Lifting Analysis

DR.AYESHA BHATTI

BSPT, PPDPT.PPTABSPT, PPDPT.PPTA

OBJECTIVES

Use biomechanical principles when analyzing a lift.

Critically analyze three lifting techniques. Critically analyze three lifting techniques.

Develop an abatement protocol to prevent commonly encountered lift-related injuries.

Definitions:

Low back.

Pain in the lumbar spine and its anterior/posterior components. Iliosacral area may also be included.

Pain.

Subjective,.. often nocuous response to stressors that overwhelm the tissues being exposed.

Prevention. The use of accepted scientific principles in the obviation of risk factors that may predispose an individual to injury.

Lifting

Essential part of everyday life

Correlation with variety of Musculoskeletal injuries especially back Musculoskeletal injuries especially back pain

High Financial cost

Workplace education and design by medical professionals as well as Ergonomists

The Biomechanics Of Lifting

Stress

Compression, shear, and torsion/tensiontorsion/tension

Training the workers to lift in a biomechanically safe manner

Stoop lift

Maneuver that typically requires maximal flexion of the trunk and as near to terminal extension of the near to terminal extension of the knees (without locking) as possible.

Squat Lift

It requires knee flexion >90 degrees and trunk flexion <30 degreesdegrees

Semi-Squat Lift

The semi-squat lift shares characteristics of the stoop and squat

Semi-squat uses a posture calling for Semi-squat uses a posture calling for knee flexion >45 degrees and trunk flexion at approximately same angulation

Greater anterior tilt of the pelvis with thisapproach in comparison with the otherlifts, promoting a lumbar Lordosis

Freestyle Lift

lift resembles in most respects the semi-squat but can differ from person to personto person

It is this variability that makes it difficult to examine during controlled studies

Trunk Kinetic Lift

The trunk kinetic lift is characterized by a sudden extensor moment of the knees before the liftbefore the lift

Load Kinetic Lift

The load kinetic lift requires a closer approximation of the load to the body just before the initial acceleration just before the initial acceleration moment.

This lift, too, is seen as a variation of the three more standard lifts

Critique Of Lifting Techniques

A) Biomechanical Analysis: Comparison of various lifting techniques

At L5/S1 lumbar moment and compressiveforces were equal for the stoop and squatin one study

One study indicated less forces in stoop liftas compared to squat lift

It is generally accepted that the closerthe load is placed to the body, the moresignificantly diminished the resultantsignificantly diminished the resultantcompressive forces to the lumbar spine

Employed more effectively in the semi-squat lift (load between the feet andknees) than with the stoop or squat lift

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

Foot placement, is contingent on the size of the load:

If the container is too wide (large) to 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.

Soft tissue compliance supraspinous and interspinous ligaments more effectively countered the lumbar moment (be it as a result 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 muscle modify shear forces….(proper lordotic posture)

Erector Spinae Muscle

(illiocostalis, longissmus and spinalis)and spinalis)

B) Physiologic Response

Oxygen uptake/consumption, %VO2 max, the gold standard of energy expenditure, was found to be greater with the squat lift 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

C) Perceived Exertion

Rating of perceived exertion (RPE), a subjective measure, rates the individual’s own awareness of 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

Increased angulation of the lumbar spine in stoop lift—through flexion—causes both increased compression and shear forces to increased compression and shear forces to the intervertebral disc, it would make to prescribe the semi-squat or squat technique when an individual is required to lift heavy objects on an occasional basis.

In addition, the squat requires more energy expenditure, thus making the semi-squat the preferred lift for occasional heavy effort (four work cycles per minute).

The semi-squat lift allows for closer The semi-squat lift allows for closer placement of the load to the body, thus creating a smaller moment arm and less compressive force. The preferred lift between the semi-squat lift and the pure squat would be the semi-squat.

Another more subjective measure of individual lifting tolerances uses maximum allowable weight (MAW) as a determining factor.

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.

Response of an individual experiencing low back pain and what adjustments are made to negotiate a lift from floor to 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

To continue: preferred techniques