Muscle strain will certainly be very painful. Because some small nerves will be damaged after the strain, which will produce severe pain; and because after the strain there are small blood vessels rupture blood seepage, local aseptic inflammation foci gradually formed, so that the hemorrhagic oozing of the swelling and inflammatory edema formed by the swelling, will lead to local stimulation around the further aggravation, will lead to the pain is more pronounced. Muscle pulling and joint mobilization can lead to further irritation of the injury site, which can lead to more pronounced pain. The pain is also exacerbated by the fact that the muscles are in a state of self-reactive tension, and the small blood vessels that run through the muscles are stimulated by vasoconstriction, decreased arterial blood supply, and decreased venous return, which can lead to a buildup of inflammatory metabolites, which can cause increased stimulation of the peripheral nerves and increased pain.