After a strenuous workout when muscles are screaming and joints aching, many people yearn for a nice hot shower or bath. A better idea is to take a cold bath - so cold that if you stayed in for longer than five minutes, you would risk death. This particular type of torture is known as cryotherapy. Many top professional rugby teams and individual athletes (for example, Paula Radcliff, 2002 London Marathon winner) sit in cryotherapy ice chambers, spending 30 seconds at minus 60 degrees Celsius, followed by three minutes in a super-cooled chamber at minus 130 degrees Celsius. Why? Cryotherapy is used for two reasons. One is to minimise the inflammation resulting from tears in the muscles during training and the second is to speed recovery by three to four times. How? Cold baths lower the body temperature, causing blood vessels to constrict which slows blood flow. This lowers the chance of cellular damage by slowing down the metabolism. The body also rids itself of lactic acid faster, so the athlete is more quickly able to go out and repeat a hard session. Apart from rehabilitation, cryotherapy has also been used by weight-lifters and baseball pitchers to improve performance. Studies have shown that short-duration and local applications of ice lower the muscle temperature, therefore delaying the onset of fatigue in the muscle. While the exact cause of muscle fatigue is unclear, temperature is definitely a factor. Numerous studies have demonstrated that the muscle is able to work the longest when its temperature is 27 degrees Celsius. Higher or lower temperatures result in a decrease in the length of muscle contractions. Applying ice between sets has also been shown to increase velocity and power in weightlifters. In one study, participants lifted 75 per cent of the maximum they could manage, 22 times faster than normal. One group of weightlifters placed ice packs over their arms and shoulders in three-minute rest periods between sets of lifts. A rest period of four to five minutes followed for both groups at room temperature. This continued until they couldn't lift any more. The group that used ice or cyrotherapy between sets increased their work, velocity and power. Other research has looked at using applications of ice between baseball innings. Ice was applied to pitchers' shoulders, upper arms and elbows for three minutes to study its effect on pitching fatigue, velocity and accuracy during simulated baseball games. Cold treatment was found to delay muscle fatigue and increase velocity but had no effect on accuracy. Icing was also shown to reduce arm soreness the following day. There are currently no cryotherapy cold baths in Hong Kong for public use. Instead use ice packs and cold baths/showers to aid your recovery and/or increase your performance. Some medical experts believe there are potential risks associated with the use of cold therapy such as local tissue damage. So, if in doubt about the use of cryotherapy to treat an injury, seek the advice of a trusted medical professional.