The common causes of small arm pain after playing badminton are too much exercise, muscle or ligament strain. 1. Excessive exercise: a long time without exercise, or too much exercise, will cause the small arm of the strain, muscle tissue produces a large number of metabolic products, resulting in the accumulation of lactic acid, lactic acid stimulation will lead to the role of the small arm of the pain, appropriate rest can be gradually relieved. 2. Muscle or ligament strain: due to excessive force, or movement is not standard, may cause muscle or ligament strain during exercise, causing pain in the small arm, accompanied by localized pressure and pain, swelling and even activity limitation and other symptoms. Small arm pain after exercise, if not relieved by rest, it is recommended that the patient timely hospital consultation, to clarify the cause of the disease for targeted treatment.