Altitude-acclimatisation is favourable in the early season. For endurance athletes, the issue goes beyond holidays and focuses on resource development. The objective is then clearly displayed: it is performance! On the return from the “training camp”, as you may know, the verdict comes quickly. Reminders on what to expect from an altitude course.
As one climbs the mountain, the atmospheric pressure declines, so the body’s ability to take oxygen (O2) declines. To compensate for this lack, our cardiac output and ventilation increase at rest. During exercise, it is a bit harder: arterial desaturation in O2 also reduces the body’s maximum oxygen consumption (VO2max). Too bad, it’s the number one endurance performance factor.
At 1500m altitude, the decrease in VO2max is estimated at 2-3% and increases by ~1% per 100m step. At 2000m altitude, 10 VO2max points can theoretically be punctured from your initial aerobic capacity. But the variations are individual and, for example, they range from 3 to 10% among athletes training in Font-Romeu (1850m).
Since it changes the body’s response to stress, this environmental constraint – called “hypoxia” – is not to mask within your reflections on training.
– In quantitative terms, the weekly volume should be reduced during the first week of training before returning to normal volume: reducing the volume by 30 to 50% can constitute a benchmark for those who are initiating to altitude.
– Also in terms of intensity, it is necessary to revise the content of endurance sessions. How? By training in “relative”.
TRAINING IN RELATIVE.
The “gold standard” to estimate your physiological response at altitude are obviously the measurements of a VO2max test (these tests are now also available in the field). But a less invasive do-it-yourself approach can also help identify the training modifications to undertake.
1- Ideally, maximum 5′ and 20′ tests performed before and after each week of training will help you determine your new work intensities. These tests are designed to define your critical intensities according to the context in which they are performed. And GUTAÏ makes this detection automatically. The only thing you have to do is perform!
2- Otherwise, the reading of your cardiac drift over 3-4 sub-maximal speeds/power outputs will allow you to obtain a physiological work intensity comparable to the plain.
3- Finally, a reliable indicator to estimate your body’s tolerance to altitude is your feeling of the difficulty of the effort (see opposite). This feeling emerges from the information sent back to the brain by the body’s various sensors (e.g. metabolic, pulmonary, cardiac) and is extremely reliable and reproducible in new environments. Your progress will be reflected by a greater facility at a given speed or by a higher speed for the same general feeling.
Note: in parallel to the endurance work, there is a real interest of training in altitude for the practice of strength training – hypoxia reinforcing the effects of a strength training on protein synthesis.
WHY ACCLIMATIZE TO ALTITUDE?
Despite their reputation, the effects of high altitude training camps on endurance performance are inconsistent. Sometimes confirmed, sometimes vague, sometimes harmful… Indeed, a recent report estimates the average gain following this type of camp at ~1%. In fact, it appears that it is more at the individual level that the regularity of these positive effects seems to be established: there are “good” and “bad responders”. Which one are you?
Moreover, it appears that “good responders” preferably take advantage from the camp within three periods from 3 to 10 hours after the descent to the plain, between the 3rd and 5th day or after the 12th day. Finally, the greatest benefits are observed following acclimatisation of more than 14 days between 2000 and 2500m altitude.
Behind these progresses, the mechanisms that reduce altitude stress (ie. tachycardia, hyperventilation) are plural. The increase in the number of red blood cells is the most famous. It is expressed after 8-10 days of acclimatisation beyond 1500m, can reach 1% per week at 2500m altitude and results in a greater oxygen transport capacity. It is this type of increase which is spontaneously sought during a training course in altitude because it is associated with a gain of VO2max during the return to the plain. Yet the magnitude of this increase remains individual.
In parallel, muscle, ventilatory, metabolic and coordination adaptations can also be shown. As examples:
1- The “buffering” power of bicarbonates develops and makes it possible to better cope with anaerobic efforts (the phases of relaunch, sprint, ascent…).
2- The ventilation function also increases, allowing a better response to the body’s demand for exercise at altitude.
3- The metabolism of sugars is triggered more quickly during exercise.
4- Finally, the lower air density facilitates the technical production of fine motor coordination. Ideal for motor learning.
Together, these improvements contribute to improved energy efficiency.
Note: As their name implies, “anaerobic” exercises (without oxygen) do not need to be readjusted during an altitude training camp (e.g.: an intense interval training session). Nevertheless, aerobic processes (with oxygen) being involved in the recovery phases, it will be necessary to multiply by two or three the inter-series recovery time.
WHAT ARE THE “PLUSES” FOR A SUCCESSFUL CAMP?
Beyond training load management, practical changes can be recommended in anticipation of an altitude course. Some are essentially common sense: arriving in top form at the stage, not scheduling a stage for the first time before an important competition, remaining attentive to behavioural problems linked to fatigue (mood swings, lack of reactivity). Others, such as nutritional adjustments at altitude, remain less spontaneous.
BEFORE – To anticipate the reduction in O2 supply and the drop in glycogen reserves induced by altitude, foods rich in iron (red meat, fish, egg, parsley, spinach, beans, fig, almond, hazelnut) and carbohydrates (cereals, dry vegetables, potatoes, fruit) should be encouraged before the camp.
DURING – To limit the cellular damage induced by free radicals in greater numbers in the body in altitude, antioxidants are recommended (garlic, almond, eggplant, beetroot, coffee, lemon). Carbohydrate intakes should also be increased to 60-65% of the total energy intake (usually 50%), targeting their intake time before and immediately after the training session. Indeed, it seems that a specific timing of collations limits the respiratory infections frequently identified during these stages. Finally, in terms of hydration, a volume of ~1.5L of water in addition to the daily volume is generally recommended to compensate for fluid losses related to altitude (evaporation, ventilation, warm clothing).
To be well faced, the stress of altitude is therefore to be anticipated. In addition to the problems of training, those of recovery (sleep, balneotherapy), nutrition and hydration become preponderant. While the distractions of the mountain can lead to going beyond listening to oneself, let us not forget that altitude is also an attitude.