Power is the amount of work that is done in a specific amount of time. Power = Work / Time.
Work = Force X Displacement. This leads to Power = Force X Displacement/ Time.
This basically means that to become more powerful we need to do more work with in a specific amount of time or to do the same amount of work in shorter amount of time. More we increase the work/time ratio the more powerful we will become. Since Displacement/Time is basically velocity this means that Power = Force x Velocity. To become more powerful we need to be strong and fast.
To develop power Martin Rooney recommends squats, deadlifts, bench press but also to do sprints, throws, etc. Basically he is saying we need to become stronger and faster to develop power.
This equation explains why olympic lifting builds power. Olympic lifters are basically increasing the work/time ratio thorough their training to break new records. There are various other ways to generate power such as medicine ball throws.
There are also other ways that can cause neurological adaptations to physiologically lead to muscles being more powerful. One of these methods is contrast training. There has been recent research that french contrast training which is a form of contrast training that has been supporting the theories on this type of training. Football players have been using contrast training to build serious explosiveness for a decade.
The most simple way to utilize contrast training is working a heavy 3-5 rep lift on a certain group of muscles and then following with an plyometric exercise that uses same muscles such as jumps and throws.
Bench Press 3-5 reps followed by 5 medicine ball chest throws
Squats followed by 5 Box Jumps.
Joe DeFranco discusses contrast training in depth and he does not recommend the lifting exercise to last more than 20 seconds to ensure the muscles are fatigued. You should rest 10-20 seconds before the plyometric exercise. There are various examples of this type of training and it is important to make sure you are lifting 3-5 reps with performing 5 reps plyometric exercises. You should rest 3-5 minute between each set and you shall perform minimum of 5 sets of this type of training. I usually work 5-8.
In theory, performing the heavy lift prior to the plyometric exercise should result in more muscle fiber contractions since the first near max (3-5) rep lift will increase the recruitment of motor units which will be used for the plyometric exercise. This type of training will remodel your central nervous system and help you become more explosive in theory. Athletes have improved their personal records with this type of training and there is a good amount of research to support this.
This type of training can be super taxing on the nervous system and it needs to be used as a part of a phasing program so it is performed for a specific amount of time (weeks ) to get the optimum benefits without risking injury. When most athletes that try this type of training, they get great results and some try performing this type of work all the time. This can lead to over training and can lead to a high chance of injury. I highly recommend working with a certified coach to help you incorporate this type of training in your current training program.