Modifying Hard Workouts for Pregnant Runners

Hard workouts (defined as speedwork, tempo runs, hills repeats – anything harder than your normal easy run) are a staple for most runners. What about pregnant runners, a growing part of the running world as we realize that you can keep training throughout pregnancy? The good news is, you can still do hard workouts during pregnancy, with some simple modifications. The whole 140 bpm is outdated misinformation (read more here). Typically, what you did before pregnancy dictates what you can do during pregnancy – including intensity. This post will guide you through modifying workouts for pregnant runners.

Pregnant runners are just like any other runner: training must be individualized. 

Not every female athlete will opt to do hard workouts during pregnancy, nor should every female runner do these types of runs while pregnant. Some women find that their bodies prevent them from running harder than an easy pace. Others will experience joint pain or pressure that prevents them from doing more than run/walk intervals. Some women use low-heart rate training or another primarily easy run approach, so hard workouts were not a part of their training prior to pregnancy. Some might simply prefer just to do easy runs! 

But for other female runners, hard workouts are a part of their routine and even their identity as a runner. Their bodies are adapted to the intensity and they know how to control their effort if needed. Most importantly, they enjoy the variety and ability to push themselves. Pregnancy slowdown happens at different rates for different women, and some will still be able to comfortably maintain modified intensity or distance.

You will need to modify your workouts as your pregnancy progresses. As your weight increases, your center of gravity shifts, and your energy demands change, your paces and ability to tolerate intensity will change. Your recovery rate will change as well during pregnancy, meaning you will gradually be able to handle less intensity.

However, it is possible to do more than just a short easy run, if you want to. The injury risk is not as scary as some people make it out to be*, nor is running while pregnant as hard or uncomfortable as some present it. You won’t shake the baby loose or harm it from elevating your heart rate. But you will feel strong and confident in your pregnant body, enjoy your running, and prepare your body for the physical demands of labor and delivery. Hard workouts, even when modified, maintain some of the neuromuscular adaptations of training throughout pregnancy, making it easier to return postpartum (when appropriately ready).

*It is worth noting that pelvic floor dysfunction and diastasis recti are a concern for female runners. Do not push through discomfort or leakage. Include a diligent strength training program as part of your prenatal routine to offset these risks. 

Listen to Your Body

It sounds so cliche, but this is true. Ultimately, the best guide is your body – runners vary in terms of their fitness level and desire to train throughout pregnancy, and then each pregnancy will vary. Listen to how you feel: don’t resign yourself to just short, easy runs if you feel good, but don’t force a workout if you have awful morning sickness, experience joint pain, or just would really rather take a nap.

It is important to add some caveats. Speak to your OB first about exercise during pregnancy. Do not do hard workouts during pregnancy if:

• You did not do them before pregnancy – now is not the time to introduce a new stimulus 
• You experience pelvic floor discomfort or urinary incontinence (leakage) while running
• You experience discomfort or pressure while running (or running faster)
• You experience bleeding while running
• You have complications or a medical reason that contraindicates hard workouts 
• Pain in your low back, knees, or other areas arises as your gait alters

Play to Your Strengths

Every runner has her favorite workouts and her strengths. Some thrive at tempo runs, while others enjoy intervals on the track. Logic may suggest some workouts are better during pregnancy than others, but ultimately coaching deals with the individual runner. The workouts that feel best for you are ones you do during pregnancy. Most likely, you will likely gravitate toward the workouts that you excelled at pre-pregnancy.

For example, some coaches will say that hill repeats are the ideal running workout for pregnancy. It is true that hill workouts minimize the impact on the joints and pregnant runners can benefit from lower impact. However, hill repeats can also spike the heart rate or just feel hard for some runners. (Trust me, running up any incline is hard when pregnant). So this workout will benefit some while be too challenging for others.

Personally, I thrive in tempo runs, short fartleks, and progression runs. Intervals are harder on my body and hill repeats are challenging for me. This knowledge of my personal strengths informed workouts during pregnancy: I stuck to steady state runs, tempo runs, and short surges. But this was me; again, what matters is the individual runner.

You might love intervals on the track. Modifying the intensity and extending rest intervals (see below) will enable you to adapt those workouts as your pregnancy progresses.

Thoroughly Warm Up Before

Every runner will benefit from a warm-up consistently of easy running and dynamic stretches before a workout. For pregnant women, thorough warm-ups are even more vital. Your gait will slightly change as your bump grows and you might feel tighter in different areas. Too much tightness can leave you prone to injury, so a thorough warm-up is necessary to loosen up tight muscles and reduce injury risk.

Give yourself at least one mile (~10 minutes) to warm up. You might find you need up to 20 minutes. It’s better to extend the warm-up and do a shorter workout than to rush into the workout.

Be Flexible within the Workout

Your body is temperamental during pregnancy. Some days, running will feel fantastic – while other days, you will feel exhausted or unwell. You cannot always predict those days until the run begins (or even until you complete your warm-up). Be flexible if your hard workouts. If you need, scale back the intensity or lengthen your rest intervals. If you start a workout and don’t feel great, don’t force it; try again another day.

You also want to adjust based on the weather. If ice or slippery conditions are present, opt for the treadmill or indoor track, do an easy run, or skip it altogether. If the heat and humidity are high, modify your effort to prevent overheating. 

Modify Your Effort

A general rule of thumb is to stay below 90% of your max heart rate. Some studies found that working above 90% of max heart rate temporarily decreased blood flow to the fetus in some women. For most runners, this is slightly harder than your lactate threshold (hour race pace) – meaning that most tempo runs and intervals at a hard (not all-out) effort are perfectly safe.

Since your pace slows as your pregnancy progresses, use your effort as a cue. If your breathing is so labored that you are gasping for breath, you may want to scale back. Don’t dip into the well and give maximum effort in a workout. Many women find that their body prevents them from working this hard, but simply be mindful of your effort levels.

As your pregnancy progresses, your paces will be slower at the same effort level. There is no pregnancy pace conversion chart. Women slow at different rates, but inevitably you will run slower. Focus on your breathing and perceived effort to guide you, rather than your watch.

The overall volume of harder running will be lower as well. In a typical pre-pregnancy tempo run, for example, you might cover 5-6 miles at tempo pace. During pregnancy, this will be scaled down to 2-3 miles. 

You can also modify the intensity by reducing the number of hard workouts you do per week. Since your recovery rate is slower, it will take longer to recover from a hard workout. Spacing out the days between hard workouts will aid in recovery and prevent you from feeling too fatigued. For example, if you do two hard workouts plus a long run each week before pregnancy, you might opt to only do one hard workout per week during pregnancy. 

Lengthen the Rest Interval

Every workout has three components: intensity, duration of work interval, and recovery intervals. You can adjust each of these to alter the intensity of the workout. During pregnancy, when you fatigue more easily and want to keep your heart rate and breathing under control, you need to add more rest. Increasing the duration of your rest intervals will scale the intensity of the workout.

For example, if you typically run 3-minute intervals with a 2-minute rest, lengthen the rest to 3 minutes.

The same approach can be applied to tempo runs. Instead of doing a continuous tempo run, break it into intervals with rest breaks in between. Rather than running 30 minutes continuous at tempo effort, run 3 x 10 minutes at tempo effort with a 2-minute jog in between each interval.

Adjust Day by Day

Some days, you will feel fantastic. Other days, you won’t feel too great. At one point, a week will come where your exercise ceiling is noticeably lower. Be willing to adjust a workout, turn it into an easy run, or bail altogether if you aren’t feeling great that day. Listen to your body – your body is smart, especially during pregnancy.  

The weather factors in significantly to your workout. If it is a hot and humid day, pushing yourself might not be the most prudent choice, as your heart rate will spike more quickly and your core temperature will increase more.

But as with any run – you never know how a workout will go until you try!

You should also know when to scale back for the reminder of pregnancy. No run should be so tiring that you require a nap immediately after. Observe how you feel after runs and make continual adjustments.

Sample Workouts for Pregnant Runners

Steady State Runs: Steady state runs are done at an effort best described as a “moderate push.” They are faster than easy runs, but not as hard as tempo runs. For many runners, this is marathon pace or slightly faster. Warm up for at least one mile, then run anywhere from 20-40 minutes (2-5 miles, depending on your fitness level) at a moderate effort, followed by a cool down. (Outside of pregnancy, a normal steady state run is 25-60 minutes

Surges: Surges are short bursts inserted into the middle of a run. During pregnancy, they allow you to push the pace without going anaerobic. Surges are great for maintaining leg speed during pregnancy. Depending on your fitness level, incorporate 8-12 x 30 second surge, 60-90 second easy jog into the middle of a run.

Cruise Intervals: Cruise intervals are a twist on the traditional tempo run. Cruise intervals are done at approximately 10K race effort (the faster end of your tempo pace range) with short rests in between. Whether you are pregnant or not, you want to keep the intensity in check – this should feel challenging but smooth and in control. These intervals last 3-8 minutes in duration, or about ½ mile to 1 mile for most recreational runners, with 1-2 minutes of recovery. A sample cruise interval workout is 4-5 x 5 minutes at 10K-15K pace with a 2 min recovery jog (plus warm-up and cooldown).

Quite simply: there is no overarching prescription for pregnant runners. You do not cease to be an individual when you conceive; it still matters to coach runners individually, even when pregnant. Be prudent about taking care of your body, listen to its signals, and run what feels comfortable (not what you feel you should be doing) during pregnant – including modifying hard workouts if you so wish. 

What about racing during pregnancy? You can do it – read more in this post on racing during pregnancy.

Linking up with Coaches‘ Corner! 

Did you do hard workouts during your pregnancy or stick to easy runs?
How do you modify a workout if needed?