I can share with you one technique that I learned in labor doula training and use with success.
When you are putting power behind your movements, use strength from your body, instead of from your arms. You do this by leaning into the other person's body. Use the weight of your body to provide pressure.
Something else that is great for working out knots in the muscles is to use an elbow on the knot in a slow, circular motion. It's very effective!