If you are interested in developing speed and power, one of the first things you should be concerned with is motor unit recruitment. Motor units are tiny. They are made up of a motor neuron as well as all the muscle fibers in which it innervates. Your gluteus maximus for example is not itself a motor unit, but it is made up of many different motor units and muscle fibers. A great metaphor for a motor unit is the light bulb analogy. The muscle fiber represents the lightbulb and the motor neuron is the wire that leads to that specific bulb. In order to light the bulb up as bright as possible, you need to be able to send as much electricity through the wire to the bulb as possible. Just as you need as much electricity as possible to light up the bulb you need to recruit as many motor units as possible if you want to perform with speed and power.
How are motor units recruited?
Motor units are always recruited in a certain order. Motor Unit Recruitment is determined by the size of the motor neuron and the number of muscle fibers that it innervates. The largest motor neurons innervate type II fast twitch muscle fibers, while smaller motor neurons innervate type I slow twitch muscle fibers. Motor units are always recruited from smallest to largest; it would not make sense to recruit large fast twitch fibers right off the bat... if this was the case, we would be doing everything at maximal effort. Instead, our nervous system knows to recruit smaller units first and then larger motor units if needed. As the force placed on the body increases more and more, larger and larger motor units are recruited.
Motor unit recruitment and exercise
During exercise, we need to recruit motor units in order to execute a given task. Whether we are doing a bodyweight squat or a One Rep Maximum deadlift, we need motor units in order to execute either task. Your body will need fewer and smaller motor units to perform the body weight squat as opposed to the one rep maximum deadlift. When you perform the one rep maximum deadlift, your body will recruit all the motor units possible. A lot of people go wrong in their training by thinking that in order to recruit the maximal number of motor units you need to do a ton of reps and feel the burn. This could not be more wrong. When we perform powerful movements such as lifting heavy weights, sprinting, explosive jumping...etc., we are heavily taxing our nervous system which means maximal amounts of motor units will be recruited in order to successfully complete the above tasks. In order to fully maximize the use of our largest and and most powerful muscles, we need to recruit the largest and most powerful motor units. To do this we need to incorporate powerful and explosive movements into our workouts. Lighter weights and controlled movements are great for increasing muscular hypertrophy, but if our goal is to get stronger and faster we must incorporate powerful and explosive movements such as 1-3 rep maxes, sprints, Ballistic Movements and plyometrics. Add these sorts of exercises into your training routine in order to increase motor unit recruitment.