Ergonomic Series – Repetitive Motions

Ergonomics

Feb 14

Silhouettes of workers in different working poses are shown.

Date Posted: 02/15/2024

The Occupational Safety and Health Administration (OSHA) estimates that musculoskeletal disorders (MSDs) account for a third of workers’ compensation costs. Repetitive motions cause many MSDs. A repetitive motion injury is any injury caused by repeated lifting, pushing, pulling, vibrations, or holding an awkward body position may be considered a repetitive motion injury. Unlike injuries from falls, electrocution, or other serious construction hazards, repetitive stress injuries, also known as musculoskeletal disorders (MSDs), can start with minor aches and pains. However, returning to the same task without time to recover can damage nerves, tendons, muscles, ligaments, and joints. Injuries could include shoulder and lower back strain, carpal tunnel syndrome, and tendonitis.

Examples of Common Repetitive Motion Injuries (MSDs)

Carpal tunnel syndrome (CTS) - Carpal tunnel syndrome is pressure on the median nerve. The medial nerve is the nerve in the wrist that supplies feel sensation and movement to parts of the hand. The symptoms of carpal tunnel syndrome can lead to numbness, tingling, weakness, or muscle damage in the hand and fingers Using tools that don’t fit your hand correctly can cause this type of injury.
Tendinitis - Occurs when tendons rub against the bone and get swollen. Tendinitis refers to inflammation of the tendon. For example, swinging a sledgehammer repeatedly can cause tendinitis in the elbow.
Bursitis - Occurs when the fluid-filled sac (bursa) that lies between a tendon and skin or between a tendon and bone gets inflamed. Bursae are found in the knee, elbow, shoulder, and wrist. The main symptom of bursitis is pain. In some cases, especially for shoulder bursitis, people may experience some restricted mobility, poor movement, and stiffness.

A worker is shown lifting and suspending a cut-off saw just below their knees.

What are Repetitive Motion Injuries and Symptoms?

Repetitive motion injuries can be temporary or permanent injuries to muscles, nerves, ligaments, and tendons caused by repeatedly performing the same motion. Repetitive Motion injuries are typically one or a combination of these symptoms:

Numbness or a tingling sensation around the joint.
An acute, dull, or throbbing pain.
Difficulty coordinating motion, often due to weakness or loss of strength.
Decreased flexibility or range of motion.

Construction Exposures to Repetitive Motion Hazards

Skilled construction and building trades are some occupations with the highest estimated prevalence of upper limb disorders. This is because some workers do highly repetitive tasks, often in awkward positions. To prevent repetitive motion injuries, a worker should limit the physically straining activities. Some of the repetitive motions injuring the body over time that you can limit include:

Repetitive static positions.
Micro-movements involving the limbs.
Regular lifting or carrying.
Using vibrating equipment or tools.
Holding an uncomfortable position for long periods.
Using one group of muscles more than the rest.
Repeating one motion involving the muscles, joints, or ligaments.
Performing your job in cold temperatures.
Regularly placing pressure on one muscle or joint

Who is Most at Risk?

According to the Bureau of Labor Statistics, the rate of MSDs is shown by occupation and is based on rates per 10,000 full-time workers.

     


  
    Rate of MSDs in Construction by Selected Occupations 
    
  

    Laborers
    42.5
    Electricians
      21
  

    Helpers
    36.1
    Brick Masons
    16.1
  

    Plumbers
    36
     Drywallers
    14.9
  

    Carpenters
    33.7
        Roofers
    13.6
  

    HVAC Techs.
    26.1
     Welders
    11.0
  

    Sheet Metal
    22.6
      Painters
    6.1
  

    Iron Workers
    22.2
      Truck Drivers
    13.0
  

Preventing Repetitive Motion Injuries

Tools – Select the right tools for the work and the user. Minimize the amount of force needed to do the task. Consider lighter tools, tool design, trigger locks, etc.
Work area – Consider the location and position of the work. Where possible, change the work's height, angle, and position to suit the person doing the task.
Work practices – Ensure the work rate is suitable for the task. Break up long periods of frequent repetition and static activity. Spread repetitions across both hands. Consider administrative controls, such as worker rotation.
Work Environment – ensure sufficient lighting so workers can see what they are doing. Avoid working in cold temperatures; provide the proper personal protective equipment (PPE). Take care when selecting gloves. The wrong ones can lead to a poor sense of touch or grip and increase effort when gripping.