The Myth and Reality of Keyboard Position in Ergonomics

).

Why do all office ergonomic authorities recommend placing the keyboard such that the elbows are at 90 degrees, while it is not possible to work on a parallel surface with elbows at a 90-degree angle and still keep the shoulders aligned with the ears? This question has puzzled many, including me, who thought that a slanted keyboard would be more aligned with the wrist and reduce the risk of carpal tunnel syndrome.

Understanding the 90-Degree Elbow Angle

The 90-degree elbow angle is a principle that has been embedded in ergonomic guidelines and practices for several years. This recommendation is based on the belief that this posture reduces stress on the upper limb muscles, reduces the risk of musculoskeletal disorders, and provides a comfortable working position for the user.

The misconception often stems from the idea that the keyboard and mouse should sit in front of the user in a way that mimics a parallel plane with the thighs. However, this idealized setup is often unattainable due to space constraints, leading many to assume that the 90-degree elbow angle is a compromise. In fact, the 90-degree angle recommendation is more about maintaining a neutral posture, rather than trying to fit everything into a parallel plane.

Why Can't the Shoulder Be Aligned with the Ears?

Placing the keyboard on a flat surface with the elbows at 90 degrees can be difficult due to the anatomical constraints of the shoulder and the position of the monitor. The natural position of the shoulders, when sitting upright, is typically not perfectly aligned with the ears. The shoulder blades are designed to allow a range of arm positions, but maintaining this neutral and relaxed posture eliminates the risk of strain or discomfort.

When you place the keyboard on a flat surface with your elbows at 90 degrees, you are forced to elevate your shoulders to reach the keyboard, which can lead to a forward-leaning shoulder posture. This is not an ideal position for sustained use and can lead to muscle fatigue, strain, and discomfort. Moreover, this posture can negatively affect the neck and spine, potentially exacerbating issues like neck pain and back strain.

The Myth of Slanted Keyboard Benefits

The idea that a slanted keyboard would be more aligned with the wrist and reduce the risk of carpal tunnel syndrome is appealing, but it is often oversimplified. A slanted keyboard may indeed provide some ergonomic benefits, such as reducing the angle between the wrists and the surface, which can reduce strain on the wrists and tendons in the forearm. However, the benefits are not necessarily enhanced simply by slanting the keyboard.

Moreover, the benefits of a slanted keyboard can be negated if the keyboard is not properly aligned. A keyboard that is not positioned correctly can lead to other issues. For instance, if the keyboard is too low or too high, the user may need to lift or lower their arms, which can cause muscle fatigue and strain. Similarly, a keyboard that is positioned too far to the side can cause the user to twist and strain their shoulders.

Conclusion

The recommendation to place the keyboard such that the elbows are at 90 degrees is not about forcing a parallel plane with the thighs. Instead, it is about maintaining a neutral, relaxed posture that is less likely to cause strain, discomfort, or injury. While a slanted keyboard can provide some benefits, its effectiveness is highly dependent on its proper alignment and positioning.

The key to ergonomic keyboard placement is to ensure that the keyboard is positioned such that the user can maintain a neutral and relaxed posture. This includes keeping the shoulders relaxed, the arms and wrists at a comfortable and natural position, and the keyboard and mouse in a position that allows for a comfortable reach without straining.

In conclusion, while the 90-degree elbow angle is a recommended ergonomic posture, it is important to consider the overall comfort and posture of the user. A slanted keyboard can provide some benefits, but it must be properly aligned and positioned to be effective. The ultimate goal is to create a working environment that promotes comfort, reduces strain, and supports long-term health.