“What do you think about stretching or yoga, are they helpful to prevent injuries, should i do before or after the hard exercises, they could count as recovery or the hr is too low ?”

I do about 30mins of stretching ~5x per week. I find it very helpful (for hiking, scrambling and splitboarding). Back when I was climbing, I also stretched, usually as a warm-up for training.

I record the workouts but obviously the TSS is very low. To the extent that stretching promotes blood flow, my guess is it will some beneficial effect on recovery.