App-Guided Grip Strength Assessment: Feasibility and Validity of Self-administered Testing with a Smart Dynamometer

IntroductionRemote grip strength assessment offers potential for scalable at-home health monitoring, yet most validated methods require in-person supervision. The Squegg Smart Dynamometer is a Bluetooth-enabled device designed for both supervised and remote app-guided, self-administered testing. Validating self-administered grip strength assessment is essential for clinical and research use. This study evaluated whether self-administered grip strength measurements with the Squegg device are comparable to supervised testing, and examined the influence of participant and procedural factors. MethodsIn this prospective, within-subject comparative study, 96 healthy adults completed grip strength tests with the Squegg device under two modalities: self-administered (app-guided) and supervised (by trained personnel). Covariates included sex, hand dominance, age, education, prior grip testing experience, and test order. Analyses included Shapiro-Wilk tests, ANOVA, and Bland-Altman analysis. ResultsGrip strength residuals met normality assumptions. Guidance modality (self-administered vs. supervised) had no significant effect (F1,270 = 1.41, p = 0.24). The mean difference between modalities was 0.68 lbs relative to an average grip strength of 83.4 lbs (95% CI: -1.77 to 0.41). Sex explained 45% of between-subject variation. Within subjects, variation was associated with hand dominance (6%), test order (4%), and guidance modality (0.4%). No significant effects were observed for age, education, or prior device experience. Bland-Altman analysis showed consistent agreement across the grip strength range. ConclusionsSelf-administered grip strength assessments with the Squegg Smart Dynamometer are comparable to supervised testing, supporting its potential for remote patient monitoring. Future work should confirm findings in broader populations, home settings, and longitudinal contexts.