The High Point
As your muscles grow weary, the temptation to pull the plug grows stronger. But if you keep going – for a total of 20 minutes or more – your natural opioid system kicks into high gear, flooding your brain with painkilling chemicals like endorphins. (According to one study, these endorphins attach to the same brain regions that light up when you’re sexually aroused!) Other researchers credit a chemical called cannabinoids for the high (yep, it’s from the same family of chemicals that gives marijuana smokers their buzz). It could be that the body releases these substances to cope with the stress of exercise, says lead researcher Dr Arne Dietrich, a cognitive neuroscientist. “If you give your body time to release these chemicals, you may feel much better during and after exercise,” he says. And not just physically: a study published in the British Journal of Sports Medicine reported that exercisers scored significant
mental-health perks after just 20 minutes. Thankfully, your brain does have a safety brake. It constantly meters out your efforts based on your training, previous experience, the duration ahead and information it’s gathering from your heart and muscles. It’s what sports scientist, Dr Tim Noakes calls the “central governor” theory of fatigue. If your brain doesn’t like what it’s feeling, it signals that you’re fatigued. In fact, research shows that even when endurance athletes quit from seemingly insurmountable fatigue, they still have glycogen (fuel) in their muscle stores and untapped muscle fibres at their disposal. Their brain has just told them it’s time to stop. POWER UP: Make high-intensity intervals – say, alternating oneminute all-out effort and oneminute recovery – a part of your weekly routine. “They teach your central governor that going harder won’t do you any harm,” says Noakes. For workouts longer than 90 minutes, make sure you have at least 30g to 60g of glucose an hour (such as fruit or sports drinks) and get plenty of fluids so you don’t feel fuzzy headed by the time you finish.