>>76607434
>explosiveness
Define explosiveness. If it's the ability to generate a lot of force in a short period of time. That means recruiting more motor units in a given muscle in a short period of time. Recruiting more motor units is a nervous system adaptation. Training the nervous system is task dependent. Moreover there are a lot of limits to what you can do. The body for the purpose of metabolic efficiency doesn't recruit any more motor units than is necessary for a task and even so. It will not use any more than a limited number of motor units at any time unless it absolutely has to such as during a 1RM attempt or lifting 85% to 90% of 1RM.
Moreover, we can also consider the reality that explosiveness is very much genetic. People who are professional athletes in more explosive sports likely were more predisposed to being explosive in the first place due to their heredity.
>quick response time
Extremely task dependent. The only real way to become more explosive and improve your response time in a given task is to practice that task.
The purpose of weight training for athletics is simply to improve a muscle's ability to generate force by growing the muscle. For non-roiders/non-bodybuilders who don't use tricks like mixing vegetable glycerine with your creatine to get more fluid into the muscle to increase their size, strength = size. Explosiveness is related to power. Power = force * velocity. More initial force = more velocity. If you increase force production, you increase power. The likelihood is that most of the increases in velocity are coming entirely from the increases in muscular size and that very little are the most you get from the nervous system during weight training and are very short term.
The speed you move depends entirely on the load. 50% 1RM can be moved extremely quickly, say explosively. Whereas moving 85% to 90% of 1RM will generally be very slow. This is just due to the initial acceleration.