Before describing how speed is trained, let's try to explain why it is important in the practice of mtb.
Speed is a useful quality in sprints, sprints, starts of a DH and the typical sprints of pedaled enduro stretches. But speaking of MTB, it is necessary to broaden the discussion also to the rest of the body and analyze this aspect from a different point of view.
Train speed in mtb
In the practice of mtb we realize that there are aspects that concern the whole body that play an important role in the riding of the bike:

the speed with which the impacts of the terrain are absorbed, or the speed with which one manages to exit a curve, are an integral part of the concept of speed.
All these driving moments in which speed plays an important role have a single common denominator; the need to have an important strength base. In the sprints as well as in the ability to absorb brake pumps it is necessary to start from a basic concept:
without an excellent level of muscle strength you cannot speed
Having said that, it is good to analyze the different job opportunities we have at our disposal, trying to understand which are the most important; depending on the moment in which we are and the training goal we have.
Speed on a bike
How do you train for speed on a bike? Simple, with series sprints. Groups of short repetitions, which can include a standing start or a jump start. 10 ”/ 15 '' of work with the aim of reaching the maximum possible speed and a high pedaling frequency.

If we talk about gravity disciplines, it is also necessary to include the work in the bmx tracks, very useful for improving the speed of the torso.
Bodyweight speed
But the best jobs for the whole body remain the free-body ones. Here the choice is very wide, we can use the dumbbells, the work with the pins, the jumping of the obstacles and the whole arsenal characteristic of the gyms. They are very varied exercises, capable of focusing on specific muscle groups or of guaranteeing a more organic increase in quality.
Often during these sessions other qualities are stimulated, such as balance and coordination.
Here, too, we work in series, the recovery between exercises is fundamental and a timed work is foreseen (max 20 '' per series); or with a predetermined number of repetitions. The goal is to express the maximum possible speed for a relatively short time that does not lead to the activation of the lactic acid energy production mechanism.
What happens to our muscles during these workouts?
Energy production is entrusted in particular to the anaerobic alactacid mechanism; it is the nervous system that is stimulated to maximum expression and the coordination capacity is massively stimulated. A good warm-up is essential, which allows the muscles to express their qualities in the best possible way; equally important will be the motivational aspect and the concentration with which one approaches these jobs. Having to express maximum energy in a short time it is strategic to focus on what is being done; an even more important element for what concerns free-standing jobs, where attention is needed to remove the possibility of errors and injuries.
