When muscle-cramping strikes, it can scupper even the best-laid plans. Andrew Hamilton looks at commonly-used strategies to minimise cramping risk and explains how the latest nutrition research provides a revolutionary new anti-cramping approach
A muscle cramp occurs when a muscle, or even a few fibres of a muscle contract involuntarily. Muscle cramps are most common in muscles or muscle groups that span two joints. These include the calf muscles, the hamstrings and the quadriceps. In addition to these areas, cramps can also affect the hands, abdominals, the muscles around the rib cage, and the feet and toes. Muscle cramps can last anywhere from a few seconds to 15 minutes or longer.
What causes muscle cramps?
The exact cause of cramps remains something of a mystery. What we do know is that cramping occurs when the mechanisms controlling the electrical stimulation of muscle fibres (contraction – motor unit firing) and subsequent deactivation (relaxation) become impaired.
Physiological factors that have been investigated as possible contributors to this impairment of electrical control include:
- Inadequate hydration and insufficient levels of the electrolyte minerals in muscles.
- Poorly-trained muscles that are inflexible and/or insufficiently conditioned for the exercise.
- Inadequate rest and recovery.
Genetics are known to play a role as does age, and the risk of cramps can also be increased by injury, where certain muscles may go into spasm in order to “brace” and protect the injured area. Most authorities agree that “true cramps” – those we normally associate with vigorous exercise, fatigue and dehydration/electrolyte imbalances etc – are caused by hyper-excitability of the nerves that stimulate the muscles, which is why much attention on preventing cramps has been focused at minimising this excitability through optimum nutrition and conditioning.
Reducing muscle cramping risk by nutrition
When it comes to improved nutritional strategies to combat cramp the scientific evidence has been far from clear-cut, mainly because there’s actually very little data from published studies.
To add to the confusion, the studies that have been conducted have often produced mixed results. For example, South African scientists studied 72 runners competing in an ultra-distance marathon and compared data from those who suffered exercise-induce cramps and those who didn’t(1). Although they found small variations in blood levels of post-exercise sodium and magnesium, they concluded that there were no clinically significant alterations in blood electrolyte concentrations and no alteration in hydration status in runners with “exercise associated muscle cramping”.
Despite the lack of unequivocal evidence however, most scientific authorities agree that any nutritional cramp-prevention strategy should aim to address three important areas:
- Maintaining adequate hydration(2) – because all electrical signalling activity in the muscles takes place in an aqueous (water) environment and even small shortfalls in hydration levels could lead to impaired electrical signalling and an increased risk of cramping.
- Ensuring adequate dietary intake of the electrolyte minerals(3); sodium and potassium because they’re involved in conducting electrical signals to/from muscles, and calcium and magnesium, which are essential for the contraction and relaxation of muscle fibres.
- Replenishing energy in the form of carbohydrate – because even small drops in the level of stored muscle carbohydrate (glycogen) can lead to increased fatigue, which may in turn increase cramp risk.
A revolutionary approach
Although there’s been agreement among scientists about the factors that are known to increase the risk of cramps, the precise physiological and biochemical mechanisms responsible for causing cramps have remained poorly understood and a truly effective means of preventing cramps has proved elusive. Very recent research has managed to unlock much of the mystery and come up with an effective prevention strategy.
The story started when two avid sea kayakers sustained serious episodes of muscle cramps while winter paddling. These were no ordinary kayakers; one was Professor Rod MacKinnon, a Nobel Laureate in chemistry for researching ion channel activation in the nervous system, while the other was Bruce Bean, a professor of neurophysiology at Harvard Medical School.
Eager to try and find ways to prevent or treat such cramps, they found no supportive data on common remedies used to ease the cramps, including electrolyte drinks and bananas. What they did learn however was that a muscle needs to be “innervated” to cramp effectively. That implicated the nervous system (not muscles) as a key element of muscle cramps – and also the intriguing possibility that a nerve block might be able to prevent cramps.
The nerve block they had in mind however was to “shock” the nervous system by providing a strong sensory stimulus input into the brainstem and spinal cord. Without delving too much into detail, it so happens that providing a shock to the input side of the nervous system (by activating proteins called “TRP ion channels”) helps to tone down over-excitability in the motor neurons that supply the muscles (known as alpha motor neuron activity), which can lead to cramps.
The trick was to find an effective way of delivering this shock to the input side of the system. The researchers’ hypothesis was that a combination of spices taken before exercise might do just that. This combination included a mix of ginger, cinnamon and capsicum from spicy pepper plants. By applying a strong sensory input and stimulating receptors in the mouth and oesophagus, the theory was that the pungent taste would overload nerve receptors, producing a kind of numbing effect.
To test the hypothesis, Mackinnon and Bean carried out experiments on themselves and then on cooperative family members. Although tested on only a few willing people, it appeared to work well.
Following this initial research, they replicated their findings in very carefully controlled scientific studies(4). Firstly, they showed that the spice combination was very effective at activating the TRP ion channels. Secondly, they tested the combination in 37 healthy volunteers across three studies. These volunteers took the spice-flavoured formulation in the morning and shortly afterwards underwent electric stimulation to induce muscle cramping.
Compared with findings in untreated participants, muscle cramp intensity and frequency was reduced three-fold. Even better, this preventative effect was evident within minutes and lasted up to eight hours.
But is this approach dangerous? Does the pain from a muscle cramp have a purpose, like the pain that makes us pull our hand away from a hot stove? MacKinnon and Bruce did consider this possibility but concluded there is no benefit to a muscle cramp. As Professor Mackinnon explained: “The debilitating pain we experience from cramps doesn’t prevent injury. We experience it not to help us survive but because the human body isn’t perfectly evolved.”
Applying the findings
Earlier this year, a product called “HOTSHOT” appeared on the market, which contains the same spice blend as used in the research above.
Taken 15-30 minutes before exercise, or at the first signs of cramping during exercise (or during recovery), this product is the first of its kind for effective cramp prevention. Unfortunately for UK readers, this is not yet available this side of the Atlantic. In the meantime there’s no reason to assume that a homemade blend of hot spices taken before exercise wouldn’t provide at least some benefits. Remember that that these spices don’t work by changing muscle chemistry in any way.
They simply provide a “shock” to the input side of the nervous system, which helps tone down the motor neurons supplying the muscles. Curry for breakfast anyone?
References 1. Br J Sports Med. 2004 Aug;38(4):488-92 2. Int J Sport Nutr Exerc Metab. 2005 Dec;15(6):641-52 3. Med Sci Sports Exerc. 2005 Jul;37(7):1081-54. Neurology April 6, 2015 vol. 84 no. 14 Supplement S17.003
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