In Resonance Repatterning muscle checking is used to access energetic patterns. A muscle's ability to relax or contract indicates, whether a person resonanates with the frequency of a pattern or not.
When a person resonates with the frequency of a pattern it is like the body-mind saying 'yes, I recognise this energy; I have a corresponding frequency, it is part of me'. And of course when a person does not resonate with the frequency of a pattern, the body-mind says 'I don't know what you're talking about; I do not have a corresponding frequency, this is not part of me'.
In practise it looks like this: At the beginning of a session a person will resonate with the problem they experience, and they won't resonante with their intention and what they want from life. At the end of a session after they had the right input at the right time and their frequency patterns have changed, a person won't resonante anymore with their problem, instead they resonate with their intention and what they want from life.