One question above all niggles runners when training for a marathon: what can I do when I hit the wall? Bombarded with advice from sports companies, internet forums and gym buddies, many try positive thinking, pumping techno or fancy drinks and gels. For Claire Squires, tragically, the answer suggested by fellow gym-goers was Jack3D, a then-legal sports supplement that the 30-year-old bought over the internet.
Squires was a reasonably experienced amateur runner who exercised regularly and had completed a marathon before she ran in the London event last year. As her boyfriend, Simon Van Herrewege, told the inquest into her death, she decided: "If I hit a bit of a wall, I might take this drink and see if it pushes me through to the end of the marathon." The wall arrived, Squires drank her water bottle containing one scoop of Jack3D and collapsed a mile from the finish line. An inquest last week ruled that the amphetamine-like stimulant DMAA found in Jack3D "on the balance of probabilities, in combination with extreme physical exertion, caused acute cardiac failure".
Squires's case is frightening because many amateur runners try gels or powders recommended by friends without thinking to check what they contain. DMAA (1,3 dimethylamylamine), or methylhexanamine, sounds benign. A naturally occurring substance in a flowering plant of the geranium family, there are plenty of endorsements online. In a popular YouTube video, two American personal trainers liken DMAA to caffeine – "It creates an adrenaline effect. When you've got adrenaline in your body, that's a very powerful thing" – and praise its ability to help weight-trainers do more reps.
But Squires and others did not realise that DMAA was a dangerous stimulant. In Britain, the Medicines and Healthcare products Regulatory Agency received complaints about Jack3D in January 2012 but did not ban it from sale until August 2012. Five days after Squires's death, in an unrelated development, the US Food and Drug Administration warned that DMAA was "known to narrow the blood vessels and arteries, which can elevate blood pressure and may lead to cardiovascular events ranging from shortness of breath and tightening in the chest to heart attack". Even so, Jack3D can still be bought over the internet.
Given the death of Squires, should endurance runners be suspicious of all supposedly performance-enhancing gels and sports drinks? "Absolutely not," says John Brewer, professor of sports science at the University of Bedfordshire, who is currently preparing for his 15th London marathon. "The most important supplement you will benefit from is carbohydrate – anything with a carbohydrate component to it, whether it's sports drinks or carbo gels that top up supplies of glycogen." The body normally has enough glycogen to get to about 20 miles before it needs replenishing – hence the infamous wall. Squires probably hoped for a mental boost from Jack3D, and plenty of runners use stimulants such as caffeine to keep going. Caffeine is not a banned substance (sports drinks or gels with caffeine tend to contain less than one cup's worth) but Brewer, who sits on the UK Anti-Doping board, says it is "really of no value" for a runner. Caffeine is also a diuretic so any momentary boost would be nullified by extra toilet stops. The energy drink and gel stations on the route of the London marathon will give any runner enough carbohydrates to reach the finish line.
The 1,500 elite athletes who work with Dr Rod Jacques, director of medical services at the English Institute of Sport, take legal training supplements. His athletes won 84% of the British medals at the 2012 Olympics but every batch of supplements his Olympians use is independently tested to ensure they contain exactly what they say they do. "They are not performance-enhancing but maximising the adaptation to training so you can recover faster and train harder," explains Jacques.
We all crave a bit of this stardust but Jacques says it is far better for amateur runners not to rely on such products. "The marginal benefit of some more risky supplements are far outweighed by just practising the basics correctly," he says. "Spend more time just hydrating appropriately, take the right sort of carbohydrates before exercise and replenish with carbohydrates after."
Jacques's nutritionists regularly study new products and he says that the science behind the benefits of "the latest smartie on the shelf" is "usually incredibly flimsy". Brewer agrees: "The most I would ever recommend for people during their training is perhaps a multivitamin with iron." Research shows that carbohydrate and protein supplements (such as protein shakes) can aid recovery after training but the latter are of more value to athletes doing a lot of weightlifting – not long-distance runners.
Some experts recommend an even more no-gimmicks approach to exercise. "No supplements are useful unless you are on the edge of an Olympic medal, and even then the evidence is far from certain," says Mike Lean, professor of human nutrition at the University of Glasgow. "The trickery over the word 'energy' is what killed Claire Squires. Caffeine, or these other chemicals that act on the brain, do not provide energy. They make people think they have more energy, but in reality they have less."
Individuals have to take responsibility for the supplements they take, says Brewer, but it isn't always easy to find unequivocal facts about them. "Performance-enhancing" substances are often banned because of health risks and so amateur runners should adhere to the World Anti-Doping Agency's list of "prohibited substances and methods", which is regularly updated and found online. This shows drugs, not brands – there is no sign of Jack3D but methylhexaneamine is there.
Rather unhelpfully, the Medicines and Healthcare Products Regulatory Agency does not currently publish a list of banned sports supplements but a spokesperson says they will soon. "Our general advice is to buy your supplements from reputable retailers," says the spokesperson. "If you are taking any supplements, consult healthcare professionals because they could interact with other medication or existing health conditions." Similarly, Brewer advises to stick to "reputable products and brands" and be wary of buying over the internet.
