Validity and reliability of THERABAND elastic resistance bands for measuring shoulder muscle strength

Validity and reliability of THERABAND elastic resistance bands for measuring shoulder muscle strength:

Lars Andersen, PhD


Background: Valid assessment of muscle strength is important for clinicians dealing with weakened patients, for athletes, and in workplace studies focusing on physical exercise and musculoskeletal disorders. The color and length of TheraBand® can be used to grade resistance. Thus, the maximal resistance that an individual can manage may be used as a measure of muscle strength. The aim of this study is to test validity and test-retest reliability of TheraBand® CLX to measure muscle strength of the shoulder.

Methods: A convenience sample of 29 women and 21 men participated. Participants went through two test rounds separated by one week. The study was approved by the local ethical committee and all subjects provided written informed consent. Isometric shoulder muscle strength was assessed during isometric maximal voluntary contraction (MVC), which is gold standard in muscle strength testing. For the TheraBand® CLX test we used the full length of the band for all participants and calculated the resistance based on the color and stretch length. Starting with the lowest CLX resistance of yellow, subjects perform a standing bilateral shoulder lateral raise to 90 degree shoulder abduction and maintained the position for 3 seconds. After 1 minute rest the subjects attempted the next resistance level, and so forth, until the resistance was so high that the position could not be maintained for 3 seconds. The maximal force value (based on stretch length and color multiplied by the cosine to 30 degrees) was multiplied by the lever arm length to obtain torque. The total torque was then calculated as the torque exerted against the CLX added to the torque exerted to resist gravity for the arm (based on standard biomechanical calculations).

Results & Conclusion: Results showed that TheraBand® CLX is highly reliable and valid for measuring muscle strength. Thus, therapists, patients, and coaches can measure muscle strength in a valid and reliable way without spending money on special equipment, simply by using TheraBand® CLX.