Hot and cold treatments are often used to treat muscular pains and other injuries. Many elite athletes subject themselves to ice baths after a training session to reduce the effect of delayed onset muscle soreness. It's also common for athletes to alternate between ice baths and hot baths in the same treatment.
Applying ice to an affected area in the form of an ice pack or a bag of frozen peas, for example, helps to reduce any inflammation that might be causing the pain. Heat treatment such as a hot bath or a hot water bottle helps to increase blood flow, which delivers more oxygen and nutrients to your muscles, speeding up your recovery.