While many people believe that muscle spasms or muscle cramps are caused by dehydration there is growing evidence that this many not be the main cause. In this article I discuss some of the more recent findings that cause muscle leg cramps and spasms when cycling, how to deal with them and how to avoid them.


Muscle cramps or spasms can start as a slight twitch or tic and can develop into a major locking up of the muscle causing intense pain. Muscle cramps can go on for a few seconds to several minutes. Muscle cramps or spasms can come and go several times and then stop.

Muscle spasms or muscle cramps caused by exercise are sometimes referred to as exercise-associated muscle cramping (EAMC).

Muscle cramps or spasms can develop in any muscle group but the most common muscle groups in cyclist are the:

  • Calf
  • Hamstring
  • Quadriceps
  • Lower back
  • Hands and feet

What causes muscle cramps and muscle spasms

There is much that has been researched and written about muscle cramps or spasms over the years. The most commonly held belief is that muscle cramps or spasms are brought on during exercise as a result of dehydration. The main reason is that when you sweat you lose fluids which include electrolytes (salt, potassium, magnesium and calcium).

These electrolytes are used to help the chemical firing of muscle fibres. When these nutrients in your body fall, the incidence of muscle spasms increases. It is a reasonable conclusion to then link electrolytes to cramps and why many sport drinks now include these nutrients; salt, potassium, magnesium and sometimes calcium to reduce the chance of muscle cramps or spasms while cycling.

The common belief that dehydration causes muscle cramps and muscle spasms is becoming less credible

However, recent researchers that studied triathletes found that those who suffered muscle spasms or muscle cramps had the same level of dehydration and blood mineral levels as those who did not get muscle spasms or muscle cramps. So this belief is slowly becoming less important and the search for the reasons for muscle spasms or muscle cramps continues.

A report from the University of Oklahoma (Sports Medicine, April-May 2007) did, however, discover that salt plays a more important role that the other electrolyte minerals. In their research, those who cramped lost more salt during a race than their peers who did not cramp. The debate still rages on…

Other treatments for muscle cramps and muscle spasms

There has been limited research that suggests that common treatments that include the following don’t provide any long or short term benefits to reduce the chance of muscle spasms or muscle cramps:

  • General multivitamin pills;
  • Chiropractic manipulation;
  • Drinking large amounts of water;

There is some evidence that if you consume a sports drinks that contains sugar or if you eat during exercise that last more than 1.5 hours, it improves endurance performance and reduces that chance of developing muscle spasms or muscle cramps.

In the past, Quinine has been used to treat muscle spasms or muscle cramps. It has been taken off the market (for over the counter sales) because it can damage blood cells. Other medications include Gabapentin (an anticonvulsant), diltiazem (a blood pressure medication), or B-complex vitamins. All have been shown in some studies to help manage muscle spasms or muscle cramps in some people (Journal of Clinical Pharmacology, 1998;38:1151).

The warning signs for muscle cramps and muscle spasms

Just before a muscle cramp and muscle spasm develops you’ll probably feel the pulling or tightening in the muscle first. At this point if you ease the pressure on the leg that has developed this pulling or tightening in the muscle then there is a good chance that it won’t develop into a full blown muscle cramp and muscle spasm.

Research now supports “altered neuromuscular control” as the cause of muscle cramps and muscle spasms

As mentioned, there is mounting research that electrolyte depletion” and “dehydration” as the cause of muscle cramps, is not convincing.

While all these theories are being studied, researchers are finding more evidence that the “altered neuromuscular control” hypothesis is the principle pathophysiological mechanism the leads to exercise-associated muscle cramping (EAMC). Altered neuromuscular control is often related to muscle fatigue and results in a disruption of muscle coordination and control.

According to a review of the literature conducted by Martin Schwellnus from the University of Cape Town; quoting the same recent article:

The evidence supporting both the “electrolyte depletion” and “dehydration” hypotheses as the cause of muscle cramps is not convincing. He reviewed the available literature supporting these theories and found mostly anecdotal clinical observations and one small case-control study with only 10 subjects. He also found another four clinical prospective cohort studies that clearly did not support the “electrolyte depletion” and “dehydration” hypotheses as the cause of muscle cramps. In his review, Schwellnus concludes that the “electrolyte depletion” and “dehydration” hypotheses do not offer plausible pathophysiological mechanisms with supporting scientific evidence that could adequately explain the clinical presentation and management of exercise-associated muscle cramping.

He writes:

“Scientific evidence for the “altered neuromuscular control” hypothesis is based on evidence from research studies in human models of muscle cramping, epidemiological studies in cramping athletes, and animal experimental data. Whilst it is clear that further evidence to support the “altered neuromuscular control” hypothesis is also required, research data are accumulating that support this as the principle pathophysiological mechanism for the aetiology of exercise-associated muscle cramping (EAMC).”

This backs up some of my personal observations with the cyclists that I coach during the mild winter here in Australia. They are cramping but they are far from dehydrated.

So what is altered neuromuscular control in its relationship with muscle cramps and muscle spasms?

In 1996, it was proposed that muscle cramps and muscle spasms are caused by a neurological response that initiated from the spine, not the site of the muscle cramp or muscle spasm. The theory proposes that muscle cramps and muscle spasms are actually caused by the muscle just not being strong enough to develop the power its being asked to develop for the duration of the race or training ride. Hence its more of a muscle fatigue issue.

So what can you do to reduce the chance of muscle cramps and muscle spasms?

Recent research suggests the following to help reduce or delay the onset of a full blown muscle cramp when the signs of muscle cramps and muscle spasms start:

  • With altered neuromuscular control, it has been suggested that muscle stretching is the best way to treat muscle cramps and muscle spasms. I’m yet to find what they mean by this and if post stretching or stretching during exercise is the best method. In my experience stretching during your cycle training ride and cycle racing is the best method to release a cramp.
  • Also, altered neuromuscular control recommends the ongoing conditioning of the muscles to avoid them fatiguing too soon during your cycle training rides and cycle racing
  • Reducing the intensity or stopping cycling also helps
  • On-going regular massage
  • Proper warm-up before going out on your cycle training ride and cycle racing
  • Post-exercise stretching after your cycle training ride and cycle racing
  • Being well hydrated with a good quality electrolyte sports drink during your cycle training ride and cycle racing

Also, there is some evidence that vitamin D helps aid the repair of muscle damage delayed onset muscle soreness (DOMS) and improves the time taken to heal injury. If your vitamin D level is low, getting some sunshine or taking at least 2000 IU each day of vitamin D may help. This may help in the after mark of a bout of muscle cramping and muscle spasms while out cycling.

More recent research from Nobel Prize winner Rod MacKinnon has found that pungent and spicy tastes can help hinder neurological misfires that cause muscle cramps.

My personal conclusion to the cause of muscle cramps and muscle spasms

I believe that there may still be a case for electrolyte depletion and dehydration playing it’s part in increasing the chance of muscle cramps and muscle spasms but I also believe that this is only part of the story. There are other reasons that a cyclist may develop muscle cramps and muscle spasms, and that muscle fatigue is a very likely candidate.

Regardless of the current theories, I still believe that being well hydrated with a electrolyte sports drink while cycling is important to ensure that the cyclist does not become severely dehydrated or run out of carbohydrate stores when cycling for events longer than 1.5 hours. By consuming a regular supply of carbohydrate during the ride, the likelihood of “hitting the wall” or “bonking” is greatly reduced and performance can continue to be maintained.

I also believe that most muscle cramps and muscle spasms are more likely to do with the cyclist’s conditioning. Regardless of the theories being bandied around, a cyclist that has correctly prepared themselves for an event will be less likely to affected by muscle cramps and muscle spasms. We have found our indoor training sessions that make up our unique coaching training programs provide very good relief at addressing general muscle cramps after several months of training.

I have successfully been able to reduce the chance on cramping in many of our athletes by ensuring that their training load mimics the conditions that they race under. I also recommend that athletes take a magnesium supplement. Finally, I’ve noticed that some athletes that I coach are more prone to cramping than others. However, none of these recommendations or observations that I have made are scientifically proven.

The hot and spicy products are gaining some popularity and many of my clients that have used them, have had good results. Only a few have found the hot and spicy products did not resolve their cramping issues.


While known medical causes of muscle cramps are still being researched the occasional muscle spasm or muscle cramp is not deemed by the medical professionals to be serious. However, if your muscle cramps are severe, frequent, constant or of concern then make an appointment to see your doctor.