What does heat do?
- Local dilation of blood vessels
This increases blood flow to a specific area. Deoxygenated blood can flow out and flush away the built up metabolic waste. Meanwhile, new blood can flow in, bringing nutrients and oxygen to promote recovery.
- Decreased pain perception
Injury causes nerves to constantly send pain signals to the muscle. This nerve irritation can be distracted with overriding heat signals.
- Reduction of muscle tension & spasm
Muscles tend to tense up and spasm when there is pain. As explained above, heat diminishes pain signals from the nerves. Tension then declines due to the decrease in pain.
When should I use heat?
- Chronic conditions
- 2 weeks or more after initial injury
- Fibromyalgia, osteoarthritis
- Muscle tension headaches
- Apply to upper back
- Cold, sinusitis, respiratory tract infections
- Before deep tissue treatment
- Active Release Technique, myofascial release, massage therapy
* For optimum effects: heat 10 min, off for 10 min, repeat 2 – 3 times.
**Do not heat an acute/recent injury! The vessels at the injury site are still weakened and cannot handle an increase in flow.
What does ice do?
- Local constriction of blood vessels
The cold constricts the blood vessels. Blood flow to the injury site lessens when ice is applied, thus lessening swelling and pain.
- Slows swelling
Fluid accumulates in the injured site, leading to inflammation. The addition of blood to the area would further hinder the injury; thus, ice is used to control the blood flow by vasoconstriction (see above).
- Decreased pain
The ice will numb the nerves in the area, decreasing soreness. It will also slow the nerve impulses, thus lessening the degree of pain and pain-spasm reaction.
When should I use ice?
- Acute injuries
- Sprains, strains, bruises
- From the moment of injury – 72 hrs later
- Flare-up of overuse conditions
- Migraine headaches
- Apply to neck when headache occurs
- After deep tissue treatment
*For optimum effect: ice until skin is pink (10 min), off 10 min, repeat 2 – 3 times
**Use a wet towel as a barrier between your skin and the ice to avoid freezing the skin.
Alternating hot, then cold: A Flushing Effect
Heat allows the blood vessels to dilate; cold then contracts them. Alternating between the two acts as a pump and increases the circulation in the area to:
- Push the excess fluid out from the area, thereby decreasing swelling
- Allow blood to bring in nutrients and oxygen, which increases healing
The ratio of heat to cold should be 3 min : 1 min.
Repeat 3 times.
Always end with cold.
Ending with heat leaves the blood vessels dilated, allowing for fluid to accumulate again. Rather than re-aggravating the injury, end with cold to constrict the vessels. This will minimize the return of any swelling.
When should I use both?
- Sub-acute stage of healing
- Considerably less swelling and heat than at time of injury
(Depends on injury/person; 2 days – 2weeks)