The Big Freeze
With the football world cup looming I just know that the media will be looking for snipets of news worthy stories about the England Football Team as they travel to South Africa and attempt to bring home the World Cup. It's almost a certainty that we will see something written or televised about the use of ice baths for recovery and we may even see images like the one above with Rooney and Co getting up close and personal in an an ice bath, attempting to improve their recovery from the demands of training and competition.
I first used Ice baths with my athletes back in 2001 and I've written about the use of cryotherapy and recovery and regeneration extensively, but it seems that every year the public fascination grows and it's usually fed by images and articles in the popular press.
So what is all the fuss about, does it work, and if so how long should you take a dip and just how cold should it be?
Here's an overview that looks at some of the latest research to shed light on the use of cryotherapy.
As a strength and conditioning coach, I accept that training and competition will place stress on my clients' bodies, and can at times result in a reduction in their ability to perform. This is usually temporary, lasting anything from minutes or hours to several days. The key is to strike the right balance between the amount of stress placed on the body and the chance for it to recover. It is during the recovery period that the body will adapt, hopefully leading to improved performance. This is the basic principle of progressive overload.
However, for many athletes, particularly at elite level, there is pressure to speed recovery times, and at all levels of sporting participation these days athletes and coaches routinely make use of a range of therapeutic interventions to accelerate the body's natural recovery processes. One treatment, which has been steadily increasing in popularity in recent years, is cryotherapy, the lowering of tissue temperature by the removal of heat from the body (3).
Cryotherapy can be administered in various ways and is purported to reduce inflammation, oedema and pain sensation, all of which are apparent after a damaging bout of exercise (2). The largely anecdotal effects reported are:
a perception of quicker recovery times, and
an ability to increase training load.
While we have no authoritative research to say which form of cryotherapy is most effective, cold water immersion, a simple and accessible procedure seems to be the most frequently used during recovery (6,15); so that is what we will explore in this blog post.
It's my guess that one individual may have played rather a significant role, probably unwittingly, in bringing cold water immersion treatment to general prominence. In 2002 the British long-distance runner Paula Radcliffe revealed to the world that the secret of her success was a 10-minute ice bath after every race. 'It's absolute agony, and I dread it, but it allows my body to recover so much more quickly,' she told reporters. The England Rugby team also used post-match immersion in iced water during the 2003 International Rugby Union World Cup tournament (12).
This is not to suggest that low temperature therapy is new; it has been documented for a very long time that the cold has an anti-inflammatory and analgesic effect. Back in the 5th century BC the Greek physician and father of modern medicine Hippocrates used cold in order to reduce oedema, haemorrhage and pain (13).But are we any closer today to understanding why it is that sitting in a bath full of ice helps the body to recover?
Cryotherapy is widely used in treating acute traumatic injuries: it is indeed the second tool in the RICE emergency injury toolkit (rest, ice, compression, elevation). As we are all supposed to know, the superficial application of ice results in a decrease in local tissue temperature, creating a chain reaction that ends up with the constriction of local arterioles and venules (9). The constriction reduces swelling and decreases cellular metabolic activity, which in turn reduces the inflammatory response and swelling (14).
This damping-down of the body's natural inflammatory response is widely thought to be beneficial to augment tissue repair and adaptation after muscle use or injury (2). This has resulted in an increased interest in the potential of cryotherapy to enhance recovery from exercise and aid performance.
Recovery from Exercise
The argument runs that a reduction in the body's inflammatory response may help to reduce the negative effects associated with exercise induced muscle damage (EIMD). The inflammatory response is the body's natural reaction to tissue damage. Its primary functions are to defend the body against harmful substances, dispose of dead or dying tissue and promote the renewal of normal tissue. The inflammatory response is normally characterised by five distinct signs, each of which reflects a physiological response to tissue injury:
pain (from the chemicals released by damaged cells)
swelling or oedema (from an influx of fluid into the damaged region)
redness (from local vasodilation)
heat (from increased blood flow to the area)
loss of function (because of increased swelling and pain)
Many of these same signs are associated with the after-effects of heavy training sessions. The ability to attenuate the damage caused in training by suppressing the inflammatory response holds an obvious plausibility and appeal for both coaches and athletes. But it may not be so clear cut.
At a presentation in 2007, Ken van Someren, the English Institute of Sport's national physiology lead, raised some interesting questions. Are we, through the use of cryotherapy, actually hindering the very adaptations that athletes need to make to improve performance and fitness? By reducing the stresses of training, are we also reducing the body's need to adapt? After all, it's safe to assume that the body created the inflammatory response for a very good reason. Do we really know better?
Ken van Someren is not alone in this thinking. An Australian researcher, Anthony Barnett, raised similar concerns in his review of recovery modalities in 2006. When discussing the inflammatory response, Barnett noted that neutrophils and macrophages, while linked to the development of muscle damage, may also have very important parts to play in muscle growth and regeneration. In a rare study looking at the long-term effects of cryotherapy, researchers from Japan found that during four to six weeks of endurance or resistance training, cold water immersion at 5C to 10C reduced adaptations in anaerobic threshold, muscle hypertrophy and angiogenesis (formation of new blood vessels) (16).
What the papers say
There is a distinct lack of high quality research papers investigating the use of cryotherapy in recovery. Although some studies have shown positive effects, they are as so often bedevilled by inconsistencies in methodological approach, to both the exercise and treatment regimes (6).
In 1997 researchers from Australia investigated the effect of cryotherapy on muscle soreness and strength after eccentric exercise. They observed DOMS in eight resistance-trained males who had performed 64 eccentric actions of the elbow flexors. Immediately after the exercise session, the relevant arm was treated with five 20-minute immersions in ice water, leaving 60 minutes' recovery time between each immersion.
The researchers were unable to find any significant changes in muscle soreness, isometric torque, isokinetic torque or limb volume between the subjects' experimental arms and their control arms, either at baseline or after the ice treatments. Neither did participants report any differences in their perception of muscle soreness.
The results from this study suggest that the use of cryotherapy immediately after damaging eccentric exercise may not provide the same kind of therapeutic benefits as are attributed to cryotherapy after traumatic muscle injury (11).
In a similar study conducted in the UK in 1999, researchers showed that muscle stiffness was reduced by immersing their exercised arm in cold water (15 C) for 15 min immediately after eccentric biceps exercise and then every 12 h for 15 min for a total of seven sessions after eccentric biceps exercise. But the treatment had no beneficial impact on muscle tenderness or loss of strength (5).
More recently Bailey et al. (2007) have written about the benefits of cryotherapy (1). They concluded that some indices of muscle damage (soreness and myoglobin efflux in blood) are reduced after a single bout of cold water immersion (10 minutes at 10C), administered after the 90-minute Loughborough Intermittent Shuttle Test. Although this investigation was not specifically designed to induce damage, it suggested that a single immersion may be of value in reducing the negative effects of exercise-induced muscle damage.
Other research has also shown that immersion in water up to the waist for more than 10 minutes provides sufficient hydrostatic pressure to displace fluid from the lower limb. (15)
Recent research in 2007 completed by Sam Erith at Loughborough University in the UK, suggests that cryotherapy treatment can improve muscle function, reduce muscle damage and decrease DOMS soreness.
With contradictory findings such as this lot, it is impossible to reach a sound conclusion on the efficacy of cryotherapy for exercise-induced muscle damage.
How long, how often and how cold?
If we choose to believe the research papers that tell us cryotherapy can work in recovery, can the science also help us to define parameters for the all-important treatment protocols? Let us return to injury rehabilitation for a moment. In 1986 a study into the use of cryotherapy in sports injuries found that a 15-minute immersion at a temperature of 15C would lower intramuscular temperature by approx 10C, which could have a potentially beneficial effect in speeding up the recovery process (9).
However, the depth of the target tissue can vary greatly from one person to the next. This is an aspect that several researchers have investigated. If you want to treat an area with a thick subcutaneous layer, such as over the quadriceps, the duration of application may need to be increased to enable the cold to reach the target tissue (7). Adipose and muscle tissue are effective insulators, so the more fat you have the longer it is going to take to cool yourself down.
How cold is cold enough? We don't know exactly but we do know that a skin surface temperature of 13.6C can provide a local analgesic effect and that 12.5C produces a 10% reduction in the speed of nerve conduction. At skin surface temperatures between 10C and 11C there is a 50% reduction in cellular metabolism, with the onset of cell hypometabolism occurring at 15°C. Together these findings define a therapeutic skin-surface temperature range of 10°C to 15°C.
US researchers looked at the time taken to cool large muscle groups after a bout of exercise. They took measurements at two depths (1cm and 2cm) and found that they were able to bring the muscle temperature down using bags of crushed ice to pre exercise levels within seven minutes (8).
Another recent study published in Athletic Therapy Today assessed how long it took to lower temperature by 7C at a depth of 1cm below the adipose layer, using a bag of crushed ice. The time required varied dramatically with the thickness of the adipose layer, giving treatment durations of 12min, 30min. 40min and 60min for skinfold thicknesses of 0-10mm, 11-20mm, 21-30mm, and 31-40 mm respectively.
So you may need to adjust your treatment times if you are using cryotherapy on:
thigh
deltoid
medial collateral ligament of the knee
calf
scapula.
At all these sites, variations between individuals in skinfold thicknesses are large enough to warrant different cryotherapy application times (10).
Practical guidelines
Given the lack of any definitive consensus we can only offer broad working guidelines. Clearly the physiological responses are dependent on a number of factors and you will have to develop your own individualised protocols based on these guiding principles.