“Do approximately 80 percent of your training at low intensity and 20 percent at moderate and high intensities, except during specific periods of training when it is beneficial to do somewhat more or somewhat less low-intensity training, and unless you learn through experience that you benefit from slightly greater or slightly lesser amounts of low-intensity running, and be sure to vary the balance of moderate- and high-intensity training in your program based on the sort of race you’re preparing for.”
