The causes of muscle laxity are mainly seen in age factors, dietary factors, muscle diseases, joint lesions, intracranial lesions and other conditions, which are clinically manifested as decreased muscle tone and decreased muscle volume. Specifically as follows: 1, age factor: as we age, muscle content decreases, the volume shrinks, so many people in old age will appear muscle relaxation. Most of the muscles are more developed and elastic when they are young, but muscle relaxation will occur in old age; 2, dietary reasons: mostly caused by a serious lack of protein, the human body protein content is insufficient when muscle relaxation, no elasticity; 3, muscle diseases: such as myositis, metabolic myopathy, myotonic dystrophy will lead to muscle relaxation, patients often also appear muscle fatigue, muscle pain, tenderness, muscle involuntary 4, joint lesions: mainly various arthritis, can cause pain in the auxiliary muscles around the joints, joint movement is limited, which leads to muscle wasting atrophy, resulting in relaxation; 5, intracranial lesions: cerebral infarction, cerebral hemorrhage can lead to local paralysis of limbs, wasting muscle atrophy, resulting in muscle relaxation; 6, other factors: such as poliomyelitis, severe cervical spondylosis 6, other factors: such as spinal cord poliomyelitis, severe cervical spondylosis, lumbar disc herniation and other lesions will compress the nerves and affect local muscle movement, which will make the muscles gradually relaxed. In addition, radiculitis, gangliositis, plexitis, neuritis and peripheral neuritis, etc., when involving the motor nerve, can lead to atrophy, relaxation and weakness of the innervated muscles.