Cryotherapy

Cold therapy, which dates back to ancient times, can be used in a localised manner or in a more global way with complete immersion. Traditionally, ice is used in the treatment of musculoskeletal injuries for its analgesic effect, while immersion in cold water or exposure of the whole body to cold is used for recovery after exercise. Cryotherapy thus has many benefits for recovery, most of which have been validated in the literature. However, it is essential to make good use of it in order to avoid inducing rather negative effects.

Physiologically, what happens ? 

Briefly, with regard to pain, cryotherapy can induce analgesic effects by inhibiting the speed of nerve conduction and by limiting the formation of oedema after an injury. This is why it is traditionally used in cases of shock or trauma. 

With regard to recovery, it facilitates tissue regeneration and reduces the spread of the inflammatory response after muscular lesions or micro-lesions during exercise (1). This reduction in propagation could be explained by a reduction in muscle perfusion that would still preserve the cellular oxygen supply, ultimately limiting hypoxic cell death and minimising secondary damage. However, some researchers have indicated that at temperatures between 8 and 15 degrees Celsius, the body responds by producing shivering, which in turn increases perfusion to the deep musculature. Thus, the authors suggested that a more tolerable treatment temperature might avoid the shivering response and at the same time increase deep tissue perfusion. Under these conditions, cryotherapy would then be a more effective option in the recovery process from soft tissue or exercise injuries (2). In addition, it is reported that exposure of the body to very cold air (between -110 and -140°) appears to have at least subjective effects on pain reduction and physiological effects. Opinions remain mixed but the literature would tend to approve this method for breaking up excessively inflammatory processes in direct post-exercise. 

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What are the methods of use ?

Cryotherapy is indicated when rapid recovery is required between exercise sessions, rather than after routine training (2). Ideally, it is recommended that these techniques are used after a match or a more intensive training session than usual, as there is some evidence that they can slow down the physiological processes of muscle and/or metabolic development (3). Indeed, evidence suggests that repeated use of cryotherapy attenuates strength gains after resistance training (4)(5)(6). Studies have also looked at the question of when to apply it to optimise recovery. It turns out that cold water immersion after exercise is a more effective modality than passive recovery (7). On the other hand, the study by Brophy-Williams et al (8), was able to show a more interesting effectiveness of immediate immersion compared to immersion delayed to 3 hours after a high-intensity exercise session. This use would be more beneficial for performance in running, jumping or other efforts the next day and/or the day after. A recent meta-analysis concluded that locally applied cryotherapy does not accelerate recovery strength after exercise (9). Since applied ice is generally limited to treatment times of less than 30 min, it is unlikely that a single application to a small area will provide sufficient cooling stimulus to elicit systemic effects that accelerate whole-body recovery after exercise. In order to obtain more systemic effects at depth, it is therefore recommended to use cold baths and to immerse the body more globally (both lower limbs, with or without the trunk or arms…).  Concerning recovery, the main objective of cryotherapy should be to maintain a cooled intramuscular temperature as long as possible in the phases following physical exercise, in order to prevent the proliferation of secondary damage (2). Concerning the duration, significant effects have been reported for an overall immersion at 15° for about fifteen minutes. This duration makes it possible to obtain results on the venous flow by reducing the latter towards the legs and the abdomen to redirect it from the periphery towards the heart. This improves venous return and cardiac efficiency (10).

In terms of acute injuries, there is a growing trend in the literature not to ice wounds in order not to blunt the natural healing response, at least not during the first 2 days (11). Localised application of cold may decrease the healing time and the inflammatory response that is essential in a healing process. However, these assertions must be qualified because the analgesic side of cold also brings important benefits, so the ideal would be to apply cold but not at too low a temperature in order to find the right balance (around ten degrees). 

What should we remember about cryotherapy ?

Cryotherapy is a modality approved by the literature for physiological recovery. However, it is important to apply it preferentially after matches and major efforts but not after sessions aimed at improving physical capacities since it could disrupt or limit metabolic improvements. It is also important to apply it immediately after the effort and in a global way, if possible with cold baths, in order to have systemic effects.

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