Does Placebo Information Affect the Trial Outcomes and Participant Blinding?

A total of 89 healthy volunteers will be recruited and randomly allocated to one of the 4 groups at an identical ratio. Four groups differ in acupuncture and placebo information. It is summarized as follows:

1. to receive real acupuncture and to read fully disclosed sham acupuncture information (e.g., fake acupuncture) written in the informed consent
2. to receive real acupuncture and to read partially disclosed sham acupuncture information (e.g., different kind of acupuncture) written in the informed consent
3. to receive sham acupuncture (Park Sham Needle) and to read fully disclosed sham acupuncture information written in the informed consent
4. to receive sham acupuncture to read partially disclosed sham acupuncture information (e.g., different kind of acupuncture) written in the informed consent.

They will read informed consent with differently described placebo information following their allocation. After participants repeatedly lift a dumbbell with their non-dominant arm to induce delayed onset muscle soreness (DOMS) in their biceps brachii, they are given allocated acupuncture treatment once a day for three consecutive days including the very first visit to compare outcomes (i.e., relief of DOMS measured with pressure pain threshold and visual analogue scale) and blinding property (the participants will be asked 'which type of acupuncture do you think you have received?' and choose 1 answer out of real, sham, or don't know options).

• acupuncture (Device): A sterilised stainless steel needle (diameter 0.25mm X length 40mm, Dongbang Acupuncture Inc., Boryeong, Chungchenongnam-do, Korea) will be given at PC3, LI4, LI11, and LU5 of non-dominant arm for 15 minutes once a day for 3 days (immediately after inducing delayed onset muscle soreness (DOMS), and 2 consecutive days after inducing DOMS).
• Park Sham Needle (Device), also known as sham acupuncture: A Park Sham Needle (Meridius Medical Ltd. \& DongBang Acuprime Ltd., Exeter, UK), non-penetrating sham acupuncture, will be given at two points on the belly of biceps brachii, 1 cun proximedially from LI11, and 1 cun laterally from PC3 of non-dominant arm for 15 minutes once a day for 3 days (immediately after inducing delayed onset muscle soreness (DOMS), and 2 consecutive days after inducing DOMS).

Primary outcomes

• the change in muscle discomfort from baseline, i.e., immediately after being induced DOMS, measured by visual analogue scale (VAS) [day 0; day 1; day 2]: Muscle discomfort of DOMS induced arm is evaluated with VAS ranging from 0 to 10 cm (with 0 indicating no discomfort and 10 experiencing the worst imaginable muscle discomfort.)
• Blinding property [day 2]: Blinding property is evaluated: participants will be asked 'which type of acupuncture do you think you have received?' and choose 1 answer out of experimental group, control group, and do not know. It is calculated following the way of Bang's Blind Index; -1 indicates opposite guessing; 0 indicates random guessing; 1 indicates correct guessing.
• the change in Pressure Pain Threshold (PPT) from baseline, i.e., before being induced DOMS [day 0; day 1; day 2]: Pressure Pain Threshold (PPT) will be evaluated on the 5 points of upper non-dominant arm. Five points are selected from 6 equidistance from origin to insertion of biceps brachii with an exception of the first and last point, perpendicular to the belly of the biceps brachii. Pressure was applied to each of these points with increasing force at a rate of approximately 10 N/cm2*sec until the participant reported a painful sensation, and the force value was recorded (N/cm2). An upper limit of PPt was set 50 N/cm2 to avoid bruising.

Secondary outcomes

• Acupuncture sensation measured by De-qi questionnaire [day 0; day 1; day 2]: De-qi questionnaire (Kim et al.) is used to evaluate acupuncture sensation measured in VAS ranging from 0 to 10 cm (with 0 indicating no feeling of respective 18 items included in the questionnaire and 10 experiencing the worst imaginable feeling of respective 18 items included in the questionnaire.)

Other outcomes

• Acupuncture credibility [day 0; day 2]: Credibility of the acupuncture treatment is evaluated using a credibility test by Vincent et al. It is a 4-item self report on a 6-point Likert scale; its score ranges from 4 to 24 point; higher score indicates more credibility over acupuncture.
• Acupuncture Belief Scale (ABS) [day 0]: A Korean version of Acupuncture Belief Scale (ABS), a 36-item self-report on a 5-point Likert scale will be used to evaluate acupuncture experiences and beliefs. Its score ranges from 36 to 180 and higher score is considered more positive attitude toward acupuncture.
• State-Trait Anxiety Inventory-X (STAI-X) [day 0]: A Korean version of State-Trait Anxiety Inventory-X (STAI-X); each item of anxiety has its own 20 different questions on a 4-point Likert scale. The score ranges from 20 to 80, with higher score correlating with greater anxiety.

Sex: All, ages: 18 Years to 65 Years, accepts healthy volunteers

Inclusion Criteria:

* age over 18
* not participating in other studies at the time of study participation
* voluntary participation

Exclusion Criteria:

* resistance training for more than 6 months
* experience of fracture of any of four limbs
* pregnancy or breast-feeding at the time of study participation
* analgesics within 24 hours before participation
* any other diseases or conditions that might prevent the participant from receiving acupuncture

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• Hyangsook Lee, Doctor, Principal investigator, Kyunghee University