Muscle Cramps - Part 1

Over the next few weeks we look at the latest evidence on what cramps are, why we get them, how to prevent them and how pickle juice may be able to help.

What are muscle cramps? 

Ah cramps! They make me nervous just thinking about them! Most of us have had one at some point or another but what are they exactly?  

A cramp is defined as a painful spasmodic involuntary contraction of a skeletal muscle which occurs during or after exercise. There are actually two main types of cramps: 

  • Whole body cramping, but thankfully these are not as common;  

  • Exercise-Associated Muscle Cramps (EAMC). This type of cramping involves individual muscles or groups of muscles and is common in the calf, hamstring and quadriceps. Think a calf cramp as you go to push off the wall in the pool. It typically involves the muscle being used.

Cramping prevalence has been reported to be as high as 6-20% during Ironman events, 30-50% in marathon runners, 60% in cyclists and 30-50% in team sports.

Although localised and short in duration, EAMC may lead to musculo-skeletal dysfunction, reduced performance and muscle damage, making prevention key for optimum performance. 

What Causes Muscle Cramps?  

There are many theories on why we cramp...

For many years it's been believed that cramping is caused by dehydration and electrolyte imbalances, in particular, sodium.  This is based on earlier research with underground miners and marathon runners. A heat exhaustion study discovered that miners who cramped were more dehydrated and more sodium depleted than those who didn't cramp. In marathon runners, they found the athletes that cramped were more likely to be saltier sweaters and have lower serum sodium at the end of a race. 

However in contrast to these earlier studies, more recent research has failed to show an association between EAMC, dehydration or abnormal serum electrolyte imbalances.... 

A more recent theory suggests that altered neuromuscular activity in the central and peripheral nervous system is the cause of EAMC. Fatigued muscles disrupt the normal functioning of peripheral muscle receptors, altering the excitability of the central nervous system. This causes an imbalance between increased muscle contraction (afferent activity) and relaxation (inhibitory afferent activity) leading to a decreased ability for the muscle to relax after contraction. This is particularly the case when working in a shortened position such as shortened calves when pointing toes in swimming or quads when pedalling while standing on the bike. This theory also helps explain why stretching out a cramping muscle can be the most effective way to relieve it. 

So which theory is it that causes cramps? The bottom line - we don't know.....cramping is still poorly understood!

Despite exercise-associated muscle cramping being a common complaint among athletes, the exact cause remains uncertain due to a lack of quality scientific evidence to guide management. Perhaps for the heavy and salty sweaters amongst us, doing some sweat testing and developing your own personalised hydration plan will assist in your management of cramping. For others, regular massage, neural stretching, adequate strength and muscle conditioning may assist.

Tune in next time where we discuss prevention and the new kid on the block - pickle juice.