Lumbar-pelvic range and coordination during lifting tasks

Area of Science:

• Biomechanics
• Spinal Physiology
• Musculoskeletal Health

Background:

• Spine motion includes a neutral zone with low resistance and an elastic zone with higher resistance.
• Passive muscles further limit the functional neutral range of lumbar motion.
• Exceeding the functional neutral range may increase loads on spinal structures.

Purpose of the Study:

• To examine the range of lumbar curvature rotation during lifting tasks.
• To define lumbar curvature during straight-leg lifting relative to the total range of motion.
• To investigate the influence of torso inclination and lifting load on lumbar posture.

Main Methods:

• Twelve healthy, untrained volunteers participated.
• Lumbar curvature rotation was measured at four torso inclination angles.
• Lumbar curvature during straight-leg lifting was quantified as a percentage of the total range.

Main Results:

• Subjects maintained a neutral lumbar orientation during the flexion phase of lifting.
• During extension, subjects adopted a kyphotic posture, nearing the limit of their functional range of motion.
• This kyphotic posture during extension was more pronounced with heavier lifting tasks.

Conclusions:

• The kyphotic posture during lifting extension may utilize stretch-shortening mechanisms in extensor muscles to reduce energy expenditure.
• This posture, however, could lead to excessive loading on spinal elastic structures and musculature.
• Increased loading may elevate the risk of spinal injury during lifting activities.