THE CURSE OF THE CRAMP
Cramping is one of the most bog-ordinary sporting ailments, but also one of the most misunderstood. That’s not your fault – theories on the causes of exercise-associated muscle cramping have changed several times over the years, but sports scientists believe they’re better on track now.
About two out of every three athletes have experienced painful cramps during sport. The term ‘exercise - related muscle cramping’ (EAMC) is used to distinguish cramping that comes through repetitive action from cramps that might come about from a medical condition. EAMC is involuntary, painful skeletal muscle spasms that occur during or immediately after exercise. It is localised cramping that happens spasmodically in different working muscle groups, most commonly the hamstrings or quadriceps, and especially in the calves. Medicine Today reports the following prevalence of EAMC:
- triathletes - 67%
- marathon runners - 30-50%
- rugby players - 52%
- cyclists - 60%.
WHAT EAMC IS NOT
There have been different theories about the main causes of EAMC, and some have been ruled out. These include:
- abnormal serum electrolyte concentrations (i.e. potassium, sodium, magnesium, calcium) from dehydration/sweating buckets or overconsumption of water
- increased core temperature (although this and electrolyte concentrations may cause generalised cramping - a different kettle of fish)
- aliens trying to claw their way out from inside your leg.
THE MAIN CAUSE OF CRAMP
The popular belief among exercise and sports physicians is that the most likely risk factor and cause of EAMC is fatigue in the muscle, which presents as cramp due to altered neuromuscular control. Increased exercise intensity and/or duration, decreased muscle energy, environmental conditions and a lack of conditioning can all send you into the muscle fatigue that sets you on your way to crampland. Unluckily for some, there are strong theories suggesting that some people simply have a genetic predisposition to cramping.
Apart from family history, there are several other risk factors that may make you more likely to get cramp. A cross-sectional survey of 1300 marathon runners for Medicine and Science in Sports and Exercise Sports found that other risk factors included:
- older age
- a longer history of running
- higher body mass index (BMI)
- shorter daily stretching time
- irregular stretching habits.
TWISTING THE KNIFE
There are some things that definitely set you up for a cramp. These include:
- not enough carbohydrate before or during exercise
- hardness of the ground (for running)
- poor biomechanics (e.g. running gait)
- hill running
- running more than 30km
- higher relative intensity (regardless of fitness).
While not the cause of EAMC, extreme heat can increase the risk of cramp. Dehydration, however, has been found to make no difference to the incidence of cramp, according to recent studies1.
If you begin cramping, here’s how you can treat it:
- Resting and stretching the working muscle is best - e.g. for the calf, grab the toes and ball of the foot and pull them back towards the kneecap. Stretching increases tension in the muscle, which tells the tensions receptors to increase their activity, which in turn tells the stretch receptors to ease up on the muscle contractions causing the cramping
- Electrical stimulation (e.g. with a TENS machine) at the tendon of the cramping muscle may also produce the effect above
- Anecdotal reports and a study in the Journal of Athletic Training suggest that gulping down 30-60ml of pickle juice can relieve cramp in as little as 35 seconds. The magic ingredient in pickle juice is believed to be acetic acid, which is speculated to trigger a reflex that increases inhibitory neurotransmitter activity in cramping muscles
- Quinine (used in tonic water) has been used for both generalised cramping and EAMC. A Cochrane review of 23 clinical trials concluded that there is 'moderate quality evidence' that quinine reduces cramp frequency and intensity, but not duration. However, quinine can increase the risk of thrombocytopenia (abnormally low amount of platelets in the blood)
- Heat packs - in cold weather
- Massage therapy.
A study of 2600 endurance athletes published in Medicine and Sport in Science and Exercise reported that most users of magnesium supplements said they were of little or no help for cramps. Medicine Today stated that the effectiveness of magnesium supplements in treating cramp has never been evaluated by systemic review. It is also claimed that despite earlier beliefs, salt tablets don’t target the main cause of cramps and are not considered to be beneficial.
REDUCING THE RISK
Since fatigue in the muscle is the primary cause of cramping, the prime way to reduce risk is to be fit – cramps are less common in athletes who are well trained and conditioned for the sport or event they’re training for. Fuelling with adequate carbs before and during activity will also help stave off muscle fatigue. These two are no-brainers, but then there are other tools sports support staff and physicians use and trust, even though they are not yet proven by science to be effective. These include:
- Massage before and during competition (used a lot in AFL)
- Compression tights, etc. - especially garments specifically for common cramp sites, e.g. compression socks or compression calf sleeves (for feet and calves) and compression shorts or compression quad sleeves or leg sleeves (for hamstring cramps)
- Adequate warm-up
- Both active and passive stretching. A lot of the stretches in yoga are active stretches. These are where you hold a position with no assistance other than using the strength of your agonist muscles, e.g. standing and lifting your leg up straight. These can be quite difficult to hold for more than 10 seconds. A passive stretch would be holding a position in a relaxed stretch with the assistance of something, such as a strap, bodyweight, or something to rest or balance on, e.g. standing and lifting your leg up straight and resting in a box to hold it there during the stretch.
1 Sports Dietitians Australia, Cramps and Stitches