Reliability and Validity of Shoulder and Handgrip Strength Testing

Area of Science:

• Biomechanics
• Musculoskeletal assessment
• Rehabilitation technology

Background:

• Accurate measurement of maximal isometric strength is crucial for assessing shoulder and hand function.
• Existing strength testing devices vary in reliability and validity.
• The JTECH computerized, wireless apparatus offers a novel approach to strength assessment.

Purpose of the Study:

• To evaluate the intra- and inter-rater reliability of the JTECH computerized, wireless apparatus for shoulder isometric and handgrip strength measurements.
• To determine the validity of the JTECH device by comparing its measurements to established dynamometers (Micro-FET2 and Jamar).
• To assess the JTECH device's performance in healthy adults without shoulder pathology.

Main Methods:

• Twenty healthy young adults participated in the study.
• Shoulder isometric strength was measured using JTECH and Micro-FET2 dynamometers.
• Handgrip strength was measured using JTECH and Jamar dynamometers.
• Intra-rater reliability and convergent validity were assessed by one rater over two days.
• Inter-rater reliability was assessed by a second rater on a third visit.

Main Results:

• The JTECH device exhibited excellent intra-rater reliability (ICC = 0.78-0.97) and inter-rater reliability (ICC = 0.76-0.95) for strength measures.
• Substantial concurrent validity was found for shoulder flexion (R=0.87), extension (R=0.87), abduction (R=0.88), and adduction (R=0.85) when compared to the Micro-FET2.
• Substantial concurrent validity was also demonstrated for handgrip strength (R=0.92) between the JTECH and Jamar devices.

Conclusions:

• The JTECH computerized, wireless devices are reliable for both intra- and inter-rater measurements of shoulder isometric and handgrip strength.
• The JTECH device demonstrates substantial concurrent validity against established strength-measuring tools.
• These findings support the use of the JTECH wireless apparatus for accurate strength assessments in clinical and research settings.