An analysis of the kinematics of the elbow and wrist joints, and the muscle activity of the arm when using three different computer mice

Abstract

Overall Aim: To investigate the effect of mouse design on static posture and movement of the elbow and wrist joint, and muscle activity of the arm, overall body posture, and mouse usability when using three different computer mice.Search Strategy: Computerized databases and books were searched (1993- 2017).Methods: This research study has been carried out with the aim to understand how the design of a computer mouse influences the biomechanics of the upper limb. A large-scale study was carried out to investigate the posture and range of movement of elbow and wrist, and the activity of muscles in the arm (biceps, triceps, brachioradialis, wrist flexors and wrist extensors) when using a computer mouse. Three different designs of computer mouse (Standard, Penguin and Evoluent) were tested during a variety of standardised computer activities. Preliminary work was carried out to ensure the validity and reliability of the tools used.Sample: Convenience sampling was used; healthy male and female participants aged 18 to 70 years old, who were either right or left handed.Results: The measurement tools from preliminary studies were shown to be valid. The accuracy of Electrogoniometer was found to be good, with random errors of less than 0.2° at rest, and 0.5° during movement; the data were also found to bereliable. The main study showed that wrist extension was significantly greater with the Evoluent mouse at rest (Evoluent 37.6˚ ±12.7˚, Penguin 24.2˚ ± 11.8˚, Standard 28.1˚ ± 9.34˚) and during movement (Evoluent 43.0˚± 11.9˚, Penguin 35.4˚±13.8˚, Standard 35.5˚± 8.67˚) when compared to the Standard and Penguin mice. The wrist posture was significantly different with the Standard mouse, since it was the only mouse design that positioned the wrist into ulnar deviation when at rest (Standard 1.33˚± 8.81˚, Penguin 8.92˚± 9.81˚, Evoluent 5.02˚± 9.88˚) and during movement (Standard 0.507˚ ±14.5˚, Penguin 3.95˚±14.0˚, Evoluent 5.17˚±13.4˚). The Penguin mouse was significantly associated with a more relaxed and neutralwrist posture whilst performing a computer task (p < 0.001). When considering the EMG data, the mean voltage and maximum voltage of wrist extensors was greatest when using the Standard mouse; mean voltage (Standard 0.0334 μV ± 0.0191μV, Penguin 0.0260µV ± 0.0139 μV, Evoluent 0.0286 μV ± 0.0185 μV) andmaximum voltage (Standard 0.0843 μV ± 0.0484 μV, Penguin 0.0703 μV ± 0.0406 μV, Evoluent 0.0697 μV ± 0.0389 μV). Looking at the overall posture, the Penguin mouse was the one that maintained the overall and forearm posture closest to the neutral position (mean grand score = 2, mean in each body part =1). The Evoluent mouse was the most comfortable (56% respondents) and the most preferred mouse (58% respondents) from the usability questionnaire.Conclusion: This study found a significant difference in the posture, movement and muscle activity of the arm and the overall body posture between the three different mice used. The vertical mouse allows a more relaxed posture whilst performing a computer task compared with a Standard mouse, reducing thepotential for musculoskeletal injury.

Date of Award	Dec 2018
Original language	English
Awarding Institution	University of Brighton
Supervisor	Lucy Redhead (Supervisor), Derek Covill (Supervisor) & Martin Bailey (Supervisor)