Eccentric muscle work is important in most sports. Eccentric muscle contractions enhance the performance during the concentric phase of stretch-shortening cycles, which is vital in disciplines like sprinting, jumping, throwing, and running. Muscles activated during lengthening movements also can function as shock absorbers, to decelerate during landing tasks or to exactly affect high external loading in sports like alpine skiing. The few studies available on trained subjects reveal that eccentric training can further enhance maximal muscle strength and power. It can further optimize muscle length for maximal tension development at a greater degree of an extension, and has the potential to enhance muscle coordination during eccentric tasks. In skeletal muscles, these functional adaptations are supported increases in muscle mass, fascicle length, number of sarcomeres, and cross-sectional area of type II fibers. Identified modalities for eccentric loading in athletic populations involve classical isotonic exercises, accentuated jumping exercises, eccentric overloading exercises, and eccentric cycle ergometry.