Why You're Running Slow

Here are 5 sneaky things that might be slowing down your runs.


By Megan Harrington


Have you ever gone out on a run and found it tougher than usual? All runners have days when the miles feel hard, but if your slow-down becomes a pattern, it might be worth taking a second look. The following 5 things might be keeping you from reaching your full training potential - read on for tips on how to turn things around!

1. Training too hard on easy days. Do you run every mile as fast as you can? Instead of helping you get fitter, this strategy might be backfiring. In order to make training adaptations, you should strive for pace variation. This means that some runs are super easy (you should be able to speak in short sentences) while other runs should feel difficult.

Avoid running hard two days in a row - your muscles need a chance to rest and repair themselves.

2. Low iron levels. All runners, but especially women runners can be at risk for iron-deficiency anemia, which means your hemoglobin levels are lower than normal. Anemia can cause fatigue and shortness of breath - two things that will be sure to slow down your run. If you don’t officially have anemia, ask a doctor about checking your ferritin (or iron storage) levels. Some runners experience a drop in performance with low ferritin levels, but don’t have an anemia diagnosis. But before you take matters into your own hands and start loading up on iron supplements, always consult with a medical professional.

3. Dehydration. During tough runs, you may lose 6-10% of your body weight through sweat. If you don’t drink on the run, you could risk dehydration. And according to the National Center for Biotechnology Information, physical performance can be negatively affected when you lose just 2% of your body weight through dehydration.

What does this mean for you? Drink up! To measure how much fluid you lose, weigh yourself nude before and after a 60-minute run. For example, If you lose two pounds over the course of the run, it means you need to replace 32 ounces of fluid per hour.

4. The weather. Higher temps = dehydration, increased heart rate, and reduced blood flow to your muscles. During a hot summer run (75-90 degrees), the average heart rate will increase by 10 beats per minute (more if it’s humid). That will make running feel a lot harder. And when you add dehydration, it’s no wonder summer running can feel like a slog. To beat the heat, run early in the morning or late at night, choose shaded routes whenever possible, or head indoors to a treadmill. Conversely, if you head out for a run in freezing temperatures, your muscles might take longer to warm-up, leading to a slower pace, especially in the early miles. To run at an optimal pace, the sweet spot for temperature is around 45-65 degrees, although each runner is different!

5. Not having a purpose for every run. If you want to improve as a runner, each workout should have a goal. Some days the purpose of a run might be to simply run easy and enjoy the miles, but on other days, you may need to focus on increasing endurance or dial in on a specific pace. Having a goal for each run will keep you motivated and on task.

Are you guilty of any of the above? If so, it’s not too late to make changes and add some pep to your step. You’ll be cruising through the miles in no time!

Megan is a writer, RRCA certified running coach, and new mom living and training in rural upstate New York. She competed in DIII track and cross-country at Wesleyan University and now focuses on the half-marathon and marathon distance.

Main Photo Credit & Second Photo Credit: lzf/; Third Photo Credit: KikoStock/; Fourth Photo Credit: Maridav/

May 1, 2019


May 1, 2019


May 26, 2019


Jul 3, 2019

I’m 54 and just figured some of this out! Great Info!!