Judging by the number of times I get asked this, there seems to be a lot of confusion and possible misinformation out there about this very question! To answer this question, some more information about the injury needs to be known, initially about the type of pain that it is present.
‘Acute’ pain comes from a sudden injury e.g. spraining your ankle. Common symptoms of an acute injury are pain, swelling, redness or heat, which generally come on after the first few days following an injury, and are all signs of acute inflammation. In this case, cold or ice therapy is the best modality to use. Studies show that icing an area causes vasoconstriction, or narrowing of the blood vessels that supply circulation to the area. This is thought to therefore limit the inflammation occurring at the injury site. The ice therapy should be applied for 15 to a maximum of 20 minutes, and should ideally be done every three or four hours over the first three days (although you don’t have to wake yourself during the night to do this!) Ice itself should never be applied directly to the skin, as it can cause an ice burn, so a wet tea-towel is recommended if an ice pack or a pack of frozen vegetables are not available. It is also very helpful during this time period to elevate and compress the area if possible.
The other type of pain commonly seen is ‘chronic’ pain. This type of pain develops over time, and may come and go. Chronic pain is often a result of overuse of the body part. Sometimes it may follow on from an acute injury that hasn’t been treated properly, or that hasn’t healed within the usual timeframes. For this type of pain, generally heat therapy is better to be used, as chronic injuries more often than not have no inflammation or swelling present. Stiff joints and nagging pain respond well to heat therapy. Heat will increase the circulation to the area making stiff joints and tight muscles more flexible. Apply the heat using a wheatbag or hot water bottle for 15 to 20 minutes. Again, keep the skin protected with a towel.
Sometimes in the presence of chronic pain, you may have an acute inflammation at the site after over-activity. In this case, you could use ice on the site for a few days, as described above.
Often over a period of exercise, you can also have symptoms of muscle soreness, and often for 24-72 hours after exercise. This type of pain is often called ‘delayed onset muscle soreness’, or DOMS for short, and is thought to be due to micro-trauma to muscle fibres. In this situation, the evidence is mixed. One school of thought says that because muscle damage has taken place and probably inflammation, cold therapy should be used, however the results of studies into this have been mixed. Equally heat has also been trialed, and in some cases was found to effective, and other times not. In high level sports therapy, immersion cold or ice baths are often used following a period of intense exercise, and a lot of athletes will testify to their effectiveness. Again the evidence behind the effectiveness of using these is also limited. It is always important to take care of the skin when using both hot and cold, particularly for the elderly or those with skin conditions.
So to recap: for new acute injuries use ice, for ongoing chronic aches, get the heat out! As always, try to get your injuries assessed as early possible, so the best advice and treatment can be given and the correct therapy commenced.