Running During Pregnancy: Guidance by Trimester

Running during pregnancy is a topic that often causes uncertainty, which may lead you to think that it isn’t advisable or safe. However, if you were a runner prior to pregnancy, and haven’t been told by a medical provider that you should stop, there is no reason why you can’t continue well into your pregnancy.

That said, there are some key physical and physiological changes that may impact running at different stages of pregnancy. Let’s cover these key changes by trimester, then provide some beneficial training strategies to help you continue to run safely and pain-free.

Read on to learn:

• General Prenatal Running Recommendations
• First Trimester Changes & Training Strategies
• Second Trimester Changes & Training Strategies
• Third Trimester Changes & Training Strategies
• Additional Resources to Support You

General Prenatal Running Recommendations

Running is perfectly safe to continue if you had been running prior to pregnancy — even long distance running. However, it is not advised to start running during pregnancy. That is because your body needs to be conditioned to handle the impact forces to minimize the aches and pains that some people experience with such a dynamic activity.

One of the most important elements for pain-free running during pregnancy is strength training — especially on one leg — so that you’re able to absorb the forces generated during impact. In other words, every time you land (when you aren’t pregnant), you must absorb roughly 4-6x your body weight. This places a great deal of stress on your soft tissues.

As weight gain increases during pregnancy, so too does the force that must be absorbed with each step. In addition, the bigger the body, the more force needed to propel it forward each step. The more you can absorb and dissipate impact forces, the less stress running will cause your joints (ankles, knees, hips, lumbar spine) and pelvic floor. Make sure to incorporate moves such as squats, deadlifts, step-ups, and lunge patterns.

Now that you understand the importance of lower body strength training, let’s look at the specific trimester-based changes and training implications.

Trimester-Specific Guidelines

First Trimester Changes

Aside from any fatigue or nausea that you may experience, running won’t feel markedly different because weight gain, and the resulting alignment shifts, have not become a factor yet. However, there are two key things to be aware of in the first trimester:

1. Potential instability: During pregnancy, hormonal changes – including the increase in the hormone relaxin – soften the joints, ligaments, and connective tissue to allow the body to adapt to carry a growing baby and to provide laxity and mobility needed to push a baby out. A consequence of this soft tissue laxity is that it often increases mobility and decreases stability. 
2. Risk of getting overheated: During the first trimester (especially the first month), it is important to avoid overheating (body temperature above 102° F), as this could interfere with the critical process of the fetus’s brain and organ development.

First Trimester Training Strategies

• Assess your stability at rest: Assess and re-assess your stability every month or so to determine if hormonal changes may be affecting your balance. For help in increasing your stability, check out these 5 moves to build lower body stability.
• Avoid high heat and humidity: Focus on hydration before, during, and after running sessions.
• Ingrain proper breathing mechanics: Learn how to perform 360° Breathing. This important for several reasons, but specific to running, it improves your cardiac efficiency (delivery of oxygen to working muscles).
• Begin pelvic floor training: Begin early to strengthen your pelvic floor (PF) so that, when you begin to get heavier, your PF tissues will be strong enough to continue to support you. Learn how to do this by practicing Pelvic Floor Activations (PFAs).

Second Trimester Changes

1. Nausea and Fatigue (typically) subside: The second trimester is often called the “honeymoon of pregnancy” because typically the first trimester nausea and fatigue dissipate.
2. Increased cardiac output: This change is pretty cool! A pregnant person’s heart pumps more blood with each beat AND beats more times per minute. This confers a cardiac advantage similar to “blood doping.”
3. Weight gain: Second trimester is when weight starts to increase. This will likely cause more noticeable changes in your running.
4. Alignment shifts: Compounding the changes caused by weight gain, the growing belly tends to pull the pelvis forward into an anterior pelvic tilt, which compresses the tissues in the lower back and increases pressure on the pelvic floor muscles.

Second Trimester Training Strategies

• Take advantage of your “honeymoon” (if it feels ok): The second trimester is often considered the time when you will feel most energetic and motivated to train. Also, remember that you do have that cool advantage of the increased aerobic capacity. So, if you’re feeling good, you can push yourself if you wish to do so.
• Use Rate of Perceived Exertion (RPE): Knowing the level of intensity to work at can be more challenging during pregnancy because heart rate is no longer an accurate gauge of how hard you are working. Therefore, it is recommended that you use a simple RPE scale of 1-10, where 1 = minimal exertion (like gentle walking) and 10 = maximal effort (like a full sprint). Generally, you want to stick to an RPE of 6-8. If you are a more experienced runner, you can push to an 8.5.
• Emphasize neutral alignment: Because greater weight gain and hormonal changes can alter your body position, you want to make sure you are maintaining neutral alignment as much during running as possible.
• Focus on lower-body strengthening: As mentioned earlier, strength is critical to absorb and dissipate impact forces. Therefore, focus your strength training on single-leg moves because running is a single-leg activity.
• Watch for signs of PFD: If you experience accidental leakage (urinary or fecal) while running, you may be experiencing pelvic floor dysfunction (PFD). This means that there is an imbalance between the loads you are putting on the body and your body’s ability to control those loads through the pelvis, creating unintended or spontaneous leakage of urine or feces.
• Use of running “accessories”: As the breasts and belly get bigger, they may become uncomfortable, but they don’t have to curtail your running. Consider doubling your sports bra and possibly using a belly support (NOT a wrap or corset). In addition, changes to your feet may necessitate an increase in shoe size. Why? Hormonal changes.

Third Trimester Changes

1. Increased Weight Gain and Alignment Shifts: The changes that began in the second trimester will be most pronounced now.  For many people, their bodies will tell them they need to lower the intensity and reduce (or stop) running.
2. Altered Running Mechanics: The pelvis widens a bit during pregnancy and, as a result, the feet get wider. This can lead to a change in your stride. Expect a shorter stride with the potential for more side-to-side shifting.
3. Constricted Breathing: As the belly gets larger, it may push into the chest area, thereby limiting how much the lungs can expand. Therefore, you might find it more difficult to take a deep breath, which may cause a change to your breathing pattern and rhythm — increasing the difficulty of running.

Third Trimester Training Strategies

• Reinforce 360° Breathing: As breathing can become challenged at this stage, you want to ensure you are expanding the ribs in all directions to maximize air intake. Be sure you have mastered 360° Breathing — learning how to expand your ribs three dimensionally when you inhale.
• Focus on lower-body strengthening: As mentioned in the second trimester training focus, continue incorporating lower-body moves, especially single-leg work to maintain your strength.
• Soft tissue care: Doing some foam rolling prior to running can help keep your tissues supple, especially when getting loaded by more bodyweight. Focus on the glutes, hamstrings, hip flexors, and quads.
• Watch for signs of PFD: If you experience any symptoms of urinary or fecal leakage during runs, this is a sign that it is best to stop running.
• Routinely “check in”: Above all else, running really comes down to: Does it feel good? If you hesitate in answering that question, then it is probably time to scale back (or eliminate) running and focus on more comfortable movements.

Your Guide to Running During Pregnancy & Returning Postpartum

Want to go deeper into trimester-specific training strategies and learn a step-by-step process to safely resume running postpartum? Grab our Guide to Running During Prengnancy and Returning Postpartum.

Want Additional Resources?

Looking for a safe & effective strength-focused workout program that can help you continue to run more comfortably during pregnancy? Explore our Prenatal Workout Programs. Just select the program that’s right for you based on your stage when starting and you’ll be guided through a structured training program to help you build strength, prepare for birth, and set yourself up for a faster recovery.  

Interested in Coaching Pre & Postnatal Clients?

If you are a health & fitness professional interested in learning how to coach pre & postnatal clients, explore our Pre/Postnatal Education & Certification for courses, resources, and community to help you build your pre & postnatal fitness expertise.