Cranial Laser Reflex Technique for Hamstring Function
Condition: Hamstring Injury; Muscle Tone Increased; Muscle Pain; Muscle Weakness
MeSH terms: Muscle Weakness; Myalgia; Muscle Hypertonia
Study type: Interventional

Summary: 
      Purpose: To conduct a pilot study of the effect of Cranial Laser Reflex Technique (CLRT)
      compared with sham laser on hamstring muscle flexibility, strength, and pain pressure
      threshold.

      Participants: Active, young adults ages 18 to 35.

      Procedures: A two-visit, assessor and participant-blinded crossover study with 1-week
      washout. Subjects will complete three functional hamstring tests before and after CLRT and
      sham laser treatment. Subjects will also complete questionnaires to assess their expectations
      and perceptions of the interventions.
    

Detailed description: 
      First Visit: Subjects who met the inclusion criteria and gave consent completed a brief
      questionnaire on their activity level, history of hamstring injuries, and perceived hamstring
      tightness and were randomized to one of the following for the first treatment period: 1)
      active CLRT; or 2) sham laser.

      After randomization, subjects were asked to complete the three functional hamstring tests:
      90-90 Knee Extension Angle (KEA) to assess flexibility, handheld dynamometry (HHD) for
      strength, and pain pressure threshold (PPT).

      Assessments. KEA: The 90-90 Knee Extension Angle test is a functional assessment designed to
      assess lower extremity flexibility and is considered the gold standard for hamstring length.
      The participant began in the supine position on a treatment table. The tested extremity (the
      right leg in each subject) was placed in a 90° hip and 90° knee position with the
      contralateral lower extremity placed flat on the table. A digital inclinometer was
      consistently placed at the level of the medial malleoli and the superior pole of the patella.
      The examiner maintained 90° of hip flexion. Pelvic position was monitored by palpation of the
      anterior superior iliac spine and lumbar spinous processes to maintain a neutral pelvic
      position. The examiner passively extended the knee to the point of a ''strong, but tolerable
      stretch," as reported by the subject. The examiner read the angle of the inclinometer and
      recorded the mean value of three attempts. A greater angle indicates greater degree of
      flexibility.

      Hand held Dynamometry (HHD) is currently considered a reliable and valid measurement of peak
      muscle contraction. The subject began prone on the table with right leg bent to 90°. The
      tester placed the dynamometer (microFET2; Hoggan Health Industries, Salt Lake City, UT) at
      the heel of the participant and applied force to the heel, gradually increasing in 3 to 5
      seconds. Participants was instructed to resist the applied force and maximally contract the
      hamstring muscle against the HHD device. The test ended once they are no longer able to
      resist the force and the leg begins to move (break point). The investigator recorded the mean
      value of three attempts.

      Pain Pressure Threshold (PPT) is a reliable, accurate and valid method for measuring muscle
      pain sensitivity and response to treatment. The digital algometer (FDX, Wagner Instruments,
      Greenwich, CT) is a hand-held muscle tester with a range of 0-100 lbf that consists of a
      padded disc with a diameter of 0.5" attached to a microprocessor-control unit that measures
      peak force (pounds or kilograms). The unit has a digital readout for peak-applied pressure
      and provides a built-in calibration routine that verifies a valid calibration. In order to
      determine PPT, the researcher applied the tip of the algometer to a tender spot in the
      participant's hamstrings and increased the amount of pressure until the participant verbally
      informed the researcher when the sensation of pressure became pain. At this point the
      algometer was removed and the peak force recorded. The mean of three repeated measures was
      reported.

      Intervention: Cranial Laser Reflex Technique (CLRT) is a novel complementary and alternative
      (CAM) medicine intervention for musculoskeletal conditions that incorporates principles of
      laser acupuncture with chiropractic cranial reflexology. Subjects wore protective eyewear.
      The hamstring reflexes are two lines on the posterior portion of the top of the head,
      approximately 2 cm long and 2 cm apart, running parallel to the sagittal suture. The
      posterior end of the reflexes can be located by finding the vertex, or CZ point in the
      standardized 10-20 EEG system, and moving laterally approximately 1 cm.

      The aperture of the laser probe was placed at the posterior end of the reflex (b), turned on
      and moved anteriorly to point (a) at a speed of approximately 2 cm/s. The laser was turned
      off and quickly returned to the starting point, turned on and moved again. This was repeated
      for a total of 30 times. The probe skimmed the surface of the scalp, moving aside as much
      hair as possible.

      Device: The treatment device used in this study is a Class IIIB 810nm 200 milliwatts (mW)
      near-infrared diode laser (THOR Photomedicine Ltd, Great Britain) that is currently marketed
      in the US. The laser probe is FDA-cleared and classified as a non-significant risk device.
      The spot size is 0.0364 cm^2, and the treatment time is 30 seconds. Current best-practice
      recommendations for laser acupuncture recommend a dosage between 1-4 J/cm^2 per point. Since
      the CRP is a line of 2 cm, for the purposes of calculating dosage, it was treated as a series
      of 10 connected points each with a diameter of 2mm. With the scanning rate of 2cm/s, each
      "point" on the line received 1/10 of each pass, totaling 3s (out of 30s total) exposure time
      per point. The dose per point for this intervention is calculated to be approximately 1.65
      J/cm^2.

      There was a one-week washout and the subject will return for the second treatment period.

      Primary Outcome: Hamstring flexibility (90-90 Knee Extension Angle, KEA) A clinically
      significant effect size is an increase of 5 degrees. The investigator recorded the mean value
      of three attempts. Hypothesis: CLRT will increase hamstring flexibility.

      Secondary Outcomes:

        1. Hamstring Strength as assessed by Handheld Dynamometry. HHD . The investigator recorded
           the mean value of three attempts. Hypothesis: CLRT will have a neutral to positive
           effect on hamstring strength.

        2. Pain Pressure Threshold. The mean of three repeated measures was reported. An increase
           in PPT signifies an increase in pain tolerance. Hypothesis: CLRT will increase pain
           tolerance.

        3. Age, gender, activity level, perceived hamstring tightness, perceived hamstring
           flexibility and perceived hamstring strength were assessed at baseline and subsequent
           follow up visit. Results were stratified by these variables to assess interaction with
           treatment.

      Sample Size and Power: Based on previously published results, a mean increase of 5º on the
      KEA (e.g., from 135º to 140º) is considered to be clinically meaningful, assuming a common
      standard deviation of 15º. It is also assumed that correlation between repeated measurements
      from the same individual will be at least 0.75 (likely a conservative assumption). Under
      these assumptions, enrolling 38 participants would provide at least 80% power using a
      two-sided test at the 0.05 level.
    

Intervention name(s): CLRT
Intervention type(s): Device
Intervention description(s): CLRT is a novel method of laser stimulation on specific cranial reflex points that modulate muscle tone.
Other intervention name(s): Cranial Laser Reflex Technique
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Subjects who meet the inclusion criteria and give consent were randomized to one of the following for the first treatment period: 1) active CLRT; or 2) sham laser. At the first intervention visit, the research assistant entered the subject's assigned identification into an online computer program (selected by study biostatistician) to determine assignment to one of the two periods. The study biostatistician used computer-generated random numbers to generate the allocation sequence using random blocks of random sizes. A one-week washout period minimized carryover effects.
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: hamstrings; flexibility; strength; pain pressure threshold; lllt; photobiomodulation; cranial reflex; cranial laser reflex technique; CLRT