Background:Shape writing is relatively new technology for on-screen keyboards that enable users of mobile touch-screen devices to input text by drawing continuous lines. With growth of touch-screen device usage, there has risen the need to investigate potential risks that may occur during prolonged usage. Objective: The biomechanical strain on upper limb muscles were assessed while study-participants used Swype technology on a tablet touch screen device and compared with traditional/regular input methods. Methods: Study-participants performed typing tasks (email and text) using Swype and regular input methods under counterbalanced conditions with sEMG data collected to measure muscle activity during tasks. Results: Email & Text had the same exertion for all muscles except the Extensor. The interaction between task and muscle was significant, F (1.6, 27.5) = 15.39, p < .001, ηp2 = 0.48. The interaction between muscle, task and method was also significant, F (2.19, 37.19) = 3.6, p = 0.03, ηp2= 0.18. Exertion was lower for Swype but with marginal significance. Overall, Email resulted in less dynamic activity than Text with Main effects F(1, 17) = 10.07, p = 0.006, ηp2 = 0.37. Extensor has more dynamic activity than other muscles with main effect F(1.8, 29.9) = 16.51, p < 0.001, ηp2 = 0.49. Conclusion: Results indicate that Swype presents no more biomechanical strain than regular input for most muscles. Swype may result in less exertion for the Extensor muscles in the lower arm. This may be particularly true for tasks requiring interactions like those found in the email task.
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