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Injury flare-ups – What they mean and how to treat them

Updated: Feb 15, 2023

It is quite common for injuries to flare up during their rehab, especially tendon injuries like patellar tendonitis or Achilles tendonitis. And it’s natural to then worry about whether you’ve made your injury worse and how far you’ve set back your rehab programme. In this article, I explain why injury flare-ups happen, why it does not necessarily mean that your injury is now worse, and how to get your rehab back on track after a flare-up. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.

Learn what causes injury flare-ups and how best to treat them.

In this article:

We’ve also made a video about this:

Why do injury flare-ups happen?

With an injury flare-up, it’s always useful to try and get to the bottom of why it happened. It will tell you how to avoid it in future. It can also tell you where there might have been a gap in your rehab. Where have you not done enough work?

Exercise or activity that your injured part wasn’t yet strong enough to handle

Whenever you're injured, the injured part (e.g. a muscle or tendon) is weakened and doesn’t have the strength to cope with all the load that you put through it when you do your normal sport or other activities. Its capacity increases gradually as you progress your strength training as part of your rehab, but sometimes we misjudge things.

It can be too much weight or intensity, but also volume or duration or frequency

A flare-up happens whenever you progress your rehab exercises too quickly. It can be the total volume of exercise and/or the intensity of one or more exercises, such as the number of repetitions, the duration, or the weights.

It can also be due to the type of activity you did. For example, you could have been doing slow repetitions of an exercise, but now you’ve changed to doing quick, explosive movements.

Doing your exercises too often can also cause trouble. Your body requires time to rest and recover and adapt after each training session. If you do your rehab exercises before your body has fully recovered from your previous session, it can cause a flare-up.

Example of a flare-up and what could have gone wrong

This article and its accompanying video were inspired by a question that someone posted on our YouTube Channel.

He’s a basketball player with patellar tendinopathy, i.e. a tendinitis or tendinosis in the patellar tendon, which is at the front of the knee. In this case, he had it in both tendons. He wrote that he was able to do really good squats with weights as part of his rehab programme. So, he decided 'to try my luck' by once again playing the sport that he loves, basketball.

He felt OK during play, but several hours later his injury became more painful than before, to the extent that the rehab exercises that he could previously do without any problems were now causing him pain.

(Before we go any further, it must be noted that I didn’t have a consultation with this person, so the analysis that follows is based only on the information at my disposal. It could be that there is other relevant information of which I'm not aware.)

So, where might he have gone wrong?

It may be that the weights he used for his squats were not heavy enough yet. When we jump, it sends forces of up to six times our body weight through our legs. So, you have to do quite a significant amount of squat weight to prepare your tendons for that.

It may be that he has not yet built explosive strength through plyometric training. Doing slow squats with weights is different from loading the tendons quickly under force, as you would do when you jump while playing basketball. The faster you load a tendon, the higher the forces. From what our basketball player wrote, I'm not sure that he did any plyometric training before he went back to playing.

It may be that the volume and intensity of play was simply too much. Maybe his tendons were able to cope with, say, ten minutes worth of playing basketball, but not yet an hour. Also, it is better to ease back into full-on sport with gentle sessions at first. It could be that this person immediately went into top-gear basketball, with the jostling and jumping that it entails.

Lastly, it is important to understand that tendons usually take longer than expected to heal. A tendon can take up to 12 weeks just to get back to base-level strength, and this is before you even get to stuff like plyometrics. If you've had the tendon injury for longer than a year, it may take a year or longer to fully rehab it again.

Have I made my injury worse?

The big questions for our basketball player are how to know how much damage he did to his injured tendons and how far this has set back his rehab.

When you’ve had a flare-up, it’s natural to think, ‘Oh man! Now I've made it worse, and it's going to take longer to recover!’ I’ve been there myself.

A flare-up doesn’t always mean you’ve made your injury worse

It’s counterintuitive, but the amount of pain you experience is not directly correlated to the severity of your injury.

We used to think that the more painful an injury is, the more severe it should be. But then we started getting fancy machines like MRI scanners, which showed us that it is not quite that simple. What we saw was that some people with severe injuries have very little pain, while others with very little tissue damage are in a lot of pain.

This made us realize that pain is just the alarm system of the body, and it's affected by many factors. One of these is, at a subconscious level, how dangerous the body perceives the situation to be. If it perceives it to be very dangerous, it increases the amount of pain.

Therefore, your thoughts, feelings, and fears about the flare-up can feed into this and make your pain feel worse. So, if there's only a bit of aggravation of the injury but your mind goes, ‘Oh man! I've made this worse! This is going to take forever!’, immediately it feels worse because your subconscious then goes, ‘Oh, this is a bad injury! These are bad circumstances!’

If, however, you tell yourself, ‘Ah, stop worrying! I know the activity I did wasn't that much; I've just irritated it again. It will calm down a few days from now,’ you'll be surprised how much less painful it can feel.

How to gauge whether you've aggravated your injury

Ask yourself how much more intense the aggravating activity was than the activities you've been doing in the last four weeks. The volume and intensity of the activities you've been able to do pain-free previously are an indication of how strong the injured body part was before the flare-up.

If the flare-up activity was just a little bit harder than what you’ve been doing before, it's very likely that you haven't made your injury worse; you've just flared up the pain signals that tell you it’s a bit more sensitive now.

However, if you did do a session that was a lot harder than what you’re used to, for example, going from no jumping at all to an hour's worth of being really active and jumping, you may have made it a bit worse. But if it was only one session, there won't be that much more structural damage. It would rather be a case of the injury having become a lot more sensitive.

There’s one exception to this guideline. If you feel a sharp, sudden pain while you were doing the activity and then your pain increases afterwards, it may mean that you've torn something. If that's the case, you definitely need to get it looked at.

What to do about a flare-up

Do not try and train through it

Initially, you should treat the flare-up like an acute injury, even if you’ve come to the conclusion that you haven’t made it much worse. If you don’t force it to work into pain during the first few days, it will calm down much quicker. It should only take a week or two and you'll be back to your normal rehab routine from before you had the flare-up.

Do what you can to reduce the pain

Secondly, use everything you found useful previously to calm the pain.

Applying ice to the painful area usually helps. Don’t use the ice for more than ten minutes at a time, and take ten-minute breaks in between, otherwise you might damage your skin.

See whether you can somehow take the strain off the injured body part. For example, injured Achilles tendons take less strain if you wear shoes with a bit of a heel or if you use heel-raising inserts in your shoes.

Often, a bit of movement that does not cause pain can be useful for pain management, so try and find low-intensity, pain-free activities. Using the Achilles tendon as an example again, it may like low-load calf raises. The basketball player's knees may like him to actually do some isometric squats or go for a little bit of a walk or an easy cycle ride or rather than keeping them still all day long.

Reduce your rehab intensity and increase it from there

Once that flare-up pain has calmed down after two or three days, take a look at your pre-flare-up exercises and then halve them. If you were using 20 kg with your squats, try 10 kg. And if you want to be more conservative, there’s nothing wrong with starting at 5 kg. Just do a gentle set and fewer repetitions than before.

If this feels absolutely fine, wait to check the 24-hour response – you should not have more pain than before you did the previous day’s exercises. Tendons especially are sneaky things that don’t tell you during an activity that you’re asking too much of them; they wait until the next day before they complain.

If there are no issues, you can increase the weight and reps quite significantly for the next training session, because we know that just a few days back, before the flare-up, you had the strength to deal with 20 kg. So, if you were doing 5 kg, try 10 kg for this session and check your response again. If it's not quite OK, then this can be your new limit for now.

It's really important to start easier rather than harder and then increase it from there. If you start too hard, you're just going to annoy the flared-up injury further, and then you’ll have to wait even longer for it to calm down.

In summary:

  • It doesn't necessarily mean that you've made your injury worse if you have a flare-up; flare-ups are really common.

  • Try and figure out why the flare-up happened and what part of your rehab wasn't adequate.

  • And then, treat it aggressively by trying to calm it down, not overdoing it, and then slowly increasing your rehab.

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.

The Sports Injury Physio team

We're all UK Chartered Physiotherapists with Master’s Degrees related to Sports & Exercise Medicine. 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.

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About the Author

Maryke Louw is a chartered physiotherapist with more than 15 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.



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