After playing badminton, the hand is not strong enough to hold things, which may be caused by incorrect posture, strenuous exercise, brachial plexus nerve injury and so on. 1. Incorrect posture: playing badminton posture is not correct, will lead to arm muscle damage, produce inflammation reaction, thus causing pain, soreness, weakness and other symptoms. 2. Strenuous exercise: a long time without exercise, after a sudden strenuous exercise, will make the body produce a lot of lactic acid, accumulate in the muscle tissue, the phenomenon of soreness and weakness. 3. Brachial plexus nerve injury: long-term incorrect posture to play badminton, will make the brachial plexus nerve is overstretched and produce damage, cause the innervation part of the sensory abnormality, dysfunction, so as to appear muscle weakness. Because there are many reasons that lead to playing badminton muscle weakness, so when the symptom occurs, it is recommended to go to the hospital and actively consult the doctor, in order to carry out professional and comprehensive diagnosis and treatment.