To determine the difference in efficacy of an all natural topical analgesic (MuscleCare) to a product containing the non-steroidal anti-inflammatory drug diclofenac (Voltaren) on trapezius trigger point pain.

Myofascial pain syndromes (MPS) are common in Western society. Vernon and Schneider note that MPS is thought to be the leading diagnosis among pain management specialists and the leading diagnosis in pain patients reporting to general practitioners. MPS can be viewed as a regional pain syndrome such as, neck, low back and upper quadrant pain syndromes. MPS can also be found focally in discrete painful sites known as Myofascial Trigger Points (MTP). Locations of MTP's have been characterized on clinical grounds throughout the musculoskeletal system, starting with the seminal work of Travell and Simons. MTP's have been described as active (clinically active with pain referral upon palpation) or latent (not clinically active, but tender on manual palpation). The presence of associated features such as "local twitch sign" and palpable taut bands is thought to confirm the presence of an active MTP, while latent TP's may not present with the classic features.

Numerous treatments are currently available for MPS and MTP's. Several systematic reviews have recently been published on a variety of treatments, including pharmacologic agents, physical agents, complementary and alternative therapies. One commonly used therapy is the application of topical agents to relieve pain. These agents can be classified as pharmacologic or non-pharmacologic. The former category includes non-steroidal anti-inflammatory agents (such as ketoprofen), opioid agents, classical analgesic agents (such as lidocaine), novel analgesic agents such as capsaicin and rubefascient agents (containing salicylates or nicotinamides). Non-pharmacologic agents generally fall into the complementary and alternative medicine (CAM) category for MPS and MTP treatments. They may contain putative analgesic agents or counterirritant agents and they may exert cold, hot or neutral effects.

The literature on myofascial trigger points and non-pharmacologic topical agents is sparse with no randomized clinical trials found to date. Several studies have investigated the effect of such topicals in the treatment of osteoarthritis, particularly of the knee. However, there appears to be a lack of studies investigating the effects of topicas for the treatment of MPS or MTP. A randomized, placebo-blinded clinical trial of non-pharmacological topical analgesics is warranted.

Inclusion Criteria:

• Between 18-65 years old

Exclusion Criteria:

• acute pain presentation preventing comfortable participation, absence of a palpable tender spot in the right upper trapezius region (this feature will be identified by manual palpation by a neutral assessor prior to enrollment), any history of allergic reaction to previous use of any analgesic topicals, any disorder of the skin over the right trapezius area.