Yesterday I wrote about a couple of outstanding long jump case studies.
Here's one of the strategies that can work to release a handbrake on a sprinter.
Address the superficial anterior lower chain e.g. anterior hip area, thigh and tibial muscles
Purpose: to improve mobility of tissue affecting hip extension and knee flexion
Description: Use techniques to influence mechanoreceptors. In addition, perform stretching of the area in the form of contract-relax and/or hold-relax, for reciprocal inhibition and improved active patterning.
Implications: as per the Modified Thomas Test, normal hip extension is at least zero degrees and knee flexion at 90 degrees on a neutral pelvis. In terminal stance of running, as well as early swing, limited mobility at the hip and knee can cause forward pelvis collapse, changing length-tension behavior of the hamstring on the other side. In this forward collapse position, it's very difficult to store and release elastic energy again. An individual becomes very prone to groin injuries, because nothing is protected. There's no force closure there at the saroiliac joint when the pelvis collapses forwards. All forces that transmit through the pelvis can not modulated by muscles that should be reflexively and isometrically tense. So the forward collapse of the pelvis is something you don't want.
Common errors and corrections: see my notes in "techniques for influencing mechanoreceptors" re creation of pain behaviours during the technique.