Does the Kinetic Chain Work in the Forehand Drive Open Stance? What Electromyographic Analysis of the latissimus Dorsi and the Posterior Deltoid Muscles Showed Us

This study examines electromyographic activity of the latissimus dorsi and the posterior deltoid, which act as competitors and agonists, respectively, during the rotational movement in the forehand drive technique with an open stance, among young tennis players aged 12-16. Eleven athletes participated in the research. The average of the maximum activation of the latissimus dorsi recorded with EMG, in the movement of the forehand drive corresponds to 4,15±1,137 and for the posterior deltoid, the maximum activation was 6,70±1,90. The results of the measurements indicate differences in the sequence of activation between the two muscles. The posterior deltoid was the second muscle to contract after the latissimus dorsi. At the start of the rotating action, the latissimus dorsi was most fully activated, while the maximum activation posterior deltoid was towards the end of the movement. The t-test showed P<0.05 between the two means. So, we found that the function of the motor chain follows the coordination of the involvement of the two muscles to perform the forehand drive with the open stance, which means that the rotational motion transfers significant energy which translates into speed and strength. These results are very important to coaches, physical trainers, and physiotherapists in providing appropriate treatment, training, and rehabilitation protocols not only for young athletes but also older in age.