This may cause a few raised eyebrows but when you’ve read this article I hope you’ll agree Repetitive Strain Injury (RSI) isn’t something that should be associated with computer use.
Is computer use repetitive? Well, obviously people think: there’s all those thousands of keystrokes, mouse movements and mouse clicks. But stand back a bit, and watch someone at a computer… what’s your overall impression? Is it of someone doing vigorous repetitive movement putting strain on their ligaments and joints? Or is it actually the opposite – little to no movement at all?
Repetitive movements can definitely be an issue from an ergonomics perspective. In the industrial setting ergonomists have known for ages the potential for injuries due to repeated motion. For example assembly line work involving repeated pushing, twisting or lifting heavy objects. Chicken processing workers apparently have one of the highest incidence of RSI’s of any industry.
But for repetition to be a health risk we usually need a combination of both force and repetition. This is how you get “tennis elbow” – lots of forceful high speed speed serves on the tennis court. While there’s apparently 8 kilograms of force involved in a tennis serve, did you know that modern keyboards are designed to require just 50 grams to press a key?
In the bygone era of copy typists and typing pools a worker might average 100,000+ keystrokes a day. And with mechanical typewriters there was some force and movement involved – pushing the carriage return lever, adjusting the paper roller, etc… There may well have been sufficient force, and sufficient repetition to cause an ‘RSI’… back then.
But how many keystrokes do modern computer users do? According to a large scale analysis of workers at nearly 100 organizations, done using the Wellnomics software, the average computer user does less than 4,000 keystrokes a day (and about 1,500 mouse clicks a day). Some repetition sure – but hardly anything compared to the 100,000 keystrokes a day professional typists might do.
In fact, compared with the old mechanical typewriters we barely move our body at all as we type on a computer keyboard, or move the mouse a few inches, or gently touch a screen.
So there’s no issue with computer use then? No, there is a very serious issue, but… its the complete opposite problem from repetition.
It’s not movement but rather the almost complete lack of movement that causes most health issues from computer use. Working with a computer involves holding your body, in particular your shoulders and arms, in a highly constrained posture (a fixed posture) for very long periods while your fingers perform very precise movement to type, move and click a mouse. The real problem with computer use is that it involves such long periods of tensed, sedentary behavior (sitting for long periods) causing fixed muscle loading of your neck, shoulder and back muscles. This can lead to debilitating pain and discomfort over time. And the sedentary nature of computer use leads to even more significant health issues long term (see previous articles on the problems with sitting).
According to Wikipedia
A strain is an acute or chronic soft tissue injury that occurs to a muscle, tendon, or both.
For there to be an injury this normally means there is damage (even if just temporary) to the muscle or tendons, e.g. a tear in the muscle or tendon. Strains are normally caused by placing too much force on a muscle or tendon. For example, you ‘pull a muscle’ in your back trying to lift something too heavy. Can you get a muscle or tendon strain of this type from the forces involved in normal computer use? No.
From a force perspective the average person’s grip strength is about 45-90 lb (20-40 kg), which is a lot! By comparison the forces required to operate a computer: 50 grams for a keystroke and perhaps 5 grams to operate a touch screen, are tiny compared to what your muscles and tendons are capable of.
This means the force involved in using a computer is simply nowhere near sufficient to cause real strain to the tissue involved (for those with a normally functioning musculoskeletal system). Trying to carry your office desk down the stairs could certainly cause a strain, but operating your keyboard and mouse – very unlikely.
So if its not a strain, why do people get pain and discomfort from computer use?
Muscles don’t like being held in one position for very long periods. Tensing muscles (which can be caused by stress as well as postural factors) reduces blood flow to the muscle, which in turn leads to a build up of waste products, and eventually causes muscular irritation and discomfort. Although there isn’t a muscle strain in the normal sense, this can definitely be painful!
Just as the word strain isn’t appropriate the word injury isn’t really either. Normally an injury is due to physical trauma to the body – such as “pulling” a muscle through over extension. There is a class of injuries – called cumulative trauma injuries – where repeated amount of small damage, that by themselves are not enough to cause an injury, can build up over time. But once again, this normally requires repeated force and repetition to develop an actual tissue injury.
One example is Carpal Tunnel Syndrome (CTS) where repeated strain on the tendons going through the wrist can lead to inflammation of the tendon sheath which compresses the median nerve in the hand. Although we’ve often heard about Carpal Tunnel Syndrome being associated with computer use, more recent studies have found this isn’t actually the case. The incidence of CTS among computer users is no higher than among non-computer users. CTS can be caused by a wrist injury, but also as a side-effect of pregnancy or health conditions like diabetes.
Although computer use is very unlikely to cause an ‘injury’, in the medical sense, people certainly develop serious long term health problems from it. Long periods of muscle tension and irritation, can lead to the development of ‘trigger points’ in the muscles – very tender areas that can cause referred pain (eg headaches). These ‘trigger points’ can develop into a long term muscle dysfunction that keeps the muscles sore long after the person has stopped doing the original activity. This problem is still not entirely well understand, despite how common it is, and it is behind things like chronic back pain.
People can effectively develop a chronic pain condition that makes their muscles more sensitive to normal activity and a physical rehabilitation program can be required. What is curious is that the recent research suggests that the traditional treatments for injury – rest and time off – actually make things worse for these chronic pain issues. The latest advice is to keep active, to actually do the opposite of the old advice, to keep doing as many activities as possible and do active muscle strengthening and and also learn muscle relaxation techniques.
It can still take a long time to recover fully and get the body back to a healthy state without pain and discomfort.
As you’ve probably guessed by now, I’m not saying computer use doesn’t cause problems – just that Repetitive Strain Injury is an inappropriate (and super misleading) term for office workers.
Why does the name matter? Because the right names leads to better the understanding and better prevention. If people go round thinking that avoiding RSI is the goal they’ll focus on the wrong things when it comes to prevention.
Changing “Repetitive” to “Constrained” would communicate that lack of movement of your body is the issue, not repetitive keying and mousing.
The word “Posture” would help focus peoples attention on the position of the neck, shoulders and back when working – rather than just what your fingers are doing.
And finally, if we replace “Injury” with “Syndrome” we are more correct medically. Syndrome is the correct medical term to use for a group of symptoms – muscle pain and discomfort – which isn’t easily diagnosed by examining the affected area for signs of injury (e.g. inflammation), or by taking a blood test (to identify a metabolic disorder). This term would stop people assuming that, as with a normal muscle ‘injury’, the logical treatment is to take time off to the ‘injury’ to heal. As discussed above, the latest research suggests that rest is the wrong solution – it could actually make things worse by causing a loss in muscle fitness and strength leading to increased issues.
Will the world start using my new acronym? Probably not. However that wasn’t really the point of this article. What I hope it’s done is cause you to stop and think about one of the most common wellness complaints in the modern office. If more people start seeing computer use health in a new way, and understand why regular breaks, postural change (e.g. sit-stand) and getting moving are so important, even if for the slowest typist among us, then the article will have done its job.