The causes of muscle strain are varied and can be divided into disease-related and non-disease related factors. However, the most common cause of muscle strain is poor posture, which is a non-disease factor. When the body maintains or repeats the same posture or movement for a long period of time, it is easy for the local muscles to remain tense for a long period of time and if they are not relaxed at the right time, this may lead to muscle strain.