When rehabilitating the quadriceps, they respond to a much greater variation in reps. This means using a variety of exercises such as step ups, squats, knee extension, squats, split squats and lunges. You also need to use a large variety of reps brackets for these exercises. So this means training anywhere from using singles to sets of 50 reps. For example.
Also to re-build an injured or atrophied quads you have to use protocols that produce a lot of lactate, and you have to use heavy-load protocols. This could mean do 2 minutes of continuous squats with a heavy loads, or for anyone who is not quite as highly conditioned it could be 2 minutes of step up with 10kg dumbbells.
Remember, any training protocol is only as good as the time it takes you to adapt to it, therefore change you exercises and reps brackets often.
Hamstrings have two major functions – knee flexion and hip extension, thus you must train both functions of the hamstrings:
The knee flexion component of the hamstring is usually trained by all variations of the leg curl: seated, prone, kneeling, and standing using a machine; Swiss ball hamstring curls, Nordic drops or theraband prone knee bends. This function of the hamstring is usually best trained using high loads, explosive concentric and slow eccentric tempos and low reps. For example you could do 5 sets of 5 leg curls or Nordic drops. This will create a lot of muscle soreness so you only need to do heavy work like this every few days.
The knee Hip extension component of the hamstring uses exercises such as Romanian deadlifts and good morning; back Extensions, and reverse hyperextensions. This function of the hamstring can be trained using moderate loads and higher reps scheme, such as 3 sets of 15 Romanian deadlifts.