Running injuries expanded

Expanding on running injuries (and some admin)

Yesterday, Jonathan did a post looking at running injuries and specifically the common training error made by runners who tend to move from one injury to the next in their training! He raised the the guideline that a 10% increase in distance from one week to the next is probably about the limit of what most people can aim for before they start running (literally) into injury territory.

And the post got some pretty good comments and discussion going, and it struck me that the whole concept of injuries in runners (and in other sports, cycling and swimming especially, since our focus is on endurance) is a topic that we have never really tackled here.

And since it's so prevalent - studies suggest that about 2 in 3 runners will be injured every year - it seems like a topic worth delving into in a bit more detail in the coming months!

Of course, it's a vast, enormous topic, and much like our Fatigue Series, it's probably too big to be discussed adequately in a nice, packaged series of three or four posts. So rather than introduce it as a series, I think I'll put forward that we will start giving a lot more thought to some posts that follow on from yesterday's post and the resultant suggestions, and then roll those posts out a little less frequently than we would in a dedicated series. But just be assured, it's on the radar screen!

So just a couple of ideas around injuries in running:

1) Running technique and injury

First, a couple of people raised the issue of running technique and injuries, which is a pretty common thought these days. I honestly don't believe that running technique, at least in the form that it's been "packaged" and then sold to runners, has a great deal of importance for injuries. I'd go with the theory that if a runner is injured, look first at training, second at training, third at training, fourth at strength and flexibility imbalances, and fifth at training. Maybe at number six, you can consider running technique.

All this is obviously within reason, and as one reader (Cassio) pointed out, there are obvious technique related things that can easily be addressed, like very obvious overstriding. So sure, in that case. But the case that is made for subtle changes is really overdone and overmarketed, in our opinion.

The issue of technique is however one that we have covered in great detail, and so this is not a debate we need to have right now - it's been had! You can read our series on running technique here for all the discussion of those ideas.

2. The inter-relatedness of it all

Of course, at this point, we must make a very very (very) important point. Nothing in your running (or cycling or any sport) can ever be looked at in perfect isolation. In otherwords, training may well be the cause of most injuries, as we've said, but there is a substantial interaction between the training you do and other variables which act externally to affect your unique response to that training. A 55 kg Kenyan might go from no running to 120 km in a matter of months, and be racing competitively in less time than that. Another person will be bed-ridden in weeks with stress fractures! Why? Because their unique physiology, anatomy and response to training means that "not all training is created equal".

So I am firmly of the belief that if correct training principles are adhered to, then any athlete can train without injury - the level they reach and their success as a runner is of course dependent on numerous other factors. But the problem that we land ourselves in is that we "train by numbers", and try to fit all athletes into the same mould. So the concept that training is simply run from a template doesn't work, precisely because we are not all average.

So the truth is, training might make up the first three areas of concern for an injured athlete (in my opinion), but you can't look at the athlete's training without considering things like flexibility and strength balance (as Sean has pointed out) because they MODERATE the athlete's response to training. That's why I'm in agreement that the athlete must address strength, flexibility and balance.

Now, if we want things to get really tricky, then we start talking about flexibility - can you be TOO flexible? I think when asked in that way, the answer is quite obviously "Yes". But what if it's asked a little differently: Should runners be stretching? Because now all of a sudden, the answer is "Maybe". And once again, we have a case where "one size does NOT fit all". There is, in other words, evidence that stretching can CAUSE injury, not prevent it. And excessive strength too. The key then is balance, and that's a topic worth getting into in the future as well

3. The influence of intensity - critical

Then lastly, the other variable in your training programme is the intensity. Yesterday, Jonathan touched primarily on VOLUME, and raised that guideline (not a rule, remember) that 10% increases are usually the limit. What that doesn't deal with is intensity, so we have to discuss the impact of increasing intensity.

What often happens is that a runner will very patiently and methodically build up VOLUME, because it's much easier to measure - time or distance. What they neglect, and it's more difficult to quantify, is intensity. Because my experience, and theory, suggests that a 5% increase in intensity is NOT the same as a 5% increase in volume.

In other words, if you increase the intensity very slightly, the volume has to drop quite a lot more in order to keep the OVERALL load the same. And so what often catches runners out is that they ramp up the volume by 5 to 10%, but the intensity goes up by 5% too, as they get fitter, or push a little harder. The net result is that the overall training quality increases too much, and they break down.

This is also why the biggest danger period for any runner is that moment when they start to add in the high intensity training to the programme. They finish base training, and suddenly start to do the odd track workout, some fartleks, or the like. But if they don't manage a reduction in volume, the combined effect can be damaging.

So that's another topic worth discussing

One final point - no research available

One thing that we must make clear right up front, is that as we tackle this topic on and off over the coming months, there is very little scientific evidence on this, and so we rely instead on theoretical insights, experience and "bald assertions". Studies often look backwards at injury, and work out after the fact that X, Y and Z are the likely predictors for injury. For example, we know that if you've had a previous hamstring injury, then you have a many-fold greater chance of a hamstring injury! (hardly rocket science...)

But scientific studies that look at the long term effects of different volumes and intensities of training are, for many reasons, just about impossible to do effectively, so it's looking backwards that reveals the evidence.

But, that's no reason not to discuss it, and we'll welcome any comment or feedback. So keep an eye out for those injury posts!

Ross

Gebrselassie out of the Olympics

Haile Gebrselassie OUT of the Beijing Olympics - the air pollution is a "threat" to his health

Dramatic news being reported today by news sources is that Haile Gebrselassie, Ethiopia’s marathon world record holder and multiple world and Olympic champion has withdrawn from the Olympic Marathon in Beijing, citing concerns over the air pollution as the reason!

Gebrselassie had previously mentioned the possibility that he might not run in Beijing, but today’s news represents a definitive ("99% sure", apparently) decision. Gebrselassie is quoted as saying the following:

"The pollution in China is a threat to my health and it would be difficult for me to run 42km in my current condition,"

“My current condition”, incidentally, refers to Gebrselassie’s asthma, which he says forced him out of the London Marathon in 2007.

How bad is Beijing? And is this a justified decision?

It is a radical decision to take, particularly with all of 150 days to go before the Olympic Games. Yes, there are concerns over the pollution, and yes, it's likely that conditions will be difficult in Beijing, heat and humidity adding to the problems. We won't go into huge detail on air pollution and exercise performance now, since we've looked at the pollution situation in Beijing in two previous posts.

First, we discussed the likely problems the athletes will encounter in Beijing, and how some nations are planning to send athletes to locations OUTSIDE Beijing to avoid the pollution. That was amidst claims and promises that Beijing was doing all it could to improve the pollution situation.

However, a few months later, it was being reported that the air pollution situation in Beijing was actually getting worse, with many of the promises about cleaning the air (including the closure of factories in Beijing) being forgotten or ignored in the face of economic pressure to keep factories open. It has been a problem that has plagued the build-up to Beijing since last year, and this is the most dramatic story arising out of the pollution controversy so far.

A premature decision?

But rather than make this decision now, why not wait out the next three or four months and see how things develop? Consult with an expert or two (because this is an issue where you'd get a sixth and seventh opinion IF you really wanted it) on asthma. Find experts on pollution, as Paula Radcliffe did, and see whether there is a contingency plan that might allow you to run and challenge for what is really the only major title or accolade you're still missing?

The British Olympic team even announced that they would provide masks to their help their athletes breathe more easily if required. Perhaps Gebrselassie has done all this, and the advice he received is that there is no way he'll be able to run in Beijing. It's still almost unbelievable that he wouldn't wait out a month or two before announcing a decision that, in the words of his manager Jos Hermens, is "99% sure".

For the reality is that Gebrselassie has achieved pretty much all he can in international running, apart from winning the Olympic Gold in the marathon. It's a goal he himself has expressed on many occasions and it really does seem peculiar to me that he could so easily let go of the goal.

Instead, his manager Hermens is quoted as saying:

"He doesn't want to put his career in danger and he still wants to run at the 2012 Olympics in London. His dream is to run in two hours and three minutes and to be the first to do that. It's more important for him than to win another gold medal."

The pollution - an unknown quantity

Quite what the long term implication for his health is is difficult to know - certainly, his career would hardly seem in danger if he raced in Beijing. His marathon race, yes, but to suggest that his long term health would be affected is a little extreme. The worst that would happen would be that he could not breathe, and so he'd stop and pull out of the race within the first 10km, and live to fight another day - there's no reason to believe that his 2012 race is at stake thanks to the Beijing air of 2008.

Then again, I'm not sure that elite athletes have ever been exposed to the kind of pollution they'll encounter in Beijing, so the Olympics will be interesting simply from that point of view. Perhaps Gebrselassie tried to jog on a recent trip to Beijing, and found that he simply could not breathe - his mind may have been made up by his lungs!

However, it would seem to be a question of priorities, which is a deviation from the usual line given by athletes (including Gebrselassie) that the medals are more important than the records. Of course, it's Gebrselassie's choice, and good luck to him going for that 2:03 marathon (that is another issue altogether - we've discussed the chances of a 2:03 before). But it certainly is a shame, and hopefully, that 1% chance will still come into play and we'll see Gebrselassie on the roads, rather than the track, in Beijing.

If not, then it's the 10,000m event, as Gebrselassie has announced his intention is to qualify for Ethiopia's team for the 10,000m race in Beijing. This might be part of the reason for such an early announcement - perhaps he felt he needed to make the decision this early to allow him to adjust the training leading into the European summer. However, even that doesn't quite ring true, and I can't help but wonder whether the decision is really as simple as saying that he has other goals, and he is concerned over his health...is there any chance that in two months' time, Gebrselassie will announce that he's changed his mind and WILL in fact run the marathon in Beijing? It would not be the first time that he'd announced his "absence" from a major championships, only to be "persuaded" to go after all...

Suspicions and questions - a valid reason?

Such is the climate around international sport these days, that there is already lively debate and cynicism about the given reason. Does Gebrselassie really have asthma? Or is this an excuse not to be tested by drug control authorities? The problem with that "conspiracy theory" is that Gebrselassie has announced that he'll try to run the 10,000m race in Beijing instead, where he'd be tested anyway. So scratch that theory off the list.

There's actually a great deal of controversy around the drug testing issue and asthmatics, incidentally - for example, if you take an average sample of people and compare it to a sample of Olympic athletes, you find that often, the Olympic group will have a much higher incidence of "asthmatics" - if , that is, you choose to believe all the medical clearances that are issued giving them exemption to use inhalers (which are otherwise banned). But again, the fact that Gebrselassie is not pulling out of the Olympics, but just the Marathon, would suggest that the drug theory is slightly misplaced, on this occasion anyway.

The Olympic Marathon without Gebrselassie

As for where this leaves the marathon, well, it's dramatically weakened by his absence. His anticipated race against the Kenyans, whoever they chose, was due to be a real highlight of the Beijing Games. The marathon will be somewhat lacking its lustre if indeed he doesn't change his mind. So a real shame for the Olympic Games, and let's hope that it's a premature decision and that he announces that he will, after all, take his place in the race come August.

Ross

Related articles

Air Pollution in Beijing: Symptoms and issues facing athletes in Beijing

Olympic events in danger: Athletes will need masks in Beijing

Ryan Shay Autopsy

Ryan Shay Autopsy: Why the delay?

In the last 4 months, everyone has waited patiently for the autopsy results of US runner Ryan Shay to be released. It was in November last year, during the US Men's Olympic Trials, that Shay collapsed at the 10km mark in Central Park, New York. He was later pronounced dead, and the story shocked the athletics world.

We have now reached March, and still no final report on the cause of death or the results from the autopsy which is performed on all sudden deaths in apparently healthy people. For example, earlier this year, actor Heath Ledger died in mysterious circumstances and an autospy report was released only two weeks later.

So not surprisingly, the voice of those who wanted to know some answers was growing steadily louder or discontented. Apparently, the Medical Director of the race was receiving 25 calls a day from various people. Even here on this site, we've received a number of questions from people asking whether we knew - of course, we are as much in the dark as anyone else. But now, it seems there may be some answers...

Runners World finds some answers

On Thursday this week, Amby Burfoot wrote an article which you can read here, detailing some of the progress made so far.

According to the article (summary for those who don't want to read the whole thing), the Medical Examiner's Office refuses to comment on any case, which is understandable, if not doubly frustrating for those wanting to know. The official word out of the Medical Examiner's office is:

"Every case is individual, and we have to do a complete job on every case that we do. We do the testing that we need until we're satisfied that we can determine the cause of death."

Apparently the four month wait for the report is not completely exceptional - it usually gets released far sooner, but four months still falls inside what the Office considers an acceptable time frame. Final testing is apparently now taking place, and according to the spokesperson, "It should be very soon now."

So within the next week or two, perhaps, we'll have some conclusive (hopefully) answers as to what would cause an apparently healthy and very fit 27 year old to collapse and die during an activity he did just about every day.

But there are some answers, provided by Ryan Shay's father, Joe. In a telephone conversation with Runners World, Shay revealed that:

A toxicology report had been conducted on the supplements Shay was using - he was sponsored by the company EAS, and so any possible contamination was investigated. Apparently, Joe Shay requested that the toxicology report be released before the rest of the results, but the Medical Examiner's Office refused, as policy is to release the report in its entireity. The toxicology report became the focus of attention because at the time, many people wondered whether drug use might have been responsible for Shay's death.

A second part of the investigation was done on tissue samples which were genetically examined. Shay's family specifically requested this to make sure that no other family members were in any danger of a similar cardiac event. Joe Shay revealed to Runners World that this testing showed that Shay DID NOT have hypertrophic cardiomyopathy, which was a widely reported candidate for the cause of death (including here).

So one possible cause has been eliminated, the others remain possibilities. The signs are encouraging that within two weeks, a report will be released, which will hopefully provide some answers. If and when that report is released, we'll do our best to bring to you.

Ross

Computer Games continued

First Post of 2008 - a New Epidemic in children: Playstation thumb!

First of all, a happy and prosperous New Year to everyone! We hope that 2008, an Olympic Year, brings everyone some Olympian success and prosperity!

I trust that all are recovered from their New Year celebrations, perhaps you've even jotted down some resolutions for 2008? Here's to making them last at least a week!

Just a short filler post today, to follow on what we have been discussing recently - health and computer games. A few days ago, we did some posts on the somewhat bizarre potential of Nintendo Wii to contribute to weight loss in children, since it is a more active form of computer game than Playstation and X-Box 360. A case of trying to gloss over a problem and justify inactivity perhaps? Or an admission that "If you can't beat them, join them"?

In any event, it reminded me of an article I came across a few years ago, while still a student. I used to share an office with three other PhD students who shared my sense of humour, and we all had a humorous appreciation for some of the more bizarre scientific research publications that our field sometimes produces (for example, check out this very bizarre case study from an Indian Medical Journal - accidental condom inhalation, anyone?).

Playstation thumb - a new epidemic in children

So here's one I came across in 2004 (don't remember how), detailing the emergence of a new "epidemic" - it's called Playstation Thumb. The condition was first mentioned in a letter written to a prestigious journal Lancet, and was followed by a synopsis in the South African Medical Journal. The condition develops due to (you guessed it) excessive use of the thumb during play - the problem is partly a dermatological one, with the formation of a blister, which can be accompanied by fatigue of the thumb. There is tendon pain (whether or not there is inflammation is debatable) which ultimately limits pain - a forced "rest" period...

In fact, there's a whole body of literature about this condition now. One of the more recent ones, in Archives of Dermatology, details "The Use of Dermoscopy to Visualize Punctate Hemorrhages and Onycholysis in "Playstation Thumb". (I don't know exactly what that means either...!)

Nintendo are not immune to this affliction. In June 2007 (last year, funnily enough!), the New England Journal of Medicine had a report detailing the condition "Wiitis". Here, a 29-year old medical student woke up with shoulder pain, had it checked out and was diagnosed with "acute tendonitis isolated to the right infraspinatus" as a result of playing too much Wii the day before! So forget Achilles tendonitis, tendinosis, ITB, patellofemoral pain and the like - computer gamers are just as injury-prone as all the runners and cyclists! Not to mention the risk of obesity, and the resultant disease - the games will one day carry a warning sticker!

But wait there's more - how about "Playstation Lip"?

If that wasn't enough, how about this letter, that was sent to the British Medical Journal in June 2000? It describes two dentist's experiences with children who apparently concentrate so hard that they damage their lower lips...

Sir, - It has come to our attention that an unusual consequence of children concentrating whilst playing their computer games of PlayStation games appears to be that of trauma to the lower lips.

We have recently seen two children who have attended Newcastle Dental Hospital children's department with severe trauma to their lower lips. On questioning it was clear that this trauma had occurred whilst playing on their PlayStations and consequently we found it necessary to provide them with lower soft splints to prevent any further damage.

Therefore, we would be very interested to know if any other readers had noticed this interesting phenomenon and had seen any other cases recently of what we have called 'PlayStation lip'.

R. L. M. Inglis
R. R. Welbury

It seems that we are on the verge of a new branch of science - computer games exercise science and medicine! First we had the possibility of studies on Wii Economy (see the comments section), now a division of medicine, even dentistry, on physical afflications caused by too much gaming! Who said that science stands still? And as for human evolution continuing to this day...

Preview of forthcoming posts

OK, so today was a bit of a tongue-in-cheek post to kick off the year. But tomorrow, I thought it would be interesting to do the "Nostradamus Post" and make some predictions for sport (and science) in 2008.

Hope you've hit 2008 running (or cycling, swimming, rowing, and figuratively!)

Ross

Muscle Cramps: Part II

The electrolyte depletion model of muscle cramps

In part one of this new series we tried to set the scene by providing some history in this area of muscle cramps. At times it might seem like we are a bit heavy on the historical side, but as we mentioned in one of our comments to Part I, understanding the historical record is crucial as often it helps us understand why we think what we do---and this affects one's interpretation of the science. In this post we will focus on the prevailing premise that dehydration and electrolyte disturbances cause muscle cramps.

The first important thing about this area of research is that Professor Martin Schwellnus is hands down the one researcher who has consistently moved this area forward. As a sports physician he has treated many a runner with cramps, and his curiosity and what he was seeing in the medical tents lead him to challenge this paradigm that dehydration and electrolyte problems cause cramps. What he found was that this model was based on not one shred of scientific data, and instead relied heavily on anecdotal evidence. Since 1997 he has published some of the only evidence available that has even attempted to determine what actually is causing the cramps and who is prone to this condition. The first paper he published in 1997 proposed a novel hypothesis for muscle cramps, but we will address that in Part III of this series.

The lab vs. the field

In our series on dehydration we discussed how the lab is not always translatable to the field, and vice versa, but that each has its own important role. Field studies are often cross sectional in nature, and although important we cannot assign direct cause and effect from them. However it is observations and findings from field studies that often lead to the very precise and mechanistic lab studies that are important in advancing our knowledge.

However one major obstacle in this area (cramping), is that no one has yet created a laboratory protocol in which we can reproduce muscle cramps in a controlled manner. Being able to do this is a crucial step in eventually identifying what causes them because it will allow us to make specific interventions to test what the effect is on cramps. So although we are still in the infancy of this area of research, the field studies are a very important starting point and have so far yielded important findings.

One study published in 1990 showed that there was no association between potassium levels and cramps. In that study cyclists rode for up to five hours. Some of the subjects did cramp, but their potassium levels were not uniformly high or low, thus showing no association between that variable and the cramps. However beyond that study (and one more that was presented at a conference but apparently not published) there is little real data out there to support or refute this hypothesis that dehydration or electrolyte disturbances cause cramps.

Study 1: Two Oceans Ultra Marathon

In a 2004 study published in the British Journal of Sports Medicine, Professor Schwellnus and his colleagues examined runners before and after the Two Oceans 56 km marathon in Cape Town. They measured quite a few variables, but since we are discussing changes in electrolytes and hydration, we will talk about those results. Remember that many people, both scientist and personal trainer alike, will profess that cramps are caused by dehydration and/or some disturbance in the electrolytes (sodium, potassium, magnesium, etc.) So the important finding from this 2004 study was that when the crampers were compared to the controls---who were matched for body mass and finishing time---the only differences were that the crampers had lower sodiums and higher magnesiums. The problem with this is that a lower sodium concentration suggests overhydration and not dehydration, and also if magnesium deficiency is meant to cause cramps then surely the crampers should have been lower here?

	Crampers (N = 21)	Controls (N = 22)
Sodium	139.8 ± 2.1	142.3 ± 2.1
Potassium	4.9 ± 0.6	4.7 ± 0.5
Magnesium	0.73 ± 0.1	0.67 ± 0.1
Osmolality	280 ± 6	284 ± 10

The relevance of this study is that if dehydration and electrolyte disturbances really play such a large role in cramps (as they are proposed to), then the crampers should have much higher electrolyte concentrations since they would be losing fluid and causing the concentrations to rise. Yet instead we see something entirely different, first that the crampers had lower sodium concentrations, and second that the crampers were not really different compared to the controls.

What is also noteworthy from this study was that the crampers had an average loss of body weight of 2.9%, compared to 3.6% for the non-cramping controls. In otherwords, the people who DID NOT cramp lost more weight than the people who did. It goes further than this, because Schwellnus et al were able to measure the change in plasma volume as well - a more direct measure for what is happening to fluids. Here, they found that the crampers actually gained a small amount of 0.2% during the race. The non-cramping control subjects LOST 0.7%. So the sum effect of this data is that it suggests very strongly that cramping is not associated with dehydration, or with lower serum electrolyte levels, which is what we have had drilled into us for many years!

The follow-up study from Iron Man - further evidence against serum electrolytes

The next year they published a study in Medicine and Science in Sports and Exercise, and instead of runners it was Ironman triathletes. According to what most of us hear day in and day out, it is these ultra-distance athletes who are exercising for 10+ hours at a time that must be most susceptible to dehydration and electrolyte deficiencies. After all, they are sweating for hours on end, and the numbers tell us that with so many liters of sweat lost then they must also be losing grams and grams of "essential electrolytes" such as sodium. Below you will see the basic data on these athletes, and the important finding here is that we see the crampers and controls were the same age and were similar in mass, had similar pre to post cahnges in mass, and also finished the Ironman in similar times:

	Crampers (N = 11)	Controls (N = 9)
Age (years)	33.5 ± 8.8	35.4 ± 8.1
Pre-race mass (kg)	79.1 ± 5.9	77.7 ± 6.4
Post race mass (kg)	76.3 ± 5.6	74.6 ± 6.5
Body mass loss (%)	3.4 ± 1.3	3.9 ± 2.0
Total race time (min)	660.8 ± 77.9	685.7 ± 48.5

So the two groups were essentially the same in that the crampers did not spend longer in the course or lose more weight (a crude measure of dehydration). Yet again the crampers and the controls looked remarkably similar on paper---except as in the 2004 study the crampers again had a statistically significant lower sodium concentration, and, we will repeat this, that suggests they were more hydrated compared to the controls. . .yet they were cramping. Here are the data from the electrolytes in the two groups:

	Crampers (N = 11)	Controls (N = 9)
Sodium	140 ± 2	143 ± 3
Potassium	4.4 ± 0.06	4.2 ± 0.5
Magnesium	0.9 ± 0.2	0.8 ± 0.1

Recall that what is most often put forward as the cause of cramps is either dehydration or some electrolyte disturbance, but the data from these two studies do not support that hypothesis. Although these are field studies and we cannot assign a cause and effect relationship, this available evidence suggests that these (normal) levels of dehydration do not appear to cause cramps. If these levels of dehydration did cause cramps and were largely responsible for cramps, then what we should see is a very high incidence of cramps in all of the race finishers with the same physiological characteristics as these subjects----or in other words, the vast majority of the race finishers.

Rejecting the old models

In science when the available evidence does not support the hypothesis, we must change the model. Based on this available evidence we see clearly that dehydration and electrolyte levels are not associated with muscle cramping during or after exercise, and therefore we must adopt a different model to explain what is causing them. We cannot just ignore the data we have shown here and keep on telling people that it is dehydration and electrolytes when new evidence suggests otherwise.

So in Part III of this short series we will lay out the newest hypothesis that tries to explain the "why" and the "how" of muscle cramps. It is novel and, as you might have guessed already, has nothing to do with electrolytes and dehydration! So come back and join us for Part III of this series, and then join us for the comments and debate!

See also:
Part I: Theories and fallacies of muscle cramps

References:
Brouns F et al., "Ammonia accumulation during highly intensive long-lasting cycling: individual observations." International Journal of Sports Medicine. 1990 May;11 Suppl 2:S78-84.

Schwellnus MP et al., "Aetiology of skeletal muscle 'cramps' during exercise: a novel hypothesis." Journal of Sports Sciences. 1997 Jun;15(3):277-85.

Schwellnus MP et al., "Serum electrolyte concentrations and hydration status are not associated with exercise associated muscle cramping (EAMC) in distance runners." British Journal of Sports Medicine. 2004 Aug;38(4):488-92.

Schwellnus MP. "Muscle cramping in the marathon : aetiology and risk factors." Sports Medicine. 2007;37(4-5):364-7

Sulzer NU et al., "Serum electrolytes in Ironman triathletes with exercise-associated muscle cramping." Medicine and Science in Sports and Exercise. 2005 Jul;37(7):1081-5.

Muscle cramp 'teasers'. . .

Apologies for the absence...and some muscle cramp 'teasers'

Ah, the joys of the University calendar! We must apologize for our somewhat lengthy absence - it has been 5 days since we last did a post, which I think is the longest break we've had since we began The Science of Sport in April earlier this year!

But we have good reason, for both Jonathan and I are both deep into marking and examination of undergraduate and post-graduate exams and theses at our respective universities. Though Jonathan and I both enjoy lecturing and find it very rewarding, when we reach mid to late-November, our disposition towards teaching changes somewhat, as hundreds of exam scripts and thesis work suddenly land on our desks for us to plough through! And funnily enough, the other work doesn't seem to realise it and let up!

So we do apologize for the break, but we're back now, hopefully with a bang, as we get stuck into a new series, this one on Muscle Cramps - Science and Fiction.

A follow on from fluids and dehydration

The series on muscle cramps is really an extension of our last series - Fluid Intake and Dehydration. In that series, we tried to explode some of the myths around drinking during exercise, describing how the prevalent "scientific" advice was in fact flawed (sadly, it's often fatally flawed). We looked at the claims and counter-claims and ultimately encouraged everyone to do the wise thing - listen to your body, and when it says you're thirsty, drink! But only then...don't let the fluid companies tell you that you're the only mammal too stupid to know when to drink by itself!

Introducing muscle cramps - some points to ponder

The muscle cramp story is similar, sadly. In South Africa, we have a host of companies who produce cures, preventative tablets, creams and liquids to help you avoid cramp. The premise, as was the case with fluids and dehydration, is that a cramp is caused by a depletion of some electrolyte - sodium, potassium, calcium or magnesium. All have been mentioned, and most often, it's sodium and magnesium that take the brunt of the blame.

We'll take a step by step journey through muscle cramps in the series. We'll tackle it in three parts:

1. What is a cramp? Very brief history and overview of what we know, and how we know it.
2. The electrolyte-dehydration-heat theory for muscle cramps
3. An alternative view - evaluating the gaps in the theory

So that is what you can look forward to (or with dread, as the case may be!) over the next week.

Until then, here are some issues to ponder:

• Despite the theory that muscle cramps are caused by electrolyte and fluid depletion, it has yet to be shown that people who cramp have lower electrolyte levels or are more dehydrated than those who do not. In fact, the studies have found that "Crampers" and "Non-crampers" have similar electrolyte and dehydration levels. Something wrong with that picture...

• If cramps are caused by electrolyte and fluid depletion, which muscles would be most likely to cramp? Would it not be ALL the muscles, because you're losing electrolytes and fluid through sweat, so then all the muscle groups should be vulnerable...yet for some reason, we cramp in the muscles we actually USE. Again, something out of place there.

(Some of you may already have a counter to these points, saying that what is happening in the muscle is not necessarily what is happening in the blood - we'll tackle that one for sure)

• And then finally, if you are reading this before heading off to bed, we hope that you don't experience the dreaded "Night cramp", which we're sure most of you have had at some stage. You wake up in the night, and feel a slight twinge, usually in the calf. Your first impulse is to point your toe, and when you do that, what happens? You may know that if you do this, you'll be writhing in agony instantly! Instead, what should you have done? The answer is you should stretch the muscle - stretching is the quickest way to get rid of cramp. Now, how do we explain that one according to a heat-electrolyte theory?

The answers to follow, so join us then!

Ross