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12 January 2021

Workload management – A simple tool for minimising injury risk

by David Barros 0

With gyms shutting down around the globe, many of us were no longer able to experience the clanging of barbells, the valuable social interactions and the amusing grunts of one sole patron going a little too hard on the leg press machine. While useful in the interim, home bodyweight training just didn’t have the same…

With gyms shutting down around the globe, many of us were no longer able to experience the clanging of barbells, the valuable social interactions and the amusing grunts of one sole patron going a little too hard on the leg press machine. While useful in the interim, home bodyweight training just didn’t have the same feel to it, leaving many with the sense that their training was missing something.

Now, with the return of gyms in Melbourne, many are flocking to their old stomping grounds in a bid to ditch the booty bands and shift some serious tin. Myself included. But, while excitement is high, so too will be the number of poor decisions made in the gym.

Many will return to their previous training programs – same weight, same volume, same rest times, etc, etc. For those who were able to train in a similar fashion at home, this won’t be an issue. But for those who had to make drastic changes and were stuck doing AMRAP air squats and push ups, going straight back into old programs may not be the best idea. 

If you hadn’t run in 8 months, but decided you wanted to pick it up again, do you go straight into what you were previously doing? Common sense dictates you would take it slow to begin with, see what your new baseline is and how your recovery looks like. You would then aim to improve from said baseline over time. 

The very same can be applied to resistance training. There is a good chance that the current state of your tissues may not be able to tolerate the stressors you are deciding to impose on them. This doesn’t mean you’re going to simultaneously combust by attempting prior loads/training volume, but it does certainly mean that the risk of injury can go up. 

Do we really want to be sidelined as soon as gyms open up? My guess is you don’t want to wait any longer. 

Today we’re going to have a look at workloads, its relationship to injury risk and how to go about managing it appropriately. 

Even despite decades of scientific research and athlete experience, no single marker of elevated risk of injury or overtraining has been identified (Soligard et al. 2016). While this may be the case, we do see that poor workload management can be one of many major contributing factors that may lead to one experiencing injury. 

In the sporting world, many injuries are seen as a result of ‘training-load’ issues and are also deemed as preventable (Gabbot, 2016). There doesn’t seem to be much research relating to resistance training workloads and injury specifically, but the same principles can be assumed and applied. 

While a very reductionist statement, our risk of injury tends to increase when the external load exceeds the capacity of the athlete. These external loads can be seen as the training variables, which some of you may already be familiar with:

  • Intensity
  • Volume
  • Frequency
  • Exercise Selection
  • Tempo
  • Rest times

Poor implementation of these variables, or not accurately measuring training loads over time may result in excessive fatigue, drops in performance, injury, illness, poor sleep and even poor mental health. 

While it may seem like common sense, we see injury risk go up when we have sharp increases in training loads week-to-week. Gabbet 2016 found a 21-42% increased risk of injury in those who increased weekly workloads by ~15+%. Bowen et al. (2020) found that there was a 5-6x the risk of injury when soccer players had low overall workloads, and then sharply increasing them. Rogalski (2013) also saw increased risk in injuries for AFL players when there were significant jumps in week-to-week workloads. Do note that in the latter study they did use AU (arbitrary units) to describe the workloads, so there may be a limitation here with the degree of accuracy in the measures. 

Nevertheless, it does give us some information as to how sudden spikes in unaccustomed load may be too much for our current tissue capacity to tolerate.

Gabbet 2016

Again, this isn’t research relating to the gym in particular, but you can see how large spikes in load in the above graph may just be too aggressive depending on our current capacity to take on those stressors. Even a 15% increase in load from prior weeks, may result in a greatly increased likelihood of injury. 

Tracking external load – i.e. the physical amount of work we’re completing

So how can we go about managing workload in order to minimise the amount of risk we’re exposing ourselves to? Well, the first is to actually measure/track how much we’re currently doing. 

Before we get stuck into it though, I do want to discuss one method popular method used in recent times, where they measure total workload across multiple weeks, spitting out a number that is called the Acute:Chronic Workload Ratio (ACWR). 

It’s a popular measure of workload in field sports, with a few individuals in the physical therapy/coaching world also discussing how this can be applied to shifting tin as well. 

What is measured is the relationship between the acute workload (current week/microcycle) against the chronic load (average over ~4 weeks/mesocycle). It determines if there are any aggressive spikes in load depending on both internal and external measures. The aim is to maintain in the “high-load, low-risk” zone i.e. the area in the graph that will give us the most bang for our performance buck. When the ACWR is too high or even too low, then the athlete may be at greater risk of injury.

Before we decide that we have to use this exact model for all of our training endeavours, just hold your horses. Unfortunately, this model doesn’t come without its own pitfalls. I won’t go into them in detail, as we can do better things with our time, but if you are interested as to why it isn’t overly useful, see Wang et al. (2020). The TLDR version is that it’s poor from a mathematical perspective and doesn’t provide us with much use as a statistical predictive model. It isn’t accurate overall as a method of assessing injury risk or as a method to track changes in training load.

So why even mention it? It’s popular. When things are popular, they get used. Now you know the issues with it (yay). In saying this, we can still use it as a conceptual model to help us understand that exposing tissue to a stimulus it isn’t adequately prepared for, can lead to higher risks of injury – a reasonable assumption that can allow for some practical strategies down the line. 

Overall it does sound quite reasonable, right? Do too much, too often, without adequate recovery and there’s a higher chance of us succumbing to poor outcomes. While this sounds awfully simplistic and reduces a complex topic to a one liner, it does allow us to make a little more sense of it. 

How can we do a little better when it comes to our own training then? Well, we can take the following steps to improve our chances of not creeping into ‘danger’ territories:

  1. Look to the literature to see what the recommended training averages are. If you’re not too hung up on reading research, head to the JPS instagram page or the JPS blog and there are plenty of posts on what the science says with regards to rough training targets. 
  2. Leave your ego at the door. Decide on what would be a suitable starting point depending on age, training age, training history, injury history and the amount of other stressors you’re currently facing. Think life, work, relationship, physical or any other stressors that may influence how much training you can possibly tolerate. 
  3. Implement the strategy you think will yield the best results with the smallest amount of observable risk
  4. Progress the stimulus at a reasonable rate. What’s a reasonable rate? If you couldn’t tell by now – it depends! Just aim to not be too aggressive with your loading schemes as we see anything above 10-15%+ of an increase per week increase our risk substantially.
  5. Assess progress. What doesn’t get measured, doesn’t get managed – cliche, I know.
  6. Refine.

To simplify the above even further – implement an appropriate strategy -> assess it -> refine as required.

So, how do we go about tracking our training loads, with the above in mind? We can:

  • Track week to week changes in work completed in hard sets* compared to prior weeks
    • Traditionally people would track in tonnage, which is sets x reps x load = xxxxkg. Tracking this way doesn’t actually tell you how hard a given set was, or how close to failure one is.
    • Hard sets are those that were at ~RPE6+ and above and can either be measured per muscle group or per movement e.g. deadlift. 
  • For strength training you may opt to look at volume per movement e.g. number of sets per week of deadlifts and track the changes over time. 
  • Track changes in absolute intensity compared to prior weeks. This will vary depending on if you’re a beginner or an advanced athlete.
  • Monitor perceived/actual fatigue and relative intensity compared to prior weeks

Monitoring week-to-week changes in training variables can help detect spikes in stressors and play a substantial role in minimising injury risk. This is one of the simplest ways we can ensure that we’re not overdoing it with our training.

*Footnote: Hard sets – more relatable for hypertrophy training; indicates that the set is at least ~RPE7

Tracking Internal Loads

What about tracking internal loads? What even are internal loads? To keep it nice and simple, these are the stress responses by the body to these external stressors (like training). These stress responses are both physiological and psychological in nature. Think cortisol secretion when psychological stress rises, the use of resources to repair muscle damage after a workout and the energy spent in creating stronger neural connections from the learning process.

There are both objective and subjective ways of measuring these changes in internal load, but we’ll see just how useful they might, or might not be. 

According to Saw et al. (2016) subjective measures were pretty sensitive in picking up changes in acute and chronic training loads. Which means they can be used to let us know how prepared we are for a given session. While the study doesn’t explicitly use a measure that is commonly used in the gym like RPE, it could still be useful in giving us a rough idea of preparedness, which may indicate fatigue levels, totality of physical/non-physical stressors, etc. 

If the subjective rating is quite high, then that will reflect our level of preparedness and can be a reasonable indicator of the current level of our internal loads. It won’t be particularly accurate – but we’ve all experienced how hard similar loads can feel after accumulating lots of fatigue, being under a lot of psychological stress or even just getting a shit night’s sleep. So, tracking internal load can be somewhat useful for some athletes that need to be a little more particular with how much they’re doing.

What about some other measures of internal load?

Heart rate monitoring seems to be another popular choice with athletic based coaches for measuring an athlete’s current internal load. What they’re doing here is essentially measuring the linear relationship between HR and the rate we consume oxygen at. The only issue is that this relationship only exists during submaximal efforts in steady state exercise (<85%) (Bosque et al 2008) – therefore it isn’t overly useful in the context of strength/hypertrophy training.

On top of this, HR seems to have a decent amount of daily variability during different activities (Bosque et al. 2008), so unless you’re calibrating your tracker for the specific types of training you’re undertaking then it might not be highly accurate in determining your internal load.

To wrap it all up, managing the amount of training stress you expose yourself to may just be one of the simpler ways minimising injury risk. Workload is one of the variables that you probably have the most control over out of a number of different factors that may influence overall stress like mental health, genetics, prior injury, etc. 

Simply understanding that sharp spikes in unaccustomed training loads may increase your injury risk is a valuable tool in reducing the number of dead ends you’re likely to run into with your training. So enjoy the return to the gym, but also remember to appropriately implement strategies that will benefit you over the long term, not just the short term. 

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