Cramp. It’s a runner’s worst nightmare. One minute you are running along feeling great, next minute you are clutching your leg trying to find a way to relieve the cramp that has taken hold of your calf or hamstring. If this happened at the finish line it wouldn’t be such a problem, but when it happens with 30k or more to go it becomes a big problem. I have either been lucky or well trained as it has never affected me in a race. But when I talk to other runners i realise it is a very common problem and there are a lot of different ideas as to the causes and remedies for it. Some of these have been shown to be scientifically incorrect. There is however one theory which seems to fit the evidence and we can use this, combined with some common findings on who suffers cramp, to outline some prevention strategies and remedies if cramp strikes.
What are cramps?
Cramps are an involuntary contraction of a muscle and in runners it most commonly occurs in the hamstrings, calves, adductors and quads. The common link with these muscles are that they are used extensively in running and they are all primarily two joint muscles – ie the muscle spans two joints. For example the hamstring operates over the hips and knee.
What causes cramps?
For a long time cramp was thought to be a result of dehydration. Studies have since shown that this is not the case. Low electrolyte levels, particularly sodium, is another common reason given for cramp however there is also no research that shows that people suffering cramp have abnormally low sodium levels. In fact Schwellnus (2009) concluded that “the available evidence to date does not support the hypothesis that electrolyte depletion or dehydration causes EAMC (Exercise Associated Muscular Cramp)“. For those interested in a full understanding of the the research behind this have a read of Tim Noakes excellent book Waterlogged: The Serious Problem of Overhydration in Endurance Sports
So if cramps aren’t caused by dehydration or by low sodium levels what are they caused by and why do so many people still use some form of electrolytes during races?
Neuromuscular fatigue
The theory that has the most scientific support is that cramp is fatigue-related and occurs most frequently in two joint muscles.
Essentially as we fatigue the mechanism that causes a muscle to contract becomes overstimulated and the mechanism that causes muscles to relax is understimulated.
When the stimulus to contract overrides the stimulus to relax you have a cramp. This more frequently occurs when a muscle only goes through a short range of movement. Think about your stride length when you are 80km into a 100k race – it’s not that long is it? That shortened range of movement means there is less time for the muscle to relax and contract. If the mechanisms to relax fatigue then the muscle held in a short position will cramp.
Cramp happens in two joint muscles more frequently because the mechanism to control a two joint muscle is more complex. A two joint muscle is required to contract over one joint whilst lengthening over the other joint. For example in the latter half of the stance phase in running (when your foot is on the ground) the hamstring is lengthening over the knee joint and shortening over the hip joint. Fatigue can lead to the wrong message being given to the muscles so it contracts over both joints rather than over one and bam, you have a cramp.
(The actual mechanisms are far more complicated but I am guessing you don’t want to read about golgi tendon organs and muscle spindles, you just want to know how to prevent cramp!)
Risk factors for cramp
There are several common factors that people who suffer cramps share including:
- Racing
In racing we push yourselves harder than in training. Since fatigue is a major factor cramps are more likely to occur when racing. We can’t (and wouldn’t want to!) avoid racing but it seems that the more we push ourselves to the edge the more likely it is that we will cramp. - Starting too fast in a race
If you start off too fast in a race you will fatigue sooner and place the neuromuscular system under greater load, hence increasing the possibility of cramp. - Significantly increasing distance or intensity
If your race is significantly longer than your training runs or run at an intensity higher than your training runs then cramp is more likely. - Not being tapered
Training more in your taper week or starting a race with muscle damage has been shown to be a risk factor. This is a good argument for taking it very easy in the weeks before a big race. - Stretching
Stretching before exercise has shown to increase your risk of cramp. There is no scientific explanation of the cause of this and it may be that people who cramp stretch more before exercise in an attempt to avoid cramp. - Previous incidences of cramp
If you have had cramp before you are more likely to suffer them again.
Preventing cramp
As fatigue is the major factor the more well-trained you are the less your chances of cramp, assuming you don’t go out too fast that is!
A trail ultramarathon has its own unique set of challenges that can lead to cramp. Sudden increases in stride length to hurdle a creek, log or rock can demand a lot of an already fatigued neuromuscular system.
Cramp often occurs when you change going from uphill to downhill or vice versa as the neural input to the muscles has to change and if it doesn’t change quickly enough you cramp.
To prevent this, training should be tailored so the body is accustomed to changing stride length in a fatigued state. Incorporating some faster efforts at the end of a long run is a good way to do this.
Running technical trails when fatigued also helps train the neuromuscular system to rapidly change in response to the different foot positions and stride length needed to negotiate trails.
Of course running fast or on technical trails when fatigued comes with risk as the more fatigued you are the higher risk of injury and should be introduced gradually into a training program.
Make sure you are well rested before your race. There is very little to be gained training hard in the last week before a big race so make sure you have a good taper.
What about electrolytes
The scientific research indicates there is no evidence for the theory that sodium depletion causes cramp and therefore no basis for taking salt tablets to prevent cramps. However there are a large number of ultrarunners that will testify to their experience that taking electrolyte tablets in a race has either helped prevent cramps or helped overcome cramps.
The placebo effect is strong and if you believe 100% that taking electrolytes prevents cramp then there may be an argument for continuing to take them.
What happens if you get cramp during a race?
First of all stretch out the cramped muscle and whilst you are doing this activate the opposite muscle. For example if your hamstring cramps, stretch your hamstring whilst contract your quads, if your calf cramps actively pull your toes up whilst stretching your calf.
Once the cramp has settled reduce your running intensity to allow the body to recover and to reduce the demand on the neuromuscular system. For most people this will mean walking for 5 minutes or more.
Once the twitches have settled slowly increase the range of movement it goes through – dynamic stretching is best for this.
Pickle Juice
You may have heard that pickle juice helps overcome cramp. No it’s not an old wives tale. It actually works. The theory is that it stimulates a reflex in the back of the throat which in turn triggers a neural reflex that reduces or stops a cramp. If you cramp often it may be worth taking 75ml of pickle juice in your pack with you just in case. Just make sure the bottle is well sealed or all your gear will smell of pickle juice! I have heard that Asian supermarkets stock pickle juice and it even comes flavoured. The key ingredient is vinegar and the more concentrate the quicker it works apparently.
