It’s All About That Altitude
Or is it?
Let’s start with the basics and define the loosely used term “high altitude.” Depending on the source there is some variation in the classification of elevation ranges, but high altitude is generally accepted as being above 8000 ft (2438m), and especially above 10 000 ft (3048m).
The Drakensberg Grand Traverse and DGT Run route has a minimum altitude of 1760m at the end point, Bushman’s Nek. It starts at 2545m at Sentinel car park and reaches a maximum altitude of 3482m atop southern Africa’s highest peak, Thabana Ntlenyana. The average altitude for the full course is 2932m, give or take a little depending on individual route choice. This means that your average altitude will fall just shy of 3000m for the duration of the race. High altitude? You bet! Lesotho isn’t called Kingdom in the Sky for no reason…
The Didima area of the Drakensberg Grand Traverse is one of the most sustained high altitude sections of the route.
When considering the effects of altitude on physical activity we can divide it into three broad but practical bands of elevation.
Low Altitude is up to 4000 ft (1219m). Here there is almost no effect on performance according to Jack Daniels’ VDOT Running Calculator which estimates a 7.7 second/km slowdown in a three-hour marathon at 1219m due to lower oxygen uptake per breath, thus slightly lower VO₂ max. Other than this there are typically no ill effects.
Medium Altitude between 4000 and 8000 ft (1219–2438m) causes a more pronounced slowdown but usually no illness. Jack Daniels’ estimate for the effect on a three-hour marathon at 2438m is slowing by 27.8 seconds/km. Races at these altitudes can generally still be undertaken successfully by athletes coming directly from sea level.
High Altitude, above 2438m but particularly above 3048m as already mentioned, results in a significant slowdown of 37.9 seconds/km according to Jack Daniels. More importantly, this is also the first altitude band where there is a risk of altitude-associated illness.
At altitude the human body is challenged by a reduction in oxygen pressure due to decreased barometric pressure. This effectively causes a worsening state of hypoxia with increasing altitude. Fortunately, a series of physiologic responses enable us to tolerate this hypoxia and maintain a sufficient oxygen supply to the tissues, at least until a certain elevation. This process is referred to as acclimatisation and adaptations are observed from 2000 m a.s.l. upwards.
From an athletic point of view, a reduction in maximal oxygen uptake impairs aerobic performance by reducing maximal aerobic power. Submaximal exercise performance is also affected (this will likely be your intensity for an endurance event at altitude such as the DGT.) When acclimatisation is not adequate, hypoxia triggers maladaptive responses that lead to various forms of high altitude illness. Acute Mountain Sickness (AMS) is the first tier of “altitude sickness” and is characterised by symptoms such as headache, nausea, anorexia, lethargy and dizziness. Rate of ascent and altitude are both directly proportional to risk, so the higher you go and the faster you get there, the more likely you are to suffer from altitude sickness. In severe cases this can progress to High Altitude Pulmonary Edema (HAPE) with a build-up of fluid on the lungs which can be very dangerous. Even worse, High Altitude Cerebral Edema (HACE) refers to fluid accumulating on the brain which is life threatening and requires immediate medical attention. Fortunately, this is fairly uncommon below 12 000 ft (3657m) and therefore of minimal risk in the Drakensberg.
The Mafadi summit at 3450m is the highest point in South Africa.
Realistically, most athletes running the DGT course will be moving slow enough to allow for some degree of altitude adaptation and therefore the prevention of serious illness. Also, very little time is spent on the high peaks themselves and even small altitude reductions can result in rapid improvement in the physical condition of AMS sufferers.
What DGT participants are more likely to experience than debilitating altitude illness are minor to moderate decreases in performance. Symptoms such as increased respiratory rate, increased resting heart rate, lower maximum heart rate, general fatigue and an inexplicable inability to really “push” the pace may be noticed. All of these are normal responses to a lower oxygen availability. Hyperventilation or “over-breathing” is the lungs’ natural mechanism of compensation and they do this by increasing tidal volume (how deeply you breathe) and respiratory rate. The former is more common below 3500m in a resting state while the latter is employed above 3500m, but both can be expected while exercising above 3000m.
The air inhaled at altitude is not only thinner but also colder and drier than at sea level. This can cause additional respiratory difficulties, particularly for asthmatic athletes. Another common consequence of reduced air humidity and temperature is increased risk of dehydration. More fluid is lost through exhalation at altitude, due to more rapid breathing and drier air. Urine output also increases as the kidneys conserve less fluid in colder conditions, and added to this downward spiral is the suppression of the body’s thirst sensation in low temperatures. It’s important to be aware of this and make an effort to maintain your hydration status at altitude through frequent fluid intake, despite lack of thirst.
But wait… It’s not all bad news for your lungs at altitude! The lower density of air actually reduces respiratory resistance, therefore increasing inspiratory and expiratory flows and compensating for some of the negative effects. Also remember the absence of, or at least reduction in, some aeroallergens and pollution which would normally cause a degree of airway inflammation!
Finally, let’s discuss the question for which you’ve all been waiting. Is it possible to train in order to reduce or even completely eliminate these negative effects of altitude on performance? The answer is both yes and no… Yes, there are interventions which may assist provided you have the time and the means available. And no, even incorporating such methods into your training will not allow you to perform at the same level as you could at the coast.
This said, one of the most important things you can do to prepare for a high altitude event is to spend time at that elevation in order to understand how your body functions there. Every individual responds differently to altitude and just being aware that you might have a headache above 3200m, or will have to force food down for the first 24 hours while you adapt, will be beneficial come race day. Having this knowledge could mean the difference between withdrawing from the race due to unexplained fatigue, versus pushing on and completing it quite comfortably once you’ve adjusted.
On a true physiological level it is more difficult to prove and quantify the benefits of altitude training. Unlike most training adaptations such as the physiological response to intermittent speed work or heat training, true altitude adaptation occurs primarily due to non-stop exposure to altitude. Basically, to train for altitude you need to be at altitude… Or have access to an altitude tent. Once at altitude though, adaptation is unrelated to effort. So simply hiking or even sleeping “high” is sufficient. Most sources, however, recommend at least 12 hours a day at altitude in order to see a benefit, with 12 to 16 hours being a common estimate. This means that altitude tents are unlikely to be of much use if you’re only sleeping 8 hours in them. But remember, data on running at high altitudes is fairly scarce and most of these statistics have been extrapolated from either professional road and track racing, or pure survival of mountaineers. Our niche of ultra trail running at altitude is still in need of more conclusive research.
If you have time on your hands you may consider arriving at altitude a while before the event in order to adjust. In this case the optimum time frame is 2 to 4 weeks prior to race day. It typically takes about 2 days for altitude to start affecting the body, and then a few more for adaptations to initialise. Full adaptation should be complete after about 2 weeks, which also corresponds well with a taper. During this period light hiking to higher peaks is the recommended activity for an optimal response to the altitude.
Unfortunately, most of us don’t have 2 free weeks to spend acclimatising at altitude before a race… But there are some interesting alternatives to altitude training, such as heat training. While altitude training stimulates the body to generate more red blood cells, heat training increases blood plasma volume. Increased blood volume doesn’t automatically guarantee increased red blood cells and more oxygen, but some studies have found a relevant connection between heat training and aerobic exercise performance. A standard protocol for acclimation would be 3-4 hour-long sessions per week for about 3 weeks, terminating 7-10 days before your race. This time frame allows heat adaptations to occur and persist until race day, without compromising peak training or recovery. Common methods of heat training involve wearing extra layers, running at midday, spending time in a sauna or even performing regular hot yoga.
In conclusion, there is one really key factor in improving your performance at altitude and it’s very simple. Improve your general fitness. The fitter you are the more efficient your body is at using oxygen, so it’s easier to keep your intensity sustainable at altitude. The fitter you are the better you will adapt to different environments and the less likely you are to feel the effects of higher altitude. Ultimately, conditioning both your body and mind for the specific terrain and intense demands of a sub-100 hour Drakensberg Grand Traverse through consistent daily training is the protocol which is going to provide the best bang for your buck.
So, let’s just say it’s less about that altitude and more about that attitude!
