Now let's get started by talking about heavy legs, which is something that can be caused by training in the heat and humidity. Does that describe Bass Pro and Dogwood Canyon training right now or what?
This was something I was thinking about on Monday as I took a much-needed break from running by doing some active recovery (pool work) exercises. I had run back to back long runs on Saturday and Sunday as part of my ultra marathon training, and I was feeling the effects big time. As I finished up Sunday morning (about 20 minutes slower than usual), I told my husband that my legs felt like lead and it was all I could do to walk it in. I felt so defeated.
Thankfully, a day of rest had my legs and my mind refreshed and my Tuesday run went better than planned.
So, here's the deal... it's not a matter of IF you will ever get heavy legs but just a matter of WHEN. Especially as the temps climb up again and your training plan calls for longer runs. Which is the very reason it’s a great time to talk about it!
But there’s good news! Heavy legs are a normal part of the training process—and understanding why it happens, and that it WILL happen, can help you train smarter, recover better, and arrive at the starting line feeling strong.
So here's what you need to know about heavy legs:
There will come a point in your training cycle (if it hasn't happened already) when your legs don't feel light and springy anymore. Instead, they feel like they're made of concrete. Every step will seem harder than it should. Your pace will slow even though your effort increases, and you will begin wondering if you're losing fitness.
You're probably not.
In fact, heavy legs are often a sign that you're doing the work necessary to prepare for long-distance running.
What Do "Heavy Legs" Feel Like?
Well.... every runner describes them a little differently, but here are the most common descriptions:
Your legs feel sluggish from the first mile.
Your stride feels shorter than normal.
Climbing hills seems unusually difficult.
Easy runs suddenly don't feel easy.
You struggle to reach normal training paces.
Your muscles feel full, stiff, or fatigued.
Heavy legs are different from soreness. They aren't necessarily painful—they simply feel tired and unresponsive.
What Causes Heavy Legs?1. Training Fatigue (The Most Common Cause)
The number one reason runners experience heavy legs is accumulated fatigue. Every workout creates tiny amounts of muscle damage. As your body repairs itself, it becomes stronger. But when you're running four, five, or six days each week, fatigue builds faster than your body can completely recover. That's exactly what marathon training is supposed to do. Your body adapts during recovery—not during the workout itself.
2. Glycogen Depletion
Your muscles store carbohydrates as glycogen, which serves as your body's preferred fuel during running. After long runs or hard workouts, those stores become depleted. Without enough glycogen, your muscles simply don't have the same "pop." This is why runners often feel much better after several days of eating quality carbohydrates and allowing recovery.
*On a side note, don’t forget that your protein needs go up as you train too. With barbecue season in full force, this is a great time to view that burger as a recovery tool. Speaking of recovery…
3. Inadequate Recovery
Training breaks your body down. Recovery builds it back up.When recovery is lacking, fatigue accumulates quickly.
Common recovery mistakes include:
4. Heat and Humidity
Missouri summers are no joke, especially in the Ozarks. This is something I talk about all the time. We don't just get heat... we get heat, humidity, and hills. But with that comes humility, so that's always a plus.
Speaking of heat and humidity though, keep in mind that when the two of them rise, your heart has to work harder to cool your body. Blood is diverted toward the skin for cooling, meaning less oxygen reaches your working muscles.
The result?
Your legs often feel much heavier even though your pace hasn't changed. That's one reason summer is the perfect season to slow down, focus on effort rather than pace, and build aerobic fitness. This discipline also builds mental fitness which is a must-have for completing the race this fall.
5. Strength Training
Many runners notice heavy legs the day after strength training. That's completely normal.
Squats, lunges, deadlifts, and hill work all create muscle fatigue that temporarily affects running performance. The key is scheduling hard runs and strength sessions wisely.
6. Poor Nutrition
Your muscles need:
Consistently under-fueling often leads to sluggish, heavy legs.
7. Iron Deficiency or Illness
If heavy legs continue for several weeks and are accompanied by unusual fatigue, dizziness, or shortness of breath, it may be worth speaking with your healthcare provider. Sometimes low iron levels, anemia, illness, or other medical conditions can mimic normal training fatigue.
How Can You Prevent Heavy Legs?Prioritize Easy Runs
Not every run should be hard.
In fact, about 80% of your weekly mileage should be easy enough to hold a conversation. Remember what we learned from the tennis balls last week?
Easy running develops endurance while allowing your body to recover between quality workouts.
Fuel Before and After Running
Eat carbohydrates before longer runs.
Within about an hour after finishing, aim to include:
Carbohydrates to replenish glycogen
Protein to repair muscles
Fluids and electrolytes to replace losses
Recovery nutrition helps prepare your legs for the next workout.
Sleep Like It's Part of Training
The most effective recovery tool costs nothing. For real! Sleep is so underrated!!
During sleep your body:
Repairs muscles
Restores glycogen
Produces growth hormone
Reduces inflammation
Aim for 7–9 hours each night—and even more during peak training if possible. I will tell you from experience that getting enough sleep will pay dividends!
Don't Skip Recovery Days
Many runners think more miles always equals more fitness. It doesn't. Recovery days allow your body to absorb training. Sometimes the smartest workout is no workout at all. But, hey, if you're like me, and the thought of taking a full day off without doing anything is a stressor, hit the pool (I do aqua running several times a week) or find another low impact way to do some active recovery.
Stay Hydrated
Even mild dehydration makes running feel harder. Drink consistently throughout the day—not just during your run. If you're sweating heavily, replace sodium and other electrolytes as well.
Build Strength Gradually
A stronger runner experiences less muscle fatigue late in races. Two short strength sessions each week can improve running economy while reducing injury risk.
How to Treat Heavy Legs
When your legs start feeling sluggish:
Slow Down
There's nothing wrong with turning today's planned pace into an easy effort.
Remember:
You don't lose fitness from one easier run.
You gain fitness by staying healthy enough to keep training.
Foam Roll and Stretch
Foam rolling can temporarily reduce muscle tightness and improve mobility.
Focus on:
Calves
Hamstrings
Quadriceps
Glutes
Hip flexors
Gentle stretching after runs can also help reduce stiffness.
Walk
Ironically, movement often helps. A short walk increases circulation without adding significant stress. This is another form of active recovery. Easy walks, like sleep, are so underrated! Many runners find their legs feel noticeably better after a 20–30 minute walk.
Eat Well
Choose foods that support recovery:
Consistently eating enough is just as important as eating healthy.
Trust the Process
Perhaps the hardest part is recognizing that heavy legs don't necessarily mean you're getting slower.
Sometimes they mean you're getting stronger.
Every successful marathoner has experienced heavy legs. They're not a sign of failure—they're often evidence that you're putting in the work. The goal isn't to avoid fatigue altogether. The goal is to balance training with recovery so your body can adapt and become stronger.
And there you have it friends. As we continue preparing for this year's Bass Pro Marathon, Half Marathon, and Dogwood Canyon Trail Runs, remember that consistency—not perfection—is what gets runners across the finish line. Some days your legs will feel light. Some days they'll feel like lead. Keep showing up. Keep recovering well. Keep trusting the process. Because when race morning arrives, all those heavy training miles will have transformed into the strength and endurance you need to reach the finish line.
Happy Running!
