The question of whether an office chair should include armrests does not have a simple yes or no answer. The function of an armrest depends entirely on how it interacts with your body and your specific workstation setup. The decision is highly dependent on an individual’s body proportions, the tasks performed, and the level of adjustability offered by both the chair and the desk. A poorly utilized or fixed armrest can be detrimental to posture, while a properly adjusted one is a significant ergonomic benefit.
Armrests and Upper Body Load Reduction
The primary ergonomic purpose of an armrest is to support the weight of the upper limbs, significantly reducing strain on the neck and shoulder muscles. The human arm and hand constitute a substantial load, typically weighing between 7.5 and 13 pounds, or roughly 5% to 6.5% of a person’s total body weight. Supporting this weight lessens the static muscle load that the upper trapezius and deltoid muscles must bear throughout the workday.
When arms are unsupported, these muscles must continuously contract to hold the forearms suspended, a state known as static loading. This sustained contraction restricts blood flow and quickly leads to muscle fatigue and chronic pain in the neck and shoulders. By positioning the armrest to support the forearm, this load is transferred from the muscle to the chair structure. The ideal position is where the elbow and forearm are parallel to the floor, allowing the shoulder to remain completely relaxed and in a neutral, lowered position.
When Armrests Undermine Proper Posture
While their function is to reduce strain, armrests can easily cause poor posture if they are not correctly positioned. Armrests set too high force the user’s shoulders to shrug up toward their ears, negating the benefit of load reduction. This elevated position creates a sustained static load on the trapezius muscles, leading directly to tension and pain.
Another common problem occurs when armrests are too wide, too low, or non-adjustable, causing the user to lean laterally or slouch. This uneven posture places a shear load on the spine, increasing the risk of lower back discomfort. Fixed armrests often prevent the user from pulling the chair close enough to the desk surface. This distance forces the user to lean forward, straining the lower back and neck as they reach the keyboard and mouse.
Contact stress is a final issue, where hard or sharp armrest edges press into the soft tissues of the elbow and forearm. This pressure can compress nerves, such as the ulnar nerve, potentially leading to numbness, tingling, or conditions like cubital tunnel syndrome. The surface of the armrest should be soft and wide enough to distribute the forearm’s weight comfortably.
Essential Adjustability Features
Since the primary issues with armrests stem from a lack of fit, their mechanical adjustability is the most important consideration. Ergonomic armrests are often described by the number of directions they can move, with 3D and 4D being the most versatile options. The fundamental adjustment is height, which must be set so the forearm is supported and the elbow is bent at approximately a 90-degree angle, keeping the shoulders relaxed.
Adjustability features include:
- Height: Ensures the forearm is supported and the elbow is bent at 90 degrees.
- Width (Lateral): Allows positioning the armrests directly beneath the shoulders to accommodate different body widths.
- Depth (Fore/Aft): Vital for allowing the chair to move closer to the desk without obstruction, encouraging proper seated posture.
- Pivot/Swivel (4D): Allows the arm pads to rotate inwards or outwards, useful for users who need to angle their forearms for typing or specialized tasks.
Desk Height and Armless Chair Use
In setups where armrests are removed or an armless chair is used, the desk surface must take on the role of forearm support. The desk height becomes the most influential factor in maintaining a neutral posture. The work surface must be adjusted to match the user’s sitting elbow height, ensuring the forearms can rest lightly while the shoulders remain relaxed.
The elbow should be at roughly a 90-degree angle, and the wrist should be straight when the fingers rest on the keyboard. If the desk is too high, the user will elevate their shoulders to reach the keyboard, creating the same trapezius strain that armrests are meant to prevent. If the chair is armless, some users find a forearm-supporting keyboard tray beneficial, as it provides a dedicated surface often easier to position precisely at elbow height than the main desk surface.