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Why is My Running Pace Getting Slower? (Top 10 Reasons)

Why is My Running Pace Getting Slower? (Top 10 Reasons)

Running is a fickle thing. One day you can be feeling great, sitting on the proverbial mountain top, and the next you mysteriously feel sluggish and in the dumps. If you’re concerned about your running pace getting slower, make sure you’re not simply having an off-day.

Everyone, and I mean everyone, has days here and there where they simply feel slow and can’t manage the paces they normally can. But if you string together three, four, five off-days of slower running in a row, then it’s time to run a diagnostic and get to the bottom of what’s going on.

Another element to clarify is that it’s common for your running fitness to plateau if you’re generally running the same types of mileage and intensity each week, but slowing down despite training consistently is a warning that something is off. But have no fear! We have you covered. We’ll get to the bottom of this and have you back on your game—back on the mountaintop—in no time at all.

Top 10 reasons why your running pace is getting slower:

1. Not Getting Enough Sleep

The effects of sleep deprivation are sneaky. One or two bad nights of sleep aren’t going to derail your fitness, but if you are consistently getting less sleep than you were prior to noticing your slow down in pace, this could be your problem. I encourage you to keep a sleep log and add up your weekly sleep hours and monitor how you feel generally.

Everyone is unique with respect to how much sleep they need to optimally train. I’m a seven hour a night guy. If I develop a pattern of anything less than that, it catches up to me and my performance suffers.

Try bumping up your sleep an hour per night to see if it helps. But give it a few weeks before you bail on this! It takes time for energy stores to replenish from sleep. Giving up one hour a night might feel like a big sacrifice, but swapping out one hour of Netflix or early morning coffee time might be all it takes to get the engine burning hot and get you back to the running pace you desire.

2. Lacking Nutrients

Food is fuel and it needs to be treated that way. Have you loosened the reigns on your diet lately? Have you developed any new habits in this area that you weren’t doing before? Did you start a brand new diet such as ketogenic or vegan diets? It’s possible you might not be getting all the nutrients your body requires.

If you think your diet might be a contributing factor, consider using one of the many phone apps for tracking your meals and nutrition. is one that has an option that focuses on getting healthy, not just losing weight! However, if you’ve suffered from any type of eating disorder, do not worry about tracking calories if it’s a trigger for you.

Instead, consult a professional nutritionist who can work through your dietary needs in a conscientious manner. For the rest of you, keeping track of what you’re putting into your body and monitoring subsequent energy levels as you trend towards more healthy eating habits might be just the thing to get you back on track.

3. Too Much Stress

What’s going on outside of running? Are you going through a particularly difficult time at work? Did you break up with a significant other? Is a family member’s health weighing on you? I’ll never forget how I felt on my runs during graduate school final exams. I’d be studying non-stop, worried sick about the test, and then go try to run but barely be able to muster a slow trot.

Nervousness, anxiety, worry, and stress will all zap you of your physical and emotional strength.

Sometimes there is nothing we can do to avoid stress. I couldn’t NOT take my final exams. But if you can identity the stressor, and see the light at the end of the tunnel, then you have good reason to believe that your running should rebound once your life goes back to normal. In the meantime, go easy on yourself!

4. Weight Gain

I think most people are pretty attuned to fluctuations in their body weight. It’s hard not to notice; you feel the extra chub rolling over your belt, you can see your cheeks looking a little more full in the mirror, you notice your quads filling out your jeans. Now, let me be clear, there is nothing wrong with weight fluctuation.

Everyone experiences it. I’m at my leanest about 2-3 weeks out from a big race. Then, after the race, I tend to put on 5-10 pounds as I relish in all the post-race indulgences.

That said, if you are putting on weight during your training cycle, it’s likely that you will slow down. Five to ten pounds of extra weight on your body is five to ten pounds of extra weight! It’s something to be conscious of. It’s important, however, to note that less is not always more when it comes to weight. It’s dangerous to restrict calories and operate in a deficit.

Your body needs its fuel. But be sensible, try to cut out the junk-food to once again find your healthy equilibrium.

5. No New Stimulus

One of the fundamentals of building running fitness is the stress, adaptation, strengthening cycle. You run hard, you break down your muscles, and they adapt and get strong as they recover from the workout. Here’s a question: when was the last time you felt sore? If you can’t remember, that probably means you are way too settled into a routine.

If you only ever do the same four mile loop, at the same pace you always run, then you are not going to get any faster. And honestly, you can get slower. When you started the routine, it was probably working for you. It was new, it was challenging, you were adequately stressing your muscles, but eventually your body adapted to the stress and stopped reaping the rewards of a new stimulus.

To combat this sort of training malaise, start integrating different types of workouts. Speed work at the track, integrating hilly terrain, tempo pace running; maybe start racing more and pushing your pace! Even simple dynamic movements at home can be really helpful to trigger muscles you don’t typically use: box jumps, lunges, jump rope, etc. 15 minutes a day, three days a week, can do wonders!

Mix things up with a basic strength routine for runners:

6. Iron Deficiency

Anemia, especially in women, is not as rare as you might think. I suffered from anemia in high school. I was totally baffled by why my 5k races times in cross country were a minute to two slower than normal. My coach recommended I get my bloodwork done, and sure enough, I was anemic. I quickly changed my diet (let’s be real, my mother started cooking iron-rich foods) and I started taking iron supplements.

Within 3-4 weeks, my 5k times dropped back down, just in time for the State meet. Whew! If you are feeling mysteriously lacking in energy, if the well feels dry, and you can’t put your finger on the problem, it’s worth a visit to the lab to get a blood panel done. It’s always a sigh of relief, even if they don’t find that you’re anemic, to know that your levels are within those normal ranges.

7. Age

I hate to say it, but how old are you? Age is one of those markers that people go great lengths to avoid reckoning with. If you’ve been doing the same routine for years and you’re starting to slow down in your 40s, 50s, or 60s, I’d say age has to be one of the contributing factors.

Speed is one of the first things to go as we get older. You might still have all the endurance in the world, but as your strength declines, so does your speed. If your think your age might be playing a part in your slow-down, you might want to consider upping your strength work. Strong muscles will prolong your ability to run fast as well as avoid injury, which becomes a bigger and bigger obstacle as you age.

8. GPS Error

Do you use a GPS to track your pace and distance? Have you gotten a new cellphone or GPS watch lately? This might be something to consider if you have. GPS technology is getting more and more accurate with each passing year. There’s an unfortunate chance that maybe your last GPS unit or phone was, how do I put this…generous?

So it might not be that you’re actually slowing down, only that your GPS is showing you a more accurate measurement of how fast and far you’re running. I have a Suunto GPS watch that always hits the mile mark about 10-15 seconds before my running partner’s. That’s a significant deviation. I just hope that mine is the accurate one. Otherwise, my pace per mile is actually 10-15 seconds slower than I thought!

9. Not Replacing Shoes Often Enough

As shoe technology improves, the cushioning and propulsive qualities of the midsole are becoming more and more pronounced.

Old school runners would scoff at this and tell you how they used to run just fine in running shoes with soles made from waffle irons, but if you’ve paid any attention at all to the new Nike Alphafly Next% shoes that many of the elite marathon runners are using, they are reported to provide a 4-6% bump in performance!

Your shoes are most responsive and efficient within the first couple hundred miles. If you’re pushing them 400, 500, 600 miles and beyond, you’re almost certainly going to be sacrificing some speed. If you’ve been slowing down, but only slightly, your fix might be as easy as heading into your local running shop for a new pair of shoes.

10. Over Training Syndrome

On a scale of 1-10, how hard have you been training for the last 6-12 months? Have you been pushing more intensity, more volume, and being lackadaisical about your recovery? It’s quite possible to train so hard that you body just throws up its hands and says it won’t do it anymore.

OTS is typically found in elite level athletes but that’s not always the case. OTS is usually paired with insufficient sleep; a real 1-2 punch.

It’s important to stay within yourself and not train so hard that your body never catches up. I’ve found that training really hard will provide great short term gains, but if left unchecked, it will come back to bite you in the long run. Remember that every runner handles the training load differently.

There are world-class marathoners that train vastly different; some might run 60 miles per week while some might run 160 miles per week. If you’re trying to follow someone else’s training program, especially someone who’s fast and more experienced, you might want to reconsider. I’d recommend hiring a coach with experience and great communication skills, one that will listen to your feedback and hold you accountable to a plan.

If you can’t hire a coach and you’ve been receiving declining returns from very hard training, it might be time for a reset. I’d prescribe two weeks completely off, then start again with a very slow training progression where you only increase your mileage 5% per week. And remember, more isn’t always better! The goal is to feel healthy, fit and strong, not tired, worked, and taxed.

Final Thoughts

There you have it! Ten reasons why your running pace might be getting slower. Hopefully I identified something with a quick fix, one you can implement today and get back to faster running immediately. If it’s going to take some time, don’t lose hope! Running is a lifestyle.

In the grande scheme of things, a temporary decline in speed is not the end of the world. Before you know it, you’ll be charging hard and feeling great once again. You got this!


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