We’ve all been there….. During training or a competition we sustain an injury. A definite moment where something cracks, pops or pulls, with pain starting immediately, later that evening or even the morning after in some cases. Advice has changed historically from ice it, to heat it, then ice it and so on. It’s a subject I still find many people are confused about, so here’s an attempt to clear up the current reasons as to when and why to ice an injury.
Icing in an acute injury setting
The main affect of icing in acute injury is as pain relief, the cold stimulates nerve endings responsible for sensing temperature, this, in turn with the actual lowering of local temperature desensitises the nerves sensing pain (nociceptors) and reduces your perception of the “pain”. The local temperature thought to be associated with this response is between 10 and 15 °C but this temperature needs to be achieved deeper into the injured tissue and not at skin level….. This is the difficult part! If you can ice the affected site in the first 24 hours after the injury it seems less pain will be experienced.
How to ice an acute injury
The previously mentioned amount of tissue temperature change is positively correlated with cryotherapy methods that undergo a phase change (e.g. melting), having a larger thermal gradient (e.g. are colder) or using more ice (e.g. 0.6kg being more affective than 0.3kg). As minimum temperature is achieved at 8-9 minutes of ice application, longer periods of icing seems redundant and may even be damaging to superficial structures. The superficial temperature drops significantly quicker than deeper temperatures. Therefore to achieve a deeper cooling affect further short bouts of icing may be useful as after the initial cooling period both superficial and deep tissues reach their minimum temperature at different times with deeper tissues reaching their minimum temperature later than superficial tissues.
Using this cyclic icing strategy may allow deeper tissues to reach colder temperatures without risking the health of superficial tissues caused by prolonged icing. As the superficial tissues start to warm as the deeper tissues continue to lower in temperature.
So what exactly is happening when icing?
Traditionally the previously mentioned cooling affect was thought to cause a reflexive vasoconstriction (narrowing of blood vessels) which may reduce blood flow to the injured structure as blood is sent to superficial structures from the deeper structures. This reduced blood flow to deeper structures reduces the amount of oedema that perhaps could affect pain and swelling, but this is not convincing. Recent studies seem to indicate compression is the key component of acute injury management that reduces/controls swelling volume whereas icing, as previously mentioned, is affective for pain relief.
That said, application of cold for long durations, 30 minutes plus, or at temperatures lower than 10°C at depth, may actually increase oedema due to cell damage. Although reaching 10°C at depth is unlikely in humans. Therefore the importance of icing duration is highlighted!
In terms of your nervous system cooling has an affect! Sensory nerves are more prolific in superficial tissues perhaps explaining why you can get pain relief from icing without affecting your mobility a great deal. But when muscle tissue is cooled significantly it may affect it’s ability to create tension, essential for movement. This is an important consideration when applying icing in a performance setting.
To conclude ice is excellent for pain relief in an acute injury setting but that’s about it. You need to think about what you may be icing in terms of tissue depth, the deeper the tissue the more bouts of icing you may need to achieve the 10-15°C promised land.
The literature seems to support this shorter duration (up to 10 minutes), frequent exposure (rest between icing bouts of 10 minutes) method of icing rather than a singular prolonged exposure. The traditional thought that icing reduces swelling seems out-dated with compression being championed as the swelling preventer!
If you have any questions regarding icing and its suitability for you and your injury please contact your health care professional as this article is for learning purposes only.
I’d like to thank Peter Thain for his input in creating this article…. Thanks buddy!