"Science says that you are at your best the first two to three days after returning from altitude, or around day fourteen," Van Thienen tells Het Nieuwsblad. "The first days at altitude you have to let your body acclimatize to the lack of oxygen. Energy goes from your system to adapting to the altitude and that is energy that is not available for training. You have to reduce the training volume during your entire altitude training period."
Whilst van Aert has already raced on the road, notably taking victory at Kuurne - Bruxelles - Kuurne, the Belgian recently returned to altitude, skipping Strade Bianche and Milano-Sanremo to focus on peaking for the
Tour of Flanders.
Van der Poel meanwhile, has been staying in the well-known sports hotel Syncrosfera on the Costa Blanca since February 17. Whilst at sea-level, the hotel has state of the art rooms that can simulate the feeling of altitude.
"Theoretically, that is an advantage. During intensive training or if you feel a little less, you can set the height a little lower," says Van Thienen. "And the disadvantage of that altitude room is that you have to spend as much time as possible in your room, which is mentally more demanding. And if, for example, you complete a six-hour endurance training outdoors, that is also six hours in which you have no altitude stimulus, which you would have if you stayed and trained outside at a real altitude."