Bulletin 233: Ergonomics ― Hazards of the Seated Posture

Bulletin 233: Ergonomics ― Hazards of the Seated Posture

Potential Hazard: 

Seated posture causes the spine to lose its healthy curves and increases the stress placed on your back. Prolonged sitting increases the risk for stiffness, pain or injury.

 

Stress on your lower back: Lower spine has a good lumbar curve while standing, a poor curve when sitting

​Your hips rotate when you move from a standing to a sitting position, which causes your lower back (lumbar region) to lose its inward curve. Your muscles are in a less efficient position to support your spine when you are seated, and unequal pressure is placed on your intervertebral discs. Sitting can significantly increase the pressure on the lower back when compared to standing. 



Stress on your upper back and neck: A female office worker slouching and reaching forward while seated in an office chair

​An improperly adjusted workstation or chair, or sitting for prolonged periods, may lead to slouching. This posture creates a poor lumbar curve as well as a rounded upper back. This causes the head and shoulders to move forward and places more pressure on the upper back and neck. Symptoms such as muscle stiffness, pain, headaches and adaptive muscle imbalances can develop from slouching.
 



How to control the hazard: 

A female office worker sitting upright in an office chair with good lower back supportWhen standing tall, the spine is in its best and most natural position and displays a slight “S” curve. The muscles are well-positioned to support the spine, and the discs between the bones of the spine have uniform pressure placed on them.

Chairs or stools designed to support or promote a proper lower back (lumbar) curve will improve seated posture and reduce the stresses placed on the back. Whenever possible, try to avoid or reduce prolonged sitting.
 



Tips to reduce seated stress: 

  • If you are sitting and your chair has a back support, the support should be adjusted to press into the lower back to maintain your inward lumbar curve, causing you to sit more upright. 

  • If your chair does not have a back support (e.g., if you are using a stool), try to sit upright as much as possible and fight the temptation to slouch.

  • If your seat has a poor lumbar support (e.g., if you are sitting in some types of vehicles), roll up a small towel to make a lumbar support for your lower back. 

  • Properly adjusted armrests on a chair can provide support for the weight of your arms and partial support for the weight of your upper body. 

  • If your chair has wheels, use them to move rather than twisting your torso and reaching. 

  • Take frequent breaks from sitting. Stand up, walk around or perform a few stretches. Use cues such as a ringing phone or a timer to remind you to get out of your chair. Stand up to retrieve binders or files on shelves above your desk, rather than reaching from a seated position. A female office worker using a sit-stand stool

  • Adjust your work schedule to allow you to get up to perform various tasks throughout the day. 

  • Consider walking to or walking with a co-worker to discuss an issue. 

  • Drink a healthy amount of water so you will need to take restroom breaks.

  • Consider a sit-stand stool if your work surface is higher or can be adjusted to be higher. These stools are designed to be taller and the seat can tilt forward, allowing a worker to “perch” on the edge of the stool in a close to standing position, which promotes a more natural back position.


Reference to legal requirements under workplace safety and health legislation: 

  • ​Musculoskeletal Injuries: Manitoba Regulation 217/2006 Part 8 

Additional workplace safety and health information:





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