If you’ve been watching the Tour De France this week, you will have seen Frenchman Lilian Calmejane in his first TDF participation win stage 8 to Station De Rousses in the Jura mountains. But not before he almost lost the stage through cramps. Almost everyone can relate to Lilians anguish, especially if you have experienced the familiar sensation of a muscle cramp on a long hot ride or at the pointy end of a race! So why do we get cramps during exercise and what can we do about them?
The short answer is that we don’t have all the answers yet. As always at Cycle Physio we will take the scientific approach to try and help. What we DO know about exercise induced muscle cramps is:
Scientists are still debating and investigating what causes cramps, more properly known as “exercise associated muscle cramps”. There are currently two main theories:
Dehydration and sweating have long been thought of as key causes of cramps, but the science behind this has conflicting results. Aside from the higher prevalence of cramps in hot weather, where did these ideas come from?
When you sweat, electrolytes are lost and the main electrolyte lost is sodium (ie regular table salt). The normal amount of salt loss in sweat varies between individuals (0.5 to 2.3g/l). This can equate to 2.5g -30g loss per day depending on duration, intensity of training / racing, the temperature and individual differences in the sodium content in sweat (Cage et al 1965). In America this has led to some recommendations regarding electrolyte replacement for athletes. The National Athletic Trainers Association recommends 0.3 – 0.7g/l sodium for your sports drink, and the American College Sports Medicine recommends a higher concentration of between 1.2 – 2.5g/l. Other high sodium supplements have been tried widely, most notably pickle juice (yep, that stuff pickles are stored in which happens to be high in sodium and fairly acidic).
Somewhat surprisingly, when sodium supplementation (via sports drinks, salt tablets or pickle juice) has been tested, there usually isn’t a change in blood sodium concentration. Despite this, pickle juice in relatively low doses has been shown to rapidly reduce cramps in one study and do so faster than water alone (Miller et al 2010). This same research group demonstrated that the relief from cramping occurs so fast (in about a minute) that there hasn’t been enough time for the salt in the stomach to be absorbed. The thought here is that the pickle juice stimulates a cardiovascular reflex when it hits the stomach that causes plasma (fluid) in the blood to shift out of the vessels to the gut to aid digestion, thus raising the relative sodium content which might alleviate cramp (ie supports the neuromuscular theory of cramp). This along with the finding that dehydration and sodium levels don’t appear to be different between ultramarathon runners who do and do not get cramps (Hoffman & Steumpfle 2015) suggests that the neuromuscular theory of cramp is the more likely cause of exercise induced cramps at the present time. Stay tuned, as this may change!
If these simple tips don't work, consult a sports dietician or sports medicine doctor.