In badminton, the muscles which are used are the forearm, Bicep Brachii and Tricep Brachii.
Deltoids , Coracobrachialis, Pectoralis major, Latissmusdorsi, Teres major, Teres minor, Supraspinatus, Infraspinatus and Subscapularis. The rotator cuff muscles are used while having any sort of shoulder rotation.(http://www.victorsport.com/coach_detail_5081.html?PHPSESSID=82c355d6e53746ec13808e20413dc687)
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