What is actually happening in your wrist and hand when typing and scrolling start to ache
Nicola Tik
Wrist and hand discomfort from desk work tends to arrive gradually and be dismissed for longer than it should be. A slight aching after a long typing session, a stiffness in the fingers first thing in the morning, or a fatigue in the forearm that builds through the afternoon are all easy to attribute to tiredness or a particularly demanding day. Understanding what is actually happening in the wrist and hand during sustained typing and scrolling makes those signals easier to recognise for what they are and easier to respond to appropriately.
The wrist and hand are among the most complex mechanical structures in the body. The wrist alone contains eight small carpal bones arranged in two rows, supported by an intricate network of ligaments, and traversed by the tendons that connect the forearm muscles to the fingers. The hand contains a further nineteen bones, multiple joints, and the same tendons continuing from the wrist to the fingertips.
What this complexity means in practice is that the wrist and hand depend on a precisely coordinated system of muscles, tendons, and supportive structures to perform the fine movements that typing and scrolling require. When that system is working well and being used variably and within its capacity, it functions remarkably reliably. When it is asked to perform the same small movements repeatedly for extended periods without adequate recovery, the effects tend to accumulate in the tendons and surrounding structures in ways that produce the familiar aching and fatigue of a heavy desk day.
The muscles that control the movements of the fingers and wrist are located primarily in the forearm, not in the hand itself. They connect to the fingers and thumb through long tendons that run through the wrist, passing under a band of connective tissue called the flexor retinaculum on the palm side of the wrist, and through a series of fibrous sheaths along the fingers.
These tendons are designed to transmit force from the forearm muscles to the fingers efficiently, but they function best when the movements they are transmitting are varied and intermittent rather than repetitive and sustained. During typing, the tendons on both the palm side and the back of the wrist are in almost continuous movement, transmitting the small muscular contractions that produce each keystroke. During mouse use, the tendons that position and stabilise the hand and fingers are under continuous low-level tension even during the pauses between movements.
This sustained and repetitive demand, particularly when the wrist is held in a position that is not quite neutral, increases the friction on the tendons as they move through their sheaths and under the flexor retinaculum. Over time this friction and the associated low-level inflammation in the tendon sheaths is responsible for much of the aching and tenderness that builds during a heavy desk session and persists into the evening.
Wrist position has a more significant effect on the load placed on the tendons than most people appreciate. The tendons of the wrist and hand pass through a fixed space, and when the wrist is bent in any direction away from neutral, that space is reduced and the tendons are required to work at a mechanical disadvantage that increases the friction and load on both the tendons and the surrounding structures.
A wrist that is consistently held in slight extension, bent upward towards the fingers, which is the position that many keyboards encourage, increases the pressure on the structures passing through the carpal tunnel on the palm side of the wrist. A wrist that is bent to one side during sustained mouse use places asymmetric tension on the tendons and ligaments on the loaded side. Even a modest deviation from neutral, sustained for hours, produces a meaningfully higher load on the tendons than a neutral wrist position would.
This is why wrist position is one of the most directly actionable factors in wrist and hand discomfort from desk work, and why relatively small adjustments to how the keyboard and mouse are positioned can produce noticeable reductions in the aching that accumulates through a working day.
The small joints of the fingers and thumb are involved in every keystroke and every scrolling movement, and they accumulate their own form of sustained load during a long typing session. The cartilage within these joints, like cartilage elsewhere in the body, depends on movement and varied loading to stay nourished and healthy. During sustained typing, the joints of the fingers are moved repeatedly through a limited range rather than through the full variety of movements that keeps them comfortable over the longer term.
The result tends to be a feeling of stiffness and slight swelling in the finger joints after a long desk session, particularly in the joints closest to the fingertips. This stiffness tends to be most noticeable first thing in the morning after a heavy typing day, reflecting the overnight accumulation of the low-level inflammatory response that sustained repetitive loading produces in the joint tissues.
The carpal tunnel is a narrow passage on the palm side of the wrist through which the median nerve and nine flexor tendons pass from the forearm into the hand. It is bounded by the carpal bones on three sides and the flexor retinaculum on the fourth, which means it has very limited capacity to accommodate any increase in the volume of the structures passing through it.
During sustained desk work, the flexor tendons passing through the carpal tunnel can become mildly inflamed from repetitive use, and the slight swelling that accompanies that inflammation reduces the space available in the tunnel. When the space in the carpal tunnel is reduced, the median nerve, which supplies sensation to the thumb, index finger, middle finger, and part of the ring finger, can become compressed.
This compression is responsible for the tingling, numbness, and aching in those specific fingers that many desk workers experience during or after a heavy typing session. It does not mean carpal tunnel syndrome has developed. It means the structures within the tunnel are under more pressure than they manage comfortably, and that reducing the sustained demand on the flexor tendons tends to resolve the symptoms in most cases.
The physiology above points towards the most effective approaches. Maintaining a roughly neutral wrist position during typing and mouse use reduces the mechanical disadvantage that bent wrist positions place on the tendons. Regular breaks from sustained typing and mouse use give the tendons and tendon sheaths recovery time that continuous use does not allow. Releasing the grip on the mouse during pauses reduces the sustained low-level contraction in the forearm that mouse use produces even when the hand is not actively moving.
Gentle movement of the wrist and hand through a full comfortable range during breaks, rather than keeping them static, maintains the circulation and movement in the tendon sheaths that sustained desk work tends to reduce. Your VIDA programme includes wrist and hand stretches with guided videos that address these patterns and are worth following as a complement to the adjustments covered in the other articles in this series.