ALTITUDE TRAINING – What are the benefits?
In recent years there has been significant publicity regarding pre-season training camps for elite sporting teams, including AFL clubs. These clubs usually spend time overseas in the lead up to the forthcoming season, usually around the November/December months in the case of the AFL clubs.
For several years it has also been popular for clubs to travel overseas to non-altitude training centres in South Africa, the Arab Emirates and California, but much of the discussion has revolved around the value of attending high altitude centres such as in Utah, Colorado Springs or Arizona in the USA.
The interest in the success of athletes who live and train at high altitude has been around since the 1960s. A watershed event was the 1968 Mexico Olympic Games held at around 10,000 feet altitude (3050m) in which African athletes from high altitude nations performed well, whereas non-African athletes were significantly disadvantaged by the “thin air” associated with the low oxygen content at such altitudes. One of the defining photos in track and field history is that of our own world record holder Ron Clarke, lying prone on the edge of the racetrack during the 10,000m event having collapsed. He was being attended to by a distraught Dr. Brian Corrigan, the Olympic team physician, and to this day, Ron Clarke has maintained that his long term health may have been affected by the stress of competing at this altitude.
Since that time there has been a great interest in the benefits of high altitude training for athletes who are not normally residing in these areas. During the 1970s it was quite fashionable for track athletes to spend time training at high altitude in an attempt to gain the aerobic benefits naturally associated with the blood cell changes, which are induced by exposure to low oxygen environments. Even as a competitive international middle distance, I too spent time travelling to Falls Creek in Victoria to do summer training camps at an altitude of 5000 to 6,000 feet (1500 – 1800m) in an attempt to replicate what was a common scenario overseas for distance runners. This practice continues to be a popular strategy amongst elite Australian distance runners who regularly spend time at Falls Creek during preparation for the Australian and European running season.
As the knowledge of the benefits of high altitude training became better understood by sports scientists, the practice of “blood doping” came into sport during the 1980s in an attempt to avoid the need to spend time at high altitudes. Blood doping is a strategy whereby athletes withdraw blood from their own system, then store it for up to six weeks in a controlled laboratory setting. They then reinfuse the blood into their veins 1 to 2 days prior to competition to increase the “blood boosting” effects. A number of high profile athletes and high profile sports followed this practice throughout the 1980s and the success of the 1984 USA Olympic cycling team was put down in large part to this practice. This strategy was clearly intended to boost performance and was considered blatant cheating. It is now banned in all sports.
As time and science practices evolved, the injection of EPO (erythropoietin), the chemical hormone responsible for stimulating the blood changes at high altitude became a more common practice. This again avoided the need to spend time away from normal training environments under the stress of high altitude training and avoided the risks of blood transfusions (HIV, Hepatitis)which were a concern in those athletes who were practising blood transfusion methods. Some athletes went to the extreme level of using blood from relatives or other individuals rather than their own blood, hence the risk of contamination and infection were further enhanced during this period of time when the practice was popular.
What is beyond doubt is that there is a range of benefits obtained from training at high altitude. EPO is naturally released from the kidney in response to exposure to hypoxic (low oxygen) environments and this results in increased production of red blood cells. The increase in the red cells produces an increased concentration of oxygen carrying cells within the blood stream and ultimately a rise in the individual’s haematocrit (% of blood concentration made up from red cells). This results in improved endurance and stamina, especially during exercise.
There is a limit to how high one’s haematocrit can go without causing problems because the increased viscosity (thickening) of the blood stream results in the blood flowing more slowly, particularly through the small blood vessels. There have been medical concerns raised with individuals who have increased their haematocrit beyond the safe range resulting in reports of cerebral strokes and even death due to the excessive thickening of the blood stream. Apart from the obvious cheating associated with this practice, the IOC and international cycling (UCI) have introduced a safety margin for the haematocrit of 50% in order to protect the health of athletes who were likely to attempt to increase haematocrit levels, particularly via illegal EPO administration .
WHAT CONSTITUTES HIGH ALTITUDE?
There are a range of altitude levels at which different effects are experienced and different training benefits gained. The common classification of altitude zones is as follows:
- 0 to 500 metres – sea level or “near sea level”
- 500m to 2000m – low altitude
- 2000m to 3000m – moderate altitude
- 3000m to 5500m – high altitude
- Greater than 5000m – extreme high altitude
It has been demonstrated that in the non-athletic population individuals experience a reduction in their aerobic capacity (V02 max) of approximately 1% deficit for each 100m they ascend beyond 1500m of altitude. However in an elite athlete who is finely tuned the reduction in V02 max has been measured at around 7 to 8% deficit for each 1000m they ascend above sea level. This is obviously substantial when talking about high performance in endurance events such as distance running, cycling or rowing.
The effect of high altitude on sports performance will vary depending on the nature of the event. Apart from the hypoxia associated with endurance events there is also the lowered air resistance of high altitude as witnessed by the world record long jump that was also set in Mexico City in 1968 at the time by US athlete Bob Beamon, who jumped 8.90 m , beating the previous world best jump by an amazing 55 cm .
Other events such as discus and javelin throwing and even sports such as baseball and soccer are affected as the implement or ball travels further and there is less spin and curve produced at altitude.
WHAT ARE THE MAIN EFFECTS OF ALTITUDE TRAINING?
The primary reason athletes train at altitude is to try to gain the haematological benefits. These have been outlined above and include an increase in the haematocrit and red cell mass and therefore the oxygen carrying capacity in the blood. This leads to increased stamina and endurance, particularly relevant with middle distance or distance events.
However, it is not just the haematological benefits which are obtained. There are also benefits of increased running economy and increased muscle buffering of exercise waste products. In particular lactic acid buffering is improved which offsets the muscle fatigue so often associated with a limitation of sports performance. These additional benefits also occur at the micro cellular level associated with the various enzymes attached to energy utilisation and elimination of the metabolic by-products of muscle exertion.
WHAT IS THE IDEAL ALTITUDE FOR TRAINING?
It is important to realise that most of the benefits associated with altitude training do not really start to appear unless training is done at an altitude beyond 2000m. For haematological changes the optimal altitude is around 2500m. Studies looking at the effects on running economy and muscle buffering have shown that there may even be better results with altitude exposures of around 3000m.
Studies have also shown that it takes approximately 14 days minimum for an athlete to acclimatise to the effects of training at altitude above 2000m,and that the optimal benefits of altitude training are obtained after approximately 3 weeks of exposure to the hypoxic environment. There appears to be little in the way of further gains from extending the exposure period beyond 4 weeks, although there may be certain individuals who benefit from longer exposure times.
It is obviously quite difficult to train with high intensity at altitude beyond 2500m, particularly in the first two weeks when acclimatisation has not fully set in. Fatigue, breathlessness, headache and overall malaise are just a few of the symptoms of altitude exposure. There has been more recently a strategy employed where athletes “live high, train low”. With this method the athlete spends the majority of their day at the appropriate high altitude level, but descends to perform training at a lower altitude closer to sea level for the high intensity sessions. This tricks the body into believing it is living at high altitude, but allows the athlete to perform better quality training during the several hours of high intensity workload.
HOW LONG DOES THE ALTITUDE EFFECT LAST?
Again there is individual variation in responses to the duration of the effect after high altitude training exposure, but most scientists agree that the maximum effect is only obtained for a 2 to 3 week period after training exposure. Athletes who return to compete at sea level can compete immediately after they return, but the haematological and other training benefits are probably only maximally obtained for the following 3 weeks. Some athletes and sporting clubs elect to continue some hypoxic training back at their sea level base by utilising hypoxic chambers, hypoxic houses or even home based hypoxic tents. This allows the athlete to spend several hours per day (including sleeping) in a low oxygen environment whilst continuing to train in their normal sea level environment. By adopting this strategy athletes can often continue the haematological and muscle buffering benefits for a longer period of time back in their normal home environment. However, scientists agree that this is not as effective as actually spending further time at “natural” high altitude. Furthermore, the amount of time that needs to be spent within the “artificial “hypoxic environment can be as much as 20 hours per day in order to achieve the desired result.
Altitude training has been utilised by athletes, especially those in endurance sports for over 40 years. More recent research suggests that apart from the blood parameters which are enhanced (oxygen carrying capacity), there are also improvements in running economy and muscle buffering ability to deal with waste products.
It appears that the benefits are optimised at an altitude of 2500m or above and athletes need to spend a minimum of 14 to 21 days at altitude to gain optimal results. Once the benefits are achieved, performance at sea level is improved for a period of 3 to 4 weeks, but this varies between individuals. The benefits may be extended for a longer period by “tricking” the body at sea level if athletes spend part of their day in an hypoxic environment such as an altitude chamber or tent.
The benefits of pre-season training camps held many months before the main competitive season have yet to be proven, including at AFL level. Clubs need to evaluate the cost benefit analysis of such ventures as these are also expensive trips involving multiple players and support personnel and clearly these resources are not always available to the less well financed clubs. Whilst several clubs have gone down this path in recent years, other clubs have been less adventurous in their pre-season training camps and it is interesting that the current reigning AFL premiers (Geelong) have consistently been in the finals series in the past 5 seasons, including 3 Premiership victories, yet have not undertaken pre-season altitude training camps as part of their preparation strategy.