Supporting the upper body with the hand on the thigh reduces back loading during lifting

Area of Science:

• Biomechanics
• Occupational Health
• Musculoskeletal Disorders

Background:

• Low back pain patients often use a hand-on-thigh support strategy when lifting.
• The effectiveness of this strategy in reducing spinal load has not been previously assessed due to measurement challenges.

Purpose of the Study:

• To quantify the effect of hand-on-thigh support on spinal loading during lifting.
• To compare the impact of this strategy across different lifting techniques.

Main Methods:

• Ten healthy males performed various lifting techniques (free, squat, stoop, Weight Lifters Technique) with and without hand support.
• Forces were measured using a six Degrees of Freedom force transducer on the thigh.
• Spinal loads (L5S1 joint moments, compression forces) were calculated using inverse dynamics and an EMG-assisted trunk model.

Main Results:

• Hand support reduced peak total moments by 17-25% for pencil lifting and 13-26% for crate lifting.
• Compression forces decreased by up to 28% with hand support, except in stoop lifts.
• Hand support increased asymmetric motions and moments, particularly during crate lifting.

Conclusions:

• Leaning with a hand on the thigh is an effective strategy for reducing low back loading during lifting.
• This technique shows potential for mitigating spinal stress in occupational and daily activities.