3. • Use biomechanical principles when analyzing a lift.
• Critically analyze three lifting techniques.
• Develop an abatement protocol to prevent commonly
encountered lift-related injuries.
4. Lifting
• Essential part of everyday life
• Correlation with variety of Musculoskeletal injuries especially
back pain
• High Financial cost
• Workplace education and design by medical professionals as well
as Ergonomists
5. The Biomechanics Of Lifting
• Compression, shear, and torsion
• Training the workers to lift in a biomechanically safe manner
6. Stoop lift
• Maneuver that typically requires
• Maximal flexion of the trunk
• As near to terminal extension of the knees (without locking) as possible.
10. Semi-Squat Lift
• The semi-squat lift shares characteristics of the stoop and squat
• Semi-squat uses a posture calling for knee flexion > 45 degrees
and trunk flexion at approximately same angulation
11.
12. Cont.
• Greater anterior tilt of the pelvis with this approach in
comparison with the other lifts,
– Promoting a lumbar Lordosis
13. Freestyle Lift
• Lift resembles in most respects the semi-squat but can differ from
person to person
• It is this variability that makes it difficult to examine during
controlled studies
14. Trunk Kinetic Lift
• The trunk kinetic lift is characterized by a sudden extensor
moment of the knees before the lift
15. Load Kinetic Lift
• The load kinetic lift requires a closer approximation of the load to
the body just before the initial acceleration moment.
• This lift, too, is seen as a variation of the three more standard lifts
16. Critique Of Lifting Techniques
A) Biomechanical Analysis:
• Comparison of various lifting techniques
• At L5/S1 lumbar moment and compressive forces were equal for
the stoop and squat in one study
• One study indicated less forces in stoop lift as compared to squat
lift
17. Critique Of Lifting Techniques
• It is generally accepted that the closer the load is placed to the
body, the more significantly diminished the resultant compressive
forces to the lumbar spine
• Employed more effectively in the semi-squat lift (load between
the feet and knees) than with the stoop or squat lift
18. Critique Of Lifting Techniques
• Shear forces are significantly higher (in some cases 180%) during
the squat lift.
• Low back loading was significantly higher during squat lifting than
with the stoop lift when lifting from the floor
19. Critique Of Lifting Techniques
• If the container is too wide (large) to allow for proper foot
placement (greater than shoulder width—approximately 30 cm
[12 in]), then the ideal lift would be the stoop, since it would
result in less compressive forces.
20. Critique Of Lifting Techniques
• Soft tissue compliance Supraspinous and Interspinous
ligaments more effectively countered the lumbar moment (be it as
a result of shear or compressive forces) during the stoop rather
that the squat and semi-squat lifts
• Activation of erector spinae muscle
21. Critique Of Lifting Techniques
B) Physiologic Response
• Oxygen uptake/consumption, %VO2 max, the gold standard of energy
expenditure, was found to be greater with the squat lift than with the stoop
• Increased muscular effort in Squat and semi squat as compared to stoop lift
• Tendency to Switch from the squat and semi-squat to the stoop lift because
of the increased energy demands of the squat lifts
22. Critique Of Lifting Techniques
C) Perceived Exertion:
• Rating of perceived exertion (RPE), a subjective measure, rates
the individual’s own awareness of the effort required to perform a
particular activity
• 90% of the subjects rated the squat lift as more fatiguing than the
stoop lift
23. Critique Of Lifting Techniques
• Maximum allowable weight (MAW) measure of individual lifting tolerances
• Researchers reported that 17 females selected a MAW 20.5% greater for the
stoop than for the squat lift.
• When comparing the squat and semi-squat exclusively, subjects chose a
greater 25.4% MAW, preferring the semi squat over the squat.
24. Critique Of Lifting Techniques
• Response of an individual experiencing low back pain and what
adjustments are made to negotiate a lift from floor to waist
• Asymptomatic group showed no preference between the squat
or stoop lift but that more than two thirds of those with back pain
(symptomatic group) had adopted the squat or semi-squat as
their preferred lift
26. • It is important for therapists to critically evaluate lifting
techniques
• Recommend those that match the client’s capacities to the task
that is to be performed
• The semi-squat lift allows for closer placement of the load to the
body, thus creating a smaller moment arm and less compressive
force
27. • If lighter loads are to be handled but at a higher frequency than
four per minute, the stoop lift would be a viable option
• The rate at which any lift is performed is extremely important
• Compressive forces increase by 15% when lifting is performed
quickly, as compared with using a steady, smooth approach when
lifting identical loads
28. • jerk lift
• Appropriate marking or “weight coding
• The National Institute for Occupational Safety and Health (NIOSH)
• Effective hand grip and couple in the practice of safe lifting
• Secure grasp when handling an unstable load
• Instability resulting from the lack of an effective grasp can adversely affect
stability (of the load) the involuntary increased recruitment of the core-trunk
muscle groups (rectus and external and internal oblique) increased lumbar
compressive forces
29. Other Considerations
• Compression at the L5/S1 joint was a poor indicator of the potential for injury
• Load rate
• Lateral shear and torsion (side bending and twisting in coupled and uncoupled
movements
• Velocity
• Acceleration
• Worker experience and attitudes toward the job
30. Cont.
• Lumbosacral moments were considerably larger when lifting from
an inclined slope compared with a declined surface
• Subsequent increase in angulation resulted in an increased
moment arm of the trunk, hydrostatic pressure of the disc, and
torque at the L5/S1 segment.
31. Stability of the Load
• Unstable loads carried significantly higher risks for poor mechanics and low
back injury
• A major goal for the therapist is to reduce the risk of lift related injuries at
both the work site and at home
• The primary concern is to recognize the presence of risk factors and
understand how each factor influences the pathologic process
32. Standards
• Keep the load close
• Ensure the placement of a secure hand couple
• Maintain a degree of lumbar Lordosis at the initiation and during the lift
• Use the lifting technique that is most applicable to the situation
33. Cont.
• Semi –squat ideal lift for heavy loads performed on an occasional basis
• Squat lift: To be used as an alternative to the semi squat when space is
limited and load size does not allow for foot placement to the side of the
object to be lifted
• This also is the lift preferred by individuals experiencing acute and chronic
low back pain
34. Cont.
• Stoop lift: Lifting scenarios requiring light loads (20 pounds and
below) on a frequent basis (defined as 33% to 66% of the
workday by the Department of Labor’s Dictionary of
Occupational Titles) are more efficiently managed using this
technique
35. Cont.
• When lifting on an uneven-sloped surface, face down the slope to
negotiate the lift
• When lifting, do so as much as is possible in the sagittal plane
36. Pushing & Pulling
• Seemingly less menacing and more biomechanically efficient,
namely pushing and pulling
• Resultant vectors changed from the vertical to the horizontal axis,
added the component of frictional resistance to the equation
when pushing or pulling
37. • Net joint torques at the shoulder were minimal during pushing
maneuvers but greatly increased during pulling efforts
• Horizontal force, as opposed to torque, at the shoulder was
significant during both activities
• Handle height and hand placement
38. • Optimal pushing height for the best performance appeared to be
at or about waist level
• Comparing pulling with pushing, the vector of force is
substantially higher at the L5/S1 joint when pulling as compared
with pushing.
• This comes as a direct result of the increased moment and flexed
posture (at the waist) inherent with pulling as opposed to pushing
39. • If possible, pushing should be the preferred method of material
transport over pulling
• The final consideration when evaluating pushing and pulling tasks
is foot placement and the avoidance of slippage resulting from a
poor coefficient of friction (COF).
• Injuries secondary to these conditions can be serious and usually
result from the loss of balance and uncontrolled acceleration of
the whole body
40. • Adding water, oil, or other contaminants to the surface, however,
greatly decreased the COF and resulted in decreased balance and
sway patterns
• Once the risk factors have been identified, it is the therapist’s
mission to control the frequency, severity, and, if possible, the
very presence of the risk.
