Hey There,
Those types of strikes are something that you have to work on over time. You build up the supporting muscle and tendon strength and then develop flexibility in the shoulders, elbows, and wrists that help you do it with power. I would suggest starting out slowly working on technique and then over time (at least weeks) adding power. Adding too much too soon is an invitation to injury. It's also helpful to do the same motion with a hammer or with a blade so that you have a clear focus on where the power is going and you are definitely hitting with the business edge rather than the oblique sides.
It's also helpful to have someone looking over your shoulder and giving you tips. Good luck.