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[[File:Cramping.jpg|right|thumb|300px|Cramping can ruin your day.]]What are the causes of cramping, what can you do to prevent them? Unfortunately, nobody knows the answer for sure, but there are a number of possible causes and corresponding preventative measures. =Introduction=Cramps are spasmodic, painful, involuntary [[Muscle|muscle ]] contractions. This page is focused on Exercise Associated Muscle Cramps (EAMC), though there are other types. Many runners suffer from cramps, and sometimes cramps can be severe enough to prevent the completion of an event, or catastrophically impact performance. What causes cramps and how can they be prevented? Sadly, no one seems to know, but here is what I’ve found out. ==Hydration and Electrolytes==Conventional wisdom is that dehydration and/or electrolyte depletion causes cramping. The science does not back up this idea. A studyThere are two leading contenders <ref name="ironmantwooptions"/> for the cause of muscle cramping; [[Sodium Deficiency]] and muscle fatigue. =Cause – sodium deficiency=''Main article: [[Sodium Deficiency]]'' The initial stages of [[Sodium Deficiency]] produce dehydration as the body excretes water to keep the blood sodium concentration at the 2000 South Africa Ironman Triathlon showed no correlation with dehydration right level. More extreme [[Sodium Deficiency]], or electrolyte levels excessive hydration, can lead to [[Hyponatremia]] where the sodium concentration in the blood drops. Either of these conditions are believed to interfere with nerve function and cause cramping. A study<ref name="Jung"/> in 2005 showed that a carbohydrate/electrolyte drink delayed cramps in athletes that have a history of cramping. However the study had There is also a small sample size large body of 13anecdotal evidence that increased salt reduces cramping. ==Preventing and treating sodium deficiency==''Main article: [[Practical Hydration]]'' [[Sodium Deficiency]] is easy to treat and pretty much risk-free. [[Sodium Deficiency]] can be either chronic (long-term) or acute (short-term). Increasing the salt in your diet can help prevent chronic [[Sodium Deficiency]], and 7 cramped with any excess will be naturally excreted. You may need to add far more salt to your diet than you expect. To prevent acute [[Sodium Deficiency]] you should add extra salt to the drinkyou take while running. I generally add a 1/4 teaspoon of salt to each quart of drink. To treat [[Sodium Deficiency]] triggered cramping, 9 without the one recommendation is 3 g (1/2 teaspoon) of salt added to 0.5 L (~16oz) of water or sports drink<ref name="twooptions"/>, which is rather salty and unpleasant shouldn't trigger [[Nausea|nausea]]. [[Heat Acclimation Training]] may also help prevent cramping.  ==Altered Neuromuscular Control & Stretching Pickles juice and cramping==There is some supportalso evidence<ref name="pickles"/> that even small amounts of pickle juice can help limit cramps. Coaches often recommend<ref name="Schwellnus2009NYT"/> pickle juice for athletes who suffer from cramping. While pickle juice is quite salty there is evidence that it is not the idea sodium that is helping prevent cramping. Studies on pickle juice show that cramps are neurological in originit takes effect within seconds and well before any of the pickle juice would've been digested. Altered neuromuscular control means Instead it is believed that it is the vinegar (acetic acid) that there is triggering a disruption reflex that stops the cramping. There is some suggestion that small quantities of vinegar are just as effective as pickle juice. (For those interested in the details, the hypothesis is that the pickle juice triggers a reflex in the [http://en.wikipedia.org/wiki/Oropharynx oropharyngeal] at the nervous control back of the musclemouth, rather than a problem purely with which acts to reduce [http://en.wikipedia.org/wiki/Alpha_motor_neuron alpha motor neuron] activity in the muscle itselfcramping [[Muscle|muscles]]. ) =Cause – Muscle Fatigue=There is some evidence<ref name="Helin"/><ref name="Schwellnus2009"/> that as [[Muscle|muscles ]] become tired the activity of the nerves changes. The mechanisms that activate muscle contraction become more active in the mechanisms that inhibit muscle contraction are cramping have weakened. This is a particular problem for muscles that will work in a higher level of electromyographic (EMG) activity contracted state such as the calf or hamstring and for muscles that a return of do not have the EMG level opportunity to baseline correlates to recoveryrelax periodically. The level There are a number of EMG is also reduced potential treatments for cramping caused by static stretching, which has lead muscle fatigue beyond the over simplistic and naïve approach of not exercising so hard. ==Stretching to an interesting theory<ref nameprevent cramping=="Schwellnus1997"/>. This One theory behind muscle fatigue causing cramping is based on the idea that a cramping muscle loses has lost its inverse stretch reflex. This The inverse stretch reflex is stimulated by a prolonged stretch and causes the muscle to relax. If a muscle’s muscle's inverse stretch reflex becomes weakened, it will tend to contract strongly. The theory also explains why cramps are more likely to occur in muscles that are contracting in a shortened position (calf, hamstring). This theory suggests that stretching [[Stretching]] will help with cramping, not because of increased flexibility, but because it will reinforce the inverse stretch reflex. This theory also suggests to me that runners  ==Running form and cramping==Runners whose muscles are not fully extending while running may be more prone to cramping, but I have seen no mention of this elsewhere. ==Exercise Level==Cramps are more common in For instance runners who go further or faster than land on their forefoot and have a relatively short stride will not allow the calf muscle to stretch out as they are accustomed torun. There is a belief that cramping is related This continual use in the contracted position may contribute to exhaustion of the cramping muscle, rather than overall fatigue. Higher levels of training Likewise runners may help prevent crampingnot extend the hamstrings as they run due to limited knee extension or reduced paw back. <ref namegallery widths=200px heights=200px caption="LoreRelaxing the calf while running">File:RunningForm-R.jpg|Toe Off from right (red) leg File:RunningForm-S.jpg|The right calf should be relaxed from this point until just before the foot touches down File:RunningForm-B.jpg|Foot extends passively (without any active calf contraction) as the leg is pulled forwardFile:RunningForm-C.jpg|Right calf relaxedFile:RunningForm-E.jpg|Right calf relaxedFile:RunningForm-G.jpg|Right calf relaxedFile:RunningForm-H.jpg|Right calf relaxedFile:RunningForm-I.jpg|Right calf relaxedFile:RunningForm-J.jpg|Right calf relaxedFile:RunningForm-K.jpg|Right calf relaxedFile:RunningForm-L.jpg|As the right leg decelerates for pawback, the momentum of the foot will cause it to come up towards the shin, [[Stretching]] the calf slightly. File:RunningForm-N.jpg|The right calf starts to tense in preparation for landingFile:RunningForm-P.jpg|The right calf absorbs landing forces, working eccentrically and stretches as the leg moves forward with the foot in contact with the ground. The calf will continue to stretch until it reaches the point where the heel comes off the ground.File:RunningForm-Q.jpg|Right calf contracts to at this point the calf is actively pushing the foot off the ground.File:RunningForm-R.jpg|Here the sequence begins again with toe off.</gallery>Changing [[Running Form]] can be difficult and risky, and evaluation should be performed using something like high-speed video to verify that a problem exists. One alternative is to vary your pace and running style slightly every few miles. This could be to pick up the pace slightly for 20 to 30 seconds, or to consciously raise the knees higher, or any other variation that helps to stretch your muscles a little. =Sodium deficiency or muscle fatigue?=Heat==It has been widely noted The following criteria can be used to determine if the cramping is due to muscle fatigue or [[Sodium Deficiency]]:* '''Sudden onset'''. [[Sodium Deficiency]] tends to cause minor cramping that cramping escalates whereas muscle fatigue is often sudden and dramatic.* '''Localized'''. Muscle fatigue is usually localized to specific muscles such as the calf where I [[Sodium Deficiency]] is more common in hot conditionsgeneralized.* '''Response to treatment'''. While this does not directly offer a way of preventing If the crampingis relieved by [[Stretching]] it is most likely to be from muscle fatigue, but if the cramping is relieved by hydration and electrolytes then it is possible that likely to be [[Heat Acclimation TrainingSodium Deficiency]] may help. Cramping that is relieved by pickle juice or vinegar could be because of either underlying cause is this treatment is working on the underlying behavior of the nerves. ==Hypokalemia=Unlikely causes of cramping=There does appear to be are a link between Hypokalemia (low potassium) and number of suggested courses of crampingthat have little or no supporting evidence.* Other electrolytes beyond sodium, but is actually very unusual without medication such as calcium or a [[Potassium|potassium]], are unlikely to have any bearing on cramping. Low levels of these electrolytes are extremely rare outside of serious medical condition conditions such as kidney problems failure or AIDS. ==Recommendations==There are no solid recommendations I * It has been suggested that sleep deprivation can makeimpair the brain's ability to accurately maintain core body temperature, but here are some suggestions and that may helpthis could lead to cramping. However there is little or no evidence to support this. * Stretch regularly using static stretching* Perform There are anecdotal suggestions that coffee and/or [[Heat Acclimation TrainingCaffeine]] for races that may be warm* Stay hydrated; it won’t help with the crampingcause cramps, but it’s still important! [[Practical Hydration]]there is no scientific support for this hypothesis. ==References==