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Risk Factors and Sources of Injury > Static Grip Force When Using the Mouse          
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Hand Gripping MouseStatic Grip Force When Using the Mouse

What is Static Grip Force?

Static Grip Force is the effort arising from maintaining an ongoing "pinch" or constant grip to hold and move the mouse.  It is largely a consequence of the symmetrical design of most mice, accompanied by the lack of either sculpting or sizing. Some mice such as Orthopedic Mice are not only asymmetric but also anatomically derived and support the bone structures and muscle systems of the hand. However, because most conventional mice have a flawed design that fails to take into consideration the anatomy of the hand, individuals are forced to maintain a steady pinch grip force on both sides of the mouse in order to accurately control the mouse and achieve precise cursor movement. This is typically applied with the thumb and fifth finger as shown in the image at right.

Individuals often exert this effort even when not actively targeting or using the mouse, resulting in far more strain and fatigue than one would otherwise expect to arise from what should be an intermittent concerted effort task. Due to the task driven nature of working at a computer, very few individuals relax the grip on the mouse or take their hand off the mouse when they complete a point and click action, likely because they want to avoid a delay before the next mousing action which could occur at any time.

Why is Static Grip Force a Risk Factor?

When an individual constantly engages the muscles in their hand, this places a Static Load and strain on the joints, muscles and membranes in the hand, wrist and arm. This constant burden can lead to fatigue, discomfort, pain and injury. 

In extreme cases this can lead to a "Death Grip" on the mouse—this is where the static grip behaviour has become so entrenched that the user is now maintaining an excessive grip on the mouse at all times, purely out of habit. This will also often lead to involuntary gripping, pinching or curling of the fingers, even when not using a mouse or pointing device. As Static Grip Force arising from significant mousing is a prime risk factor for anyone who uses a traditional mouse, prevention of this behaviour should be a key consideration.

How Much Static Grip Force (or Pinch Force) is "OK" and not a Risk Factor?

Everyone has different level of strength, dexterity, endurance and fatigue rate in the muscles in their hands. For most, anything other than a minimal amount of pinch or grip force can cause fatigue and pain in the muscles if the action is continually performed over an extended period of time (e.g. gripping the mouse even while not actively using the mouse through the workday). If an individual uses their mouse for only brief periods without intensity, this temporary non-neutral posture and muscle exertion may not cause any long-term hand condition. However, as noted earlier, the failure to relax the grip or remove the hand from the mouse significantly extends the period. Anyone who intensively uses the mouse for even an hour a day or regularly performs mousing activities throughout the day is at risk of injuring themselves over a period of time.

Top View of Hand with Tendons ExposedWhat are the Symptoms of Too Much Static Grip Force?

When the muscles of the hand are called upon to maintain a Static Grip Force for an extended period, the flexor muscles of the hand (those used to close the hand into a fist) will be overused, creating a strength imbalance relative to the extensor muscles which are used to open the hand. Typically the pain will be throughout the hand and wrist and radiate up the forearm.  The localized pain is most commonly in the underside of the hand under the thumb (thenar eminence), the top or back of the hand (transverse carpal ligament), the underside of the forearm either at the wrist (flexor retinaculum) or about 2-4" up from the wrist (flexor carpi radialis). Typically the pain presents itself as a constant burning pain, without any pulses or variance.

What is "Death Grip"?

A subsequent more serious condition which can arise from Static Grip Force is "Death Grip". This refers to when, even during periods of inactivity, a viselike grip is maintained on the mouse to the point where the hand never gets a chance to rest. Exacerbating this is a common bad habit of many, who in order to increase the feeling of control while working, grip the mouse harder than is actually required. This becomes such an ingrained effort that it seems that not even death would abate the gripping action, thus the term "Death Grip". 

What is surprising is that gripping a mouse with more force than is required or optimal will actually reduce the amount of control. This reduction arises because when muscles are held in tension they must relax and recover before they can work again. As such, sustained Static Grip Force actually reduces the ability to control the mouse because the muscles are never relaxed to the point of recovery. However, when a user feels that they have less control they will instinctively tighten their grip further, resulting in a further reduction in control, with a corresponding increase in Static Grip Force. This cycle is what develops into the "Death Grip".

How Can the Choice of Mouse Help to Reduce Static Grip Force?

Orthopedic Mice are sized and sculpted to fit and provide support to the hand. By employing gravity and specifically contoured profiles these designs can provide control without the requirement of grip force. This can reduce or even eliminate the possibility of static grip force issues being encountered. Other types of pointing devices such as Central Pointing Devices, Touchpads, and Trackballs remove the source of grip force, through the alternate paradigm employed for mousing and removing the action (grasping an object) from the action of mousing. Fingertip Mice can replace the traditional pinch force with a lower force precision grip which is for most individuals not a risk factor. How are these two actions different? When one holds and turns a key, that requires pinch force which is static, whereas when one writes with a pen, that is precision grip and the application of the force is dynamic.

What Other Strategies Can be Used to Reduce Static Grip Force?

A simple do-it-yourself solution is to take the hand off the mouse when not actively mousing, which greatly reduces the amount of time spent gripping the mouse. This will ensure that the hand is only grasping a non-ergonomic mouse when actively mousing. Alternatively, paying attention to the tension in the hand, and learning to consciously relax the muscles while maintaining relaxed contact with the mouse will actually result in greater cursor control. With time this new behaviour could become habitual.

Last edited July 17th, 2018

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