Australasian Science, National. 01 Sep 2013, by Blake Mclean http://www.australasianscience.com.au/
Altitude training has been used for decades by endurance athletes in an attempt to improve performance. In recent times this technique has been gaining popularity in professional team sports, perhaps most notably in the AFL. Before this season began no less than six AFL clubs participated in some sort of altitude training camp, and a number of clubs have now also installed simulated altitude, or hypoxic (low oxygen), rooms in an attempt to further enhance performance throughout the year.
However, many are still asking whether altitude training really works and, if so, how does it work? At Collingwood, we are confident that with the right preparation and implementation, altitude training has a positive impact on our athletes. The club has now ventured on eight sojourns to various altitude venues around the world, and has been using hypoxic rooms to implement intermittent hypoxic training (IHT) for more than 5 years.
Although we have been using these techniques for years, we don’t know it all and are constantly searching for ways to optimise the use of traditional altitude training camps, IHT and how these two techniques might complement one another to produce the best results for our athletes. As such, we constantly have research evolving in this area, working closely with the Australian Catholic University and the Australian Institute of Sport to answer many questions relating to altitude hypoxic training.
There are a number of different training techniques available within the realm of what many consider altitude training, with the two most common being traditional altitude training camps and IHT. Despite wide use in the AFL and other team sports, until recently there was no published research on how either of these techniques affect team sport athletes - all of the attention has been on how these techniques impact endurance athletes.
In research published in the International Journal of Sports Physiology and Performance we recently reported on how our athletes respond, in terms of physiological changes and running performance, to a 19-day pre-season altitude training camp. There is still currently no published data on how team sport athletes respond to IHT, but a number of projects currently underway around the world, including at Collingwood, will hopefully lead to a better understanding of how this training technique affects team sport athletes.
Altitude exposure has the ability to influence an athlete’s physiology, including evidence of improvements in the oxygen-carrying capacity of the blood, running economy and muscle buffering capacity. The most well understood of these physiological changes is an increase in the oxygen-carrying capacity of the blood.
These changes in the blood arise from increases in a well-known hormone called erythropoietin (EPO) following hypoxic/ altitude exposure. Hypoxic environments stimulate the natural production of EPO within the kidneys, leading to an increase in the total number of red blood cells produced within the bone marrow. This is an adaptive mechanism within the body, responding to a lack of oxygen by increasing our ability to transport oxygen around the body within these newly formed red blood cells.
The ability to transport oxygen around the body is vital when exercising. Any increase in the body’s oxygen transport capacity should lead to improvements in endurance performance.
We can measure changes in the oxygen-carrying capacity of the blood by looking at total haemoglobin mass. Haemoglobin is the oxygen-earning protein in red blood cells. Most researchers report a 48% increase in total haemoglobin mass in endurance athletes after living at altitude for 3-4 weeks. Do AFL players respond in the same way? Compared with endurance athletes, AFL players typically have lower haemoglobin mass prior to altitude exposure, and therefore may have an even better opportunity to increase haemoglobin mass than world-class endurance athletes. In our recent publication we reported an average increase in total haemoglobin mass of 3.6% in our players after living for 19 days at moderate altitude. This is similar to the 4% increases commonly reported in endurance athletes after 3 weeks of altitude exposure. We also confirmed that the athletes beginning with the lowest total haemoglobin mass stand to gain the most, in terms of physiological changes, from the altitude camp.
While our findings on the change in haemoglobin mass are interesting, what we are most concerned with is the bottom line: performance. So how did our athletes perform after the altitude camp?
To answer this question, we really need to compare them to a similar group of athletes completing similar training. We did this by comparing 21 athletes who travelled to altitude with a group of nine who stayed at home and completed their pre-season training in Melbourne.
All of our athletes were training extremely hard, and as such all of our athletes improved their running performance, which we measure with a 2 km time trial. However, athletes that participated in the altitude training camp had a 2.1 % greater improvement than those who stayed in Melbourne - a very promising result for the overall efficacy of our altitude training camp.
One of the caveats of altitude training camps is that increases in red blood cells generally return to pre-altitude levels about 4 weeks after returning to sea-level, due to self regulatory mechanisims within the body. This is because the athletes are no longer living with less oxygen available, and their bodies are able to sense this and return to the status quo. Therefore, endurance athletes often plan to return from altitude camps just a few weeks prior to their most important competitions, with the goal of "peaking" to perform at their best during that competition.
Similar timing is not possible for AFL players, as they need to be at their best for 26 weeks of the year, with the most important matches coming at the end of the season. So how can they maintain their improvements from a pre-season altitude camp? The reality is that athletes won’t maintain increases in red blood cells upon returning to sea level, unless they continue to live in a hypoxic environment. Dormitories at the Australian Institute of Sport and Victoria University provide this option.
We confirmed that the red blood cells of our group returned to baseline values 4 weeks after returning to Melbourne - just as it has been shown in the past with endurance athletes. The good news is that this group was able to maintain their greater improvements in running performance, which they gained from the altitude camp. This outcome is important for performance.
The underlying thinking is that when athletes return from the altitude camp with an increased physiological (and running) capacity, they are able to train harder during the post-altitude period, allowing for greater training adaptations that allow them to train harder in the following weeks, and so on. Here the athletes are essentially training to train which all athletes are doing during preparatory phases of the season, building each week’s work on top of another to gradually improve their performance.
For AFL players, this means getting a boost during their pre-season so they can train harder during the late pre-season and carry these improvements into the season itself. We are confident that these altitude camps give our athletes the edge to take full advantage of the off-season period and optimise their preparation leading into the season.
This brings us to IHT, and how may it be integrated into the training program to further improve performance. IHT is even more poorly understood than traditional altitude training camps and academics are still debating the ethcacy of its use with athletes.
IHT does not have the ability to enhance red blood cell production in the body because the duration of hypoxic exposures is too short to stimulate long-term elevations in EPO. However, there is some evidence to suggest that IHT may lead to changes in the muscle, similar to those mentioned earlier, possibly affecting muscle-buffering capacity, lactate kinetics and glucose transport.
Physiological changes within the muscle cell are difficult to assess because they require expensive imaging techniques or an invasive muscle biopsy, and these procedures are not typically feasible with elite athletes.
Nonetheless, we can still examine running performance after IHT, which ultimately is what we are interested in. Similar to traditional altitude training, research into IHT focuses predominantly on endurance athletes. There are somewhat conflicting results, with many studies showing no improvement in performance and a few showing improvements.
However, endurance athletes present a very different model to team sport athletes, with prolonged continuous exercise capacity the most important outcome. Team sport athletes are more interested in improving intermittent, high intensity running because this is what is required during matches. The proposed physiological changes within the muscle may potentially have a greater impact on high intensity intermittent performance (much of which is regulated by enzymes within the muscle cell) than any improvements in the oxygen-carrying capacity of the blood.
At Collingwood, we have been using altitude training techniques for almost a decade, but we still have much to learn. In conjunction with Australian Catholic University, we are constantly developing structured research projects that allow our strength and conditioning/sports science team to reassess and evolve our training program, providing our players with the best possible preparation for matches and to work towards our ultimate goal - success on the last Saturday in September.
Blake McLean travelled with the Collingwood Football Club for its altitude training camp in Utah as part of his PhD with the Australian Catholic University's School of Exercise Science.