Calf Cramps: Muscle Fatigue or Missing Electrolytes?

Have you ever experienced calf cramping during a run, particularly late into a long distance race?

Unfortunately, I have experienced cramps during three out of my twelve marathons, and there's really nothing more frustrating when it happens.

Because if you have experienced this too, you know that there's no going back once it starts. 

But as a physical therapist and run coach, I don't want you to automatically assume that every calf cramp means you need more salt and potassium.

Your calf cramping could actually be a sign that the demands of of your run could be exceeding the current capacity of your body.

One of the biggest clues is WHEN the calf cramping happens.

If your calf cramps early or after a particularly hard effort…

I'm thinking more about muscle fatigue and your current training capacity.

For example, if your calf starts cramping during or immediately after:

• A hill repeat
• An interval workout
• A faster-than-usual pace
• A hard surge or finishing kick
• A workout that is simply more demanding than what you've been doing

…it's likely not because you're suddenly low on electrolytes.

It may be because your calf was asked to produce more force than it was prepared to handle.

For instance, if you were cruising along easily and then your calf cramps during your fourth hill repeat, that's different from cramping at mile 22 of a marathon.

And the same thing can happen when you're building mileage.

You might be able to run 8 miles comfortably, but if you've only been training for 8-mile runs, your calves may not yet have the capacity to handle 15, 20, or 26 miles even if your cardiovascular system feels like it could keep going.

Research on exercise-associated muscle cramps supports the idea that neuromuscular fatigue plays an important role in cramping, rather than cramps being caused solely by dehydration or electrolyte loss.

So what can you do about it?

Strength train your calves!!

They are one of the most forgotten muscle groups, but the most important for long distance recretaional runners! 

Especially if you're training for a long-distance race, I'd recommend building in some version of consistent single-leg calf raises throughout your build.

But what if the cramping happens later in your run?

If you're deep into a long run or race, there could be multiple things going on at this point. 

You may simply be reaching the limits of your muscular endurance because your body isn't adequately trained for that distance.

But if it's a hot, humid day and you're sweating heavily, fluid and electrolyte losses become much more likely.

Some clues that your hydration/electrolyte strategy may need some attention include:

• You're running in significantly hotter or more humid conditions than you're used to.
• You're a heavy or salty sweater.
• You're losing a substantial amount of body weight during a long run.
• You're also experiencing significant thirst or other symptoms of fluid depletion.
• Your hydration and sodium intake are exactly the same regardless of the weather or duration of your run.

This is where I want to be careful about giving a blanket recommendation like “you need more electrolytes.”

Your needs are going to depend on things like the weather, humidity, duration of the run, intensity of this particular workout, sweat rate, and your individual losses.

So electrolytes do matter, and although they aren't the only reason for muscular cramping, it is important that you increase your amount of water and electrolytes with respect to the run you're in. 

So, what should you do?

If it's a consistent problem, then I'd be sure to address both the strength and the electrolyte/hydration piece of training.

This can look like:

1. Strengthening your calves consistently. Ideally 2-3x/wk during training.
Single-leg calf raises are a simple place to start. Progress the resistance or repetitions as you get stronger. Eventually adding in plyometrics.

2. Build your running gradually.
Your cardiovascular system can sometimes feel ready for more before your muscles and connective tissues are.

3. Practice your race fueling and hydration.
Don't wait until race day to figure out what works. There's plenty of options for products out there that can help you maintain ideal fluid balance throughout your runs.

4. Adjust for the weather.
A hydration strategy that works beautifully on a cool morning may not be enough when you're running for hours in heat and humidity.

5. Pay attention to the timing of your cramps.
That information can actually help you figure out what your body is telling you and whether its a muscluar fatigue issue, hydration/electrolytes, or both.

Either way, this is a treatable issue.

If you're looking for exercises or ways to improve your overall strategy with run training, then shoot me a reply and we can talk about it! 

If you're a newer runner and would like a clear pathway into run and strength training strategies to build your capacity safely, then I made my Run Ready Roadmap specifically with you in mind. 

We're almost to fall running!! In my opinion, the best season of running there is. 

Happy running,

—
Dr. Erin Kennedy Dalisay, PT, DPT, OCS
Doctor of Physical Therapy & Run Coach