Fatigue development in the finger flexor muscle differs between keyboard and mouse use

Area of Science:

• Physiology
• Biomechanics
• Ergonomics

Background:

• Intensive computer use is prevalent, raising concerns about potential musculoskeletal disorders.
• Understanding the physiological impact of specific computer peripherals on muscles is crucial for injury prevention.

Purpose of the Study:

• To investigate physiological changes in the Flexor Digitorum Superficialis (FDS) muscle due to intensive computer use.
• To differentiate the effects of keyboard versus mouse usage on muscle fatigue and potentiation.

Main Methods:

• A repeated measures design involved 18 subjects undergoing 8-hour conditions: control, 6 hours of keyboard use, 6 hours of mouse use, and 6 hours of combined use, followed by 2 hours of recovery.
• Neuromuscular electrical stimulation (2 Hz) was used to assess temporal muscle fatigue (twitch force, contraction time, ½ relaxation time) of the FDS muscle before, during, and after computer use.

Main Results:

• Six hours of keyboard, mouse, or combined use induced temporal fatigue-related changes in the FDS muscle.
• Keyboard use led to muscle potentiation (approx. 30% increase in twitch force, 3% decrease in duration).
• Mouse use resulted in potentiation and fatigue (increased twitch forces, prolonged twitch durations by 11%).

Conclusions:

• Mouse use induced more substantial physiological changes (potentiation and fatigue) compared to keyboard use (potentiation only).
• These findings offer physiological evidence linking mouse use to a greater association with computer-related injuries.