The Rift Valley in Kenya is a world-renowned destination for altitude training
By Randall L Wilber
US Olympic team physiologist
As elite athletes prepare for the 2012 London Olympics, many will be seeking to maximise their impact with training sessions at high altitudes.
A popular destination is the Great Rift Valley in Kenya, where athletes arrive from around the world, swelling the local population in peak season.
Altitude training has been used by endurance athletes for many years but there is growing evidence that the conventional wisdom should be challenged.
Training at altitude - where the oxygen level is considerably lower - allows athletes to increase their red blood cell count. This enables them to compete more effectively at sea level because more oxygen is delivered to the muscles.
The main limitation of LH+TH altitude training is that many athletes find themselves unable to produce the level of training intensity (running velocity for example) and oxygen flux necessary to bring about or preserve the physiological changes that have a positive impact on performance.
It is not uncommon to hear athletes remark that they seem to lose "speed" or "turnover" as a result of LH+TH altitude training, which ultimately has a negative impact on their sea-level performance.
In short - training high may increase the blood's ability to transport oxygen to where it is needed, but the ability of the body to keep exercising at altitude can be limited as tiredness increases.
"Live high-train low" (LH+TL) altitude training is a different method. It allows athletes to "live high" for the purpose of facilitating altitude acclimatisation, as characterized by a significant and sustained increase in red blood cell count, while simultaneously enabling them to "train low" for the purpose of replicating sea-level training intensity.
So, what is the right combination of factors to best improve performance?
"Live high-train low": Optimum conditions
In a recent study,
48 competitive runners were tested at a variety of altitudes, using both geographically high elevations and simulated conditions such as so-called "altitude tents".
Our results showed that to effectively acclimatise and achieve an increase in red blood cell volume significant enough to enhance post-altitude endurance performance, they needed to live at an altitude of 2,000- 2,500 metres.
ALTITUDE TRAINING - THE FACTS
The key to successful training at altitude is to live high and train low
2,000m-2,500m: The optimum altitude for acclimatisation
28 days: Number of days required for noticeable increase in red blood cell count
22 hours: Daily exposure sufficient to boost performance
So, how many days living at altitude are needed? Several investigations employed an altitude exposure of 28 consecutive days at moderate altitude (2,500m). There was little change in blood cell count for the first seven to 10 days, and then only a minimal increase after two weeks.
There was, however, accelerated increase in cell count during weeks three and four.
A daily exposure of 22 hours or more at natural altitude of 2,000-2,500m should be sufficient to enhance post-altitude sea-level endurance performance.
For those using simulated altitude (nitrogen dilution or oxygen filtration), fewer hours of exposure appear necessary (12 to 16 hours), but a higher elevation (2,500-3,000m) is required to achieve similar red blood cell production.
What does this mean for elite athletes?
The US Olympic speed skating team successfully integrated several LH+TL altitude-training methods in preparation for the 2002 Salt Lake City Winter Olympics.
Three years before the Salt Lake City Olympics, the speed skaters began living in the Deer Valley and Park City areas of the western US state of Utah, which lie at about 2,500m above sea level - markedly higher than their competition venue, the Utah Olympic Oval at 1,425m above sea level.
The skaters were able to enhance red blood cell volume and acclimatise effectively through moderate intensity training at Deer Valley and Park City and high-intensity workouts in Salt Lake City.
US speed skater at Salt Lake City Olympics
The US speed skaters enjoyed unprecedented success at those Games, with six athletes winning eight medals, including three gold medals and two world records.
Speed skaters also compete internationally and therefore spend several weeks away from their natural altitude training base in Park City. In an effort to maintain altitude acclimatisation, they have frequently relied on simulated altitude devices.
Initially, they experimented with using altitude tents while travelling to Europe but found them difficult to transport and relatively uncomfortable to sleep in, thereby compromising recovery from training and competition.
In recent years, however, the US speed skaters have worked out an agreement with several of the Scandinavian speed skating teams to use nitrogen apartments and dormitories located in those countries.
As they did at the 2002 Winter Olympics, US speed skaters performed very well in the 2006 Torino Olympics, capturing three gold, three silver, and one bronze medal.
Several of these altitude training strategies and devices have undergone critical review by the World Anti-Doping Authority (Wada) for the purpose of potentially banning them as an illegal performance-enhancing method.
Ultimately, Wada decided not to include artificially induced altitude conditions on the 2007 prohibited list.
World Olympic Dreams have also teamed up with the Open University to answer some of sport's big questions
However, it should be noted that the International Olympic Committee has prohibited the use of simulated altitude devices within the boundaries of the Olympic Village since the 2000 Sydney Olympics, and this mandate is expected to apply to all future summer and winter Olympic Games.
Looking forward, there is considerable individual variation in the physiological responses of athletes using altitude training - probably based in part on genetic predisposition.
Future research should be directed toward identifying the specific genetic factors that influence variation in the altitude acclimatisation response.
A clearer understanding of the key factors (genetic or otherwise) affecting an athlete's individual acclimatisation response at altitude will enable sport scientists and coaches to better determine an optimal altitude training programme for each athlete.
Randall L Wilber is a senior sport physiologist at the US Olympic Training Centre in Colorado Springs, where he oversees the operation of the Athlete Performance Laboratory.
He will be presenting his studies at the first World Conference of Science in Triathlon at the University of Alicante from 24-26 March.
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