I got a great question the other day about hip lifts. First to clarify, hip lifts and bridges are synonyms. We often use the terms hip lift and bridge interchangeably. That's probably a terminology thing we need to fix as I can be a stickler about other people's terminology.
However, I think in my writing I've called them by both names at different times.
The question I received was why do we ( at CFSC? MBSC) cue toes up and heels down while FMS and McGill cue a flat foot.
I'm not sure anyone has hard data ( EMG etc.) on this but, we are adamant about toes up.
In the MBSC/ CFSC system bridging is used to attempt to isolate ( god forbid I say activate) the glutes. We know from our understanding of functional anatomy that we cannot ever truly isolated a muscle but, we can bias movements to favor one muscle or muscle group over another.
The purpose of the single leg bridge (or hip lift) at MBSC/ CFSC is a to attempt to bias the exercise in favor of the glutes.
We know from our understanding of the concept of length tension relationships that attempting to contract a muscle in a shortened position will cause that muscle to cramp.
The reason that we flex the knee is to decrease the capability of the hamstring to work as a hip extensor. We are trying to bias hip extension toward the glutes. We also know that if the glutes are not functioning properly, the hamstring will attempt to assist and or become the prime mover in spite of the bad length-tension relationship. This will result in a hamstring cramp.
Pushing through the foot defeats the purpose of the exercise as we intend it to be at MBSC. Pushing into the forefoot creates a leg extension type action that now adds the quadriceps into the equation.
If we are using the exercise to recruit the glutes ( and that is why we use it) pushing through the heel makes more sense.