Recent research has shown significant improvements in running and cycling performance and other sports using pre cooling equipment (or 'precooling' or 'pre-cooling'). The first devices to create this effect were the cooling vests, otherwise known as ice vests or by the brand name 'precool' vests. Even an ice cold slushie or an icy drink can induce the effect. In the extreme case, athletes may take an icy bath before an event, especially in very hot conditions. The athletics company 'Nike' developed the 'Nike Precool Vest' for Olympic athletes prior to the Beijing Olympic Games and they claimed up to a 20 percent increase in athletic endurance.
There is growing evidence that pre cooling can boost performance during exercise at variety of temperatures, not just in extremely hot conditions. Furthermore athletes have used pre cooling during training exercises as well as throughout competitive events. It also has been shown to provide benefits for non-continuous sports as well, such as lifting weights, boxing, judo, as well as running, walking and cycling. Although relatively few technical studies have been undertaken on pre cooling for athletes, the outcomes of various studies shows a genuine performance advantage for warm climate endurance. In a 1995 study released in the Journal of Applied Physiology, several athletes ran to exhaustion in hot conditions after pre cooling in a cool-room for about 30 minutes. Pre cooling was found to cool the core temperature of the runners by about a degree, and that this significantly boosted their running endurance. The researchers proposed that the better performance was due to the cooling reducing stress on the metabolic and cardiovascular systems of the runners.
Various research studies have suggested that there are several reasons for this:
1.Pre cooling holds your core temperature below the critical temperature limit for longer. When you work during exercise your muscles develop heat as a by product from metabolism. It is very hard to eliminate this additional heat and this induces an increase in your interior body temperature. The more you work, the quicker the internal body temperature will rise. Research has indicated that there is a critical threshold for your core temperature. When you exceed this threshold your performance will decline sharply and you may risk heat stress or heart problems. Exercise physiologists have various theories why this occurs. It could be that your muscles are starved for blood and oxygen and you feel exhausted. It could be that your brain gets overheated. It could also be that your heart can no longer beat fast enough to meet all the demands for blood and the shift of more blood to the skin leads to a fall in blood pressure. It is clear that if you can reduce your core temperature, and the temperature of your muscles before a workout, it will take longer to reach the critical threshold and so you will perform better for longer. Essentially, pre cooling lowers your core temperature at the start, and this means that it takes longer to reach the critical high temperature which causes exhaustion and makes you reduce you pace.
2. Pre Cooling between workout sessions and 'Feeling Better'. Although there is less available research there is come evidence that you can get multiple benefits of pre cooling by using ice baths and ice-vests between bouts of exercise. Some of the benefits appear to relate to the athletes feeling better rather than a physiological benefit. Cooling also induces other effects such as reducing heart rates, and changing the blood distribution throughout the body and these changes may also have benefits. Further work is required on this topic.
3. Pre Cooling causes changes in Blood Circulation. About 60% of the energy generated by working muscles is heat, not muscle pulling power. When running in hot weather, a lot more of your blood is sent to your skin for cooling to regulate you body temperature, and consequently less blood flows to your working muscles. The result is that your heart must beat much faster for you to maintain your speed. Pre cooling simply acts to reduce your body temperature a little before you start exercising. After pre cooling, less blood has to be shunted to the skin, and so more oxygen-carrying blood can go to the muscles. The result of this is that you will have a lower heart rate when running at a given pace. You will be able to maintain a faster pace for longer period, especially in hot conditions. The changes in heart rate have been documented. Recent research looking at the effect of icy drinks has shown that exhaustion generally occurred when heart rates started to exceed about 180 beats per minute. Athletes who drank the icy drinks reached this critical heart rate about 10 minutes later than other athletes who drank cold water. The reduced heart rate and lower sweat rate means less blood flow is needed for regulating temperature.
It is suggested that a runner should put on an ice vest about an hour or so before a race, and continue to wear it during warm-up. This will mean less sweating during the warm-up, preserving precious fluids for the race itself. For the best boost to performance the ice vest should be left on until just before the start of the race. In summary here are some pre cooling tips and ideas:
Recent research has suggested that all you have to do is drink an ice and cordial slurry, also known as a 'slushie', before exercising to get the benefits of a pre cool. This is much simpler than having to take an ice bath or donning an ice vest. There may be added benefits from the calories in the sugary syrup. But one negative aspect for this is how to stop the ' ice cream headaches' that you get when you drink slurries quickly. But to many athletes the pain of the headache may be worth the extra performance. Another point is that ice vests may reduce the temperature of the skin and muscle mass as well as the internal core temperature, and this may provide extra benefits compared with drinking a slushie.