Ranking
''Gaining Momentum''
Usually we gain momentum to break or make fractures by the following ;
1) Getting away from the oppent in certain distance ( Raise arm , Contract sholder for ex)
2) Some times relax knee, Ankle
3) Rotating Use grabs To support(Boost) Your kick/ Punch
4) Long Ex;
4 ex:when you grabbing with your left arm, Raise it and contract your Shoulder then..
Extend The shoulder, Lowride arm or Contract elbow, Depends on your position.
And then Mostly Relax ankle/knee(Not that needed sometimes) Then Extend it.
Play Taekkyon or Erthtkv2 to Provide your Momentum tests,
Pm me and i will Come to help you,sir.
Just to know: THE MOMENTUM IS GAINED BY POSITIONS.
So you have to choose your movements to your positions.
Well the only ways you can gain momentum is from uke (you're opponent) or the ground.

You can kick or push off the ground with your hands and feet or you can grant uke and give yourself momentum that way.
Ok these are long nice answers but I am gonna keep mine short:
1: jumps. They are great if you can launch your self foward with alot of spin but mostly only in replays

2: pecs and lumbars+chests. Easy way to build momentuem is pec and lumbar+chest control for example: if you right rotating the chest+lumbar contact ur left pec and extend ur right

3: push/pull also a in match momentum gainer. Perticually in abd . Try to pull one side of the opponent close to your body and the other one away from your opponents body. Rotate ur lumbar +chest accordingly.