Texting with touchscreen and keypad phones - A comparison of thumb kinematics, upper limb muscle activity, exertion, discomfort, and performance. (July 2018)

• Record Type: Journal Article
• Authors: Gustafsson, Ewa; Coenen, Pieter; Campbell, Amity; Straker, Leon
• Is Part Of: Applied ergonomics. Volume 70(2018)
• Page Start: 232
• Page End: 239
• Publication Date: 2018-07
• Subjects: Smartphones -- Hand size -- EMG; Human engineering -- Periodicals; 620.82
• DOI: 10.1016/j.apergo.2018.03.003
• Languages: English
• ISSNs: 0003-6870

Abstract

Abstract: This study aimed to compare thumb kinematics and upper limb muscle activity, and the influence of hand size, when texting on a keypad smartphone and a touchscreen smartphone. Furthermore, the study compared exertion, discomfort, and performance when texting on the two phones. The thumb kinematics were tracked using a 3D motion analysis system and muscle activity was registered in six upper limb muscles using surface electromyography in 19 participants. When texting on the touchscreen phone compared to the keypad phone thumb flexion (p = 0.008) and flexion/extension range of motion were smaller (p = 0.02), the thumb was on average less internally rotated (p = 0.02), and activity (50th and 90th percentile) of the thumb and forearm muscles was lower (p ≤ 0.05). The differences in thumb flexion were found only in the group with shorter hands and the differences in muscle activity was found only in the group with longer hands. These findings suggest there are differences in risks for developing musculoskeletal disorders during smartphone use with different key activation mechanisms and different hand sizes. Highlights: Thumb kinematics and muscle activity differed when texting on a touchscreen phone compared to a keypad phone. Users with shorter hands had smaller thumb flexion and internal rotation when using a touchscreen phone. Users with longer hands had lower muscle activity in the hand and forearm when using a touchscreen phone. Lower proportion of correct typed characters when using a touchscreen phone.