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Monday, December 03, 2007

Muscle Cramps: Part V

What all this means for you

We have now run the entire gamut in this series on cramps, and it has been quite a ride. This series generated the more reader interest than any of our other posts or series, and let us say again how grateful we are for your participation in the debates and discussion. As academics, we hold fast to the old adage that there is no such thing as a stupid question, and all of us, expert or novice, must ask questions to learn and advance our own knowledge. And this was a complicated series, so we really thought it might be a good time to try to summarize what, exactly, does all of this mean for you the athlete?

Who experiences cramps?

There does seem to be a predisposition cramps. To date no one has even tried to identify the gene(s) that might predispose one to cramping, but even a general survey of the active population will reveal that some people cramp both at night and during exercise, while others never cramp. So you might indeed be a "cramper" before you even toe the line!

What causes them?

We have presented two models for the cause of cramps. The first model tries to explain them based on electrolyte disturbances and dehydration. The second model is based on neural activity and muscle excitation and relaxation. So which one is correct?

The short answer is that we do not know exactly what causes cramps, and it will likely be many years (perhaps even decades) before someone presents a more definitive model that better explains their cause. As we mentioned in a recent post, science is like watching one chess square and trying to create hypotheses based on observations of that one square. We have presented the available scientific evidence, and have drawn our conclusions based on that evidence. Does that make our conclusions correct? To be certain, "No not necessarily!" It merely represents our interpretation of the data.

The bottom line here is that it is a complicated mechanism, like so many others in the body. Also, just as our many different systems are affected by a vast array of factors and circumstances, so is the cause of cramps, and until we have a reliable laboratory protocol that can reproduce cramps in a predictable manner, we cannot really test the models further.

Ok, so I am a cramper. . .now what do I do?

There are a couple of key points here:
  1. Regular stretching will help reduce the incidence of your cramps. This is because, as we explained in Part III, stretching will reduce the alpha motor neurone activity, and thus reduce muscle contraction---which is all a cramp is anyway, an uncontrolled contraction. Therefore stretching often is recommended especially if you know you are a cramper.
  2. "I swallow an electrolyte pill and my cramping stops." This is a comment we hear often, and although we cannot explain this physiologically, the more important message is that you have found something that works for you. We cannot stress how important this is! All the science in the world can point to something, but if what you are doing works for you, then you are better to stick with that technique. We invest so much time and energy (i.e. blood, sweat and tears!) into our training, and if you know that taking some supplement---providing it is legal, of course---will prevent a cramp during your marathon, then by all means you must take it.
But wait. . .I am not a cramper, how can I reduce my chances?

Fatigue appears to be a common factor in cramps, and so preventing fatigue or delaying its onset is crucial. However, we can hear you all the way in Chicago and Cape Town saying, "Great! if only it were that easy. . why didn't you just say so?"

First of all, "Out running" your training could be a likely contributor to cramps. By this we mean that you know good and well that you have done the training for a 3:30 marathon, but in spite of that you decide you are going to go out at 2:55 pace. You feel great for about two hours, and then all hell breaks loose, the wheels fall off, and you are left in a crumpled heap with 5-10 km to go. Therefore we would suggest trying to race closer to your abilities in an effort to reduce the amount of fatigue you acquire during the event.

Second, progressive training is something else that we can all practice that will likely help reduce the chances that we cramp. Don't go from "zero to hero" and make large increases in your training from week to week. As many of you might already know, rest is just as important as all the intensity and distance work you do, because it is during rest periods that your body actually makes the adaptations. Therefore small and incremental increases in training with appropriate rest will provide your body with the maximum time to make the necessary adaptations, and it is those adaptations that will delay the onset of fatigue.

Physiology is a complicated topic, and the available evidence on cramps is sparse. To really advance our knowledge we need solid lab studies that help us identify exactly what is going on and why the cramps occur. In fact, just creating a reliable and reproducible lab protocol would be a major step in identifying what causes the cramps in the first place. However cramps tend to be unpredictable in most people, and even in the known "crampers" it is difficult to bring them in the lab and make them cramp 100% of the time. So the beat of science marches on, and we can only hope that even as you read this, some PhD student out there is hard at work dreaming up a thesis that investigates this issue and tries to advance our knowledge!


Meg & Dave said...

"You feel great for about two hours, and then all hell breaks loose, the wheels fall off, and you are left in a crumpled heap with 5-10 km to go."

Here here! I remember trying to do my first 20mph century. Got to 50 miles and the cramps set in. I'm a 15-17 mph century rider event though I can do much better over 20-25 miles.

Way to bring things back to earth.


Stan Silvert said...

Yup. I learned that lesson too. I tried to BQ in my second marathon and cramped at mile 16. Our pace leader had taken us out so fast that even with the cramping I was still on pace at mile 19. Of course by that time I was going so slow that it didn't matter.

Despite being in MUCH better shape, I barely beat my time from my first marathon.

In my third marathon, I trained even harder and I was older so I got an extra 5 minutes to BQ. The pace leader this time kept us at a nice even pace and I finished right on time.

Since then I've suspected that cramping was much more due to fatigue than electrolyte problems. Thanks to this series my suspicions are confirmed.

I still wish that we knew more, but thanks for bringing us up to date on the latest that science has to offer on the subject.


Ross Tucker and Jonathan Dugas said...

Hi guys

Thanks for sharing the experiences!

Glad the series was helpful and enjoyable - it certainly stimulated some debate and discussion. We hope that people will evaluate the evidence and that hopefully, as you've pointed out D, the drink to thirst idea is the way to go! It did become bogged down in complexity, unfortunately, but there was some lively discussion with people who had opposing views!

And yes, Stan, it is true that despite the fact that we know so much, we have much to still figure out! Roger Bannister, who I'm sure you know is the man of the 4-minute mile, went on to become a distinguished neurologist, and he once said that

"The human body is centuries in advance of the physiologist, and can perform an integration of heart, lungs and muscles which is too complex for the scientist to analyse"

Putting a man on the moon was easy by comparison, then! We have a long way to go!

But we'll certainly go our best, even though we might be 100 years behind! But we're learning all the time!

Thanks again!

Anonymous said...

"You feel great for about two hours, and then all hell breaks loose, the wheels fall off, and you are left in a crumpled heap with 5-10 km to go."

It's not the wheels that fall off, most usually it's the calves as you pointed out in a previous post. But I am "encouraged" by the fact that the second place runner (who ran a 2:13) also had a problem with cramps during my last Marathon. So I guess cramping is an issue for elite runners as well as us poor mid-packers who finish an hour later.

Keep up the good work (as always)

Anonymous said...

I have run 3 full marathons total...a rookie. I ran the Memphis Marathon last two years with cramps coming in 06 at mile 17 and this year (12/1) at mile 20. I trained properly and think I drank plenty of fluids (accelerade). I don't think I overdrank, but I supposed it's possible. Any advice--running St. Louis in April!

Anonymous said...

FYI, I just ran across this recent article that contradicts nearly everything you're said. Might be interesting to get the author to comment here.


Brook said...

Great series. As a veteran of over 20 marathons, I have struggled with calf cramps consistently at the end of all my marathons since 1995. In 94-95 I was able to run in the low 2:50's a few times but the more I raced (and got older, I'm now 50) I cannot seem to break 3:00 or sometimes even come close due to cramping.

My training has been similar throughout this time (I never cramp in training runs, only in races) and I have tried various electrolyte strategies without success. I had read about the central nervous system theories a few months ago and that seems to fit with my experience much better than dehydration or electrolyte depletion.

I really think that Dr. Scwellnus is on to something. Hopefully, some enterprising researchers will come up with something that will help us crampers overcome this frustrating problem!

Anonymous said...

Not sure if you are still checking these posts or not, but thought I'd send in a comment as well. First, this is incredibly interesting stuff - great job in explaining a complex topic and yet also being honest about the reality of not truly knowing THE answer. Very impressive.

Here's my comment/question. The only time that I've experienced serious cramping has been during the last two Boston Marathons (the only two years I've run at Boston). Moreover, the cramping started early in the race (in both years) - around mile 11 I could feel the first few "twinges" in my calf muscle. This, of course, got progressively worse as the race went on and, by the last few miles, it was really bad and I was repeatedly stopping to stretch out my legs (calfs and hamstrings eventually). The weird thing is that this never happens during training runs - even those that are 20 plus miles. I have trained extensively on hills (to simulate the Boston course) - and yet to have this happen early on in the race, when I don't feal any degree of fatigue seems quite odd and doesn't therefore seem to fit with the fatigue explanation that is the basis of the theory.

I believe that I hydrate properly and have even taken sodium tablets just in case it was an electrolyte issue. Which is consistent with your comments on the inadequate support for the electrolyte loss theory - so I was glad to read that.

Any thoughts on what might cause this early on when fatigue shouldn't be a factor?

Ross Tucker and Jonathan Dugas said...

Hi anonymous

THanks for the question - I hope you read our reply (we get all the questions and comments as emails, incidentally).

I think your story illustrates two very important points:

Firstly, it is not an electrolyte or fluid issue, because how is it possible for you to complete 20 mile runs without cramps, in situation where access to water may be far more limiting than during a race, where water tables are present every mile? For unless you did something different in Boston, you will be at the very least hydrated THE SAME as when you train. Probably, you'd drink even more, but you certainly wouldn't drink less. Also, there is nothing that would suggest that during these races, you'd be losing more water or salts, so I think you demonstrate quite clearly that it's not electrolyte or fluids.

Secondly, your story shows just how little we knwo about the cause of cramps! Because while I can say with 100% certainty that it's NOT caused by salt or fluid loss, I can't say with any certainty what it is.

One thing you might look at is what I alluded to earlier - is it possible that for the Boston races, you are changing what works for you in your training run? Perhaps you take salt tablets and electrolyte supplements just for Boston, and they are in fact causing the problems? Or, perhaps you are drinking a little more during the Boston races and this is causing your problems. Just a possibility.

I recently advised a guy who ran in our local Two Oceans 56km race. He experienced massive cramps at 30km, causing him to abandon the race. About a month before, he'd done a marathon at a substantially faster pace than he was running during this 56km race, and so he, like you, can't explain his problem. And my other theory (and this is just a theory), is that the race situation creates "tension" which affects this neural control of muscle that I tried to explain in this series (I think it's Part 4). |But that's very speculative.

Final theory, is that you might doing strength training in the buildup to the Boston race, and then with a week or two to go, you stop doing your strength work as part of your taper. We know that strength training has neurological effects, and so it's possible that the strength training is actually preventing cramp when you train. Then, during your taper, less strength training, more cramping...?

All just guess work, I wish I could give a specific reason and solve your problem, but such is life and science!

Thanks for reading, perhaps some day, we will answer you properly!


Anonymous said...

Thanks for your thoughtful response. It is much appreciated. You are correct about the fluid intake during Boston. If anything, I consume more fluid and more frequently (every mile). During training runs, I'll have bottles of gatorade strategically located on the course - but usually at 4-5 mile intervals. So, the actual race environment is different in that way. It would seem unlikely that would create such problems - but I'm not doubting any possibility.
The tension of the race is something that I've also thought of. I can't say that I felt to terribly tense on the day of this years race, but then again I would guess that there is tension that goes unrealized and unobserved.
It's all very interesting (in an odd sort of way), and hopefully there will be some resolution. Will find out the next time I'm in Boston!
Thanks again for your reply.

Allan Holtz said...

I enjoyed your cramping discussion.

While purely an experiment of one, my experience is that I cramp when I exercise at a level that exceeds my training. I've cramped as early as 11 miles into a marathon and I can typically cramp at about 35 miles into a 100 mile run if I do not ingest a significant amount of sodium salts. Higher air temperature and humidity and higher pace increases the odds of my cramping at any race length. Of course I run 100 mile runs at a much slower pace than I run marathons, so cramping occurs at a much later point in time.

That said, if I do ingest salt tablets (S-Caps work well for me - Enduocaps do not work at all for me) on an early and regular schedule, I can complete 100 mile runs in heat and humidity without any cramping. So that is what I do. I also ingest home mixed maltodextrin gel (no electrolytes) and drink water (at .5-2 pounds an hour while moving strong (first 40 - 60 miles of a 100 mile run) - depending on the heat and humidity of the venue)

Regarding the idea of plecebo effect, I discount that in my case. During the Voyaguer 50 mile race a couple years ago that race switched to using Ultima as their "energy" drink. With aid stations every 2-4 miles I decided to simply fuel my run with Ultima. I both bonked and cramped that year. Previously that race used a Succeed energy drink, which I further supplemented with salt with not energy or cramping issues. A review of the composition of Ultima after the race revealed that sport drink did not contain much carbohydrate or very much sodium. Since then I have used my personal blend of maltodextrin supplemented with S-Caps without bonking or cramping.

I do not believe much can be learned by studying the effects of 2 hour runs. 100 mile races however magnify the effects of faulty electrolyte, caloric and hydration decisions. Most people will typically be running for 20-35 hours at 100 mile races. You can not simply ignore water ingestion or salt replacement for that long of a time without consequences. Dehydration, inadequate electrolyte consumption, inadequate calorie consumption or excessive electrolyte, calorie or water intake will result in diaster at that distance.

A few times because I thought it might be helpful, after finishing a marathon I would go to have a massage, because they were offered for free. Usually I would cramp during the massage, when without the massage, I would have avoided the cramping.

I also have found that 2-10 hours after finishing a 100 mile run my hands (not my feet, calves, quads or hamstrings) will cramp. If I don't get enough electrolytes during a 100 mile run, then its my legs that cramp during the run.

I think interesting research would be to take people prone to cramping during exercise and then study the effect of electrolyte supplementation on them while having them perform at a level that without electrolyte supplementation would result in cramping and to then monitor their electrolyte concentration levels when they cramp and when they don't (assuming that a particular level of electrolytes prevented their cramping).

Something further personally. I have been diagnosed with low bone density. I am a 59 year old male who has run 119 marathons and 70 ultramarathons in the last 16 years, including completion of the Grand Slam of Ultrarunning last year, i.e. finishing 4 particular 100 mile trail runs in the same year, so I have spent a lot of time doing weight bearing exercise. I wonder what effect electrolyte loss during running might have on my bone density. I get a lot of sodium in my diet when I eat at restaurants, very little when I eat at home and a lot when I run 100 mile runs.

Best Regards,

Allan Holtz

Anonymous said...

The series was a very interesting read and I will agree that through my experience.
1. Fatigue is a major factor.
2. Muscle position does trigger cramping.
3. Stretching alleviates the cramps till you violate #2 again.

Where I will disagree is the idea that hydration isn't a factor. For 25 years I've run at night and when doing my long runs, without fail, if I do not rehydrate to within 1 or 2 lbs of pre run weight before I go to bed, I will wake up in the middle of the night with crippling calf cramps. Rehydrating before going to sleep will keep me from cramping, without fail. On very long runs in hot weather I have to drink till I'm nearly sick to rehydrate, (my sweat rate is more like 2 to 2.5 liters/hr) but it still works to prevent cramps. There's no doubt that muscle fatigue is also a precursor but hydration, and/or electrolyte levels certainly have some bearing. By your examples, I should be making myself hyponatremic every time I rehydrate and I've seen no evidence of this.


David said...

Hello..Cramping is a big issue with me. I have run 23 marathons and cramping has been an issue for at least 16 of these races. I get cramps so bad that I can barely walk. At the Country Music Marathon on April 25, 2009, I ran 25 miles with no problems and then ...bang..cramp cramp and start walking. I crossed the finish line and the medical staff told me to lie down...big mistake!!..I could not get up until I was out of the hospital where I received 1 bag of fluid....it really hurt.
Do I need to do more speed or tempo work? I trained at 70 miles per week for 3 months...
I do not stretch or do strength training...hum.
Love your articles...please solve this cramping problem :)

Ed said...


I'm not a professional, but you probably should do some strength training, and you should definitely stretch!

Dave Wyman said...

I'm so late to the party. But I've totally enjoyed reading these articles on cramping.

From my own experience, cramping seems to occur to me for more than one reason. Usually, when I do cramp, and its exercise related, it comes after a long bike ride - 100 miles - and it comes hours after I finish the ride.

Sometimes, with this kind of cramp, I seem to sense it coming -usually the back of my thigh - an instant before it actually hits. It's as if I'm thinking "cramp" and the deed follows the thought.

It doesn't matter how much I eat or drink after an event. I can cramp.

What does seem to matter is stretching. If I stretch after a long ride, I don't seem to cramp. But as all the variables might not be the same, it's difficult to know if, in my case, stretching truly helps; e.g., sometimes I don't stretch and I don't cramp.

The other kind of cramp: on occasion, during a long, hard ride, I'll cramp. Example: a few weeks ago, I rode at a fast pace for miles, in high heat/humidity. I had some serious calf cramping in each calf after 40 miles. I slowed down my pedaling, and the cramps went away.

At the end of 50 miles, when I climbed off the bike, my entire body was fatigued - I felt nauseous, hot, my legs were like wooden blocks. And I had 50 more miles to go. I wasn't sure I could ride one more mile.

However, after a 20 minute rest, and consuming what's listed below, I felt fine. The one major change: I rode slower. Also: I ate and drank more - for the first 50 miles, I'd only had some Gatorade and a Clif Bar, maybe a packet of Gu.

At the rest stop I had:

- One large, very salty pickle
- Two electrolyte tablets
- Gatorade
- Can of diet Coke
- Water
- Clif Bar
- Gu packet

When I climbed on the bike, I was a new person. I don't know what alone item alone or what items in combination did the trick - and I didn't stretch - but I'm guessing my body needed energy, and when it had it, cramping stopped.

For me, then, fatigue - i.e. lack of energy - definitely has something to do with cramps, at least while I'm exercising.

Pics and more about my bike ride, and my cramping, are here: http://icyclist.blogspot.com/2009/07/rapha-continental-century-ride-around.html

Dave Wyman said...

Although it doesn't look answers are forthcoming from the site authors at this late date, I have a question about depletion of salt during exercise.

I understand that the concentration of salt during exercise goes up, relative to the amount of fluid in teh body. That is, more fluid is lost than sodium.

However, sodium is still lost. Is it possible that total amount of sodium is important, and that its concentration - or lack thereof - in plasma is just part of the issue?

JB said...

Is there any data on how homogeneous the distribution of electrolytes is before, during and after exercise?

Could there be a local imbalance correlated with a local muscle cramping? I'm a local Cat 2 (bike) racer who occasionally cramps in crits as short as 1h15m.

Andrew said...

Hey Ross,

Not sure if you watched the cricket last night, where Andrew Strauss declined Smith a runner after he was cramping.
The question is, are cramps a form of injury?
Your thoughts on this would be interesting.

Ross Tucker and Jonathan Dugas said...

Hi Andrew

Man, I wish I had a bit more time today, I've been denying to do a post on that incident, actually. I've just got such a lot to do.

I'll try to squeeze it in a little later.

To answer though, Strauss was 100% correct, in my opinion. Cramp is not injury, it's a sign of being unit. You can't get a runner just because your body is packing up because you're too unfit to run for the length of time it takes to bat out the innings.

And Smith played brilliantly, no doubt, but his problems were caused by nothing more than not being conditioned enough to bat for long enough at that intensity.

Maybe Strauss knew something the SA guys did not, and that is that cramp is not some medical emergency or unfortunate injury.


Anonymous said...

Is there any evidence that caffeine can cause cramping? I am a mountain bike xc racer and use caffeine because I've heard that it aids in muscle contraction and performance. Lately I've had cramping issues. Most recently it cost me a position by a half tire length because I locked up 10 yards from the finish and couldn't peddle across. I should have been able beat my competitor but 2 to 3 miles out I started feeling the twinges that indicated that cramps were coming. Any thoughts on caffeine and racing?

tandemman said...

You make a point about the levels of electrolytes tested, but is it possible that there is a matter of ratios of one to the other? and that this might be very sensitive when pushing near one's limits?

I have found that supplementing Magnesium make a BIG difference, especially if I have had a lot of calcium (I am a big milk/ice cream eater)
I have also had a few bouts of Tachycardia, rather scary at times with pulse rates over 220 (I am in my 50s) and some lightheadedness. If I am popping my magnesium tablet in the morning this doesn't happen. Then I'll have an "attack", and I realize I have gone a a few days or a week without doing the Mg. I have gotten much more consistent taking it since I realized that.
I, know, anecdotal, but I want to put it out there.

Kevin said...

I have had continual cramping problems in long triathlons. I have completed 7 half Iron Man races and 1 full. My cramps always start on the bike with the exception that one year during a cold swim my hamstring cramped. Though I have played with the salt and various electrolyte replacements and drinking more on the bike I have met similar results, after the run starts the quads start to cramp. I have run through them and and walked them out but they never totally go away until the race is done. I am considering doing some traing rides concentrating more on the fuel (carbs and calories) and less on salt and fluid and see what happens. It is very possible that I am working above my fitness level and that is causing the fatigue that leads to cramps. I have enjoyed all these posts and it gives me something new to consider.