How precise does hydration need to be? You just drink water and stop being thirsty, right? Well, not if you want to take on more serious challenges, or even set a new PB at your local 10k. As you sweat, you lose natural salts and electrolytes, which the body needs to perform at high intensities – that’s the basic premise of loads of sports nutrition products. The thing is, though, some people sweat more than others. That’s why Precision Hydration creates differing strengths of its supplement, which contains sodium, magnesium, calcium and potassium. Take its free sweat test online to find out which strength you’re best suited to.