Lumbar compression forces while lifting and carrying with two and four workers.

Area of Science:

• Occupational Health
• Biomechanics
• Ergonomics

Background:

• Manual handling of loads exceeding 25 kg often necessitates team lifting when mechanical aids are unavailable.
• Construction sites present frequent manual lifting and carrying tasks, posing risks of lumbar injury.

Purpose of the Study:

• To quantify mean, maximum, and variability of peak lumbar compression forces during team lifting and carrying tasks.
• To compare lumbar forces between two-worker (50 kg) and four-worker (100 kg) lifting scenarios.
• To investigate the impact of terrain (level ground vs. obstacles/platforms) on lumbar compression forces.

Main Methods:

• Twelve ironworkers participated in a controlled laboratory experiment.
• Participants performed two-worker (50 kg) and four-worker (100 kg) lifting and carrying tasks.
• Peak lumbar compression forces were measured during these tasks.

Main Results:

• Two-worker lifts (50 kg) generated significantly higher mean (537 N) and maximum (586 N) peak lumbar compression forces compared to four-worker lifts (100 kg).
• Lumbar compression forces were lowest when carrying loads on level ground.
• Forces increased significantly when navigating obstacles and ascending platforms.
• A rectangular four-worker line-up for 100 kg lifts resulted in lower compression forces than a two-worker setup for 50 kg lifts.

Conclusions:

• Distributing heavier loads among more workers (e.g., 100 kg with four workers) can reduce individual lumbar compression forces compared to lighter loads with fewer workers (e.g., 50 kg with two).
• Carrying routes should be cleared of obstacles to minimize biomechanical stress during manual load handling.
• Ergonomic guidelines should consider load distribution and terrain when planning team lifting operations.