Heat therapy is divided into two principal categories based on the heat’s ability to penetrate your skin and affect your underlying tissues: superficial and deep. Examples of superficial heat therapies include hot packs and hydrotherapy. Examples of deep heat therapies include ultrasound. Applying heat to your tissues increases your circulation or blood flow and causes your connective tissue to become more flexible. It also promotes a transient reduction in your joint stiffness, pain and muscle spasms. Using heat therapies can help you reduce inflammation and congestion in your tissues. Heat therapy is used to treat many health complaints, including arthritis, muscle spasms, muscle sprains and strains
Cold therapy or “cryotherapy” is used to treat acute injuries of your musculoskeletal system. It is intended to reduce inflammation, circulation, muscle spasms and pain. Cold therapy cools your skin’s surface and underlying tissues, which results in the narrowing of your blood vessels—a process called vasoconstriction. Vasoconstriction of your blood vessels causes a reduction in the blood volume to the site of your injury, resulting in reduced swelling.