The 80/20 running principle is a training method where 80 percent of your weekly training consists of lower-intensity runs, while the remaining 20 percent involves higher-intensity workouts.

The 80 percent is focused on easy-paced runs that allow for conversation, while the 20 percent includes activities like interval sessions that raise heart rates significantly. Implementing 80/20 running properly helps enhance cardiovascular, respiratory, and muscular systems, improves endurance, and reduces the likelihood of injuries, ultimately leading to better race-day performance.

Via The Running Channel.