Reliability, Responsiveness, and Criterion Validity of the Kiio Sensor, a New Tool for Assessment of Muscle Function

Abstract

Musculoskeletal injuries are a leading cause of disability in both the general population and military, and the ability to effectively quantify musculoskeletal function remains problematic. The aim of the current study is to investigate the reliability, responsiveness, and criterion validity of the kiio Sensor for measurement of muscle strength, a key aspect of comprehensive functional assessment. Forty-four (24 male, 20 female) physically active civilian adults (mean [SD] = 21.2 [1.5] years of age) with no history of upper extremity injuries in the last year and no current complaints of pain, weakness, or functional limitation completed two sessions of maximum shoulder external rotation contractions. The forces were measured with a kiio Sensor and isokinetic dynamometer. The devices showed strong correlation (r = 0.89) and no significant mean difference (0.3 ± 3.3 lb, p = 0.47). Intrasession reliability for both devices was analyzed using intraclass correlation coefficients (ICC = 0.96 [95% confidence interval = 0.93-0.98)], with the kiio Sensor having slightly less standard error and trial-to-trial variability. The kiio Sensor 7-day reliability was ICC = 0.97 (95% confidence interval = 0.94-0.98). The kiio Sensor demonstrates excellent reliability, responsiveness, and validity compared with a gold standard isokinetic dynamometer. Several key attributes contributing to this technology's military relevance are discussed.

Measurement Properties of Isokinetic Dynamometry for Assessment of Shoulder Muscle Strength: A Systematic Review

“…All 21 studies evaluated reliability in a test-retest design. 6,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] We present the summarized results, the overall rating of the results, and the quality of evidence in the summary of findings table (table 3). Most studies reported the ICC, but 5 studies used Pearson correlation coefficient, variability, or coefficient of variation.…”

“…Measurement error was investigated in 13 studies. 6,[21][22][23][24][25]27,29,31,34,[36][37][38] The summarized results, the overall rating of the results, and the quality of evidence are presented in the Summary of Findings table (table 4). Seven studies reported SEM only as an absolute value but provided sufficient data to calculate the %SEM.…”

Assessing the Validity and Reliability of A Low-Cost Microcontroller-Based Load Cell Amplifier for Measuring Lower Limb and Upper Limb Muscular Force

“…Fortunately, there are tools that provide more objective and accurate results. Commonly referred to as the “golden standard”, are the isokinetic dynamometers (ID) such as the Cybex II isokinetic dynamometer [ 11 , 12 ]. However, their clinical use is limited, due to their high cost, non-portability, and their complicated setup and operation [ 12 ].…”

“…Commonly referred to as the “golden standard”, are the isokinetic dynamometers (ID) such as the Cybex II isokinetic dynamometer [ 11 , 12 ]. However, their clinical use is limited, due to their high cost, non-portability, and their complicated setup and operation [ 12 ]. Similarly, the load cell, coupled with a signal conditioner, is a laboratory setup commonly used to accurately measure isometric muscle strength.…”

“…Fortunately, current technological advances open the door to many portable, fast and easy to perform methods for quantifying muscle strength. A commonly used compromise between MMT and ID devices is a portable device known as the handheld dynamometer [ 12 ], a clinical instrument that quantifies isometric strength. However, it is known that measurements obtained with the handheld dynamometer are influenced by the practitioner's strength [ 13 ].…”