Acupuncturists and other therapists use Dry Needling techniques. That is, needling with solid needles rather than hypodermic needles filled with injectable medications. Trigger Point Needling, Motor Point Needling, and Dry Needling are excellent for pain relief. Probably the best and fastest acting I have seen for pain relief due to tight, contracted, dysfunctional muscles.

Trigger Points can create pain, numbness, tingling, or other abnormal sensations in the muscle where they reside, or they can refer pain to distant areas. I think of trigger points as the areas of the muscles where fibers contract and get stuck, and cannot unravel on their own. You can release trigger points using a needle, pressure (finger pressure, lacrosse ball, foam roller, cupping), friction (scraping, gua sha), stretching, relaxed movement (yoga, qigong, training, althetics, dance). Electrical stimulation through acupuncture needles or using TENS pads enahnces the releasing effect of TrP needling.

Motor Points are the areas where motor nerves enter the muscles in a high concentration. It's more efficient for the body to have one spot where a motor nerve enters, and then branches off to innervate multiple fibers in the muscle. This allows one nerve impulse to stimulate the entire length of a muscle. It also allows an acupuncturist to access the entire muscle through one or two points. Motor points are effective to release tight muscles similar to TrP's, or to activate inactive muscles. The effect for inactive muscles is net partial however - you will need to follow up by practicing isometrics or full ROM movements during the period when you are coming for motor point needling. Microstimulation can also help to activate muscle fibers.