PHYSIOLOGICAL EFFECTS OF DRY NEEDLING

A muscle can be needled superficially (depth of 2mm) or deep (depth of 1.5cm). Studies have shown no difference in the immediate effect between the two methods, but after 3 months the deep dry needling technique resulted in more effective pain relief.

Histology of a myofascial trigger point:

Extreme sarcomere contraction leads to localized hypoxia in a muscle. This in turn leads to the release of local nociceptive chemicals eg. Bradykinin( responsible for a perpetual pain cycle), CGRP(responsible for excessive ATP), and substance P. Myofascial trigger points function as peripheral nociceptors that can initiate and maintain central sensitization. Trigger points can unmask sleeping receptors in the dorsal horn, leading to the appearance of new receptive fields called trigger points.

Mechanical effects:

Dry needling is most effective when a local twitch response is elicited. Dry needling can disrupt the integrity of the dysfunctional motor endplates related to extremely shortened sarcomeres. A dry needle placed accurately can provide a localized stretch response, which will assist the sarcomere to return to its original resting length (decreasing overlap between actin and myosin). This causes a release of excessive energy consumption and capillary compression.

If a needle can mechanically stretch muscle fibres, rotation of the needle will be beneficial. Winding up of the connective tissue is called a needle grasp. This causes collagen bundles to straighten. Brief mechanical stimulation increases interleukins and the expression of proto-oncogenes.
Moving the needle up and down (fanning) may lead to a needle grasp and a local twitch response. This may activate the pain gate system by blocking nociceptive input from the myofascial trigger point.

Neurophysiological effects:

Superficial dry needling stimulates the A-delta nerve fibres, blocking transmission to group IV nociceptors, closing the pain gate in return. Prolonged stimulation activates the enkephalinergic inhibitory dorsal horn interneurons. This happens due to the activation of seratonergic and noradrenergic descending inhibitory systems, blocking nociceptive input.


Deep dry needling causes opiod-mediated pain surpression. Large diameter sensory input occurs via afferent fibres into the dorsal horn blocking nociceptive input.

Chemical effects:

Chemicals like, bradykinin, CGRP and substance P builds up in a myofascial trigger point. By eliciting a twitch response these levels are corrected. High metabolic demand and impaired metabolic supply in a myofascial trigger point causes an energy crisis and hypoxia. When the needle approaches the trigger point there is a compensatory hypereamia, causing an increase in oxygen supply. After reaching a peak, the tissue oxygen tension falls rapidly decreasing the amount of vasoactive substances like histamine.



Chronic muscle strain causes stored calcium to be released. The pump that returns the calcium to the sarcoplastic reticulum is dependent on ATP which is not available due to the energy crisis. As needling relieves the energy crisis, calcium can get resorbed.