Interfering effects of multitasking on muscle activity in the upper extremity

Area of Science:

• Ergonomics
• Occupational Health
• Biomechanics

Background:

• Multitasking, involving simultaneous physical and cognitive demands, is prevalent in modern workplaces.
• Such dual-tasking is hypothesized to cause task interference and elevate muscle activity.
• Understanding these effects is crucial for preventing workplace injuries.

Purpose of the Study:

• To investigate the interfering effects of multitasking on upper extremity muscle activity and grip force.
• To quantify muscle responses under various grip and shoulder exertion conditions, with and without a cognitive load.

Main Methods:

• Sixteen healthy participants performed hand and shoulder exertions under varied grip and shoulder conditions.
• Surface electromyography (EMG) recorded activity from eight upper extremity muscles.
• The Stroop test was administered concurrently to assess cognitive load effects.

Main Results:

• Shoulder exertions increased forearm muscle activity, while certain grip exertions reduced deltoid activity.
• Force-controlled shoulder moments elevated deltoid activity compared to posture-controlled moments.
• The Stroop test increased trapezius activity but decreased deltoid activity; both tasks reduced maximal grip force.

Conclusions:

• Complex workplace tasks can increase muscle load and interfere with task performance.
• These findings suggest a potential link between multitasking demands and the development of musculoskeletal disorders.
• Ergonomic interventions should consider the combined physical and cognitive loads in task design.