Electronic Inspiration LLC. The Muscles That Initiate and Assist in Backhand Motion A two-handed backhand also lets you play high-bouncing balls with topspin and power. deltoids needed to serve and overhead smash. That said, the major muscles involved would be in the arms and trunk, especially the biceps, deltoids and triceps muscles. An incorrect grip will always hold you back in some way when you’re hitting your strokes as it will force you to improvise in some way instead of allowing your body to swing in a bio-mechanically optimal way. The lob is used to put the ball over an opponents head. The muscles that allow for this internal rotation of the shoulder from the racket drop position to the contact point are the Subscapularis, Latissimus Dorsi, Teres Major and>Pectoralis Major muscles. The stroke’s aim is to hit the ball over the net and inside the lines of the opponent’s side of the court. Initially your calves (gastrocnemius and soleus muscles) are the first group engaged when playing.