Cramping Myths and Hydration Truths

This is an article I wrote for ilovebicycling.com back in June when it was more relevant Northern Hemisphere summer riding.

Cramping and fatigue in general are still relatively poorly understood physiological phenomena, but every cyclist has experienced Exercise Induced Cramping, and knows exactly how uncomfortable they can be! There are plenty of myths, anecdotes, and magic cures peddled by companies and fellow riders alike, but what can the Science tell us about cramping?

What Causes Cramping?

• Cramping is not necessarily a sign of poor hydration or electrolyte imbalance.
• Cramping is not necessarily a sign of poor nutrition, poor warm-up, or poor preparation for race day.
• Cramping is not necessarily even a sign of poor fitness…
• But all of those factors may contribute to fatigue and cramping.

Exercise Induced Cramping occurs when you push yourself harder and for longer than your body is used to: ie. a combination of greater duration and greater intensity than your body has adapted for.

The current best theory for Exercise Induced Cramping is related to neuromotor fatigue: Basically, the nerves that carry signals between your muscles and your brain get tired just the same as your working muscles and begin to misfire. This neuromotor fatigue can send overlapping, uncontrolled signals to your muscles. This results in twitching, cramping, complete locking up of your working muscles or the feeling of ‘dead-legs’ and an inability to produce power.

Hydration and Electrolytes

When you sweat you lose both fluid and ‘electrolytes’, which refer to a variety of minerals dissolved in the body’s fluids and tissues, and are essential to overall function. Sodium is the most abundant electrolyte lost in sweat, and so ‘salts’ are occasionally used synonymously when talking about replenishing electrolyte balance.

Sweat is hypotonic, that is: the electrolyte concentration of sweat is lower than the electrolyte concentration of your blood. This means that when you sweat you lose more fluid than you lose electrolytes, and therefore fluid loss will be the limiting factor to performance and is more important to replenish during exertion. During activities longer than 90min, and especially endurance events longer than 4 hrs you will lose both fluids and electrolytes to sweat, and both will need to be replenished.

Studies have shown that performance is negatively affected when total body weight loss approaches -2% via fluid loss (although even this finding has conflicting evidence). You should aim to replenish fluids during activity to avoid this extent of fluid loss. A general guideline is to drink at least one bottle – 500-750 ml – of fluid per hour.

Can you Drink Too Much?

You may have heard horror stories about athletes over-hydrating during endurance events and suffering from hyponatremia, or severely low electrolyte imbalance. These instances are an extremely low percentage occurrence and most often only seen in extreme ultra-endurance events. When studying a competitive ultra-endurance population researchers found that only 0.1-4.0% exhibited signs of hyponatremia, compared with 80% occurrence of simple dehydration!

Dehydration can affect your performance during even short-duration activities and should be a far more significant consideration than over-hydrating. You have to try really hard to give yourself hyponatremia, but dehydration takes active steps to avoid.

Fluid and Nutrition

Drinking an electrolyte-fluid mix can be effective to maintain performance and avoid cramping and fatigue, but the fluid is certainly more important than the electrolytes in that bottle of mix. Mix also offers a more obvious advantage to performance: as a nutritional source of carbohydrates. Some electrolyte supplements can be low- or zero-calorie, but more common is for drink mix to contain both carbohydrates and electrolytes.

Nutrition

Nutrition is a completely different topic which I won’t tackle here, but suffice it to say that calories from carbohydrates, protein, & fats are significantly more important to performance over a multi-hour endurance event than electrolytes.

But you don’t have to choose one or the other! carbohydrate + electrolyte mixtures can be a great way to replenish both on the bike! For optimal performance, you probably need to eat more on the bike than you think!

I would suggest that if you find that drinking a carbohydrate/electrolyte mix helps you avoid cramping and boosts your performance, this is more than good enough reason to continue what works! I would attribute this, in order of importance to:

1. Fluid
2. Nutritional calories, and finally
3. Electrolytes.

So What Should You Do?

I’ve intentionally saved all the actionable advice for the end 🙂

The first thing that needs to be said is don’t worry about changing anything if you know what works best your you! Your body is very good at regulating itself: It will take in whatever you give it with very little fuss.

The science indicates it should be unnecessary to supplement salts or electrolytes as long as you eat properly leading into your cycling event. You should get all the salts, minerals and electrolytes you need from a nutritious diet, not to mention ensuring optimal performance on the bike. Longer events will require fluid, electrolyte, and calorie replacement and you can get that from any combination of solid foods, gels, or drink mixes.

How to Prevent Cramping?

• No magic cure, just expose your body to greater duration and intensity of training stimuli. ie. go harder for longer, and next time you won’t cramp as early into your event! Training in the heat will assist acclimatization to the heat, and training in the cold, to the cold. You can experience cramping in any conditions to which your body is poorly acclimatized to.
• Take care of the low-hanging fruit as part of your pre-race preparation: Ensure you are fresh, well-rested, with sufficient nutrition and hydration in the days leading up to a particularly hard event. Come prepared with sufficient nutrition and hydration for the length & intensity of the event and for the expected conditions on the day. TrainingPeaks has a fantastic guideline for basic pre-, during, and post- race nutrition & hydration planning.
• There is also a potential genetic predisposition to cramping. so… get different parents? 🙂

How to Relieve Cramps Once They Start?

• The fastest & most reliable method of temporarily easing cramps is passive stretching. Trying to stretch a cramping muscle on the bike is a good way to have a close encounter with the pavement, but if you can slow down or even dismount and stretch the affected muscle it can provide much needed relief.
• Continuing to hydrate remains important when you begin to cramp. Cooling via fluid intake will also help. However by the time cramping is occurring, hydrating and cooling probably won’t have an immediate effect. You’ll be forced to slow down first, which probably has a more direct benefit.
• Speaking of slowing down, an obvious (and often unavoidable) way to reduce cramping is simply to reduce your effort. This eases the demand on your working muscles, your heart & lungs, and also your neuromotor system by reducing the amount of voluntary nerve signalling to your muscles. This allows your entire neuromotor system to relax and recover.
• Finally, recent headlines have highlighted using pickle juice, capsaicin (spicy pepper, chili powder, etc.), vinegar, or mustard as cramp cures. I haven’t explored the evidence in-depth, but the proposed mechanism is not actually the salt in those foods, but rather that the spice/acidity of these foods overpowers the rest of the neurological system and reduces neural activity globally through your body. Similar to how biting your tongue “distracts” you from the pain of your stubbed toe.

 

Quick recommendation: VeloNews’ Fast Talk Podcast published an episode on cramping soon after I published this article. It goes over much of the same literature and discussion on cramping and hydration, with much higher production value!