With about 10 kilometres left in the race, Lanni Marchant took a safety pin and jammed it into her left quad. She was desperate to fight through the muscle cramps that were hobbling her as she raced through the streets of Moscow at the 2013 world marathon championships.
But the drastic act turned out to be no better than other supposed cures offered to cramp-prone runners, from bananas to salt tablets to sleeping with a bar of soap under their bed sheets.
Marchant, the Canadian marathon record-holder at 2:28:00, struggled to a disappointing finish and concluded – contrary to the advice one of her competitors had offered – "self-acupuncture doesn't work."
By some estimates, nearly 40 per cent of marathoners, 60 per cent of cyclists and half of soccer players will experience muscle cramps at some point. So a presentation from researchers claiming to have developed a new way to prevent and treat muscle cramps generated plenty of buzz at the American College of Sports Medicine annual meeting in Boston earlier this month – especially since their solution runs counter to the conventional cramp wisdom.
The standard view, which dates back to studies of coal miners and labourers a century ago, is that exercise-induced cramps result from dehydration and electrolyte depletion. When you work hard in hot conditions, you lose sodium, potassium, and other electrolytes in your sweat. That, in turn, is what is thought to trigger cramps, and it's the reasoning behind remedies like salt tablets, sports drinks, and bananas.
(Former Toronto Blue Jays infielder Munenori Kawasaki also offered the following impeccable logic for eating three bananas after a bout of cramping: "A monkey never cramps.")
In the past decade, though, researchers have begun monitoring competitors before and after marathons, ultramarathons and triathlons, comparing those who cramped with those who didn't. In study after study, electrolyte and hydration levels were nearly identical between the two groups.
Electrolyte depletion is real, but it doesn't seem to explain who gets cramps.
That fits with an alternate theory proposed by South African sports physician Martin Schwellnus in 1997, blaming cramps on "altered neuromuscular control." Instead of a muscle problem caused by electrolyte depletion, Schwellnus argued that cramps result from a disturbance in the nerves that control the muscles. A neural switch gets stuck in the "on" position, causing a prolonged and painful contraction.
Schwellnus and his colleagues have identified a series of minor risk factors, such as starting too fast and the use of certain medications, as well as family history. One recent study of 15,000 runners found cramp risk was increased by 34 per cent for those carrying a particular variant of a gene called COL5A1. The most effective remedy, Schwellnus says, is to slow down, and if necessary stop and stretch the affected muscle – hardly an appealing option for a competitor in a race.
In 2010, a possible cure emerged: pickle juice. It had long been used as a folk remedy by athletic trainers, who assumed the salty brine was replacing lost electrolytes. But researcher Kevin Miller, now a professor at Central Michigan University, showed the effect of pickle juice was so rapid the juice hadn't even left the stomach. Instead, he proposed, the strong taste of pickle juice was disrupting the neural malfunction that caused the cramp, consistent with Schwellnus's theory.
The new anti-cramp product, developed by Harvard neurobiologist Bruce Bean and Nobel Prize-winning neuroscientist Rod MacKinnon, works along similar lines. Bean and MacKinnon were ocean kayaking off Cape Cod on a windy day in 2006 when they both suffered muscle cramps in their arms – a potentially dangerous situation that led them to look into the research on cramping.
They eventually concluded that the acetic acid in pickle juice activates a set of receptors in the mouth, throat, and stomach called "transient receptor potential channels," which jolt the nervous system out of its cramp state. Better yet, they noted other substances, like mustard oil and capsaicin from hot peppers, stimulate the same receptors even more strongly and with a longer effect, perhaps making it possible to prevent cramps altogether.
Bean and MacKinnon eventually launched a startup called Flex Pharma, which raised over $80-million U.S. to develop and market their product, a propriety blend of natural ingredients designed to stimulate the relevant receptors. Their "Hotshots" have a hot, pungent taste (though much more palatable than pickle juice!), and sell for $35 (U.S.) for a six-pack. They're not yet shipping to Canada.
Do they actually work? At the ACSM conference, Bean and his colleagues presented a summary of data from several studies, including one by independent researchers at Pennsylvania State University, showing the product reduces susceptibility to cramps induced in the lab by electrical stimulation or voluntary muscle contraction, with an effect that starts within 15 minutes and lasts six to eight hours. The studies haven't yet been peer-reviewed, but the researchers plan to submit them to academic journals.
Schwellnus, who isn't associated with the company but was also at the conference, offered a note of caution: be wary of just treating the symptoms without addressing the cause. The approach may be appropriate for straightforward exercise-induced cramps, but you should be sure your cramps aren't associated with an underlying medical condition such as diabetes.
For Marchant, who hopes to run both the 10,000 metres and the marathon at this summer's Olympics in Rio, that's evidence enough to at least give the product a try. The research may still be preliminary – but it can't be worse than a safety pin in the thigh.