Early acceleration

In the blocks the front foot should be placed behind the “plum line” of the hips inorder to have an effective push. Is this also required for the 2nd and maybe 3rd step, should touch down happen behind the hips? Or is it only important to have them touch down behind the COG? (I am thinking if the athlete maintains a lean his COG would be infront his hips)
Thanks

For good sprinters, touch-down during the early steps occurs almost directly beneath the hips. The position of maximum force would likely happen just afterward (slightly behind). Not sure it would be wise to focus on foot placement in practice, though. Better to stay relaxed, and not overstride–the feet will fall where they need to.

Also, if the COG were not displaced in the direction of the sprint, acceleration would be very difficult. The feet should always hit behind the COG.

I know the feet should hit behind the COG during the acceleration phase, my question is how far. The athlete I am working with brings his feet down behind the hips on the first two steps and it couses his hips to drop imo. Is he making a technical error that I should try and fix, or just let him run.

I suspect that his hips drop because he just can’t hold the lean he’s got. Maybe the solution to the problem is not in those first few steps, but rather before he starts. Does he have too much weight on his hands in the set position? Check the block angle to make sure it’s not too extreme.