Cocoa Intake and Muscle Pain Sensation

This experimental randomized, double-blind, and controlled study included fifteen young, healthy, and pain-free men and 15 age-matched women. It lasted for three visits with at least one-week washout. Pain was experimentally induced, twice at each visit, with intramuscular injections of 0.2 mL hypertonic saline (5%), before and after intake of one of the different chocolate-types; white (30% cocoa-content), milk (34% cocoa-content), dark (70% cocoa-content). Pain duration, pain area, peak pain, and pressure pain threshold were assessed every fifth minute after each injection, between the time-points 5 to 30 min. Prior to inclusion, all participants underwent an examination in a dental chair. This included a clinical examination of the orofacial region according to the Diagnostic Criteria for temporomandibular disorders (DC/TMD) by a blinded examiner. Participants were also examined regarding their psychosocial status prior to inclusion, this included depression, somatization, anxiety, pain catastrophizing and stress.

The chocolate given to the participant was of a different concentration of cocoa, distributed in a randomized and double-blinded order. The participants where given the chocolate with their eyes closed. A non-blinded examiner fed the chocolate to the participant at each clinical trial, while a blinded examiner did the assessments. The different types of chocolates were given at three different visits to all participants with at least one week of washout in between. To randomize the order in which the chocolates were given to each participant, an internet-based site was used (www.randomization.com; Seed 19525). The randomization was done in five blocks of six participants each, by a researcher who did not participate in the data collection

Pain intensity will be assssed using a 0-100 visual analoge scale (0-no pain; 100-worst pain ever experienced)

Peak pain intensity will be asessed from the 0-100 visual analoge scale (0-no pain; 100-worst pain ever experienced)

Pain area will be marked on lateral charts of the head before and after intake of chocolate and measured in au.

Pressure pain thresholds are assessed using a digital algometer over the area of injection in the masseter muscle with a pressure rate of 30kPa/s.

Inclusion Criteria: good general health age between 18-40 years Exclusion Criteria: any pain-related diagnosis of TMD or of the orofacial region any headaches a diagnosis of systemic muscular or joint diseases (fibromyalgia or rheumatoid arthritis) whiplash-associated disorders neurological disorders psychiatric disorders any allergy to the substances used