Accuracy of a portable lower-limb muscle strength measuring device with a training function.

The study used healthy university students, not older adults or patients, so it does not show how the device performs in the people most likely to need lower-limb strength assessment. LCS values did not agree closely with Cybex torque, and the authors caution against comparing the values directly. Muscle mass correlated with LCS force, but intraclass agreement was 0.031, so the two measurements were not interchangeable. The device measured only the right lower limb, and the posture had no backrest, so hip extension and upper-body stabilization may have affected the force. All measurements were taken by one assessor, so examiner variability was not tested. The study did not test whether the device predicts falls, gait speed, sarcopenia, locomotive syndrome, or treatment outcomes.

Government grants from the Ministry of Health, Labour and Welfare in Japan and Japan Society for the Promotion of Science funded the work. The authors declared no benefits or funding from a commercial party related to the subject.

Do not treat LCS values as interchangeable with Cybex torque or as a way to estimate muscle mass. It related to both, but agreement with Cybex was only moderate to substantial and agreement with muscle mass was 0.031, and the study tested only healthy university students.