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

ABSTRACT Introduction Remote 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. Methods In 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. Results Grip strength residuals met normality assumptions. Guidance modality (self-administered vs. supervised) had no significant effect (F 1,270 = 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. Conclusions Self-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.