This is a VERY important rule. It can make or break your training camp.💪🏼
Being at high altitude is a form of stress for your body. It's a good form of stress because it can make you stronger, but it's still a form of stress.
You will see the effect on your heart rate ❤️: your resting pulse (your HR when you wake up in the morning) will be 10-20 beats higher in the first days. Also, throughout the entire day, your heart rate will be higher than at sea level. That is why you should take it really easy in week one.
Some athletes tell me on day 1 or day 2 (after arriving) that they don't feel the altitude. This is likely caused by elevated levels of adrenaline. Adrenaline is a stress hormone. It's normal to have higher levels of adrenaline in the first days. This is fine. But the tricky thing about it is that it can make you feel good during training, so you are tempted to run faster than you should.
Others tell me that 'the key is to run easy, but you can run long'. So they want to do a 90 min longrun on day two. This is wrong. If all elite runners start with 30 to 40 min easy runs, why do you think you can do 90 minutes? It's too much stress for your body in the first days (those who did that, paid the price later).
A few rules I tend to stick to for my athletes:
✅️ run easy (zone 1) and short on the first 3 days
✅️ If you feel okay, you can do a bit of zone 2 (moderate) on day 4
✅️ Something at zone 3 (marathon effort) on day 5 or 6.
✅️ Or something in zone 4 (threshold effort) on day 6 or 7, for example, 5 x 6 min at a controlled effort.
The key is that your morning HR keeps coming down, which shows that you are getting adjusted to the altitude. As long as it remains much higher than usual, don't train hard!
This especially counts for those who come for 4-6 weeks. In order to have the maximum benefit, train easy in week 1, so you can increase the load after that.
Those who come for 2 weeks only, can afford to build up quicker since there's less risk of overtraining.