Insertion loads and forearm muscle activity during flexible hose insertion tasks

Area of Science:

• Occupational biomechanics
• Human factors engineering
• Industrial ergonomics

Background:

• Hose insertion tasks in automotive assembly are physically demanding.
• These tasks can lead to worker fatigue, pain, and injury, impacting production.

Purpose of the Study:

• To quantify the physical demands of hose insertion.
• To evaluate the impact of different insertion methods and mechanical interference on these demands.

Main Methods:

• Six male and six female participants performed simulated hose insertions using three methods: rock, straight, and twist.
• Muscle activity of finger flexors was measured to estimate grip effort.

Main Results:

• The twist method reduced axial force by 26% compared to the straight method (114.8 N vs. 155.7 N).
• Average muscle activity varied from 14% maximum voluntary contraction (MVC) in men (straight method) to 67% MVC in women (twist method).
• Men exerted 6% higher resultant forces with 37% less muscle activity than women.

Conclusions:

• Twisting can reduce axial force during hose insertion, which may be beneficial in specific situations.
• Forearm muscle activity was highest during twisting for both sexes.
• Findings can inform the design of tasks involving the joining of parts like hoses and flanges.