This document discusses aerobic capacity and how to improve it through training. It defines aerobic capacity as the maximum amount of oxygen the body can use during exercise. The document outlines different types of aerobic training like continuous training, Fartlek training, and interval training. It also describes short term adaptations to exercise like increased heart rate and breathing during and after exercise. Long term adaptations are discussed like increased red blood cells and maximum oxygen uptake from changes in lungs and heart over time from regular aerobic training. Anaerobic training is also covered to improve performance at high intensities by increasing stores of fast-acting energy sources and muscle fiber strength.