Tennis elbow (also called lateral epicondylitis or lateral elbow tendinopathy) is an overuse injury and the most common cause of pain on the outside (lateral) elbow. We explain tennis elbow’s causes and how to know whether you have tennis elbow, including three simple tests you can do yourself. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.
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What causes tennis elbow?
Tennis elbow develops in the tendons that attach the muscles in your outer forearm to your outer elbow. These muscles work together to extend your wrist (bend it backwards).
The most commonly affected muscles are the extensor carpi radialis brevis and extensor digitorum.
The natural cycle of tissue breakdown and repair
Tendons are made up mostly of collagen fibres, packed tightly in parallel. It is this parallel structure that makes them so strong.
When we exercise or do activities that use our muscles and tendons, they naturally sustain micro-injuries. These injuries are normal and signals to the brain that it needs to make these areas stronger.
👍 If you allow enough recovery time between bouts of work or exercise, the body repairs these small injuries so that the tissues grow stronger and stronger over time. This is why someone who has been doing a physical job or specific exercise for a long time can do so much more than someone who is just starting out.
Where things go wrong
👎 If you don’t allow enough recovery time between hard bouts of work or exercise, or you ramp up the intensity or volume too quickly, the body doesn’t have enough time to repair all these micro-injuries. When they accumulate, they can cause overuse injuries like tennis elbow.
Typical activities that cause tennis elbow
Any activity or action that overworks the wrist extensor muscles will also cause excessive force on the tendons and their attachments into the outer elbow and can cause tennis elbow.
Typical activities that can cause tennis elbow include:
Typing
Using a computer mouse
DYI, e.g. using a screwdriver, painting, and bricklaying (especially if you’re not used to it)
Gardening
Knitting
Carrying shopping bags for long distances
Gripping, pushing, and pulling heavy weights
Sports like tennis, squash, or gymnastics.
None of these activities have to be a problem – it is only when you do them excessively or you suddenly ramp up how much you do that the injury might develop.
Why tennis elbow isn’t the best name for this injury
“Tennis elbow” is not the best name for this injury, since it’s rarely caused by playing tennis. (When it is caused by playing tennis, it’s mostly the backhand that’s the culprit.)
The medical term is lateral elbow tendinopathy. However, I’ll continue to use the terms tennis elbow and lateral elbow tendinopathy interchangeably, as the former is what most people know and understand.
Why not lateral epicondylitis or tendinitis? Medical terms that end in “itis” imply that inflammation plays a major part in the injury process, and this is simply not the case for overuse tendon injuries such a tennis elbow, as you’ll see in the next section.
The stages of tennis elbow (and why this matters)
You tennis elbow will be in a specific stage of healing or injury depending on how long you’ve had it for. This matters, because the best treatments in the various stages differ quite a bit.
The three stages of tennis elbow (and other overuse tendon injuries) are:
1. Reactive tendinopathy
This is typically the stage your tendon is in when you first injure it, e.g. your tendon pain and stiffness only started a few days ago.
What scans show: When you scan the tendon, it typically shows an accumulation of fluid between the collagen fibres, but without any major structural changes or injuries to the collagen fibres. There may be a few inflammatory cells, but researchers seem to agree that inflammation is not the main cause of the injury.
Impact on recovery: The good news is, if you apply the correct treatment during the reactive stage, the tendon can fully recover without suffering permanent structural changes.
The best ways to deal with tennis elbow during this stage are rest, load management, and treatments that will help it settle. The worst thing you can do during this stage is strength training exercises (more on this in our treatment article).
2. Tendon dysrepair
If you don’t allow the tendon to rest and calm down and you continue to irritate it while it’s in the reactive stage (either through too much physical activity or perhaps by applying the wrong treatments), it might enter the dysrepair stage. Instead of healing, the injury gets a bit worse.
What scans show: During the dysrepair stage, in addition to tendon swelling, you start seeing the collagen fibres moving away from each other and starting to lose their nice, strong parallel structure. It’s worth noting that this tends to affect only a small portion of the tendon – the rest of the tendon is usually still strong and healthy. There are usually also small blood vessels growing into the tendon, which are normally absent, and there are no signs of inflammation.
Impact on recovery: Recovery tends to take a bit longer than in the reactive stage. There is evidence that the tendon structure can mostly revert to normal with the correct mix of load management and careful loading (learn more about this in our treatment article).
3. Degenerative tendinopathy
Your tendon might have entered this stage if the tennis elbow injury has dragged on for several months.
What scans show: The injured area of the tendon (remember, this is usually only a small part) now show signs that the collagen fibres have been damaged and have totally lost their parallel structure. You also see many blood vessels growing into the area. There is no inflammation.
Impact on recovery: You can still restore full pain-free function in your tendon, but the injured area will likely not be normal again. Recovery now depends on getting the rest of the tendon (the uninjured part) to grow stronger and to take over the work of the injured part.
The best treatments for tennis elbow during this period should focus on reducing pain and increasing the tendon’s strength with a training plan that gradually becomes more challenging.
Pain is no indicator of the severity of your tennis elbow
The pain people experience when they have lateral elbow tendinopathy can vary dramatically. Some people may feel only a bit of discomfort or only have pain with activities that really load the tendon, e.g. carrying a heavy bag or gripping something strongly, while others may have lots of pain even when the tendon is not working.
It’s important to understand that pain is not linked to how severe your tennis elbow is. There's evidence that your tendon might show only a minor injury on scans, but your pain can be very intense, and vice versa.
Research has shown that the level of pain can be amplified when you’ve had your injury for longer than three months, are under a lot of stress (work or otherwise), don’t sleep well, and believe that the injury won’t get better. So, in addition to treating the tennis elbow itself, these are all factors worth addressing if your pain persists or is very intense.
How to know whether you have tennis elbow
Tennis elbow symptoms
The best way to diagnose tennis elbow is to combine information from:
What the symptoms feel like: The main symptoms of tennis elbow are pain and stiffness. 💡If you’re getting tingling, funny sensations or numbness, it might mean that you’ve injured a nerve; this can be in addition to or instead of having tennis elbow.
Location of the symptoms: The pain is mainly in the tendons of the wrist extensors or where they attach to the outer elbow. In ongoing cases, you may get some stiffness and pain going into your forearm or upper arm. 💡If you’re getting neck, shoulder, or wrist pain, it might be worth getting it checked by a physiotherapist, as you may have a different injury.
How the symptoms started: Tennis elbow symptoms usually start gradually during an activity, several hours after the activity, or you may even wake up with the pain and stiffness the day after an activity. 💡If your symptoms started when you felt a sudden, sharp pain while doing something, it might be a tear rather than tennis elbow.
How the symptoms react to activities: You usually experience pain with activities that require extending the wrist or gripping, pulling, pushing, or turning things. Some people may only feel mild discomfort, while others may get intense pain when they do something as simple as lifting a cup of tea. 💡If your pain is mainly aggravated when you move your elbow (without involving the hand) you might have an injury inside your elbow joint rather than tennis elbow.
Tests for tennis elbow
You can further hone the diagnosis with three simple tests:
Important: You might not experience pain in all of these tests. If your symptoms fit the above descriptions and you have at least one positive test, you might have tennis elbow.
Cozen’s test
The aim of this test is to strongly contract the wrist extensor muscles to see if it causes pain. The test focuses on the extensor carpi radialis brevis muscle, but all the other wrist extensor muscles also have to work.
Sit with the arm to be tested straightened at the elbow.
Turn your wrist so that your palm faces down and make a fist.
Now, move your fist slightly inward (abduction) and up.
Place your other hand on top of your fist.
Now try to tilt your fist on the injured side upwards (extending your wrist) while pushing down on it with the other hand, creating a strong isometric contraction of the wrist extensor muscles – don’t allow it to move.
If this causes pain over the outer elbow where the tendons run or attach, you might have tennis elbow.
Mill’s test
The aim of this test is to stretch the wrist extensor muscles and their tendons to see whether it causes pain.
Sit with your arm extended at the elbow.
Turn your wrist so the palm is facing down and your hand is horizontal.
Now use your other hand to push your hand downwards as far as it will do.
If this causes pain over the outer elbow where the wrist extensor tendons run or attach, you might have tennis elbow.
I often adapt this test – if it doesn’t cause pain at first – by getting the patient to make a fist with their hand before they push it downwards. This increases the stretch on the extensor digitorum and can sometimes cause pain if that is the tendon that is affected most.
Maudsley’s test
This test targets the extensor digitorum muscle further by getting it to contract against resistance.
Sit with your injured arm straight out in front of you and your palm facing down.
Extend your fingers so that they form a straight line with your arm.
Use your other hand to press down on your middle finger but resist the downward pressure by pushing back up with your finger; in other words, don’t allow your finger to be pressed down.
If this causes pain over your outer elbow, you may have tennis elbow.
What about scans for tennis elbow?
The best scans for diagnosing tennis elbow are ultrasound scans and MRI scans.
However, you usually don’t need a scan to diagnose tennis elbow. The few scenarios in which scans are useful are if your injury isn’t healing as expected or your doctor or physiotherapist suspect that you may actually have a different type of injury, e.g. a tendon tear or ligament injury.
Okay, so if you or your physio have figured out that you do have tennis elbow and in what stage of the injury it is, what do you do next? Here is our article on the best treatments for tennis elbow.
How we can help
Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.
We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine or at least 10 years' experience in the field. But at Sports Injury Physio we don't just value qualifications; all of us also have a wealth of experience working with athletes across a broad variety of sports, ranging from recreationally active people to professional athletes. You can meet the team here.
About the Author
Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.