Digital handgrip assessment in musculoskeletal health: reliability, measurement precision, interchangeability, and clinical implications for rehabilitation and sports medicine

Handgrip strength is a widely used indicator of upper extremity function and a critical field-based tool in sports medicine for injury screening, rehabilitation monitoring, and return-to-sport decision-making. Despite the growing application of digital dynamometers, comparative data on their measurement precision and interchangeability remain limited. This study aimed to assess the test-retest reliability, measurement precision, and inter-device agreement of three digital handgrip dynamometers: GripAble, K-Force Grip, and JTech Commander Echo Grip. Twenty-five healthy adults (15 females, 10 males; mean age 36.2 ± 11.8 years) with no history of upper extremity injury participated in two identical testing sessions held 7 to 18 days apart. Intraclass correlation coefficients (ICC), standard error of measurement (SEM), and minimal detectable change (MDC 95 ) were calculated to evaluate reliability and measurement precision. Inter-device agreement and interchangeability were analyzed using repeated-measures analyses, fixed and proportional bias assessment, and Bland-Altman limits of agreement. All three devices demonstrated excellent test-retest reliability (ICC = 0.88–0.95). K-Force showed the lowest SEM (1.36–1.63 kg) and MDC 95 values, indicating greater measurement precision and sensitivity to change. Inter-device agreement was good (ICC = 0.851–0.873); however, GripAble consistently produced substantially lower force values than JTech and K-Force (≈ 26.37–30.47% bias), with wide limits of agreement and evidence of both fixed and proportional bias. JTech and K-Force showed comparatively narrower limits of agreement and minimal bias, suggesting closer relative measurement alignment between these two devices, although the magnitude of these limits remains clinically non-negligible in the absence of predefined acceptance criteria. Although all three digital dynamometers demonstrated high test-retest reliability, the observed systematic differences in absolute force values suggest limited interchangeability between devices. We recommend that clinicians and researchers use the same device consistently across longitudinal assessments. The device-specific MDC values reported here, ranging from 3.77 to 5.87 kg, provide useful benchmarks for interpreting measurement change in healthy adults. As the current sample consisted of healthy adults, further studies are needed to establish device applicability in athletic and clinical populations.