There are 3 ways to improve your 40
Start needs to be explosiveFAST Top SpeedArm swings So for #1 your start is so important. You need to keep an explosive pad level and drive for the first 10 yds then you get up to your top speed. Working explosive lifts in the weight room like power cleans and jump squats help with this kind of thing along with a lot of technique training. For #2 your top speed is for that 20-30 yd range and that can be improved by a lot of resistance training and speed work. (Message me on Instagram if you want some speed drills to do) For #3 your arm swings are what gets you to the finish. A lot of guys are super tense and their arms either flatten out or go across their body and they rotate. You want your arms going right past your pockets up to your cheek. Keep a 9 degree angle in your arm and drive. Also keep your chin down so you don’t slow yourself down. If you do all 3 of these things you are going to improve your time.