Cerebral Palsy maybe/maybe not

If, however, the rectus femoris is acting by mass action as being a hip flexor then detaching it distally and even reattaching it on the flexion side of the knee will reduce some of that knee locking. Some. Not all, as the reflexively recruited portions of the quadriceps may still trigger, even if less so. This distal transfer of the RF was worked out by Dr. Perry at Ranchos Los Amigos where many adult stroke patients are treated. Some of childhood hemiplegia have similar reactivity and may be candidates for that transfer. It has been used to derotate malrotation, eh, so-so. Long climb for a short slide.

There is a danger. When hamstrings are firing very strongly, the quadriceps must counter fire to offset the effect. That COMPENSATORY over firing can be misinterpreted as mass action quadriceps activity. There are kids who are getting transfers of the rectus femoris at the time they are having hamstring lengthening.

In our experience, this reflects that more hamstrings (there are 4) are being blamed for over activity than ought to be. The high velocity components trigger the slower components (which are far stronger). If you attack only the high velocity portions, then the rest quiets down and the apparent mass action goes away. Why? Not all mass reaction is from the brain. We were able to mimic this phenomenon in NORMAL volunteers by using elastics that required strong output to overcome (see elastics). Mass action is seen in motion under high tension in neurologically intact people. FUN EXPERIMENT TIME! Go to a blackboard and in nice script write out your full name. Have somebody make a video of your face as you do that.