hey star61 when you do box squats do you try and keep your shins perpendicular to the floor? becuase i find it very ackward to do it thatway… plus its alot harder to move the weight up that way…
To do a box squat without your shins perpendicular would probably make the lift more quads and less glutes, which as a sprinter you don't want. If I understand you right, it sounds like you are trying to stand straight up off the box making the lift all up and down and very little back and forth. Am I close? You may want to try leaning foward a bit before you come up, remember that your back can be straight without being perpendicular with the ground.