Reliability and validity of an electronic dynamometer for measuring grip strength

Aims: This article describes a study aiming to establish the concurrent validity and test-retest reliability of the Biometrics E-LINK EP9 electronic dynamometer. Methods: Grip strength testing was performed on 49 healthy participants. Three trials were completed for the right and left hands on the Biometrics and Jamar dynamometers, using a repeated measures design. Data was compared and used to establish concurrent validity of the Biometrics dynamometer. Fifteen participants repeated the testing a week later, for test-retest reliability of the Biometrics dynamometer. Findings: The Biometrics E-LINK EP9 evaluation system was found to have excellent validity (ICC 0.983-0.986). However, a small but statistically significant difference between the right hand grip strength scores of the Biometrics (31.65 +/- 8.89) and Jamar (30.44 +/- 9.49) dynamometer was revealed (p <= 0.05). Test-retest reliability of the Biometrics system proved excellent, with ICC scores of 0.986 for the left hand and 0.996 for the right hand. Conclusions: The results indicate that the Biometrics E-LINK EP9 evaluation system is valid, reliable and comparable to the Jamar hydraulic dynamometer, when used for measuring grip strength with the second handle position. However, due to the statistically significant differences found for the right hand grip strength scores, therapists should exercise caution when interchanging instruments.