The good news is that you can train your body to go harder before your anaerobic turbo boost kicks in.
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. Back out on the road, with the number in hand, Carmichael could direct Armstrong's training to elevate his lactate threshold.