The Key to Preventing Overuse Injury in Runners is Load Management

{NOTE: random thought and rant warning on}

I was contemplating on this morning’s run (the 1000 steps up in Ferntree Gully for those familiar with it) about the length of time I have gone without an injury. Its been a while. Contrary to the predictions in the comments of some posts by fan boys that I would be getting some because of the things I do, it never happened. I thought about what I am doing differently to before; and more importantly, I thought about the research I had blogged about to try and put my personal experiences into context. I am the first to acknowledge that what works for me is not necessarily going to work for someone else and the blanket one size fits all promoted by the fan boys, does not fit all and never would I evangelize what works for me will work for others. One word kept coming back to me in that reflection: load management.

In a previous post I talked about the cause of an overuse injury comes down to the cumulative load on the tissues being greater than what the tissues can tolerate. So prevention is all about managing the load on the tissue and increasing the ability of the tissue to take the load…. ie load management. If you look differently at all the risk factors that get identified in all the multiple studies on all the different overuse injuries, they all come back to: load management.

The training routine:
The key to load management is the training routine. That is where a good coach or at least good commonsense comes in. Its all about managing the load on the tissue to such a point that the load encourages adaptation and the load is not so high that the tissues get injured. Way back there was the good old 10% rule to not increase the weekly total by more than 10% or the length of the longest run by more than 10%. The evidence does not actually support that and most coaches have become more sophisticated than that. Its more now about increasing the load, then backing off a bit to allow some consolidation, then upping the ante again. It also the old fashioned hard day/easy day. This is where the value of a good coach comes in as every one will respond differently to training loads. Compared to the time way back when I used to run competitively, I am surprised how many runners have days off these days; but it is probably one of the more effective ways to prevent injury – reduces the cumulative load in the tissues.

Its getting the load management right as part of the training that is key, but then there are also a number of issues that mean specific tissues are loaded higher than ‘normal’ and those specific reasons may need to be addressed:

Foot biomechanics:
This puts into a different perspective the issue of ‘overpronation’ (especially the nonsense that I tried to address here). Some studies show that it is not a risk factor (and get promoted via over-hyped press releases and the gullible give a lot of weight to these studies) and some studies show it is a risk factor (and don’t get promoted via press release and the gullible have not even read them). The most recent systematic review and meta-analysis of all the studies and all the data concluded that it is a small, but statistically significant risk factor for injury. The reason that it is probably only a small risk factor is that ‘overpronation’ is a motion and not a force. Injuries are due to the force and load in tissues, not motion. I hypothesized that supination resistance (which is a force and load in the tissues) is the missing link between ‘overpronation’ and injury. That is just one potential reason for higher loads in specific tissues and there are many more. Another example is the force to get the windlass mechanism going (I wrote about that here). If that force is high, then all the tissues are going to have to work harder to get the heel off the ground. If these sorts of forces (eg supination resistance; windlass mechanism; etc) are high then the higher loads that they are creating in the tissues need to be managed. To do that, you deal with the cause of the load. There is no one blanket, one size fits all to do that. If the loads are due to ‘overpronation’ then you treat the cause of that ‘overpronation’ and despite what the fan boys say, muscle weakness is not a common cause. For more, see: The Windlass Mechanism of the Foot; The nonsensical understanding of ‘overpronation’; Short or Long Term Use of Foot Orthotics?).

Stretching
There is increasing evidence that stretching might not have much to do with preventing injury. That kind of makes sense as being more flexible has nothing to do with reducing the load in the tissues. Obviously those with a pathological tightness might lead to a tissue overload. For example, tight calf muscles leads to a midfoot collapse (ie ‘overpronation’) and this might lead to injury, IF the loads associated with the mid-foot collapse are high enough and are allowed to accumulate. So, in these sorts of situations stretching can lead to a reduction in the load in the tissues, but if there is a normal range of motion of the ankle joint, then stretching is probably not going to do anything or much to prevent injury. (This does not mean that runners should not stretch or do things like yoga for general well-being).

Strengthening
I recently looked at a meta-analysis of strengthening and in the discussion there is some speculation on how that affects the injury rates. It all comes down to load management. It is possible that the strengthening (especially possibly the eccentric contractions on tendons) increases there ability to take the load. The other mechanism is that strengthening helps with running form issues, but will only helps there if the running form adopted decreases the load in the tissues (and not increase it).

Running Shoes
Different running shoes have different design features that will affect different runners differently and load the tissues differently. The challenge is getting that right and we are so far away from being able to do that on a wide scale that it is a little worrisome. There is no one right running shoe with the one right design feature(s) and most of what we have is rhetoric and propaganda and individual runners evangelizing what works for them must work for everyone else. Most runners eventually stumble into a shoe that seems to work for them, but that is not good enough and we need to find a better way of doing it. I am working on this as a project at the moment – more on that in subsequent posts. But if we take, just one example, the drop. We see a lot of evangelizing and rhetoric and propaganda that for all runners the shoes should be zero drop (ie no differential between heel and forefoot height). I have yet to see any evidence for that and when I look for a theoretically sound, coherent and biologically plausible reason as to why there should be a zero drop, I can not find anything (I am not for one minute saying it shouldn’t be). In the context of all that evangelizing and rhetoric and propaganda, all I see is the overuse of the naturalistic logical fallacy to argue that everyone should be zero drop. Perhaps those who would argue that could explain why a 12-14mm drop would NOT hypothetically be good thing for someone with a medial STJ axis and high supination resistance (see the comments on this thread). Hopefully down the track we will have better data and guidelines on what drop is most appropriate for individuals and it won’t be the one size fits all advocated by the fan boys. Now, drop is just one characteristic of running shoes, we need the same guidelines on all the other different design features and how different individuals respond to those design features in order that the load on specific tissues are decreased and not overly increased on other tissues.

Running Form
As I have repeatedly said, different running techniques load different tissues differently and there is no one right way to run. The fan boys think there is. Each way of running will load a different set of tissues more than another set (its a zero sum game). There is no point changing the running form or technique to one that increases that load on the group of tissues that there is a problem with. Likewise, there is probably great reason to change the running form if that change decreases the load in the tissues that there is a problem with. When you look at the preponderance of evidence on running economy in different running techniques, there are either no differences or heel striking is more economical. When you look at the preponderance of evidence on injury rates in barefoot/minimalist vs shod and rearfoot strike vs forefoot/midfoot strike, the injury rates are the same. The fan boys will cherry pick one or two studies to make a point, but when I read ALL the injury and economy studies,  I see no global advantages of one over the other. For individuals though, one will probably be better than others and that will all depend on which tissues that need to be offloaded more than another. I will hopefully get another post up in a few days on joint axis variations, as I think that this will eventually go a long way to explaining these individual responses to changes in running form (and running shoes, and strengthening, and foot orthotics). So its not about one running technique being better at managing the load, its about which one for the individual.

Proviso:
In the context of all of the above there is the proviso that this is a zero sum game. You can not decrease the load in one tissue with changes in running technique, running shoes, strengthening or foot orthotics or any other approach without increasing it in another tissue. (Well actually you can decrease the load if you loose weight, but lets put that to one side for now). If you use foot orthotics to reduce the load in the posterior tibial muscle, you increase the load in the peroneal tendons. If you increase the cadence to help with patellofemoral pain, you increase the load in the Achilles tendon. If you start forefoot striking to help anterior compartment syndrome, you increase the forefoot dorsiflexion moments and problems associated with that. Etc. Etc. Get the point? It then comes down to: can that tissue take it? Is the load in that tissue already low and the increase only raises it to the “normal” range? Or is the load in the tissue that you moving the forces to already close to pathological and the change moves it over the threshold? Do we take the risk and only use it as a short term measure while we do other things to adapt the tissues or are the forces so high in the problematic tissue that there is little chance of adaptation; or if there is, is the effort worth it? Is there life on mars? So many questions that need to be weighed up here as part of the “clinical” decision making process.

It all boils down to: load management.

{NOTE: random thought and rant warning off}

Enough random thoughts for today. Its Saturday and the girls deserve some of my time.

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4 Responses to The Key to Preventing Overuse Injury in Runners is Load Management

  1. Colm McCarthy November 9, 2013 at 7:39 am #

    Great post Craig. Enjoyed the read. Agree that no one-size-fits all, and a good clinician or coach will look at all the areas you mentioned to endeavour to keep runners running. Enjoy the weekend.

    • Matthew Spiegel November 9, 2013 at 9:57 pm #

      Great read. I do have one question though about stretching. My last encounter with any research in the area (not something I really follow) indicated that stretching did not appear to reduce injury rates. Worse, there was some indication that stretching prior to a race not only resulted in slower times but also increased injury rates. Am I remembering this incorrectly or has more recent evidence contradicted that conclusion?

      I hope you and your family have a wonderful weekend.

      • Craig Payne November 12, 2013 at 1:35 am #

        That is my recollection of all the most recent research.

  2. Ivan Rivera April 10, 2015 at 6:34 pm #

    Craig:

    I’m not sure that running is a zero-sum game, as you said. For example, increasing cadence reduces flight time, meaning that contact velocity is also reduced (since you spend less time accelerating towards the ground). Isn’t that less newtons of force on a step-by-step basis?

    On the other hand, the findings of the dissertation linked to below (and other studies cited in it), suggest that internal load caused from muscle action is more correlated with injury than external load. Internal load was found to be bigger in forefoot-strikers than heel-strikers. It kind of adds another variable–I typically see people fighting mostly over impact transient, which does seem to be smaller in forefoot-strikers.

    http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1677&context=etd

    Maybe–and I am just speculating here–increased impact transient is worse for joint-related injuries (like patellofemoral pain), while increased internal loading is worse for muscle/tendon (like is the case for achilles tendonitis and gastroc-soleus tightness)?

    On that note, what do you think of strengthening/increasing mobility of the damaged tissues in addition/instead of reducing load, on a case by case basis? For example, I was consistently trashing my extensor digitorum longus until I strengthened it and integrated it with the rest of my stride mechanics (I wasn’t supinating correctly due to a tight soleus and weak peroneus).

    Stride seems fine now, AND my speed at the same HR took a faster turn.

    In any case, I’d love to see your analysis of that dissertation.

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