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running while pregnant

Running While Pregnant: Everything You Need to Know

As a committed runner, I always imagined that I would keep running very close to my due date when pregnant. I envisaged it feeling comfortable and enjoyable. When I became pregnant, I confidently told my athletics coach that I wanted to train with the track team until my final few months. “Nothing is going to stop me from setting an example for other pregnant track runners,” I told him. 

Despite an unwavering mental determination to continue running while pregnant, the end of my first trimester forced me to rethink, as block starts, hurdles, and simple warm-up drills fast became uncomfortable. By my second trimester, the pelvic floor heaviness I was experiencing caused me to make the disheartening decision to pull back on running. 

The important aspect to note here is this was my individual experience. I hit the brakes on my running because of how I was coping, but many women can continue clocking up the miles through the more advanced stages of their pregnancy – and others who can run all the way through.

As with all aspects of this baby journey, one size does not fit all. That maxim applies as much to our well-meaning family and friends who may caution us to stay clear of any running as it does to the potential for running to remain one of our ways of staying active during pregnancy. 

Image credit: Sally Goodall

Can you run while pregnant?

As a specialist in pre/postnatal exercise, the most common fear I’ve encountered from pregnant runners is a hesitancy to run during pregnancy for fear of miscarriage. However, modern research suggests miscarriages – particularly in the first trimester – have no connection with exercise. Instead, they’re linked to a range of possibilities, including genetic abnormalities, infection/disease, chromosomal defects, older maternal age, serious physical injury, and hormonal imbalances. 

Modern research suggests miscarriages – particularly in the first trimester – have no connection with exercise.

Given that, the question ‘can you run while pregnant’ is less about miscarriage and instead about what signs and symptoms you’re experiencing during your pregnancy. For example, many runners begin to feel pelvic floor pressure from the second trimester onwards as the baby’s weight starts to place a significant load on the pelvic floor. 

Typically, when women begin to feel any form of pelvic floor ‘heaviness’ or discomfort, it is a sign that their pelvic floor is struggling to handle the new demands placed on it, so I advise pulling back on activities such as running. I also remind clients that safeguarding their pelvic floor during pregnancy can help mitigate the risk of damage and may assist in speeding up post-baby recovery!

Is it safe to run while pregnant?

Staying active while pregnant can help:

  • improve your mood
  • boost your energy
  • reduce the risk of gestational diabetes
  • maintain physical fitness
  • improve sleep
  • decrease postpartum recovery time

That’s quite the list of positives, so it is no surprise many women now forgo outdated advice that advocates a more sedentary lifestyle during pregnancy. However, while physicians and prenatal experts champion daily exercise, running is not always top of the list because it is considered relatively physically demanding. 

Running while pregnant requires conscious monitoring of intensity, training volume, and remaining on high alert for complications including:

  • severe headaches
  • chest pains
  • vaginal bleeding
  • muscle weakness
  • calf pain
  • amniotic fluid leaks

As a prenatal exercise coach, I always ensure women understand that pregnancy can be an ever-changing journey with the presentation of potential complications such as placental issues, bleeding, or pre-eclampsia. 

For uncomplicated pregnancies, physicians advise:

  • remaining well-hydrated on runs
  • avoiding overheating, as this can increase fetal temperature
  • monitoring perceived exhaustion. You should always be able to string a sentence together
  • steering clear of bringing your heart rate into the red zone (I use my Polar Vantage V2 to track this)
  • treading with caution on uneven surfaces that can compromise your balance as your center of gravity changes

During pregnancy, your body produces the hormone relaxin. Its role is to loosen ligaments to give your pelvis and surrounding structures the required laxity to push out the baby. However, the presence of relaxin throughout your body can also cause your lower back, sacroiliac joint, and pelvis to feel increasingly sore post-run and can make them more susceptible to injury because these ligaments are craving more stability. 

I advise developing a personalized strength program with a prenatal fitness coach to provide your body with additional strength and stability to support your runs during pregnancy. 

How far can I run while pregnant?

Well, how long is a piece of string? Finding your sweet spot for running while pregnant ultimately depends on you – your training background, current fitness level, stage of pregnancy, and any signs or symptoms as discussed above. 

The general rule of thumb is that pregnancy requires a reduction in overall exercise intensity and volume. How this plays out can vary depending on your running discipline – are you an endurance runner or a sprinter? If you are a short-distance sprinter, a 5km run would likely feel far whether you are pregnant or not. On the flip side, a set of sprints would not suit a distance runner – particularly when pregnant. Again, when it comes to distance or intensity, one size does not fit all. 

The general rule of thumb is that pregnancy requires a reduction in overall exercise intensity and volume.

As your body adjusts to changing hormones and grows with your baby, there will be an impact on your running distance and your times. 

Research has shown that more than 45-minutes of exercise will potentially elevate core maternal and fetal temperature, a known risk to the baby. So, I recommend if you want to, or can go for longer, proceed with caution, reduce your speed, take more breaks and monitor for signs of fatigue or other pregnancy contraindications. 

Lastly, as your baby’s weight grows, there is increased pressure on your bladder, so bathroom breaks necessarily become more frequent. If you’re uncomfortable taking an essential, secluded pee-break in nature, I’d strongly recommend factoring in bathroom pit stops along your run route before heading out.

Can you run a marathon while pregnant?

A marathon is a tremendous feat – pregnant or not! It is incredibly taxing on the body regardless of pace, and for these reasons alone, I wouldn’t commonly advise it during pregnancy.

Coaching and personal experience have also shown me that athletes (particularly endurance athletes) tend to struggle most with generalized pregnancy advice like ‘just listen to your body.’ They are so accustomed to pushing their body past fatigue, hurt and psychological discomfort. 

Marathons also require many massive running hours in preparation and hours to complete the event itself. Unless you’re able to take multiple breaks, walk a bit, hydrate, eat, and keep your heart rate especially low, I’d recommend a shorter running aspiration during your pregnancy. 

Is it important to monitor your HR when running while pregnant?

running while pregnant

There are two key measures for tracking exercise intensity during pregnancy: heart rate and the perceived effort scale. The best practice for monitoring these two measures in combination is to ensure an overall reduction in your intensity and effort when running.

I generally recommend runners prioritize the perceived effort scale over heart rate as it estimates training intensity based on feel, ensuring the athlete’s effort never exceeds an 8/10 (10 being a maximum, unsustainable effort). 

There are two key measures for tracking exercise intensity during pregnancy: heart rate and the perceived effort scale.

This perceived effort scale accommodates the adjustments your body is making, particularly in the first trimester, when a flurry of new hormones can result in some athletes finding their heart rate reading confusing to read and inconsistent with their level of fatigue.

Pregnancy hormones tend to level out in the second trimester, and monitoring via heart rate monitor can prove slightly easier. When measuring your heart rate while pregnant, I usually recommend working to approximately 70-75% of maximum heart rate (Zone 3) intensity unless you’re a trained pregnant woman or athlete, in which case this can be adjusted to 80-85% (Zone 4).

It is critical to remember that this is not at a sustained effort but a max intensity. No matter your training background, it is not recommended to stay in Zone 4, the ‘orange zone’ (80-90%), for extended bouts of time.

Whether you’re a runner who is considering becoming pregnant or you’re newly pregnant, running can often remain your exercise of choice as your pregnancy progresses. Most importantly, understanding your medical conditions and closely monitoring signs and symptoms is vital for knowing when to pull back or stop.

Keep in mind that chasing running PBs is still possible postpartum. This has been increasingly showcased by many female athletes who return to compete in an elite-level sport after having their baby, and you will see it in everyday life where women are back out on local roads and tracks, clocking up the miles.

Stay positive, keep moving, and relish in the excitement that you are in the midst of creating your own little athlete. 

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Please note that the information provided in the Polar Blog articles cannot replace individual advice from health professionals. Please consult your physician before starting a new fitness program.

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