Muscle aches and pains should be applied with heat, because muscle aches and pains occur mainly due to strenuous exercise that produces more lactic acid and metabolites such as inflammation or due to excessive fatigue of the muscles and surrounding soft tissues from holding a posture for too long or frequent muscle contractions, resulting in strain, which can also form inflammatory lesions and also metabolites such as lactic acid. It is also possible that the inflammatory lesions may be due to cold, as cold causes the muscle tissue to become more tense and blood circulation to slow down, resulting in the accumulation of metabolites. The metabolic products will be metabolized. After cold compresses, the blood circulation will be further slowed down, leading to further accumulation of inflammation and gradual aggravation of the disease.