My name is Chris. By day I run a content marketing company. By night I pace the streets of London training for my next marathon. I’m an enthusiastic amateur, slow but committed. I’ve done six marathons over the last few years, my best in just under four hours. This year I fancied a bigger challenge, so in April I’m doing three marathons in three weekends for the Lullaby Trust: Milan, Zurich and London.
Like many runners, professionals and amateurs alike, I do my best to stay injury free. I stretch when I should, and rest when something hurts. Yet I’ve struggled for years with one serious issue that no one seems to be able to help me with: cramp. Actually, to be precise, cramp and sweating, but they are related. Let’s start at the beginning.
The curse of cramp
Many, if not most, runners will have experienced cramp, either during or perhaps after a race. I suffer particularly badly from it, and it has affected every marathon I’ve ever done to varying degrees. Normally, it appears around the 18-mile mark, and at its worst has stopped me dead in my tracks. A few years ago, at the London Marathon, I terrified an old lady as I gasped and contorted my way to the side of the road, desperately trying to hide the pain as my legs went into spasm.
The thing with cramp is that no one really knows exactly what causes it. Several field studies have been carried out over the years, but the results are not conclusive. I can’t find evidence of a properly controlled study, in a lab, though that’s surely in part down to the difficulty of predicting when cramp will occur.
So we are left with two competing theories. One will be familiar, and involves electrolytes and dehydration. The second is down to conditioning. Lets deal with conditioning first.
A lack of fitness
In simple terms, the theory is that cramp occurs when you push your body too far: when you pick a pace on race day that is greater than your body can handle, or run a lot further than you have practised for. To some degree, your body will do its best to cope. But the cramp is screaming: “I’m very much not coping, so I’m going to close this down thank you very much!” The solution? Train harder, or ideally smarter. There is a world of advice out there, much of it on this blog, on how to approach training sensibly.
Unfortunately, this theory hasn’t been much help to me. My training tends to be good, with a well-planned 16 weeks or so of strength training, hills, speed work and long runs. I’m no Mo Farah, but I get the basics right. I generally get to 22 miles in training; yet, on the day, my body hits 18 miles and the dreaded cramp strikes.
A lack of sodium
The other mainstream theory states that cramp is caused by an imbalance of electrolytes in the body. Most of us sweat when running, and we excrete a degree of sodium. This disturbs the delicate balance in our bodies, leading to cramp. The theory has been extended in recent years to take into account “salty sweaters”. Some people sweat a lot more sodium than others, and thus are particularly susceptible to cramp.
This is particularly interesting to me, as I do sweat a lot. On a long training run, I’ll even stop halfway and change kit. I can often been seen wringing out headbands at traffic-light stops, and, on really hot days, I finish runs with visible lines of salt on my clothes. Not a pretty picture, I grant you – I look more like I’ve been swimming than running – but this does tally with the sodium theory. I sweat a lot, I must lose a lot of sodium, so I cramp a lot.
Yet, as I started off saying, the science isn’t really there. Indeed, the whole theory of sodium and cramp has its roots 100 years ago, in the hot and humid conditions of shipyards. Workers suffering from cramp seemed to be soothed by drinking salty milk. Not the most scientific of starts for a theory. More recently, the sports drink and supplement industry – not a bastion of independent peer-reviewed science – has pounced on the subject of hydration and electrolytes. Running magazines are full of adverts for special formulas, salt tablets and all sorts of supplements. Have they wiped out cramp? Certainly not for me.
At this point, it is worth noting a passage in the excellent The Runner’s Body, which argues that the science in the sodium theory not only doesn’t stack up, but flies in the face of common sense. It suggests that as you sweat, the concentration of sodium in your body actually increases. Sweat contains a much greater volume of fluid compared with sodium. So sweating some of this fluid out leaves your body with a larger concentration of sodium. So if cramp is down to a lack of sodium, it surely isn’t down to sweating.
Whatever the prevailing theories, with my April challenge rapidly approaching, I needed answers. As a result, the last few months have seen me seeking answers from all corners of the running world.
The marathon coach
I’ve seen many personal trainers – experienced guys with many marathons under their belts – and their advice is pretty varied. Indeed, just about the only thing they seem to agree on is scepticism of the sports-drink industry. Their suggestions range from a salty pretzel pre-race, compression tights and focusing on running up hills. One did suggest that I needed more high-intensity speed work midweek, which I’ve taken onboard over the last few weeks.
The nutritionist
Good nutrition is a big part of marathon training. I spoke to a nutritionist who thought my relative lack of protein could be a factor. Like many runners, I probably eat too many carbs, and she thought a better-balanced diet might make my legs more efficient in the way they burn fuel. I have tweaked what I eat, and it makes good sense for all sorts of other reasons, but I’m yet to be convinced it’s the answer to cramp.
The sweat test
Many runners will have conducted the ritual of the sweat test – weighing themselves pre- and post-run to find out how much weight, and thus fluid or sweat – they have lost. My figures put me at losing between one-and-a-half and two litres of sweat an hour, which is at the high end of the scale. So certainly I sweat a lot, but is this contributing to my cramp?
The sodium test
Most recently, I went to get my sweat sodium levels tested. This is a fairly new procedure, where small pads are attached to your arm and a tiny amount of sweat is extracted and analysed. The whole thing takes less than an hour, and no running machine is needed. My results show around 1.4g of sodium per litre of sweat, which again is at the high end of the scale. People vary from 230mg to 1.7g.
Adding these results to my sweat test, it’s clear that I have got a fair bit of sodium and fluid to replace over the course of a four-hour marathon run. Is the gradual depletion of both contributing to my cramp?
Trial and error
Frustratingly, my research hasn’t lead to a clear answer, just lots of good advice. I have tweaked my training plan, modified my diet and will be replacing my usual drink with water and a salt supplement on long runs – so let’s see what happens. My sweat sodium levels suggest to me there is something in the hydration theory, but it is all very much trial and error. I do know one thing for sure: I certainly don’t want to spend April stumbling to the sides of roads clutching my thighs. Wish me luck!
In April I’m running three marathons, in three different countries, on three consecutive weekends for the Lullaby Trust who support those affected by sudden infant death. You can sponsor me here.
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