Why does heating pad can help to relieve pain?

Everyone know that the heat can relieve pain, so electric heating pad become a very popular choice for people to relieve pain and bring a comfort feel for our body, this pad can use for shoulder, neck, waist, back, stomach and so on.

But did you know, why does the heating pad can relieve pain?

Decreased blood flow to the damaged muscles means that the lactic acid stays in that area and applying heat to an area that's aching it facilitates blood flow to that spot, which then helps remove the lactic acid waste that has built up, thus lowering the pain. below have four point explained the relieve reason:
Applying heat can make the local capillaries in blood circulation dilate and reach to the pain relief effect.
Applying heat can make vein dilate, reduce the local ache that oedema causes.
Applying heat can promote the absorption of inflammation and congestion, and achieve the effect of pain treatment
Applying heat also can help to reduce inflammation, reduce swelling, accelerate tissue regeneration, can relieve local pain.
But remember not to use overheated temperature hot compress, will achieve the opposite effect, choose the appropriate hot compress. Should cooperate enough rest and correct nursing, can not be excessive exercise, but also not to exercise, appropriate to do can assist the wound healing movement, can accelerate the wound healing.