This Magic Moment

May 1, 2000
Outside Magazine

The good news is that you can train your body to go harder before your anaerobic turbo boost kicks in. First, you have to be able to identify the point at which your body switches from creating energy aerobically to creating it anaerobically—your lactate threshold. Most athletes use heart rate to gauge their effort. But in January of his winning season Armstrong started using watts, an absolute measure of power output. Unlike heart rate, watts are not affected by variables such as how much sleep or caffeine you've had. If you know that you're pedaling along at 300 watts, you know exactly how hard you're working.

In the lab, Carmichael pinpointed exactly how hard Armstrong could work the cranks, in watts, before his muscles began accumulating lactic acid. "Determining that benchmark is what's critical for us," Carmichael says. Back out on the road, with the number in hand, Carmichael could direct Armstrong's training to elevate his lactate threshold. In addition, given that one can calculate precisely how much power it takes to pedal, say, a 12 percent grade at 14 miles per hour (the formula for watts is simple physics), Carmichael knows just how high Armstrong needs to boost that threshold to win.

"When you define what it takes to ride with the leaders of the Tour in the hills, given Lance's body weight, it requires about 460 watts for 30 minutes," he explains. "Before, let's say 60 percent of Lance's power came from his anaerobic system. He could stay with the leaders one or two days, but by the third day he'd be screwed from all the lactate." Today's Tour-conquering Texan culls a greater amount of his power from his aerobic system, accumulating less lactic acid over the course of a race, which in turn allows him to sustain higher outputs day after day.

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