Let us first understand the physiological effects that hot or cold pack have on our body. This is important to know, because it’s based on this, we would be choosing the appropriate method. (Also read: Sports concussions increase risk of injury: Study)

The effect of heat therapy

“Hot pack or heat therapy increases joint and skin tissue temperature and increases metabolism, increases blood circulation causing vasodilatation, relaxes muscles through inhibiting gamma efferent nerve fibres, and helps in reducing joint stiffness. Also, it produces analgesic effect,” says Pragnya Ravichandran, Executive Physiotherapist, Cloudnine Group of Hospitals, Chennai, T Nagar.

The effect of cryotherapy

“Cold pack or cryotherapy has the opposite effects to that of heat therapy. Cold helps in decreasing the skin tissue and joint temperature thus reducing the metabolic demand, initially reduces blood circulation causing vasoconstriction and a sudden release of blood flow or vasodilatation which is called as Lewis Hunting Reaction. This facilitates faster healing. Cold therapy also reduces inflammation, muscle spasm and provides analgesic effect,” says Ravichandran.

Hence, when to apply cold or hot depends on the type of injury or muscular problem. Ravichandran shares the right therapy to use depending on the situation.

1. DOMS

Delayed onset of muscle soreness (DOMS) usually is described as pain or discomfort of the muscle that occurs after performing any new physical activity or any activity with a sudden high intensity. This pain usually increases in the first 24-48 hours and stays until 72 hours post the activity and gradually lessens. In this case, hot therapy is shown to be effective when used within 48 hours. The reason being the ability of the heat therapy to increase the skin tissue and joint temperature thus preventing heat loss and causing vasodilation and speeding up the metabolism for healing.

2. Acute musculoskeletal injury or sprain/strain of ligaments, joints, muscles

In the initial period it is advised to use ice for reducing swelling and inflammation. However, recent evidence support Peace and Love injury management protocol by Blaise and Esculier in 2019 which does not advice ice, instead advises on P- Protection E – elevation A- avoiding anti-inflammatory drug C- Compression E- education & L- load O- optimism V- Vascularisation E- Exercise.

However, if in any of this acute injury, swelling is noticed to be more, icing can be applied. Simple strains or sprains which does not involve much of swelling or edema, icing is advised to be avoided.

3. Chronic muscle pain or joint pain

In conditions like chronic neck pain, back pain or knee pain etc hot therapy is advised. Especially in specific conditions like rheumatoid arthritis or any arthritis of joint.

4. Joint stiffness or muscle tightness

In these conditions, hot therapy is advised as it improves tissue and joint flexibility, decreasing the synovial fluid viscosity and impacts the tissues and connective tissue distention.

5. Menstrual pain

Menstrual pain is a result of uterine contraction. Hot packs help in relaxing the uterine muscle and the abdominal muscle when applied on lower abdomen. The effect of vasodilation helps in increasing the blood flow to the pelvic region there by reducing pain.

6. Labour pain

During labour pain, it is again advisable to go for hot packs rather than cold packs. However, hot packs are advised to be used over the lower back and not directly over the lower abdominal muscles. The effect of hot pack here is through blocking the nerves carrying pain signals based on pain gate theory.

“Both hot and cold therapy are generally used based on the pain condition. Hence it is always wiser to choose the treatment type based on the effect it produces physiologically on the body and what is required during that particular painful condition,” says the expert.