Ergonomics advisors often recommend “rules” for proper work posture…. e.g., sitting with knees and hips at 90 degrees, elbows at 90 degrees, wrists neutral. Some will recommend keyboard position for wrists slightly flexed, or slightly extended, or neutral. Some will recommend using a standard mouse versus trackball. So what is the correct definition of proper posture?
But really, does it matter? Maybe not!
Could it be that “proper” posture is actually BAD for you?
Consider this: It is not the posture that is good or bad.
Rather, IT IS THE SPENT NOT CHANGING POSTURE !
The true issue is: time + gravity.
Even ‘good’ posture must endure weight-bearing over a period of time.
Joints and discs are compressed by wieghtbearing…
muscles sustain their contraction…
while tendons sutain tension to mantain that posture.
These loads create tissue pressures that exceed perfusion pressures feeding those tissues… shutting down blood supply, accumulating anaerobic metabolic wastes that lead to irritation, pain, inflammation.
THIS IS POSTURE LOADING… TIME exposure is the hazard, not the position per se.
Yes, poor posture may increase these stresses.
But good posture is stressful if it is SUSTAINED.
The true risk is not the posture; it is the time spent NOT CHANGING posture.
So when I am asked the proper desk chair setup, or keyboard tilt, or mouse versus trackball… my answer is: IT DOES NOT MATTER. The prevention intervention is POSTURE VARIETY. Set up the chair any old way, But CHANGE that setup every half-hour simply by changing seat height 2″ up or down; change seat tilt or any other adjustmentevery half hour to create posture VARIETY.
Same with keyboard tilt. Flip the rear legs of keyboard out for half hour, then flip them in half hour, to create wrist position VARIETY.
Switch between mouse versus trackball every hour to rotate work stresses between tennis elbow versus golfer’s elbow loading. Reduce TIME EXPOSURE or loading to each vulnerable tissue.
Even better… switch between sitting versus standing every 30-60 minutes
This strategy, of course, extends beyond office ergonomics to include manufacturing and other work categories. Driving jobs should allows frequent posture changes, and these can be effective even if the changes are subtle or slight (shifting seat adjustment slightly often; lumbar roll or pad placed and moved often; switching sit versus stand; rotating between different tasks or jobs; changing how certain items are held or grasped or handled).
Simply ask workers how they may alter postures and movements and actions… after you have educated them on the basic strategy of rotating workloads. Certain individuals will likely have suggestions that can be shared
This is really cheap and highly effective “ergonomics” …and is a greatly under-utilized tactic.
This is what gives us PTs advantage over the engineering-based ergonomists who spend their days arguing over what is proper posture… which misses the boat entirely.