Hello, Im 16 and im in the 10th grade. my current 400 meter dash time is 55.28 seconds. I just started track this year. i began with my times being at 60 and now im down to 55. ive been going down either .5 of a second to a whole second each meet. According to my couch i have perfect form (fast pumping arms, torso is motionless only legs and arms move, sprint the first 100m then i open up my stride for the next 100m for the 100m turn i pump my arms harder and sustain my placement and for the final 100m i give it everything i have left) i have full access to protprotein creatine. i want to improve my times to be -50 seconds. i want to know what how i should be working out and what is 400m dashers physical build.