Mobile input device type, texting style and screen size influence upper extremity and trapezius muscle activity, and cervical posture while texting

This study aimed to determine the effects of input device type, texting style, and screen size on upper extremity and trapezius muscle activity and cervical posture during a short texting task in college students. Users of a physical keypad produced greater thumb, finger flexor, and wrist extensor muscle activity than when texting with a touch screen device of similar dimensions. Texting on either device produced greater wrist extensor muscle activity when texting with 1 hand/thumb compared with both hands/thumbs. As touch screen size increased, more participants held the device on their lap, and chose to use both thumbs less. There was also a trend for greater finger flexor, wrist extensor, and trapezius muscle activity as touch screen size increased, and for greater cervical flexion, although mean differences for cervical flexion were small. Future research can help inform whether the ergonomic stressors observed during texting are associated with musculoskeletal disorder risk. •Input device type and texting style affect ergonomic exposures when texting.•Touch screen texting requires less muscle activity than a physical keypad.•2-Handed texting elicits less wrist extensor muscle activity than 1 thumb/hand.•Muscle activity and cervical flexion increase as touch screen size increases.•Fewer choose to use thumbs only when texting with larger touch screen sizes.