I have used hypopressives with some of my patients with hypertonicity with good results. It is not for everyone and needs to be introduced at the right time. But for some patients who cannot relax or contract voluntarily it helps to get some movement back into the muscles. Much like you would use a contract/relax exercise to release a hyper-tonic skeletal muscle else where in the body this can help to gain movement and relaxation in the pelvic floor through gaining movement. The muscle is more easily released during the refractory period. Remember in hypos you are not actively contracting the pelvic floor muscles. There is no clenching happening. You are using breathing and a decrease in intra-abdominal and intra-pelvic pressure to create an automatic lift of the pelvic floor muscles. This can help release the hypertonic clenching that a lot of people with this condition have. I always do this with internal palpation to make sure the muscles are moving correctly and releasing properly.
Women´s health physiotherapist