Why Is My Heart Rate High On Easy Runs: 6 Possible Reasons

If you find that your heart is racing even on those low and slow runs, there may be a perfectly reasonable explanation. Before you fall down a scary WebMD hole to nail down the reason for an elevated heart rate even though your fitness level is good, a high heart rate may boil down to something as simple as not enough sleep. 

Below, I have compiled a list of 6 reasons why your heart rate monitor is showing an elevated heart rate on your slower pace runs and simple solutions to fix the problem. 

1. Weather Conditions

Something as simple as changes in the weather can make a big difference on your runs. Running on a perfect 75 degree sunny day is often much more manageable than running on a 90 degree summer day – but you already knew this. 

Slight fluctuation in the heat, as well as humidity, makes your body work harder to cool itself down. When the heat and humidity rise, your body shifts into overdrive to help cool itself down, which can lead to your chest strap or watch showing your maximum heart rate.

Solution: Keep yourself cool! Invest in a cooling cloth to drape on the back of your neck, pack some ice water into your water bottle or hydration pack, or just splash some cool water on your face. It’s important to know when to take your running session indoors if the temperatures are just a little too high for an easy run. 

2. Dehydration

 When your body is dehydrated, your heart has to work a little harder to pump blood throughout your body, leading to max heart rate levels.

Dehydration can happen if you are running after a night of partying, or you just aren’t getting enough water throughout the day. Be sure to take in enough water before, during, and after your runs. 

Solution: Taking in enough water is something you should strive for throughout the day, not just at the end of your runs. Even though the weather is cooler, hydrating is just as important!

3. Not Enough Sleep

More often than not, performance issues boil down to lack of sleep. To ensure that your body is up to the challenge, you must get good restful sleep each night. Without enough sleep, your heart rate can climb up to 10 extra beats per minute while you run. 

Solution: For many, getting enough sleep is easier said than done, especially if you have a brain that likes to kick into high gear the moment your head hits the pillow. 

On average, runners need around 9 hours of sleep to perform at their peak. If you struggle with restful Z’s, I suggest setting a sleep schedule, taking a warm lavender bath an hour before bedtime, and keeping your phone slightly out of reach!

4. Stress

A high level of stress can also cause your heart to race, even if your runs are slow and easy. I am certainly guilty of this. When my brain shifts into a meditative state as I run, my brain likes to cycle through everything that stresses me out. Keeping your brain clear of distractions is key to lowering your heart rate. 

Solution: Clearing your mind of stress is just as tricky as getting enough sleep! The key is to keep your mind distracted. Load up your playlist with some of your favorite songs, or go running with a friend to help keep the conversation light. 

If you still find that your mind wanders while running, loading up an audiobook or a podcast is a great tool to keep your mind off of your problems.

5. Overtraining

If you have pushed your body past its limits, it will cause your heart to work overtime. If you get enough sleep, are stress-free, and are hydrated to the brim – your elevated heart rate may be a symptom of overtraining and too much cardio/aerobic exercise.

While overtraining causes your heart rate to climb while running, it’s more noticeable when you’re resting. If your resting heart rate is also high, it’s time for a break. 

Solution: Taking a little bit of a break from training may be difficult (especially if you see noticeable progress), but it’s a necessary evil. Taking a few days off from running is a great way to give your body a break. 

Engaging in a little bit of yoga or other low intensity workouts on those easy days is a great way to keep your body active while doing something that will show a lower heart rate.

6. Difficult Terrain

This is a no-brainer. If you are running a particularly hilly trail, your muscles will need to work a little bit harder than when running on a flat sidewalk. With more muscle engagement comes a higher heart rate as your heart sends blood to the affected muscles. 

Solution: No rule says you have to run up that steep hill. If you want to keep your heart rate low, lower the effort level as well; there is no shame in simply walking up or down that hill at an easy pace.

When To See A Doctor

More often than not, an elevated heart rate when running is no cause for concern. However, if you are ever experiencing other symptoms that include excessive fatigue, chest pain, lightheadedness, or fainting, it may be time to get checked out.