Posted by: JC | 2004/02/16



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Our expert says:
Expert ImageGynaeDoc

In pregnancy you should not push your pulse rate up too high for too long. Also you should not get too hot, as the fetus has no way of getting rid of excess heat. Provided you keep within these limits, you should be fine.

Best wishes

The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.

Our users say:
Posted by: Theresa | 2004/02/16

Hi JC,

I am currently 20 weeks & 2 days pregnant and also a runner. I run about 8 - 10km per day and still going strong. I was also concerned about my developing baby and if I was doing any harm, so I also did some reading to try and find out.

I am going to attach an article that might help. It is from the "FitnessDoc" from this site.
A personal and professional view

Angie Lander
Peak Biokinetics
Sport Science Institute of South Africa

For years pregnant runners have been keen to establish what effects running may have on the health of the developing foetus during pregnancy. Most guidelines are conservative and suggest “no jarring or high impact activities” during pregnancy, instead encouraging walking, stretching and swimming and avoiding strenuous activities. This type of advice didn’t really suit my lifestyle, being an avid runner and wanting to continue this activity to maintain cardiovascular fitness.

When I discovered I was pregnant I had just completed my first marathon and was developing into a distance runner. In addition to the excitement that goes with a first pregnancy, I had a few concerns about my running and how pregnancy would affect it. I envisaged my fitness dwindling if I was unable to run for the next 9 months and was determined that this should not happen.

I had already planned my next half marathon, which meant I would be 4 months pregnant when the race came around. Would it be safe to run 21 km whilst 4 months pregnant? At what stage of my pregnancy should I stop running? With what intensity and for how long should I run? What about weight training? How much weight should I gain?

My obstetrician gave me sound advice and told me to continue with whatever exercise my body was accustomed to – but to stop if there was any pain or discomfort. This was good news, but I still felt I needed more specific guidelines about an appropriate exercise regime before continuing with my regular running programme. Therefore I decided to do a bit of research of my own.

This was what I discovered……

Scientific evidence mainly indicates that running during pregnancy is associated with normal foetal development and that runners tend to have a lower incidence of pregnancy complications. In general, running is a safe activity that many pregnant women continue, with modification, throughout pregnancy.

Most studies indicate that regular running is preferable to intermittent training, which places more stress on your body. If you were well conditioned before pregnancy, exercising during your pregnancy should be ‘a walk in the park’. If, however, you were not running regularly before your pregnancy, now is not the time to start. If you want to start exercising during your pregnancy, the second trimester, not the first, is the time to begin.

You will need to modify the intensity, frequency, speed and length of your runs while pregnant and gradually reduce these factors more as your pregnancy progresses. Remember you are training to maintain fitness, not to win races!

In terms of intensity most research recommends training at a heart rate of less than 150b/min. Your resting heart rate while pregnant increases by 10-20% more than your non-pregnant state.

Exercise intensity affects a mother’s core temperature, so if your heart rate exceeds 150b/min, your core temperature can increase significantly. However, given that exercise intensity generally decreases as pregnancy progresses, core temperature generally decreases too. Therefore it would be inappropriate to run in hot, humid weather, particularly in your first trimester, as this will increase core temperature. An increase in core temperature (of more than 38º C) will increase foetal temperature and can impair development, particularly if it occurs during the first trimester, when most foetal development takes place.

As your uterus enlarges, so the diaphragm is raised, particularly in late gestation. Breathing during exercise then becomes more laboured and the oxygen consumed relative to your body weight is progressivelly reduced. Therefore your exercise intensity will largely be dictated by the difficulty of your breathing.

Dehydration is another matter highlighted in research. Whilst you are running you should ensure you consume adequate quantities of water before, during and after your run, particularly if it is a hot day. If your core temperature rises above the recommended level and you are dehydrated, uterine blood flow is reduced, which has a negative effect on foetal temperature regulation. Fortunately your body will let you know when you are overdoing it and you will feel these effects before your baby does. So listen to your body!

Stop running and walk if you feel Braxton-Hicks contractions or ligament pain. As the contractions stop you can slowly start up again. Remember to stop if you feel any pain, persistent contractions, leakage of fluid, fatigue or dizziness.

If you are the type of runner who bounds out of the door without stretching, you are going to need to change your ways. Appropriate stretching both before and after running will help to prevent injuries. Relaxin, the hormone that relaxes your ligaments to facilitate both the carrying and passage of the foetus, works throughout pregnancy. Loose joints and stretched ligaments, however, make you more vulnerable to injury whilst you are carrying a future little runner. Therefore it is important to focus on stretching your hamstrings, quadriceps, hip flexors, glutes, lower back and calves; these are all important if you continue running. If you experience any lower back pain while training then it is advisable that you stop and continue with another form of exercise.

In the first 3 months you may experience nausea and fatigue. Most runners find that running in the morning helps to alleviate these symptoms. If you are losing weight from vomiting then you need to cut back on your running until you start gaining weight again. Fatigue tends to be worse in the first and third trimester, so try to schedule your runs at a time of day when you are least tired. If running feels too much, then substitute it for a walk or a few laps in the pool.

As your breasts get bigger and more tender, running may cause discomfort if you don’t wear a supportive sports bra (or two, as I ended up doing!)

Urinary frequency can also challenge your running routine, so plan your running routes around a nearby toilet, but don’t cut back on your fluids.

As you reach the second trimester you may feel your best; however, it is time to slow down and reduce your mileage. Most women cut back on their mileage by 40% in the second trimester and up to 70% in the last trimester.

As your pregnancy progresses, running gait and balance change due to the extra weight and abdominal pressure and your stride tends to shorten. If running becomes uncomfortable at this stage with pelvic or abdominal pain, then it’s time to consider non-weightbearing options for exercise. Other activities you may wish to try are swimming, cycling, cross training or walking.

I ran until 28 weeks, although the length and intensity of my runs had significantly decreased by then. One day out the blue, ten minutes into my run, I started having a lot of discomfort in my pelvis and lower legs. I tried to persevere but realised that my running days were over for the next 12 weeks and had to walk back home. From then on I continued to exercise with the rotex crosstrainer, I swam and did weight training.

Although I had to have an emergency caesarian, the cord being wrapped around my baby’s neck, I was back running eight weeks postpartum and found I was able to run at my pre-pregnancy level by 10 weeks. The 11kg weight gain during my pregnancy dropped off and by 12 weeks postpartum I was back at pre-pregnancy weight. A year later I am now back running marathons without much change in fitness, although the sleepless nights do tend to take their toll.

So my advice to those of you wanting to stay fit while you are pregnant is to keep running and stay healthy!! Listen to your body.

If, however, you have had a complicated pregnancy with any of the conditions below, then it is NOT recommended that you continue running.

Ø Bleeding
Ø Incompetent cervix
Ø Pre-eclampsia
Ø Multiple pregnancy
Ø Diabetes
Ø Poor physical fitness before pregnancy

Some of the benefits of running while pregnant are:

Ø Shorter labour
Ø Less maternal weight gain and reduced “postpartum tummy”
Ø Improved circulation and reduced risk of varicose veins
Ø Reduced risk of back pain
Ø Reduced risk of gestational diabetes
Ø Lower incidence of pregnancy complications
Ø Reduced fatigue and anxiety

By: Angie Lander
Peak Biokinetics
Sport Science Institute of South Africa
Cape Town
Tel: 689-2707 (021)

Sorry for the long article - I hope that I have helped with this info from Angie?

Good luck and enjoy the running!


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