The Injury Bucket. The key principle to injury management. Part 1: the premise

‘The injury bucket’ is an analogy that nearly all of my patients are probably sick of hearing me ramble on about. It’s a simple concept, however, once fully understood and appreciated has helped a lot of people to get a better grip on the management of their injuries. In light of that, writing this could serve one of two purposes. Annoy my patients further, or, save me time in appointments by sending them here and subsequently shutting me up! Either way here goes….

The anatomy of a bucket
The initial premise is very simple. Picture a bucket, sitting on a fancy rug. As in the film Gremlins, this particular rug shouldn’t get wet (as an aside, if you don’t understand that reference, forget reading this, go and watch Gremlins instead!). The bucket has a small tap at its base which diverts liquid off to a sink.
The size of the bucket and the amount of liquid it holds dictates its capacity. Thus, a larger bucket = larger capacity. The tap empties the bucket at a set rate, its ‘emptying capacity’. Imagine the bucket being filled with water. If the rate at which it is being filled exceeds its emptying capacity the bucket will begin to fill up. If the flow of water into the bucket is not stopped or slowed it will eventually overflow. Wet rug.

For the more mathematically inclined. For the rug to stay dry:

 Capacity of bucket + emptying capacity ≥ Volume of liquid + rate of filling

If you prefer a visual representation, here’s a bucket:

Translating the bucket to the body

The bucket represents one of the many tissues which make up our body (muscle, tendon, ligament etc.). The liquid filling the bucket represents the demand placed upon the tissue. Liquid on the rug represents damage or dysfunction to the tissue. As with the bucket, each tissue has a set capacity. The greater the overspill and subsequent volume of liquid on the rug, the worse this damage is!
Just as with the water in the bucket, when the demand placed upon the tissues outweighs its capacity the tissue will become damaged and this will lead to pain or dysfunction. It’s important to note here that although they are often linked, the correlation between tissue damage and the pain experienced by an individual is not proportional.

Translating this into our equation:

Capacity of tissue ≥ demand placed on tissues

The left side of this equation must always be equal to or greater than the right (red) side. If this is not observed the result is tissue damage/dysfunction.

When the bucket overfills

Injuries are often classified into two distinct categories: acute and chronic.

Acute: Let’s begin with an acute injury, a major hamstring strain, or tear. The hamstring is a group of muscles which act as the primary benders of the knee and takes the brunt of huge forces when sprinting. For a well-conditioned athlete (with a nice big hamstring bucket) the demand of sprinting often isn’t an issue. Conversely, if Steve, a bloke in his mid 40’s, who doesn’t normally run for anything but a bus, gets over-competitive and decides he can sprint at his child’s sports day (without warming up) his ‘hamstring bucket’ becomes full very quickly. Steve’s hamstring bucket dramatically overflows and the rug is soaked. Steve has torn his hamstring. *UCKET!!

Chronic: Rather than one dramatic overspill, think of chronic injuries as a cycle of overspill, inadequate emptying of the bucket and subsequent overspill. Tendon issues are a common example of this. Take Carla, a basketball player suffering from patellar tendinopathy (often referred to as ‘Jumper’s knee’). After a period of an increased volume of running and jumping activity in pre-season, Carla notices a low-grade pain, just below the kneecap. Initially, she thinks nothing of it and continues the training camp. The pain continues to bubble away and it reaches the point that her coach spots that it is affecting her movement, her knee is regularly feeling stiff and the tendon itself becomes swollen. She responds by taking a few days off training and things ease up. However, when she returns to training, the familiar low-grade knee symptoms return. Using the bucket analogy: Time away from the activity allows the rug to dry and some of the liquid to empty from the bucket. When the sporting demand returns the bucket begins to fill up again and it doesn’t take very long until it spills over. If Carla and the people around her don’t understand or consider the principles of the injury bucket, what may initially appear to be a very minor issue could have a severe impact on her basketball season.

In either case, the principle remains a simple one. Injuries occur if the demand outweighs the tissue's capacity and ability to recover. If we update our equation.
To stay injury free:

 Tissue capacity + rate of recovery ≥ demand placed on tissue + rate of demand

Early injury management: dry the carpet, empty the bucket

As health care professionals, the majority of patients come to us for help at the point that there has been an imbalance in the capacity equation. Their bucket has been overfilled and the rug is wet. Our job is to identify which tissue (or tissues) has been affected and understand the root as to why. We use interventions which aim to speed up the process of drying out this rug and start emptying the bucket so that it can be used again.

Unfortunately, allowing sufficient time for recovery by avoiding the activities which will add excess liquid to an already full bucket is the first port of call here. Returning to Steve and his hamstring tear. Adequate rest has allowed the worst of the pain and bruising to settle and his bucket has enough available capacity to wean him off crutches and put weight through his leg during walking. Steve’s bucket will still be pretty full as only some of the liquid has been drained by the tap. If he tries to walk too quickly or too far at this stage, you guessed it…. another damp rug!

The jury is out on the effects of various passive treatments. Arguments take up a lot of space on social media, and quite frankly I get bored of the often massively polarised opinions. It’s Camp A (X is magic and will cure any injury) vs Camp B (X is utterly useless). In reality, in most cases, the answer probably lies somewhere in the middle ground and common sense should prevail.  Take acupuncture for example, where scientific evidence for its effectiveness is relatively limited, some people swear by it and anecdotally I’ve seen it reduce pain and improve function in some patients. Therefore, if a patient is really struggling to return from injury, utilising acupuncture may assist in drying the rug and increase the emptying rate of the bucket. In that case, great, count me in. What is absolutely clear, however, is that using this type of passive treatment as a stand-alone approach should never be the answer……

Focus on increasing the capacity

The good news is that the size of our buckets is not set in stone. Yes, some individuals are gifted with genetics predisposing them to large ‘bucket capacities’ but ultimately everyone’s bucket can increase or decrease in relative size.

Ironically, to increase capacity, the bucket must be stressed with a load similar to that of the one that overfills it. The regular pressure of liquid pushing against the sides of the bucket stimulates it to grow. In fact, the more stress that is placed upon it the more effective the growth. In an ideal world, we want the stress on the bucket to be as high as possible without exceeding its capacity. Conversely, if the bucket isn’t filled regularly, it shrinks.
We also need to be specific to increase bucket capacity. If the bucket was initially overfilled with water, don’t focus on loading it with Guinness! Asking an untrained individual to squat 200kg without warming up won’t end well, but encouraging them to squat a challenging amount of load would be a great way to begin stimulating favourable strength adaptations in that movement pattern. Hence, one of my go-to phrases: “The most important exercise in rehab is…… the exercise which injured you in the first place”

Why ‘Drying the rug’ is not enough

Where physio adds value by assessing the tissue damage and guiding you on returning to normal activities, effective treatment must address increasing the capacity of the bucket (and surrounding buckets, i.e., other tissues that will impact the injured structure). This allows you to complete activities in the future with a reduced risk of overspill. It frustrates me when healthcare practitioners do not educate on the capacity vs demand principles and focus ONLY on a new gadget or trend with an aim to reduce the pain of the damaged tissue. If this is your therapist's approach, they are acting like an expensive hairdryer!

 If we return to our basketball athlete, Carla. Imagine that she frequently sees her ‘fantastic sports physio’ who ‘always reduces her knee pain’. She visits him every time her pain flares up and she ‘wouldn’t possibly get through the season without him’. The physio is doing some passive treatment and promoting rest when her pain has become particularly severe and has given her some simple exercises. There has been no effort to build a comprehensive loading programme to ensure her tendon gains the sufficient capacity to deal with the huge demand basketball places upon it, and they have provided no education on the condition to ultimately put the power of injury management in Carla’s hands. Without sufficient loading and education, Carla’s injury cycle is going to continue. She will likely view physio as a constant necessity to complete her sport. Despite being a hypothetical example I regularly hear this narrative from patients about previous treatment. If I’m having a particularly cynical day (likely because I’m hungover or haven’t drunk enough coffee) I rant at length about how some professionals purposely hide the principles of injury management from patients to create a continuous stream of income and maintain a sense of reliance on their ‘magical healing powers’ divinely passed to them / learnt during their time at Hogwarts. I prefer to hope that instead these therapists just aren’t very good or knowledgeable. Either way, a reactive treatment style is not helpful for patients in the long-term and cannot continue (thankfully, it does seem to be happening less frequently!)

Final thoughts

The injury bucket premise may be simple. Yet, a solid understanding of capacity vs demand and the principles within the equation will help you with injury management. I would however be doing myself (and other therapists) a massive disservice by overlooking the complexity of the factors which feed into the equation.

As discussed above, treatment must address tissue capacity, but we also have the ability to influence every part of this equation to optimise injury recovery and prevention. As a brief example of where the equation could be modified at multiple levels for a running injury:

• You can enhance emptying capacity (recovery rate) by focussing on sleep and nutrition.

• By analysing the overall training load we can pre-emptively stop filling the bucket when it is close to full by backing off training.

• The demand can be modified. A 5k run on a treadmill in new trainers with absorbent soles is very different to one on concrete with bare feet.

·      modify the mechanics of movement to reduce the flow of water into a small bucket and instead fill another

Adding depth to these concepts is beyond the scope of this piece. For now, take a moment to digest the importance of considering the injury bucket and balancing your capacity vs demand equation. I will be using the concept several times in future content to illustrate simple ways where things go wrong.

If you are struggling with injury and would like to talk with someone who will not only identify the root of your problem but educate you on long-term management and guide you on the optimal way to build tissue capacity…… please do not hesitate to drop me a message! I offer both in-person and virtual consultations and have a diverse background working with elite athletes and the general public.