and oral language skills at 5 years of age, than the control group.

The study was published in the Journal of Paediatrics. It showed no negative findings at all among the children who mothers participated in the exercise group while pregnant.

Dr. Clapp is continuing to follow these children as part of his studies and at this stage, intends to repeat a lot of his earlier research.

It should be noted that there are many variables involved with this kind of study, so it is hard to make any meaningful conclusions. However, providing a woman has a medical clearance from her doctor, exercising throughout pregnancy is certainly very beneficial and should be encouraged!

Top

Special considerations for exercise in pregnancy

• Increased risk of injury to the muscles and joints for the mother during pregnancy.
  
  Following the Guidelines in Considerations for pregnancy and post natal exercise can reduce the risk of injury.
  
  
• Up to 12 weeks of pregnancy the uterus (womb) is protected inside the bony pelvis.
  
  
• After 12 weeks there is a risk of injury to the baby with direct contact sports, and falls from horse riding or gymnastics - otherwise the risk of injury to the baby with exercise is rare.
  
  
• Activity can produce painless contractions due to the release of the hormone norepinephrine.

Precautions of exercise:

• Training intensity should be moderate, i.e. less than 80% of maximum heart rate.
  
  
• Moderate exercise duration per exercise session is recommended (Hill 1994):
  ~ 30 minutes - 1st trimester
  ~ 43 minutes 2nd and 3rd trimester.

Top

More exercises to avoid during pregnancy

• Excessive twisting and turning activities.
  
  
• Exercises that require you to hold your breath.
  
  
• Asymmetrical weight bearing activities, i.e. those involving standing on one leg for a period of time as these can place excessive strain on your symphysis pubis or sacroiliac joints (the joint at the front and back of your pelvis).
  
  
• Pushing off with one leg at a time when swimming - try to push off with both feet when you turn at the end of the pool.
  
  
• Prolonged standing static exercises.
  
  
• Highly choreographed exercises or those which involve sudden changes in direction.
  
  
• Lifting your hip up to the side (hip abduction) while kneeling on your hands and knees.
  
  
• Activities involving sudden changes in intensity.
  
  
• Exercises which increase the curve in your lower back (your lumbar spine).
  
  
• Prolonged bouncing as this can overstretch the pelvic floor muscles.

Top

Changes to your body affecting exercise performance

Pregnancy is a time when there is increased demands on your body. Exercise further increases the demands on the heart, lungs, muscles, joints, metabolic and hormonal systems beyond those already established. Some of the physical changes which influence exercise in pregnancy are outlined below.

1. Increasing uterus (womb) size:
   
   
   • Your uterus size can increased by up to 150 fold (normally it's the size of a pear). This stretches and weakens the abdominal muscles and increases strain on the spine as the curve in your lower back increases. Refer to Stomach Muscle Strength and Stability for further information on your stomach muscles or As Your Shape Changes to learn abdominal bracing to cope with the extra weight of your uterus during pregnancy.
     
     
   • As your baby grows, your center of gravity continues to change during your pregnancy. This affects your posture and balance and you may notice that you feel less coordinated as your pregnancy progresses.
     
     
   • Shortness of breath can occur as the uterus pushes up onto diaphragm. You may feel more short of breath than usual when you exercise and at other times.
     
     
   • After 19 weeks of pregnancy, it is recommended that you do not lie flat on your back due to the pressure of your uterus on your major blood vessels, which can cause dizziness or fainting (also known as supine hypotension).
     
     
   • Up to 12 weeks the uterus is protected inside the bony pelvis. After 12 weeks the baby is protected by thick spongy uterine wall and up to 1 litre of amniotic fluid.
   
   
   
2. Increased ligament laxity and hormonal changes:
   
   
   • During pregnancy there is an increased level of the ovarian hormone RELAXIN. This can occur as early as 2 weeks of pregnancy. This increases the flexibility of collagen, which means that your ligaments are looser. Your joints (especially around your pelvis) are therefore more vulnerable to injury or strain and this can contribute to backache or symphysis pubis pain (pain around your pelvis and groin area). (See Jessica's Story)
     
     
   • Round ligament pain may occur - these are the ligaments that support your uterus (also due to increasing size of uterus). This may be felt as a sharp catching type of pain in lower abdominal area on either side, just above your groin. This can occur when you move or change directions, such as rolling over in bed, going up and down stairs or getting out of a chair. Learning abdominal bracing (See Stomach Muscle Strength and Stability) can help to relieve this pain as your abdominal muscles can then help to support your uterus as it grows.
     
     
   • Softening of collagen/connective tissue in the pelvic floor can occur, so its supportive role may be reduced. This is one of the reasons for avoiding high impact or bouncing exercise during pregnancy.
     
     
   • The walls of veins are also softened by pregnancy hormones and this can contribute to varicose veins (also due to increased blood volume and the increased size of the uterus increasing pressure within the abdomen).
     
     
   • Hormonal changes can contribute to reflux and nausea.
   
   
   
3. Breast Enlargement:
   
   
   • The increase in the weight of the breasts can cause rounding of shoulders and the upper back. It is important to take extra care with your posture to prevent this from causing backache or becoming permanent. Refer to the posture tips and advice in As Your Shape Changes and A simple way to improve your posture.
   
   
   
4. Increased weight:
   
   
   • An average weight increase during pregnancy is 10 - 12 kg., although this can vary. Half of this is the uterus, baby and amniotic fluid, and the other half is body fat stores, fluid and breast fluid.
     
     
   • This increases the magnitude of jarring forces and joint stress by 5 times body weight in running and jumping.
     
     
   • Carrying this increase in weight can contribute to tiredness.
   
   
   
5. Increased volume of blood and fluid retention:
   
   
   • Blood volume increased by 40 - 50% during pregnancy.
     
     
   • Leg cramps can occur due to increased fluid volume and retention and reduced venous return (blood flow back towards the heart). See Calf cramps in pregnancy for advice on what to do if you experience legs cramps.
     
     
   • An extended cool down is important after exercise to prevent pooling of blood in the legs.
     
     
   • The pressure of the water on the legs during water exercise may help to reduce swelling and aid venous return.
     
     
   • Together with the effect of the relaxin hormone, there is an increased risk of the development of varicose veins or vulval varicosities (like varicose veins, but in your vulval area, which can lead to an ache or heavy feeling around your vaginal area). See Another reason for discomfort in the vaginal region - varicose veins (also known as vulval varicosities) for further information.
     
     
   • Core body temperature increases.
     
     
   • Sodium retention in the kidneys may result in swelling especially of the hands and feet.
   
   
   
6. Increased Heart Rate and Respiratory Rate:
   
   
   • Resting heart rate increases 7bpm in the first four weeks of pregnancy (Hill, 1994) and 15-20 beats per minute in mid-pregnancy.
     
     
   • Your chest size and capacity can increase.
     
     
   • The pressure of the increasing size of your uterus on the diaphragm may cause you to feel more short of breath, especially in the later stages of pregnancy.
     
     
   • Aerobic capacity may stay the same or increase due to heart rate changes.
     
     
   • "Masking" of conditioning effects may occur late in pregnancy. This may mean that although you are maintaining your fitness levels, because you can feel more short of breath, and your heart rate increases more quickly during exercise, you feel like you are losing your fitness. Your body is working harder anyway, so you may actually be maintaining your fitness levels as you continue to exercise, despite the need to slow down later in pregnancy.
   
   
   
7. Gastrointestinal Changes:
   
   
   • Can cause nausea, gastric reflux and constipation.
   
   
   
8. Abdominal muscle changes:
   
   
   • Role of abdominal muscle wall is to support the spine, abdominal organs, and the baby during pregnancy. Refer to Stomach muscle strength and stability for more information.
     
     
   • Lengthening of the abdominal muscles occurs due to the increasing size and weight of your baby and uterus.
     
     
   • Abdominal muscle separation (diastasis) can occur. This is the separation of the rectus abdominus muscle at the linea alba (which is a fibrous band of connective tissue down middle of abdomen between the muscles). This occurs as your baby grows and stretches the muscles. The softening effect of pregnancy hormones also allow the fibrous tissue to loosen and stretch. Sudden exertion can also increase the separation of the recti. Women with abdominal muscle separation may have a weakness of the deeper abdominal muscles. This may contribute to lower back pain if the separation does not close after the birth.
     
     To find out how to check for an abdominal muscle separation, refer to your booklet As Your Shape Changes.
     
     
   • 50-60% of women have a separation of more than 2cm after the birth of your baby. So it is quite common for this separation to occur, but it should go away within a few months after the birth.
     
     
   • The mechanical stretch together with changes in the direction of pull of the abdominal muscles means that the abdominal muscles are not as efficient during pregnancy.
     
     
   • Loss of muscle strength and tone can occur, which can result in an increased curve in the lower back, however learning to 'actively carry your baby' using abdominal bracing can prevent or reduce this weakening.
   
   
   Refer to Stomach muscle strength and stability for more information.
   
   
   
9. Pelvic Floor Changes:
   
   
   • The effect of the Relaxin is to weaken the connective (fibrous) tissue in your pelvic floor.
     
     
   • The increased weight of your baby on the pelvic floor may also cause it to weaken.
     
     
   • Intermittent repeated stress of high impact exercise can weaken the pelvic floor muscles, therefore lower impact exercise is the preferred option for exercise.
   
   
   For further information on the pelvic floor muscles, refer to As Your Shape Changes

References:

Bramwell, K. and Sherburn, M. (1995). 'Changing Shape: Exercising for Fitness and Wellbeing During and After Pregnancy'. Chapter 3, Guidelines for Minimizing Risks, p. 24-35. ISBM 0 670 85735 1.

Brayshaw, E. and Wright, P. (1994). 'Teaching Physical Skills for the Childbearing Year'. Chapter 2, Physiological Changes and Minor Physical Problems in Pregnancy, P. 19-27. ISBN 1 898507 02 3

Curtin University of Technology, School of Physiotherapy. 'Women's Health Obstetric Physiotherapy Manual'.

Hill, T. (1994). 'The risks and benefits of exercise in pregnancy. Unpublished Masters Thesis, submitted for the dissertation requirements of the Masters of Public Health Degree'. Department of Public Health, University of Western Australia. 541 pertinent research and review articles and books cited.