When deadlifting, if you can break the barbell off the floor just fine but struggle mid-shin, the problem is likely weak quads. That portion of the movement includes a lot of leg extension, and weak quads will obviously be a problem.
There are a few ways to strengthen this weak point, including fronts squats, leg presses, and squatting from starting at a 90-100 degree knee angle. But here's a favorite of mine:
Partial Deadlift (Floor to Knees)
- Stand on a slightly elevated surface so that the bar starts about half an inch from the floor.
- Pull the bar to the knees only.
- Perform this movement slowly to keep the tension on the target muscles.