Key Finding
This pilot study found good to excellent intra-rater reliability of the EasyForce dynamometer and strong concurrent validity compared to the Lafayette Manual Muscle Tester for measuring isometric muscle strength.
Abstract
A new pull-type dynamometer, the EasyForce®, may offer clinical advantages for measuring strength.
The purpose of the current study was to assess the intra-rater reliability of the EasyForce® and its concurrent validity compared to the Lafayette Manual Muscle Tester in healthy individuals.
Methods
Maximal voluntary isometric contraction was tested using the Lafayette Manual Muscle Tester and the EasyForce® to explore the association between the two instruments. Measurements of the shoulder girdle and knee were performed on healthy, active individuals recruited from the undergraduate and graduate student population on two separate days, with 48–72 hours between sessions and at the same time of day for each participant.
Results
Thirty participants (age 29.97 ± 3.25 years) were enrolled in the study. Intraclass correlation coefficients for the EasyForce® ranged from 0.87–0.98 for the shoulder and 0.80–0.81 for the knee. Assessment of concurrent validity demonstrated strong correlations between the EasyForce® and Lafayette dynamometers for all measurements in both sessions, which were statistically significant (r_b = 0.45 to 0.78, p < .001).
Conclusion
The EasyForce® dynamometer demonstrates good to excellent intra-rater reliability and strong concurrent validity compared to the Lafayette Manual Muscle Tester, supporting its clinical utility for isometric strength testing of the upper and lower extremities.