Cramping: What Causes It & How To Combat It

Cramping During Exercise Sucks!

Almost everyone has experienced muscle cramps during or following a prolonged or intense endurance exercise session.

Muscle cramps can be painful and result from spasmodic, involuntary skeletal muscle contractions.

Cramping can stop you dead in your tracks and is responsible for derailing the races of elite and amateur endurance athletes alike. Although numerous theories have been proposed to explain the cause of cramps, the exact cause of exercise-induced muscle cramps remains an open debate.

Currently, there are four primary theories to explain exercise-induced muscle cramping.

Briefly, these are cramping is caused by:

  1. Dehydration and electrolyte imbalance
  2. Altered neuromuscular control
  3. A drop in muscle pH
  4. Glycogen Depletion

This article will briefly discuss each theory, the likely hood of each being the culprit behind cramping, and conclude with how to train and eat/hydrate to stop cramps dead in their tracks:

Theory #1: Cramping Is Caused By Dehydration & Electrolyte Depletion

How Likely Is This The Main Reason Behind Cramping: Highly Unlikely

The electrolyte depletion and dehydration theory predict that exercise-induced muscle cramps occur due to the electrolyte imbalances in the blood and extracellular fluid.

Supporters of this theory argue that exercise-induced loss of body water and sodium via sweating results in electrolyte imbalances that trigger muscle contractions by causing motor nerve terminals to spontaneously discharge.

To date, most of the support for the electrolyte/dehydration theory comes from anecdotal clinical observations. Further, several recent scientific studies do not support this theory.

Nonetheless, before this theory can be completely rejected, additional studies are required.

Theory #2: Cramping Is Caused By Altered Neuromuscular Control

How Likely Is This The Main Reason Behind Cramping: Highly Likely

The altered neuromuscular control theory contends that exercise-induced muscle cramps occur due to the abnormal activity of both the muscle spindle and Golgi tendon organ.

In short, this theory proposes that exercise-induced muscle fatigue results in increased muscle spindle activity and decreased Golgi tendon activity.

This abnormal function of these two muscle-sense organs results in the increased firing of the motor neurons located in the spinal cord, which results in involuntary muscle contractions.

Evidence to support this theory is growing, and abnormal reflex activity is likely a key factor that promotes exercise-related muscle cramps.

Theory #3: Cramping Is Caused By A Drop In Muscle pH & Acts As a Protective Mechanism

How Likely Is This The Main Reason Behind Cramping: Very Likely

It is well known that prolonged or intense endurance exercise (or a combination of both) causes the environment of the muscle to become more acidic.

This is caused by a rise in hydrogen ions from the breakdown of substrate (carbs, fats, and protein) via anaerobic glycolysis/oxidative metabolism that fuels muscular contraction.

As exercise increases in duration, intensity, or both the body is unable to fuel the muscular contractions efficiently, and muscle pH begins to drop (becomes more acidic).

Supporters of this theory argue that the drop in muscle pH and subsequent cramping acts as a protective mechanism to prevent muscle damage.

Theory #4: Cramping Is Caused By Glycogen Depletion/Inadequate Blood Glucose Levels

How Likely Is This The Main Reason Behind Cramping: Somewhat Likely

Glucose and Glycogen (stored glucose in the muscles and liver) act as the main energy sources to fuel muscular contractions during endurance exercise, especially as intensities approach and go beyond 75% maximum heart rate.

The muscles and liver store enough glycogen to provide energy for muscular contraction for ~ up to two hours during prolonged, intense exercise.

If you are familiar with the term “hitting the wall,” this refers to when glycogen stores have been depleted, and blood glucose levels are low.

Both glycogen depletion and low blood glucose levels occur when the athlete fails to eat/drink adequate amounts of carbohydrates during training or racing.

While the body can break down fats and protein during endurance exercise, they are a less efficient fuel source, especially as exercise intensity increases.

In sum, supporters of this theory state that when glycogen/glucose levels become depleted, less efficient muscular contractions occur eventually leading to fatigue and muscle cramping.

How do I stop muscle cramps from occurring during races or training?

Based on the theories above here is how to stop cramping dead in its tracks:

Adequate Hydration:


  • First eat a diet high in fruits which are high in electrolytes (e., bananas).
  • During exercise lasting longer than 1 hour consume electrolyte-rich foods and beverages (i.e., gels, chews, carb/electrolyte sports drinks) to prevent electrolyte imbalances and limit the risk of hyponatremia.

Train Properly:

I’ve worked with many racers over the years who fail to train properly and without fail cramp during a race.

This usually boils down to not coming into the race with an adequate base, failure to perform anaerobic/threshold workouts leading up to the race, and not performing prolonged race pace efforts during training.

Simply put as you begin your racing reason:

  • Start with at least a 6-12 week aerobic base that consists of easy miles (below 75% maximum heart rate).
  • After 6-12 weeks decrease overall miles and incorporate 2-3 anaerobic/threshold workouts a week (i.e. 2 x 20 minutes hard at threshold).
  • Finally, 1-2 months before your goal races replace one anaerobic workout with a race pace effort lasting 1-3 hours. Yes, some of these workouts are going to hurt, but it will be all worth it when you’re riding/running strong and not cramping. Check out this article for more information.

Eat a Diet Adequate In Carbohydrates During Exercise and Throughout the Day: Read this article for recommendations

Get Your Butt In The Gym A Couple Times A Week:

Stronger muscles produce more powerful contractions and are more fatigue resistant which will help with cramping.

Contrary to popular belief endurance athletes should not perform lightweight and high reps but instead, should perform exercises with heavy weights and low reps.

This will produce more power production, more efficient pedal strokes (as it relates to cycling) and minimize weight gain in the form of more muscle mass. Need even more reasons to go the gym….read this.

Consider Supplements That Can Decrease Cramping:

Some supplements have solid research behind them demonstrating they can combat rises in muscle acidity as exercise increases in duration and intensity.

  • One of my favorites is Beta-Alanine. I won’t bore you with the mechanisms of how it works but strive to take 3.2 grams daily.
  • Sodium bicarbonate (plain baking soda) is another option at 1 gram before exercise, but I recommend trying this is training before utilizing it in a race as it commonly causes vomiting and diarrhea in some athletes.
  • Products like EndurElite's top-selling pre-workout PerformElite contains beta-alanine and other ingredients that can prevent cramps.