You head out the door for an easy run. Same route, same pace, same plan as always. But something feels off. Your legs feel heavy, your breathing laboured. A run that should feel smooth and controlled suddenly becomes work.

…don’t panic, as less-than-optimal easy runs often happen …

First of all, don’t panic, as less-than-optimal easy runs often happen over the course of a training cycle. However, it’s important to determine whether sluggish easy runs are just an obstacle to push through or if something is amiss in your training.

To help you find out, we consulted two run coaches and compiled a checklist of seven reasons why you might not feel your best on an easy run. Plus, what to do when you’re not operating at 100 percent.

1. Are You Running Too Hard?
Running too fast will turn an easy run into a hard one every single time. “Easy runs aren’t about pace,” says New York City-based certified run coach, Kai Ng. “They’re all about effort.” Going too fast is often unintentional, especially in social settings, like run clubs. However, learning to keep your effort in check is crucial to benefit from the aerobic effort of an easy run.

What to do: Run at a conversational pace, which means you should be able to speak in full sentences. If you can’t hold a conversation, it’s time to slow down.

2. Are You Recovering Enough Between Hard Workouts?
Sometimes, an easy run just never clicks. You get through the first few kays expecting to shake off the early sluggishness, but it actually lingers through the entire run. This is often due to cumulative fatigue.

“Every run we go on, we tend to think it exists in this random silo all by itself,” says Alabama-based certified run coach Alex Morrow, founder of Resolute Running. But it doesn’t.

Cumulative fatigue is primarily a muscular issue, so easy runs following races, hard workouts, or strength training sessions can bring on a heavy-legged feeling. “It’s like your muscles aren’t able to fire,” says Ng. “It feels like you push off and you’re not going anywhere.”

Both coaches say it’s important to remember that cumulative fatigue isn’t necessarily a bad thing, in moderation. If you just crushed a tough workout the day before and your easy run feels less than optimal, that’s okay. Giving your body a chance to run on tired legs can help build race-day resilience.

However, if you can’t shake off sluggishness on every single easy run, then it may be time to adjust your training schedule.

What to do: Most times during the run, Morrow encourages his athletes to slow down slightly and get through the discomfort. But that doesn’t mean forcing your way through symptoms like knee or ankle aches. Pain in specific areas of the body is different from general fatigue, and overlooking those signals could result in injury.

If you’re continuously sluggish on easy runs, prioritise recovery. Focus on quality sleep, eating healthy, and spacing out your quality efforts. Many of our marathon training plans include just two quality efforts per week, each separated by two or three days of either easy running or complete rest, which is by design, so your body has time to recover.

3. Are You Eating Enough Carbs?
While cumulative fatigue feels like heavy legs, having low glycogen stores feels a bit more like you’re just running on empty. “You just feel flat and like you don’t have any energy,” Morrow explains.

Glycogen is the main fuel source your body uses to power through runs. Running too often without replenishing glycogen (via carbohydrates) can wipe out your body’s supply and, therefore, leave you without enough fuel to recover and perform again.

Not eating before an easy run can contribute to this issue, Ng explains. Skipping fuel after a run can also affect the next one. Runners who take in lots of ultra-processed foods, which increase inflammation, have a tougher time recovering as well.

What to do: You can avoid feeling completely drained by eating before and after your runs. Before you set off, prioritise easy-to-digest carbs, Ng recommends fruit and toast, to top off your body’s fuel.

After your runs, take in a combination of carbs and protein, with a snack like a slice of toast with peanut butter or cottage cheese and granola, to kickstart your recovery and begin refuelling your body’s energy stores.

If optimising your fuel intake doesn’t do the trick, allow your body more time to naturally replenish glycogen by adding more recovery days between quality runs, as mentioned above, while still making sure you’re eating carbs and protein.

4. Are You Drinking Enough Water?
Fuelling isn’t just about what you eat surrounding your runs; it’s also about daily hydration.

Morrow explains that even slight dehydration can negatively affect performance. “If your body is just 1 percent dehydrated, there’s an impact on physical performance,” he says. “Two percent, and it becomes noticeable.”

Runners often experience a higher-than-normal heart rate and poor heat regulation, which feels like you’re giving out more effort running the same easy pace you normally do.

What to do: Morrow’s rule of thumb is to drink about half your bodyweight in ounces of water per day. Short, easy runs generally don’t require midrun water breaks, but carrying a small bottle to sip can help battle dehydration, especially as outside temperatures increase in the summer months.

5. Are You Getting Enough Sleep?
Sleep affects nearly every other internal factor on this list, but it’s worth calling out on its own because it’s one of the most powerful (and fixable) elements of your training.

Essentially, your body repairs and rebuilds itself during sleep. Not getting the correct amount slows down recovery, allows fatigue to build, and results in a decline in performance. “You’re just not going to be able to work at maximum potential without good sleep,” Ng says.

What to do: Remember, having a bad night’s sleep every so often isn’t a big deal, as long as you’re aiming for the recommended seven to nine hours of shut-eye every night. However, if this becomes a regular occurrence, adjusting the time of day you run could help your body establish a more productive routine.

For example, if you’re constantly forcing your way through sluggish runs at 5am, your entire day, including your easy run, may feel better if you move that run to 6pm. Basically, your body thrives on routine, and switching yours up to something more manageable may lead to stronger runs. “Whatever that ideal [routine] is for you, your physical performance will probably match that,” Morrow says.

6. Are You Stressed or Anxious?
Not all fatigue is physical. Stress, whether from work, relationships, or life in general, can make runs feel less enjoyable, harder to focus on, and more draining. “Sometimes stress is just back there [in your mind], and you’re carrying that weight with you unintentionally,” Morrow says.

What to do: Identify the source of your stress and address it when possible. Solving issues that cause tension is easier said than done, but identifying your stressors is a good first step. For example, do you have a looming work deadline? Are you busy running your kids around this time of year? Are you feeling anxious about a disagreement you had with someone? Even issues that seem small can affect your runs.

If running ends up causing you more stress, then it might be time to reevaluate your overall training expectations. For example, ease up on your schedule by taking extra time off so you can focus on your life outside of running for a bit.

7. Have You Checked Your Surroundings?
Even if you optimise all of your body’s internal components, stepping outside on a hot and humid day could completely change your easy run.

“Your body always wants homeostasis,” Ng says. That means abnormal heat, cold, or humidity force your body to work harder to regulate its internal temperature, which makes it feel more difficult to maintain your easy pace. Humidity has a greater influence on the body than most people think, Morrow adds, because it limits the ability to cool through sweat evaporation.

What you wear can have a similar effect: Overdressing traps too much heat, while underdressing forces your body to burn extra energy to keep warm. Even worn-out shoes can reduce efficiency and make runs feel just a tad harder, Ng says.

What to do: Adjust your training paces based on the temperature outside. In hotter conditions, expect to slow your pace by about 12 to 18 seconds per kilometre for every 3°C increase above 15°C. When it gets colder, make sure you pick the right outfit for the temperature.

At the end of the day, don’t expect to run the same pace every single day. Conditions change, and your paces will too. It’s your effort level that should remain constant through easy runs.

A Major Marker to Pay Attention to When It Comes to Difficult Easy Runs
Before you start self-diagnosing potential issues because one single easy run doesn’t feel great, turn to heart rate variability (or HRV). A lower-than-normal HRV reading can signal that your body is under stress, making it an effective tool to determine if there’s actually something wrong, and your running watch likely already measures it.

“A low HRV isn’t the cause of a bad run,” says Morrow. “It’s the guiding [metric] that lets you know what’s happening in your body.”

HRV won’t tell you exactly what’s wrong, but it does a good job of alerting you when a problem could result in a less-than-optimal easy run. For example, a low HRV reading can signal an oncoming illness even before you experience physical symptoms. It’s also negatively affected by poor sleep, overtraining, or a number of other internal factors, a majority of which show up in our checklist.

The Bottom Line
Easy runs won’t always feel 100 percent, and that’s okay. The key is listening to your body and responding to those signals when necessary.

If your easy runs continue to feel like a drag after about a month or so of trying the solutions above (some take more time to adjust to than others), something more serious, like undiagnosed illness or hormone imbalance, could be to blame. In that case, seeking the care of a medical professional is the best course of action.

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