Table 3: The putative relationship between NAU properties and needling sensation.

NAU propertiesComponents of needling sensation
Aching/soreness/warmthNumbness/heaviness/distension

Type of NAUsCutaneous-receptor-rich NAUs with a predominance of nociceptors.Muscle-spindle- and tendon-organ-rich NAUs.
NAU reactionsBiochemical reactionBiophysical reaction
Dominant afferent fibersAδ and CAβ and Aδ
Acupuncture stimulation modesaPrick; shallow needling; high-frequency EA; laser acupuncture; heat acupuncture.Most manual techniques in gentle and repetitive manipulation; low-frequency, high-intensity EA and TENS.

aLow-frequency, high-intensity EA and TENS is thought to dominantly activates myelinated fibers (Aβ and Aδ), whereas high-frequency EA mainly activate small-diameter myelinated Aδ fibers and unmyelinated C fibers [133, 134].
bEA, electroacupuncture; TENS, transcutaneous electrical nerve stimulation.