In my view, to use medical acupuncture effectively, the needle becomes an extension of our fingers. Our fingers should begin the needling process by carefully palpating, becoming attuned to the patient's tissues, being responsive to feedback.
Such feedback may be a response from the tissues such as altered muscle tone, tension, thickening, congestion, bogginess, stringiness, stiffness, guarding and more. These are loose terms, more descriptive than scientific, not always reliable, but meaningful to the expert clinician.