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When to Use Hot Treatment for Sprains and Strains

Hot packs can be dry such as electric pads, hot water bottles and gel packs, or moist such as damp clay packs used in physiotherapy clinics and hospitals. Hot packs dilate blood vessels and increase blood flow, delivering needed nutrients and oxygen to cells in the area being heated, aiding the removal of cell waste and promoting healing.

Therapeutic heat is often used in the chronic phase of an injury. It may also be used prior to physiotherapy or exercise to decrease muscle tension and increase flexibility and range of motion. It also plays a role in pain management and reduction of muscle spasms, muscle tension and joint stiffness. Heat therapy should be avoided in the acute phase of an injury when swelling is present and the skin is hot to touch.

Moist heat is preferred over dry heat since it penetrates deeper to reach muscles, ligaments and joints. To create the effects of moist heat at home when using a non-electrical heat source, first wrap a damp towel around the hot pack then cover it with dry toweling before applying it to the treatment area. No matter the type of heating agent used, several layers of toweling should be used as a barrier between the skin and the hot pack to help prevent skin irritations or burns.

Hot packs should be applied for 15 to 20 minutes. Visually check the skin every 5 minutes and discontinue treatment if there are abnormal changes in skin colour or you experience increased discomfort. Do not lie on a hot pack or apply heat when going to sleep since it increases the likelihood of burns resulting from close or prolonged contact with the heat source.

Heat therapy is a good treatment option for many1, however, it is generally not indicated for people with:

  • Decreased sensation to heat
  • Impaired circulation
  • Areas of recent bleeding or severe bruising
  • Open wounds
  • Areas that are infected or ischemic
  • Cancer if treating the region over the tumour site
  • Tuberculosis if applying treatment over a lesion
  • Swelling or acute inflammation
  1. This information is provided by the Canadian Physiotherapy Association. The CPA presents its educational references as a public service and for informational purposes only. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. The opinions expressed do not necessarily represent the opinions of the CPA membership.