Heart-rate training is the key to gauging your aerobic intensity and
building endurance.
1. buy a heart-rate monitor (HRM): Acumen Basix EX($90); Cardiosport
Autozone ($70); Polar A5($110); 其实手表也就勉强凑合了。
2. Calculate your maximum heart rate(MHR) Your MHR will determine the
numbers that define your training zones.
217-(your age X 0.85) = MHR (beats/min)
最大心率是因人而异的，但这个公式误差不会太大。
3. Heart rate zone:
Recovery 60%
aerobic: 60-75%
乳酸阀值：Lactate threshold(LT): 75-90% 也是因人而异的
anaerobic: 90%
