Historically a sedentary lifestyle has been encouraged for pre and post-natal women. Recent thinking has seen a shift in this advice and exercise if performed wisely is seen to be beneficial for both mother and child.
There are a number of physiological changes to consider in pregnancy, and extra screening should be performed to minimize any potential risks.
Cardiovascular Changes During Pregnancy
Early in pregnancy blood vessels increase in elasticity resulting in dilation and an increase in volume of the entire vascular system (there is more space for the blood to flow).
No change in blood volume in this stage of pregnancy results in a lag behind the increase in vascular volume, and so a decrease in blood pressure is observed.
Venous return (your body’s ability to return the blood to the heart) becomes less efficient as a result of ‘vascular under fill’ we see a reduction of blood pumping into and being ejected from the heart.
Effects of vascular under fill:
- Waves of sudden fatigue
- A racing pulse
- Nausea
- Pale in pallor
- Sweating
- Dizziness (particularly in getting up or standing)
- 1st three months resting heart rate (RHR) will increase so better to use rate of perceived exertion (RPE) in exercising. HR will change regularly during pregnancy too.
Following initial vascular under fill a response of increased blood production increases blood volume to meet the capacity of the vascular system. Overproduction of blood may in this case result in an increase in blood pressure (hypertension).
Oxygen demanded by the body increases as the demands placed on the body are greater than any other time in a woman’s life. In practical terms the mother may tire sooner especially during exercise. Exercise intensity take this into account and be reduced accordingly.
Benefits Of Appropriate Exercise:
- Better or increased circulation and a reduction in oedema (swelling)
- Reduced leg cramping
- Reduction in gastro-intestinal discomfort
- Enhance muscular strength, endurance and balance
- Improved posture and reduction in lower back pain
- Minimize maternal weight gain
- Improved self esteem and self image
- Shorter and easier labour
- Eased post-partum recovery
- Stronger pelvic floor muscles
Thermoregulatory Adaptations
Abnormal foetal development resulting from hyperthermia may be of concern to the mother. This situation may occur due to excessive heat production, and an increase in the mother’s core body temperature (37.5°C) during and after exercise. Physiologically the body will adapt to this heat by increasing the efficiency of heat dissipation through the skin and so removing the risk to the baby.
The aforementioned increase in blood volume and vascular volume both help to dissipate the heat keeping the baby safe from hyperthermia. In addition to this the sweat point temperature will decrease eliciting a sweat response sooner on an increase in core temperature. The body’s effort to keep the baby cool results in the ‘glow’ often seen in pregnant mothers.
Regular exercise increases the capacity for heat dissipation through increased blood volume and subcutaneous vasodilation. It is recommended to keep cool and well hydrated during exercise and to avoid the sauna, steam room and hot baths. Very vigorous activity may increase the risk of overheating, but exercise if well hydrated and in an appropriate environment will minimise the risk of overheating.
Respiratory Adaptations
Lung function improves during pregnancy. An increase in the hormone progesterone results in increased sensitivity of the breathing centre of the brain to CO2 and a faster breathing rate. A feeling of breathlessness may be felt during both rest and mild exercise.
The growing foetus hinders the function of the diaphragm fundamental to breathing. As a result the inter-costal muscles of the ribs (ribs are able to expand at this point), pectorals end even upper trapezius muscles will work harder. Becoming a chest breather is normal but these newly recruited muscles may become tight or fatigued and breathlessness from over-breathing may occur.
Adaptations:
- CO2 sensitivity increases – 4% less CO2 will trigger breathing
- Dyspnoea results – short breaths – chest breather
- Increased tidal volume of lungs – increased alveoli
Some Hormonal Changes
Increased levels of relaxin result in softer ligaments, cartilage and cervix allowing the tissues to spread during delivery. The pubis symphysis – cartilage joining the pubic bones – and sacroiliac joint (SIJ) – where your hips attach to your spine become unstable during pregnancy to aid delivery. This must therefore be considered in exercise.
Exercise considerations:
- Do not overextend the range of motion
- Do not perform developmental stretches
- Do not do hip adduction or abduction exercises and beware of hips and lower back in exercise
Oestrogen levels will change too resulting in increased body fat levels and female characteristics will be emphasised.
Insulin is a key that opens doors in cells and shunts nutrients into them. Insulin resistance increases during pregnancy and so energy patterns similar to a mild diabetic may arise.
Gestational diabetes is a common concern for pregnant women, characterised by too much glucose present in the blood. This excessive glucose ‘feeds’ the baby and may result in a large baby that may become prone to type II diabetes in later life.
Nutritionally, keep away from sugary foods, fast, processed foods and ready meals. Eating lots of vegetables and lean proteins, fruit and nuts and seeds will be a good start.
Getting enough EPA ad DHA fatty acids from fish oils may also help both mother and baby. Getting your carbohydrates from vegetables rather than cereals reduces your glycemic load and the stresses placed on the endocrine system. Exercise has been shown to have positive effects on insulin sensitivity.
Exercise should be performed up to 2 hours after eating, and a small snack consumed immediately post exercise. Fasting for more than 4 hours should be avoided and rapid weight gain in the early stages of pregnancy is normal.
Musculoskeletal Adaptations
Pregnancy results in a shift in the centre of gravity of women, as a result of a growing uterus and normal weight gain. The shift both up and out increase the stress in certain areas of the body.
An increased curve in the lumbar spine (hyperlordosis) along with stretched, lengthened (possibly strained) abdominal muscles may result in lower back pain (LBP) due to a tightening of the muscles in the area.
Increased leptin levels exacerbate changes further by stretching and loosening of stabilising ligaments of the pelvis, hips and back.
Abdominal Muscles
In increased tummy size stretches and weakens the abdominal muscles. This weakness may cause concern:
- The weight of the baby should be carried by strong abdominal muscles
- Strong abdominal muscles will give the muscles of the uterus assistance in delivery.
The abdominal muscles (rectus abdominus) are divided by a vertical sheath known as the linear alba which splits during pregnancy. Known as diastasis recti this splitting is more likely with weak abdominal muscles. Although a common occurrence it can be a problematic cause of backache both during and after pregnancy.
Pelvic Floor
Acting as a hammock that cradles the uterus, bladder and bowels the pelvic floor is often forgotten in every day life. Forming a ‘figure of eight’ around the urethra, vagina and anus, the pelvic floor becomes overly stressed as the uterus grows. Sagging of the pelvic floor may cause incontinence.
Kegel exercises are simple to perform exercises for strengthening the pelvic floor. Used daily, the combination of these two exercises will help to strengthen your pelvic floor muscles.
Identify Your Pelvic Floor
Before you start, identify the set of muscles you are going to exercising, as it’s easy to accidently recruit other muscles when trying to exercise the pelvic floor. When you exercise your pelvic floor do not: –
- Pull in your stomach
- Tighten your bum muscles
- Hold your breath
- Squeeze your legs together
A simple way to identify the pelvic floor muscles is in the loo. Try to stop urinating mid-flow – the muscles you flex to stop urinating are your pelvic floor muscles. To flex your muscles, simply tighten the muscles around your bottom, urethra, and, vagina.
Slow Kegels
This exercise will improve the length of time you can consciously hold your pelvic floor muscles for, and improve overall muscle strength.
- Breathe in. As you breathe out, slowly clench your pelvic muscles up as far as you are able and hold them for 5 seconds whilst continuing to breathe normally. Slowly release the muscles until all the tension has dissipated.
- Repeat this process 4 or 5 times, and gradually build up the length of time you clench your muscles to 10 seconds. As your muscle tone improves, you should also be able to slowly increase the number of repetitions for better results.
Fast Kegels
Fast kegels are performed in the same way as the method above. The only difference is that you clench your muscles quickly and let go quickly. Rest for at least 3 seconds between repetitions, and repeat up to 10 times.
Elevator
Start clenching easily to begin with and gradually increase the clench until it becomes hard to very hard. Repeat as above.
Exercise considerations
Before exercise consult a GP for a thorough screening. Regular checkups with a midwife are essential to monitor blood pressure amongst other things. Ensure considerable care is taken in all stages of pregnancy.
Four main contraindications that require evaluation before exercise is undertaken are as follows:
- Significant physical injury
- Acute illness or chronic underlying disease
- Onset of localized, persistent or recurrent pain – in particular the lower body for risk of DVT
- Abnormal or heavy vaginal bleeding
Return To Exercise Post Delivery
| Type of delivery | Advice |
| Normal delivery
· No caesarean section · No delivery or post birth complications |
Following 6 week post-natal check up with doctor |
| Caesarean delivery | 12 weeks following delivery providing that post natal check with doctor has been satisfactory |
Exercise guidelines:
- Avoid supine and prone positions (lying on front or back) after first trimester. The front will become too uncomfortable. Supine the baby will sit on the inferior vena cava and inhibit blood flow.
- Reduce impact. Joint instability should be considered, and a reduction in running volume is advised.
- Risk of abnormal trauma – do not get hit in your tummy!
- Due to unreliable and variable heart rate through pregnancy, it is advised to use RPE rather than HR as a guide to exercise intensity.
- As a mother you will have a varying comfort zone – use this as a guide to exercise intensity and type.
- Keep well hydrated and cool to minimize risk of hyperthermia
- Change your program or day’s workout if you feel uncomfortable, faint, ill, hot, or in pain
- Strengthen stretched and weak muscles
- Stretch tight muscles but do not do developmental stretches. Avoid any stretches of the lower back, hips, or any abduction and adduction exercises of the hip joint.
- Perform pelvic floor exercises
- Eat as advised by a GP or midwife, follow a low glycemic load, nutrient dense diet and maintain hydration levels.
- Mother knows best – remain in your comfort zone!
Post Natal
Reduced joint stability in response to relaxin levels increase injury risk in post natal females. Progress your exercises from machines to free weights, gradually destabilising the exercises.
Weak abdominals should be strengthened initially with a static plank exercise, progressing to a crunch and further advanced exercises.
Focusing on the transverse abdominus muscles (TVA) may be beneficial, and no abdominal exercises should be performed before the diastatis recti of the linear alba decreases to <2 fingers width.
Considerations for breast feeding should include the fact that lactic acid taints the taste of breast milk. It may therefore be wise to breast feed before exercise or express prior to feeding.
Return to exercise slowly and exercise caution in all that you do. I hope this
helps and all the best in the future. If you would like further information about exercising during and after pregnancy, and in particular nutritional considerations, then please get in touch using the form below.