By Chris Carmichael
Endurance sports are all about pushing yourself and testing your limits. Sometimes your brain has to step in and protect you from yourself, like when you bonk and your brain conjures up nausea in an effort to get you to slow down and address the problem. Other times your body skips protection and moves straight to kicking the crap out of you in a creative and painful way, otherwise known as cramping.
Muscle cramping is something cyclists deal with at all levels of the sport, yet they’re often talked about with a sense of mysticism, like there’s a cramp fairy who magically appears and zaps your hamstring just as you get up to sprint. Science offers a number of theories for the cause of cramps, two of which are particularly interesting for cyclists:
As you pedal, the muscles in your legs contract and relax over and over again in rapid succession. At some point, those muscles start to fatigue and this theory of cramping says that the muscle spindles that stimulate contraction stay or become more excited, while the inhibitory feedback from the Golgi tendon organ (a structure that signals the brain about the force of muscle contractions) becomes suppressed. In other words, the horses start to stampede and the guy holding the reins lets go. The result is a long and incredibly powerful muscle contraction that’s completely involuntary.
Overload cramps may be fitness related, meaning you may be more vulnerable to them when you are less fit. Anecdotally, novice athletes tend to experience them more than veteran athletes, and longtime athletes often get them more frequently in the early season.
For a long time, athletes have defaulted to the exertion theory of cramping, which cites electrolyte depletion, dehydration, and/or heat stress as the cause of muscle cramps. There’s a lot of anecdotal evidence to support the theory, it generally seems to make sense, and cooling down and replenishing fluids and electrolytes tends to make the cramps go away; so the theory seems like a winner. Unfortunately, the science is problematic because it’s difficult to pinpoint a consistent cause-and-effect mechanism directly related to fluid loss, electrolyte imbalance, or core temperature. More likely, exertion cramps are caused by a combination of factors arising from fluid loss, electrolyte imbalance, and heat stress.
Though the exact mechanism for exertion cramps is inconclusive, there do seem to be some distinct differences between the characteristics of these cramps compared to neuromuscular cramps. Exertion cramps provide a little warning in the form of fasciculations, those small muscle twitches you can see and feel at the skin level. Once the cramping begins in earnest, however, it can spread to muscles that are not being directly stressed. In contrast, neuromuscular cramps are localized to the muscle that’s overloaded and provide no warning.
The big question is what to do about cramping, and this is where science collides with the real world. In the real world, the pragmatic view is that cramps are caused by a combination of stresses from heat, dehydration, electrolyte imbalance, and neuromuscular fatigue. They each contribute to varying degrees, depending on the conditions and how hard you’re pushing yourself. The reason I take an “all of the above” approach is because it works: when you minimize these stresses you experience fewer cramps.
Training and Pacing: When you’re more fit and you set a pace you can sustain, you’ll delay the onset of neuromuscular cramps, and you’ll also lower the heat stress you’re placing on yourself.
Nutrition/hydration strategy: Aim to replenish at least 80% of the fluid you lose per hour, and separate your nutrition from your hydration by drinking water and electrolyte drinks while getting calories from the food in your pockets. This allows you to increase fluid/electrolyte consumption with increased heat stress, without overloading the stomach with calories, which would lead to nausea, which would then reduce your fluid/electrolyte intake.
Temperature strategy: Overheating kills performance, puts tremendous stress on your body, and accelerates the loss of fluids and electrolytes. Ice socks, dousing yourself with water, and even slushy drinks can help reduce this stress.
When cramping starts, it’s time to go to war. The cramps are caused by multiple factors, so you hit them all. As one of my coaches puts it, you don’t call in a sniper to find the one, you call in the bombers to level them all. Across the spectrum of events and athletes, the steps are the same:
Reduce intensity: back down your pace, hide in the pack, stop taking pulls. This will reduce neuromuscular fatigue as well as the heat your producing through muscular work.
Cool down: Douse yourself with water, get into a cooler environment, or go sit in the creek. But if you have to make a choice, put water in you instead of on you.
Get more fluids: If you’re drinking sports drinks and/or eating regularly during your ride, you’re risks for hyponatremia are very low. It’s far more likely that additional fluids will help alleviate dehydration and heat stress.
Get more electrolytes: Aim for 700-1000mg but be sure to consume at least 20 ounces of fluid (one water bottle) with it. For a quick fix at a convenience store, a bottle of V8 will do the trick.
Get more calories: Although caloric deficiency doesn’t seem to be directly related to muscle cramps, this is a good opportunity to achieve balanced replenishment.
Massage: If cramps have you sitting (writhing) by the side of the road, rubbing the affected muscle has been shown to be an effective way to get the involuntary contractions to stop.
The treatment for cramping is imprecise, but so is the reality of what’s causing them. And pragmatically we know that reducing the overall stress from exertion, heat, dehydration, and electrolyte imbalance is what gets athletes moving in the right direction, which is forward.
Bergeron, Michael F. Current Sports Medicine Reports. 7(4):S50-S55, July/August 2008.
Miller KC, Stone MS, Huxel KC, Edwards JE. Sports Health. 2010 Jul;2(4):279-83.
(Article originally published in Road Bike Action Magazine)