September 5, 2022

Muscle cramps and how to prevent them

It’s the hottest part of the year, training and racing is in full swing, and for many cyclists and endurance athletes out there, unfortunately so are muscle cramps.

What are cramps? What causes them? And how can you prevent or treat them for your next training session or race?

We’ve asked EF Education-EasyPost medical and sport science director Dr. Kevin Sprouse and our nutritionist Spencer Miller for their advice.

What is cramping?

Dr. Kevin Sprouse

Cramping is what we call a ‘Tetanic Muscular Contraction’, it’s basically a contraction that will not relax.

Most athletes, if not all athletes, have experienced this at some point, where the muscle just locks down and it's very uncomfortable at best, can be quite painful at worst and certainly debilitating in terms of performance.

If you're on a bike and your hamstring cramps it's both painful and difficult to continue making revolutions with the pedals, so it's certainly problematic and something that everyone wants to avoid.

The action of a muscle relaxing requires energy and requires certain cellular channels to be open and closed. In other words, muscle relaxation is an active process. It requires ATP (Adenosine triphosphate - the fuel that powers muscles) or energy, and it requires certain electrolytes to trigger that process.

A lot of us think of relaxation as being totally passive, and so if you just stop doing something, why won't the muscle relax? A lot of time it's because there's an environment in which that active process of relaxation can't occur.

Spencer Miller

According to research, Exercise-associate muscular cramps have been reported to affect 67% of triathletes during or after training, so it is common for most of us to experience them at some point during your riding.

What causes cramp?

Dr. Kevin Sprouse

When you ask that question to a group of doctors or scientists you could probably get four or five, maybe 10 different answers.

And the reason for that is that is that we don't fully know, there's probably multiple things, but in my opinion there's numerous scenarios that can lead to cramping.

Some of the things that have been pointed out kind of most recently in the science are:

1. Genetic predisposition.

There's a very strong hereditary component to this where if as an athlete your parents tended to cramp and even if they weren't athletes but they had cramps at night, things like that, there's a good likelihood that you're going to have a predisposition to cramping. And the inverse of that is true, as well if nobody in your family cramps very much, you probably won't experience it nearly as often.

2. Muscular fitness

This is one that's come to light, probably more so in the last five to 10 years from a research standpoint, but a muscle that is tasked beyond what is really fit to do will eventually shut down, maybe from a protective mechanism, so in other words, if your training is consisted of a bunch of, 20, 30, 40 kilometre rides or short rides and you sign up for 100 kilometre race in the mountains, there's a good chance that on one of the climbs late in the race you're going to cramp because you're asking so much of your muscles that they're not conditioned to do it and it's thought that there's maybe a component of that this is protective whereby a muscle instead of pushing to the point that it might tear or injure itself, it just kind of locks down and says ‘Nope, we're not doing this anymore’.

3. Dehydration

Dehydration does seem to play a role, but probably not as much as we have thought in the past. Electrolyte Imbalance or a lack of certain electrolytes probably plays a role, but also not as much as we were maybe led to believe. There's been some fairly elegant animal studies, that lower electrolyte levels in and around muscles quite dramatically, and show that they're able to continue working without cramping, and so I don't think there's a real type causative argument to be made for like low sodium, low potassium, things like that. However, I do believe that at the extremes of those things, so extreme loss of salt, extreme dehydration. Extreme electrolyte dysregulation cramping can certainly occur, but it's not one of the more common causes, I would say, even though it's commonly thought of as a cause.

Spencer Miller

From a nutrition point of view the oldest, and most talked about theory behind muscle cramps is the ‘dehydration/electrolyte theory’. It suggests that a significant disturbance in fluid or electrolyte balance, usually due to a smaller amount in total body sodium stores, causes contractions of the interstitial fluid section around muscles and misfiring of nerve impulses, leading to cramps.

This means that if you lose a lot of sodium and don’t replace it (which is extremely common when you sweat a lot), it will lead to fluid shifts in the body that cause cramps. There are plenty of studies behind this theory with observational data, case studies, and expert opinions. However, there isn’t much concrete proof behind this theory. There haven’t really been any large scale randomized controlled trials which are highly regarded as the best evidence-based approach to accept the theory as fact.

Despite this, there was a recent lab-based study that found that the severity of cramps experienced by athletes were “reduced when they consumed sodium” rather than plain water or placebo drink. So, there is some evidence, but even so, electrolyte imbalance is not the only cause of muscle cramps. Additionally, as research has advanced there was a 2019 study that looked at how electrolytes could change the cramping threshold and another study from 2021 that found electrolyte drinks could reduce the incidence of cramping, so it’s not entirely disproven but as Kevin says, there’s lots of contributing factors and other theories.

An interesting one, still needing more research, is cramps coming from anxiety and stress. Anxiety can cause a considerable amount of muscle tension, and muscle tension leads to cramps. The muscle tension is a lot like exercise or overreaching, so it is the same mechanism causing a cramp but resulting from stress in the form of anxiety.

Another one is adrenaline. Yes, an adrenaline rush can cause a muscle spasm or cramp because adrenaline excites the nervous system giving the “need” to move.

Of course, when you look at it deeper, these all go back to the neuromuscular theory or 'muscular fitness' , just from a different source of stimulus that ‘excites’ the muscle.

Preventing cramp

Dr. Kevin Sprouse

The number one thing that you can do is make sure the muscle is up to the task.

So for endurance athletes, a lot of times that means strength training, and I've seen this numerous times in my career where somebody who tends to cramp a good bit, we put them on a strength training programme, often for another reason, like we're addressing something else or they're just, it's decided they wanted to do some strength training and we really build the muscular strength, the stability of the postural muscles that support those big active movers and kind of improve the whole biomechanical pattern.

In concert with improving the strength and fatigue resistance of the muscle, and then their propensity to cramp drops significantly. I'm a big proponent of strength training for endurance athletes, and this is one reason why.

Another thing that I do think is important is to make sure you do maintain hydration and maintain fueling, one of the things I didn't mention early on, but total depletion of glycogen from muscle can cause it to cramp because there's just no energy left to facilitate that active process of relaxing.

So, fueling is important, and making sure the electrolyte balance is maintained within reason. Again, you know a salt tab here or there, or you know a single banana isn't going to do it, but just making sure that you've got a proper hydration and fueling, an electrolyte plan that keeps you within kind of normal margins can go a long way as well.

Spencer Miller

If you are more of a casual rider, spending less than 5 hours a week on the bike, then a lack of sodium is probably not your issue and it might be worth consulting with a medical professional on how to deal with your cramps.

For more serious athletes that train hard, but still struggle with cramps, you want to make sure that when you do increase sodium intake, you are intaking enough to make a difference and that you have a good balance of potassium in your diet to make this amount of sodium effective.

Most electrolyte drinks out there don’t put very much sodium at all. With less than 400mg per liter of fluid. If you are a high sodium sweater, this might not be enough.

There are various ways to figure out how much sodium you need personally. You can find a sweat test which is as simple as a patch you wear during exercise and then it analyze your sweat and can give you a really good estimate of how much sodium you need. You can also do something as simple as paying attention to your helmet straps or kit. Do your helmet straps and kit always end up with a white, salty coating once it is all dried up after the ride? That is a sign your sweat has a high sodium concentration.

On average, human sweat is about 900mg of sodium per liter, and many athletes can be upwards of 1,500mg per liter (me included). So, if you are wanting to test out increased sodium to see if that can alleviate cramps, make sure to use enough sodium.

What we've seen work well with our coaching athletes using a drink mix with 400mg of sodium, is adding a ¼ tsp salt which is just shy of 600mg sodium. It doesn’t take a lot but can make a huge difference.

It is important to note that table salt is only about 40% sodium (and 60% chloride) so to get 1,000mg sodium, you need just under 3,000mg of table salt.

Experiment with it yourself. Start by adding a little bit at a time and see if you feel better. It is easy to see what works for you by experimenting on training rides. You are your own test subject but remember that everyone reacts differently to substances, even sodium!

There are other ways of helping prevent cramp too, making sure you lessen fatigue is a good place to start.

As obvious as it sounds, you need to train specifically for the event which you are targeting, and this might also be the type of riding which you notice cramping most. This includes the right mix of volume and intensity to prepare you for race day.

You also want to be honest with yourself and your fitness levels to pace yourself appropriately. It won’t do you any good following the front group or riding beyond your level just to end up cramping later and going slower than you would had you ridden within your limits.

Preparing adequately for the event, outside of training is imperative. Did you rest enough? Did you fuel right? Are your glycogen stores full? All of these are key factors that can come into play when cramping from any of the reason talked about previously.

Self-care is another way to reduce the risk of cramp.

Not necessarily well studied or proven in research, but things like the following can reduce the stress, relax the muscles, and set your body up for optimal performance.

· Stretching

· Massage

· Acupuncture

· Proper warmup prior to training

· Relaxation/Meditation

Treating cramp

Dr. Kevin Sprouse

To stop a cramp, what we call abating a cramp, i'm sure a lot of people have experienced that if you get off the bike and stretch a little bit sometimes, whether you realise it or not, that activates the muscles that oppose the cramping muscles. So, if your hamstring is cramping, really activate the quads which in turn leads to a neurological signal to relax the hamstring.

Ideally you want to get to the point where you're not having to get off the bike to manage the cramp, there was some interesting literature that came out maybe 6-7 years ago on using very strong tasting or noxious food items to trigger a sensor in the mouth that would kind of ‘short circuit’ the neurologic impulse that is leading to a cramp.

So I think it was a group at MIT basically identify that there are sensors in the mouth that when you are cramping, if you stimulate these sensors it will stop that cramp signal, so using things like pickle juice, or you know, really salty, sour or bitter, it really tends to be stuff that you don't want to eat, which is why we call it noxious. it stimulates those sensors and for some people it helps abate a cramp and there's some argument that it might help prevent it as well if you take it on a regular basis.

You can get pickle juice in packets or in small containers you can carry with you on the bike as well and those things can be beneficial. Certainly not a cure all, there's plenty of times where they just don't work, maybe something to take in your back pocket if you're prone to cramping and you've got a big event coming up.


As mentioned, there are a variety of likely contributing factors for cramp, be it genetics, muscle fitness or hydration, these factors can differ in impact from athlete to athlete.

The important thing, like most areas of training, is to be in tune with what your body is telling you and train it to deal with those situations - whether that's increasing strength training, adjusting your electrolyte balance in your hydration or making sure you stretch before a ride or get a massage after.

Work out what helps your body and what doesn't.