The omni-contraction method is a type of rest-pause training. The goal is to reach contractile failure on all three types of muscle action: concentric (lifting), isometric (holding), and eccentric (lowering). This approach is arguably the strongest hypertrophy stimulation you can have. The only downside is that you need a training partner... and it really hurts. Here's what a set looks like using the hamstring curl.
Hamstring Curl: Omni-Contraction Method
Each set is made up of three mini-sets. The pauses are 10-15 seconds long.
Start with a weight you can do for 8-10 quality reps and go to contractile muscle failure. Rest 10-15 seconds.
Using the same weight, lift the weight until you reach the maximum tension position (hardest position or angle of the exercise). In most exercises this is the mid-range point. Hold that position while flexing the target muscle as hard as you can until you can't hold it anymore, reaching isometric failure. Rest another 10-15 seconds.
Still using the same weight, have a partner assist you in doing the lifting portion of the movement and do the lowering portion by yourself in 4-5 seconds. Do reps like this until you can't control the weight during the lowering phase.