LECTURE 6 MMH

Manual handling

• means using your body to exert force to handle, support or restrain any object, and includes not only lifting and carrying but also repetitive tasks.

Hazardous manual handling task

• A manual handling task that has the potential to cause injury.

Sprain

• Injury or tear of ligaments.

Ligaments

• tough connective tissue that connect bone to bone.

Strain

• Injury to muscles that have been stretched or used too much.

10:1 ratio

The human back operates on a __________, with the waist acting as the fulcrum

NIOSH Lifting Equation

• a tool used by occupational health and safety professionals to assess the manual material handling risks associated with lifting and lowering tasks in the workplace.

Recommended Weight Limit (RWL)

• The primary product of the NIOSH lifting equation.

Lifting Index (LI)

• LI = Load weight/RWL.

• can be used to estimate the relative physical stress and injury risk for a task or job.

• Weight ÷ RWL = LI.

• A value of less than 1.0 indicates a nominal risk to healthy employees, while a value of 1.0 or more denotes that the task is high risk.

Load Constant (LC)

• set at 51 lbs. (U.S. Customary) or 23 kg (Metric).

Horizontal location of the object relative to the body (H)

• measured as the distance (inches) between the employee’s ankles to a point projected on the floor directly below the mid-point of the hands grasping the object.

Vertical location of the object relative to the floor (V)

• measured from the floor to the vertical mid-point between the two hands.

Distance the object is moved vertically (D)

• determined by subtracting the vertical location (V) at the start of the lift from the vertical location (V) at the end of the lift.

Asymmetry angle or twisting requirement (A)

• the amount (in degrees) of trunk and shoulder rotation required by the lifting task.

Frequency and duration of lifting activity (F)

• the appropriate lifting frequency of lifting tasks by using the average number of lifts per minute during an average 15 minute sampling period.

Coupling or quality of the workers grip on the object (C)

• the classification of the quality of the coupling between the worker’s hands and the object as good, fair, or poor (1, 2, or 3).

• 1 = Good (Coupling)

  • Optimal design containers with handles of optimal design, or irregular objects where the hand can be easily wrapped around the object.

  2 = Fair (Coupling)

  • Optimal design containers with handles of less than optimal design, or optimal design containers with no handles or cut-outs.

  3 = Poor (Coupling)

  • Less than optimal design container with no handles or cut-outs, or irregular objects that are hard to handle and/or bulky (e.g. bags that sag in the middle).

Load (L)

• the weight of the object lifted.

Duration (Dur)

the lifting duration as classified into one of three categories: Enter 1 for short-duration, 2 for moderate-duration and 8 for long-duration.

1 = Short (Duration)

• lifting ≤ 1 hour with recovery time ≥ 1.2 X work time.

2 = Moderate (Duration)

• lifting between 1 and 2 hours with recovery time ≥ 0.3 X lifting time.

3 = Long (Duration)

• lifting between 2 and 8 hours with standard industrial rest allowances.

Horizontal Multiplier (HM)

• (10/H) for U.S. Customary or (25/H) for Metric.

Vertical Multiplier (VM)

• 1-(.0075 |V-30|) for U.S. Customary or 1-(.003 |V-75|) for Metric.

Asymmetric Multiplier (AM)

• 1-(.0032A).

Back injuries

• Injuries that are exceedingly painful, difficult to heal, and account for one of every five workplace injuries.

Tendons

• bands of tissue that attach muscles to the vertebrae.

Disc

• a cushion between each vertebra known as a pad or pillow.

Spinal Column

• the vertebrae thought of as building blocks.

Spinal Cord

• runs through the long, hollow canal formed by the vertebrae from the base of the brain.

Nerves

• branch out from the spinal cord and leave the spine through the spaces between the vertebrae.

Golfers Lift

• a lifting option appropriate for light objects that can be lifted with one hand; a good lift for those with painful knees.

Micro breaks

• frequent, short breaks measured in seconds not minutes.

Stretch break

• a one minute break taken every now and then to help avoid the body protesting.

Frequency Multiplier (FM)

• a multiplier used in the NIOSH Lifting Equation determined by Table 5 based on lifting frequency, work duration, and vertical location.

Coupling Multiplier (CM)

• a multiplier used in the NIOSH Lifting Equation determined by Table 7 based on coupling type and vertical location.

Common Causes of Back Injuries and Pain

• Repeated lifting of materials.

• Lifting too much weight.

• Sudden movements or shifts of the load.

• Whole body vibrations.

• Lifting and twisting at the same time.

• Bending over for long periods of time.

Risky Moves

• Heavy lifting, specifically repetitive lifting over long durations.

• Twisting at the waist while holding or lifting a heavy load.

• Reaching and lifting over the head, across a table, or out of a truck.

When to Seek Help

• When a load is too bulky to properly lift or grasp.

• When the load blocks your vision.

• When you cannot safely handle the load.

Safe Lifting Guidelines

• Break the load into smaller parts.

• Get help with bulky or heavy items.

• Lift with the legs while keeping the back straight; do not twist.

• Use handling aids (steps, trestles, shoulder pads, handles, wheels).

• Avoid lifting above shoulder level.

Contributing Factors to Injuries

• Poor posture: Failing to maintain the back's natural "S" curve.

• Poor physical condition: Having weak stomach muscles that fail to support the back.

• Extra weight: Stress on the back increases at a 10:1 ratio for every pound of extra body weight.

Injury Prevention Methods

• Use mechanical aids (carts, dollies, cranes, hoists, lift tables).

• Avoid lifting and bending whenever possible.

• Place objects off the floor to avoid reaching down.

• Raise or lower shelves.

• To reduce frequent lifts: Use mechanical assistance, avoid unnecessary lifting, and use mobile storage shelves.

Proper Lifting Checklist

• Before You Lift: Plan your route (clear path, no trip hazards, dry surface) and assess the load (weight, need for mechanical help).

• When You Lift: Position the body close to the object and keep the back straight. When lowering, bend the knees rather than the waist.

• Get Help If Needed: Communicate with your partner and don't try to be a hero.

Golfers Lift Steps (for light objects)

1. Bend at the hip while raising one leg behind you.

2. Use the leg lift to maintain a neutral spine.

3. Place one hand on a fixed object or your thigh.

4. Push off the thigh or object while lowering the leg to complete the lift.

Multipliers/Variables

• H: Horizontal location of the object relative to the body.

• V: Vertical location of the object relative to the floor.

• D: Distance the object is moved vertically.

• A: Asymmetry angle or twisting requirement.

• F: Frequency and duration of lifting activity.

• C: Coupling or quality of the worker's grip on the object.

Lifting Index (LI) Risk Categories

• ≤ 1.00 (Very Low Risk): No action required for a healthy population.

• 1.01 – 1.50 (Low Risk): Pay attention to low frequency/high load or extreme postures; try to lower the LI.

• 1.51 – 2.00 (Moderate Risk): Redesign tasks and workplaces based on priority.

• 2.01 – 3.00 (High Risk): Changes to the task are a high priority.

• > 3.00 (Very High Risk): Changes must be made immediately.

Corrective Actions for Low Multipliers

• If HM < 1.0: Bring the load closer to the worker or remove horizontal barriers.

• If VM < 1.0: Raise or lower the origin/destination of the lift to avoid lifting from the floor or over shoulders.

• If DM < 1.0: Reduce the vertical distance of the lift.

• If AM < 1.0: Move the origin and destination closer to reduce twisting, or further apart to force the worker to step rather than twist.

• If FM < 1.0: Reduce the lifting frequency or duration, or provide longer recovery periods.

• If CM < 1.0: Improve hand-to-object coupling by adding handles or cutouts.

• If RWL at destination < at origin: Redesign the job to eliminate the need for significant control at the destination.