STUDY DESIGN

Case series (longitudinal).

INTRODUCTION

Only few reports concerning the efficacy of commonly used strategies for preventing upper limb occupational disorders associated with prolonged typing exist.

PURPOSE OF THE STUDY

We aimed to investigate whether the duration of typing and the use of 2 strategies (hand rest and wrist support) changes muscle physiological response and therefore the electromyography records.

METHODS

We enrolled 25 volunteers, who were unfamiliar with the task and did not have musculoskeletal disorders. The subjects underwent 3 prolonged typing protocols to investigate the efficacy of the 2 adopted strategies in reducing the trapezius, biceps brachii, and extensor digitorum communis fatigue.

RESULTS

Typing for 1 hour induced muscular fatigue (60%-67% of the subjects). The extensor digitorum communis muscle exhibited the highest percentage of fatigue (72%-84%) after 1 and 4 hours of typing (1 hour, P = .04; 4 hours, P = .02). Fatigue levels in this muscle were significantly reduced (24%) with the use of pause typing (4 hours, P = .045), whereas biceps brachii muscle fatigue was reduced (32%) only with the use of wrist supports (P = .02, after 4 hours). Trapezius muscle fatigue was unaffected by the tested occupational strategies (1 hour, P = .62; 4 hours, P = .85).

DISCUSSION

Despite presenting an overall tendency for fatigue detected during the application of the protocols, the assessed muscles exhibited different behavior patterns, depending on both the preventive strategy applied and the muscle mechanical role during the task.

CONCLUSION

Hand rest and wrist support can successfully reduce muscle fatigue in specific upper limb muscles during prolonged typing, leading to a muscle-selective reduction in the occurrence of fatigue and thus provide direct evidence that they may prevent work-related musculoskeletal disorders.

LEVEL OF EVIDENCE

N/A.