Something I have heard Gray Cook speak about over the last few years if this concept of using a high threshold strategy. I sort of understood what he meant by this but not fully. At the Level 1 SFMA course in Holland earlier this month Kyle Kiesel touch upon this the topic of High Threshold strategies, which helped my understanding of it greatly.
Basically a High Threshold means using global muscles to always stabilizes rather than the authentic reflexive stability by the intrinsic (or local) stabilizers close to the joint.
Kyle quoted a study that showed athletes with a history of a previous low back injury would use and keep on for longer (after the task they were require to do had finished) their global muscles (Obilques, rectus, erectors, hip flexors, hamstrings). This is what a high threshold strategy is.
Kyle gave the example of an athlete attempting to perform a shuttle run, or a 10-5-10 test with a high threshold strategy, basically stating that this high threshold strategy would impair his/her performance. This is because the global prime movers also have to stabilize the spine and truck, so their prime movers cannot produce optimal mobility and force production to adequately perform the task (shuttle run, etc).
If the athlete had authentic stability at the spine, he/she would be able to contract and relax more efficently to complete the task at hand. But the high threshold strategy as pointed out above can leave certain muscle's contracted for a longer time period of time, even when the task requires for a relaxation phase.
Basically this is just another way of stating a prime mover is acting as a stabilizer. When this happens a prime mover(s) has to sacrifice mobility and force production for stability, as the stabilizers have for some reason (injury, postural problems, etc), have become ineffective at offering authentic stability.
Doing planks, side planks, pallof presses, etc with someone with a high threshold strategy may very well only feed this dysfunction. This made me re-think some of my core training with some of my athletes and clients.