Investigating thumb mechanics in texting using novel instrumentation methods

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University of New Brunswick


As text messaging becomes a primary form of communication, risk of pathophysiological consequences rises. Evaluating thumb mechanics during one and two-handed texting, may increase understanding of how texting methods influence parameters such as texting forces and muscle activity. Comparing texting between normally limbed and people with limb loss may highlight the influence of previously existing musculoskeletal symptoms. A unique instrumentation method was created to capture thumb forces on a cell phone screen. Myoelectric signals were recorded while an 8-camera Vicon M-Cam system was utilized to capture the motions of texting. Results indicated that females had larger texting impulse and net joint torques than males, possibly due to hand size, which was also found to have an effect on phone stability; as phone size increased in relation to the person’s hand, the phone positioning became more unstable. Thumb speed and duration of muscle activity were both significantly higher for one-handed texting. Increased pain, coupled with significantly slower texting rates and modified posture for people with limb loss, suggest more presence of previously existing musculoskeletal symptoms. One–handed texting increases the concern for increased musculoskeletal injuries, especially for people with limb loss. Key words: texting, kinematics, RSI, postures, forces, motion capture