Biomechanical features of locomotion when hitting the ball by football players with musculoskeletal system disorders

The authors investigated the biomechanical characteristics of locomotions when hitting the ball with the middle part of the instep in players with such musculoskeletal system disorders (MSD) as scoliosis of II-III degree and flatfoot of II-III degree. It was shown that athletes with musculoskeletal system disorders have a different dynamic stereotype of hitting the ball with the middle part of the instep than healthy athletes. The main differences are related to the phase structure of the movements in the leg joints. Athletes without MSD mainly use the hip joint in the initial phase of the movement. The angular velocity is maximum in this phase, the angle increases. In the middle of the movement the leading role goes to the knee joint: the speed of movement in it grows in parallel with the fall of the speed in the hip joint. Athletes with locomotor pathology have disorders in the consistency of leg joints motion. The speed of movement in both joints, knee and hip, is maximum in the first half of the movement, and then it starts to slow down. A small increase in the speed in the knee joint in the final phase is very insignificant and cannot compensate for the completion of movement in the hip joint. At the same time the angle structure of the movement changes: extension of the knee occurs earlier, and the hip joint extends additionally in the final phase of the kick. Athletes of the control group actively involve the movement of the upper limbs when kicking. There is shoulder extension and elbow flexion. The shoulder joint works in the initial phase of the kick, and the elbow in the final. These movements obviously are compensatory in nature, helping to maintain balance. In addition, the movement of the upper part of the body is capable of providing an additional moment of inertia of the center of gravity motion which will increase the power of hitting the ball. Obviously, this function is performed mainly by the movement in the shoulder joint. Athletes with locomotor pathology practically do not employ this mechanism: the angles of the shoulder and elbow joints do not virtually change throughout the kick. The angular speed in both joints increases sharply in the final phase of the movement, when the kick is made. As a result, movement of the arm helps keep the balance after the kick and does not participate in hitting the ball.

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