Every run isn’t always a good run. I’m sure other runners have also noticed this. Some days, you put on your best trail running shoes and hit the ground running, but no matter how far you think you’ve come, you always seem to have a bad day where your legs feel like they’re made of concrete and you can’t find your flow.

When you haven’t done anything big to explain why you’re suddenly tired, like taking a much steeper route or going up in altitude, it can be very discouraging and feel like you’re taking one step forward and two steps back. What makes some runs more difficult than others? The truth is that it could be due to a number of different things, or even a mix of several things. In this piece, we look at six common reasons why you might feel stuck on the trail sometimes.

1. Training too much

Even if it’s been a few days since your last run, this could be because you haven’t given yourself enough time to heal. Overtraining syndrome, which might be called “burnout” in the sports world, is what happens to your body when you work out too much without getting enough rest. It can cause signs in the nervous system, the endocrine system, and the immune system. It is caused by overreaching, which is when more training leads to less improvement in performance.

If you’ve recently increased your running speed, distance, or number of runs to reach your goals, you may need to plan for longer healing times than you did in the past. Many of us have trouble knowing when our bodies are fully recovered. If this sounds like you, you might want to use a GPS watch like the Garmin Forerunner 955, which was the first watch to include heart rate variability (HRV) and training readiness scores to help you understand how your body is responding to life and training.

In addition to giving yourself more time between runs, you should also get a good night’s sleep before a run. If you go to bed late or wake up often during the night, you may not have as much energy as you should. Read our tips on how to fall asleep anywhere to help you get more sleep.

2. Dehydration

You probably already know this, but how well you stay hydrated has a big effect on how well you run, and it’s not just about how much water to bring with you. Susan Kitchen, a registered dietitian and endurance teacher who is certified by USA Triathlon Level II and IRONMAN, told us that dehydration is the main reason runners get tired.

“The first thing you will notice is that your heart rate goes up. Even if you don’t keep track of your heart rate, you’ll feel like you’re working harder than you should be. Your heart rate goes up, you feel like you’re working harder, and you start to feel sick.”

If you think you might be dehydrated, read our piece on how runners can stay hydrated and make sure to drink a lot in the 24 hours before you run. You should also avoid things that can make you dehydrated, like alcohol, too much caffeine, and saunas.

3. Nutrition

Not drinking enough water in the days before a run can affect how you feel, and nutrition is a big part of how much energy you have. You shouldn’t run too soon after a big meal because you’ll probably get a stitch or have other GI problems, but if you don’t eat enough or eat the wrong foods, you won’t have the energy to enjoy your run.

Jenny Tschiesche, also known as the Lunchbox Doctor, is an expert on nutrition. She gave us some of her best nutrition tips for runners, such as not relying too much on running gels for an energy boost, eating a wide range of veggies, and getting Omega-3s.

“Anyone who works out for a long time will be in a state that makes inflammation worse, so I recommend eating oily fish at least twice a week,” she says. Salmon, mackerel, anchovies, sardines, and herring were the best picks she gave, she said.

4. Muscle stress

A 2004 study looked at how muscle strain affects running economy in trained long-distance runners. If your legs feel like lead and you’re pretty sure you’ve been eating and drinking well, this could be why. This has to do with your muscles’ ability to store and release elastic energy. You can improve this by making your muscles stiffer.

Many of us learned to stretch before a run, but when I went to a running class with Malcolm Balk a few years ago, he told us that we should actually keep our muscle fibers tighter before a run to help with rebound energy and then stretch them out after a run. If you’ve been stretching before you run or doing a lot of yoga on your rest days and you’re finding it hard to pick up the pace, try just walking quickly for a few minutes to warm up and add plyometrics to your training. You could even try ice baths, which are used by some sports.

5. Your way of thinking

Sometimes it’s great to hit the trail at the end of a long day to clear your mind, but sometimes it just feels like an extension of a bad day at the office. An old saying says that when it comes to performance, the mind is more important than the body. Physical training is important for performance, but sport psychologist Kirsten Cooper says that as you get older, your mind may have a bigger effect on your experience than your body.

“As we get older in sports, we become more aware of pressure, and the longer we’ve been playing, the more our success and identity in that sport matter to us.”

If you’re training for something like a race, your mind could be getting in the way and slowing you down. Even if you’re just going to run a 10k after work, you might be more busy or in a bad mood, which could hurt your performance. Check out Cooper’s advice in our piece on the mental traits of top athletes. If you’re a runner, you might want to try meditation or run before work instead of after, so that your mind doesn’t have time to fill up with bad thoughts.

6. The climate

Many runners find it hard to run on icy or snow-covered trails in the winter, while sunny days seem like they were made for running. However, the truth might be a little more difficult than that.

Extreme cold can make it hard to run, but a study from 2021 says that London marathons are always run slower when it’s hot outside. Running in hot or even warm weather makes your heart beat faster, puts more stress on your body, causes you to lose water faster, and makes you feel tired. This effect is worse when it’s hot and humid, so if it’s more sticky than normal, it could be because of the weather forecast. Read our tips on how to run in hot weather, and don’t expect to keep your usual pace or distance.