Effect of Vagus Nerve Stimulation on Trapezius Trigger Point

Arm 1 (Vagus Nerve Stimulation (nVNS)) is an experimental intervention, as it tests a novel approach (non-invasive vagus nerve stimulation) for trigger point treatment.

Arm 2 (Ischemic Compression) is an active comparator, as it uses a standard treatment (trigger point massage) commonly applied for myofascial pain.

Arm 3 (Exercise (Control)) is explicitly labeled as the control group in your document, using a standard exercise program, which aligns with an active comparator (since it's an active intervention rather than a placebo or no intervention).