One of my favorite methods to build strength on an exercise, especially in the disadvantageous or weak part of the lift is to use one and a quarter reps.
The name speaks for itself with one and a quarter reps. Simply during each rep you do an extra quarter rep at either end of the range of motion.
Check out the video of Tyler demonstrating one and a quarter reps in the squat.
We often utilise one and a quarter reps on squats, because in most trainees the weakest most under developed muscle of the quadriceps is generally the vastus medialis oblique (VMO). The VMO is the tear drop shaped muscle on the inside of your quad. This muscle is most active during the first 15 degrees and the last 15 degrees of knee flexion and extension. So doing that extra quarter rep at the bottom will not only improve your strength out of the hole but will also give the VMO a double hit on every rep, which many people would benefit greatly from.
One and a quarter reps tend to work best when done at the hardest part of the movement so other exercises you could use them on are.
At the bottom of a lat pulldown.
At the bottom of a bench press.
At the top of a lying leg curl.
At the bottom of a Bicep curl.
Rowing movements when the weight is against the body.
At the bottom of a shoulder press.
You get the idea.
If you want a real doozy of a modifier to add to your squat, try the Double Barrel 1 and 1/4 Squat where on every rep you perform a 1/4 rep at the bottom and at the top of the squat. I can guarantee your VMO's will be on fire after only a few reps.
Have a go at using one and a quarter reps in your training. It's a great method to add to your tool box for busting through plateaus and adding another element of variability to your training.