You may hear of applied kinesiology, muscle testing, or manual muscle testing and they are all the same thing.
Your body tells you what it likes and what it doesn't like.
Say "I like to drink water." Then say "I like to drink paint."
Please don't drink paint! But the point is, I'm sure your body reacted negatively to the idea of drinking paint.
If you're sensitive you could feel the difference between saying yes, and saying no. Or maybe you prefer to use a tool that relays the deep messages, associations and beliefs that may be hidden deep within your subconscious mind.
Muscle testing is that tool that can guide you to knowing the answers to some of your most pressing questions, and you don't need to learn to be an adept psychic or go to one!