Acute Effects of Therapeutic Ultrasound on Passive Muscle Stiffness and Pain in Patients With Neck Pain

Continuous ultrasound applied to painful/stiff cervical muscles during a single clinic visit; frequency 1-3 MHz, intensity 1.0-1.5 W/cm²

Single session mimicking active procedure; device displays appear normal but acoustic output is 0 W/cm²; \~10 minutes;