BEAT THE HEAT
A hydration and sodium strategy is key to taming temperatures…
A famous study led by professor Yannis Pitsiladis examined pre- and post-race bodyweight data from legendary distance runner Haile Gebrselassie. Pitsalidis and his team showed that in winning the 2009 Dubai Marathon, Gebrselassie dropped 9.8% of his mass. That’s 9.8% of fluid and significantly over the 2% dogma; in other words, lose more than 2% of bodyweight and your performance will suffer.
Further studies of Ironman athletes showed high-performers thrived despite drops between 1 and 6%. What does this tell us about racing in the heat? We’re individual; our genetics, fitness and anatomy influences how well – or not – we cope when temperatures rise.
Broadly speaking, one litre of sweat loss equates to 1kg of weight loss that, taking into account weeing, should be replaced with 1.5l of fluid. You can gauge sweat loss by weighing yourself before and after a 60min session in the heat and using this as your foundation for future fluid intake. Just note that the stomach struggles to absorb more than 1l of fluid per hour; anymore can lead to discomfort.
And it’ll only absorb that optimum if sodium is present. Sodium helps to maintain blood plasma volume and transport water from the bloodstream to working muscles. Sweat contains sodium so the more you sweat, the more sodium you lose. But replacing these sodium losses accurately is difficult without knowing the composition of sweat that contains sodium.
That’s where an outfit like Andy Blow’s Precision Hydration comes in. The hydration specialists offer a sweat test that requires attaching a couple of electrodes that have been applied with polycarbonate to the skin. This simulates the sweat glands. Blow then draws sweat, puts it through a sweat analyser and discovers the composition of sweat in millimoles per litre. Blow and his team will then prescribe products ranging from 250mg of sodium a litre to 1,500mg.
“One of the severest was Moto GP rider Eugene Laverty, who’d endured problems for years with fatigue and listlessness, especially during races in the heat,” says Blow. “His sweat test showed he lost 1,800g of sodium per litre, which is huge.” Laverty’s now using sodium nutrition strategies to overcome this deficit, consuming high-salt foods like pretzels. An alternative to a sweat test is looking at your trisuit in the heat. White marks signify a heavy sodium sweater.
Sodium’s importance is why we’d recommend you maximise both bottle cages with one bottle of electrolytes and the other with either carbs or water. You’ll find that the hotter it is, the more you might veer toward the electrolyte/ water combo and consume carbohydrates via bars and gels. You can rely on fuelling stations during the run – or wear a hydration pack if going long – and also make a conscious effort to sip water and/or an electrolyte drink 48hrs from racing, with a simple urine chart a good gauge of hydration.