Investigating Eccentric Contraction Mechanism in the Prevention of Sports Injuries

Abstract

Introduction: Eccentric contraction exercises such as hamstring Nordic have been used nowadays to prevent injury. Maximum force in the muscle happens when the outer force is more than the force made by the muscle. Muscle force can reach its maximum in eccentric contraction and this damages contraction components and cytoskeleton (infraconstruction) of the muscle fiber and weakness and pain happens. But how a contraction which causes pain and injury can help in preventing injury? The goal of the present study was to evaluate the eccentric contraction mechanism in the prevention of sports injuries. Materials and Methods: For this study, background research has been done using search engines from 1980 to 2017. Studies including information about eccentric exercises and sports injury prevention have been chosen next after eliminating unrelated articles. Results: Eccentric exercises affect muscle morphology and peripheral and central nerve activities. Muscle structure characteristics can create force which include pennation angle, muscle thickness, and fascial length and differ according to mechanical trigger. When the muscles are lengthened, the force attracts the mechanical work and acts as a spring. The energy which has been attracted during muscle and tendon lengthening, is usually wasted as heat and then recovery of stretching combustion energy happens. Stretching and energy recovery depend on the energy and resilience of the muscle. Eccentric contraction respectively causes more stretching of the sarcomeres, detatchment of the sarcomeres, cortex damage, localized contraction, muscle fiber inflammation and eventually inflammation and pain which shows injury to the muscle tissue. Moreover eccentric exercises change the call for alpha motor units, sarcomere activity, corticopostal sensitivity and brain activity. Continual muscle adaptation ability to tissue damage is a step for preventing acute injury in the future in eccentric contraction. Conclusion: Eccentric exercises have caused small injury in muscle tissue which eventually causes adaptation in the muscle and increases their strength and resistance and this happens by increasing muscle diameter and fascia length and pennation angle. Although it could be damaging but it is better to consider useful as muscle adaptation. Keywords: Sports Injury, Eccentric Contraction, Preventing Injury, Eccentric Exercises, Nerve-Muscle