Ankle joint load and leg muscle activity during lifting.

Area of Science:

• Biomechanics
• Ergonomics
• Human Movement Analysis

Background:

• The talocrural joint is crucial for mobility and susceptible to injury during lifting.
• Understanding lifting biomechanics is essential for preventing musculoskeletal disorders.
• Ergonomic assessments inform safe lifting practices in occupational settings.

Purpose of the Study:

• To compare the load on the talocrural joint during different lifting techniques.
• To analyze the biomechanical and ergonomic implications of lifting a box from floor to table-level.
• To identify optimal lifting strategies for reducing ankle joint stress.

Main Methods:

• Healthy subjects performed lifting tasks with varying knee positions (bent vs. straight).
• A computerized static sagittal plane model calculated the loading moment of force about the ankle axis.
• Electromyography (EMG) recorded muscle activity of the tibialis anterior, gastrocnemius, and soleus.

Main Results:

• The mean maximum loading moment reached 68 Nm, with an estimated joint compressive force of 2.9 times body weight.
• Lifting with bent knees and keeping the load close to the pelvis resulted in the lowest loading moments.
• Muscle activation patterns varied depending on the lifting technique employed.

Conclusions:

• Bent-knee lifting, keeping the load close to the body, significantly reduces talocrural joint loading.
• These findings have implications for designing safer lifting protocols in occupational health and ergonomics.
• Minimizing ankle joint stress through proper lifting technique is vital for preventing injuries.