Hill training with gradient
One of the typical sessions in your UTMB training schedule will be to do some hill training with a significant gradient to simulate the climbs and descents you will encounter in the event.
Choosing a significant climb
Depending on the topography of the terrain near your home, you will have to choose a climb that offers a positive difference in altitude of 500 to 1000 m. If this does not exist in your area, choose the largest hill that comes close.
Doing uphill and downhill sessions
The UTMB offers long climbs on its courses, followed by equally long descents which can be traumatic if you are not prepared for them. You will therefore need to train to absorb long gradients. You should therefore do at least one session per week where you will ride up and down with a minimum of 500 m of difference in altitude. If the hill you have chosen is not so important, ride it as many times as possible until you have accumulated this amount of elevation change. The idea is to tire your muscles and teach them to react better to the constraints of the terrain and to develop mountain running reflexes.