This document discusses physical conditioning for high school athletes. It was written by Yu Re, the physical coach for the South Korean national handball team. The document provides guidance on developing an effective conditioning program for high school athletes and coaching them on the importance of physical fitness. It outlines a sample 4-month conditioning plan with exercises to improve strength, speed, agility and endurance through progressive training. The plan aims to help high school athletes improve their overall fitness and prepare their bodies for the demands of their sport.