YouTuber and physician Rohin Francis, MBBS, searches for an explanation to a common medical problem he suffers from: cramps.
The following is a partial transcript of this video; note that errors are possible.
Francis: Cramp. Probably everyone watching has experienced it at some point, so it’s truly one of the most universal human physical experiences, if not one of the most pleasant — and yet we don’t really understand it. Sure, you can do what every serious medical professional does when they don’t know something — look it up on YouTube — and you will find no shortage of videos telling you the cause of cramp, except they don’t. They tell you risk factors for cramp or things we think precipitate it. Things I’m sure you’ve heard before: excessive exercise, dehydration, electrolyte disturbance, medication, blah, blah, blah. They don’t actually tell me anything about what is going on inside my muscles to cause them to lose the f**king plot. The information contained therein is useful, but boring and this is Medlife Crisis where we focus on the useless but interesting. I don’t know why I used the plural there. It’s… it’s just me. What I, a senior doctor with a longstanding interest in exercise physiology, do not know is what exactly is happening when we get a cramp? I have genuinely never learned this. What is the mechanism? Why do our stupid, moronic, junkheap, meat popsicle bodies do this to us?
Well, after the scientific resource that is YouTube let me down, I did what I probably should have done in the first place. Anyway, I went to the medical literature. Researching cramp has actually produced a few valuable lessons about the state of science and research overall. In a way, I love the fact that there are these really fundamental questions about basic things in human biology that remain unanswered, like why we yawn or how the placebo effect works — I just made a video on that one — why we age, how general anesthetic works, or why Americans say aluminum. Let’s see if we can figure this one out.
As a demonstration of how niche this is, I have a medium-sized Twitter following of just under 50,000 followers, who are mostly medical or science-adjacent, and I asked if any were or if they knew any experts in cramp. Not a single reply. If you are an expert in cramp, please do get in touch, although I will declare now that as soon as I hit publish on a video, I typically completely stop caring about it and the subject matter entirely.
However, I have an ulterior motive, why I have spent so much time looking into this, other than just dedication to the noble vocation of YouTubery. I get absolutely agonizing cramp. Not the kind when you’re playing sports or sitting on the floor for a while in your thigh or your foot. That’s okay. I get those too. I can just stretch them out and no big deal. I’ll talk about the different [types of] cramp a bit later on. But in my calves, invariably when I have just woken up in the morning, the slightest flex of my calf muscle, the gastrocnemius, literally just moving my foot a millimeter downwards and like a hair trigger, boom. My calf cramps up and I leap out of bed in pain. The pain is bad, but I have realized the main reason I have come to dread this so much is not the immediate pain, it’s because I know in that split second that I’m going to be in pain for a week and there is nothing I can do to stop it.
If as the normal definition you’ll find online for cramp is the transient, temporary, contraction of part of the muscle, why am I left out of action for days afterwards? Is this like some evil version of muscle memory or have I actually damaged the muscle in some way? I’m sure I can’t be the only one who experiences this, so I would really love to hear your cramp experiences, which is probably a sentence that hasn’t been said before, because this isn’t something that’s well documented or talked about in a scientific way all that much.
Now, I have something called benign fasciculation syndrome — which is where muscles twitch uncontrollably like a lot of people get in their eyelids — but I used to get it in my abs, or my glutes, biceps, and those kinds of muscles quite frequently. It has actually pretty much gone in recent years as I’m getting old. But I was already aware there was an overlap between that and cramps, so assumed I’m predisposed to getting cramp in some way.
You might have seen these viral videos where someone has filmed a severe muscle cramp, with the muscle visibly sucking in, cramping up. I don’t understand these because the person seems quite calm and able to hold a camera. That is not my experience at all. No matter how quickly I get up to stretch the muscle out, I am left with a tender lump in my calf for the next few days and me wondering what the hell that lump is is the question that prompted this whole video because I simply couldn’t get an answer from anywhere online.
But luckily I have access to ultrasound machines at work and a little while ago, after I had one of my fairly regular acute agony sessions, I scanned that lump in my leg and I was really surprised with the result. As a quick aside, I learned from Tom Scott that a leg cramp has actually got a specific name on the other side of the Atlantic. Charley Horse worth 400 points.
Tom Scott: That is?
Francis: Is that like some American…?
Scott: That is an American term for a cramp, I think.
Francis: I see. All right.
Scott: Some sort of cramp, I don’t know what. These are all very American cards, all right.
Francis: Well, you’re paying for your surgery here, Tom. Did that not give you a clue it’s an American game?
Scott: Fair. Fair.
Francis: The one thing everyone will tell you about when you mention cramp is dehydration and electrolytes. Sorry, that’s actually two things, isn’t it? But I’m pretty confident that when I’m getting cramp, my electrolytes haven’t gone up the spout. My blood test is not going to show an abnormal sodium or potassium, magnesium, calcium. Those are quite pathological states to be in.
Even when patients come into the hospital who are quite sick, their electrolytes aren’t always deranged and I don’t have overt evidence of dehydration. But blood tests measure exactly what they sound like. They do blood levels, which is often not the same as what’s going on inside a cell. That was my initial starting point when trying to figure out why this happens because it can’t be as simple as just an abnormal electrolytes or dehydration because that isn’t reality for most people. Let’s start by looking at the different types of cramp.
Period cramps are, of course, one of the most common and can be intensely painful as well. These are caused by contraction of the large, powerful muscle in the uterus. Obviously, I don’t have firsthand experience of this one, but there is some interesting research suggesting it can be as painful as a heart attack.
Uterine muscle is smooth muscle, which is different to striated — or literally stripy — muscle, which is skeletal muscle. In essence, smooth muscle is not controlled voluntarily. You find it in many places in the body: your blood vessels, your gut, the muscles that move food along. I don’t know why I’m doing this motion. Maybe this is medical sign language for peristalsis and that’s the word we give the movement of stuff through the gut.
Do you know what the word is for the sound of all that movement, the tummy rumbles? Borborygmi. Any OG subscribers may remember my medical words video from a few years ago, which legitimately I think is still one of my favorite videos that I have made. Honestly, I think… I don’t know why I have gone on this massive tangent. I think thinking about cramp for so long has driven me a bit peculiar. Of course, you have one other type of muscle in the body, which is the heart, and thank goodness we don’t get cramp in the heart, but that’s also kind of interesting. Why not? That’s a rhetorical question, we don’t know. But it’s doubtless something to do with the fact that the heart muscle cells are just so highly specialized and insanely efficient compared to other cells, which also might give us a clue to the crampy cause.
Then we have what’s called pathological cramp. This is muscle cramping in the context of a disease, such as things like liver disease, or diabetes-causing problems with the nerves — which is a neuropathy — or diseases affecting the neuromuscular junction, like motor neuron disease or ALS. Remember, the ice bucket challenge? That seems like a lifetime ago. Sometimes cramp can be caused by medication.
I’m not going to be considering any of those types of cramp in this video. I’m going to focus on cramp affecting healthy skeletal muscle. In general, this is classified as exercised-induced cramp or nocturnal leg cramps. It’s actually unclear if they’re different phenomena. In fact, some papers go further to subdivide multiple types of cramp: calf cramp that footballers get an extra time, full-body lockups that American footballers and tennis players apparently describe, cramping small muscles that typists might get, cramps that are preceded by fasciculations or twitching, cramps that occur at the start of exercise, cramps that occur at the end of exercise. You can keep going further and further down the rabbit hole, which is kind of cramped. But to preserve my sanity, I think we can group them together as cramp affecting striated or skeletal muscle in the absence of any systemic disease or toxin, i.e., in healthy people.
Rohin Francis, MBBS, is an interventional cardiologist, internal medicine doctor, and university researcher who makes science videos and bad jokes. Offbeat topics you won’t find elsewhere, enriched with a government-mandated dose of humor.