make your brain do all the work

Head Strong
Push your strength and endurance to insane new levels--and make your brain do all the work
Matt Fitzgerald

You're hell-bent on finishing your final set of lunges. But your body is rebelling: Lunch is threatening to leap out of your stomach, and your legs are on fire. Just a few years ago, scientists would have blamed your roiling insides and screaming stems on energy depletion and lactic acid buildup. But more recent studies show that lactic acid actually feeds your muscles during a hard effort. In other words, it's trying to help you, not slow you down.

What's really standing between your will and your workout is your brain. In 2007, researchers at the University of Wisconsin measured electrical activity in the muscles of exercisers while they pedaled stationary bikes. As their performance declined, so did electrical activity, which is doled out directly from--you guessed it--mission control. Turns out your brain can give out on your muscles whenever it wants to--even if your body has enough energy left for five more sets. Of course, everyone has a true limit (don't try to bang out an Ironman tomorrow), but your noggin often puts on the brakes sooner than necessary.

So why does your brain act like an overprotective parent on prom night? Especially when you know that getting through the last painful set of lunges increases your chances of waking up tomorrow with buns of Biel? Here's what's going on: When you work out harder than you're used to, your brain thinks, we have no data on whether an extra set of deadlifts will damage her body. I'd better make her pretty damn uncomfortable by reducing electrical output to the muscles so she'll quit this nonsense. That's when you start to poop out, cut your losses, and head for the showers.

But you can recalibrate your brain to chill--whether you're strength training or trying to shave a few minutes off your half-marathon pace. The key is to train it to think Been there, done that. According to studies by Tim Noakes, M.D., a professor of exercise and sports science at the University of Cape Town in South Africa and the author of The Lore of Running, exposing your muscles to fatigue in a systematic and progressive manner sensitizes your brain to the extra effort in a way that keeps it from freaking out about sudden changes. One way to get the job done: isometrics, exercises that work your muscles without your actually moving them. Instead, you hold specific contractions for a set amount of time; adding more time increases your endurance. Dive into this heady isometric workout and within five weeks, you'll have your melon completely brainwashed.