You are correct. As ESTI mentioned earlier, the dynamics of sprinting, from a muscular standpoint (specifically regarding the hamstrings) exist as:
- start and early acceleration - lesser hamstring involvement
- as the upright position and max V is approached the stress placed on the hamstrings is at its height
Thus, from a weight training perspective, far greater liberties may be taken during the GPP and early phases of a short to long program because the stresses associated with max V and speed endurance runs are not yet present and any strength gains yielded from posterior/hip/leg resistance training are likely to be realized in improved start and acceleration.