The short answer is both. Ice is typically used for a newly injured, swollen tissue, and/or muscle spasm to reduce inflammation. Heat is typically used for stiffness and muscle pain greater than 72 hours post injury.
Ice is typically used for a newly injured, swollen tissue, and/or muscle spasm to reduce inflammation. It can be applied for 20 minutes at a time no more often than every 2 hours. Icing is most effective when the area is rested, iced, compressed, and elevated.
Heat is typically used for stiffness and muscle pain greater than 72 hours post injury. Heat promotes blood flow to the affected area in order to heal and decrease muscle tension. This therapy can be applied for 20 minutes no more often than every 2 hours.