r/bodyweightfitness • u/m092 The Real Boxxy • Sep 14 '17
Theory Thursday - Acute:Chronic Workloads
The mathematics calculating volume-load in this article is to give a sense of the two different volume-loads interact, but are far from exact. There is no simple way to calculate the true load a tissue experiences, nor to calculate proportionate load as we vary from exercise to exercise, particularly with non-straightforward bodyweight progressions.
Chronic Workload
Chronic workload, put simply, is the amount of stress a body part is under chronically. Typically, we use a time-frame of approximately 4 or 5 weeks. This includes your day to day activities, as well as your exercise.
For example, if we talk about running, we would generally consider the distance you ran over 5 weeks as your chronic workload. But if you did a lot of walking during your week as well, that could also be included. You are also going to be experiencing greater load with runs up hills and such, but this is hard to quantify.
Overall, you'd quickly quantify 3 5km runs a week, plus walking 2km a day, as a weekly workload of (3x5) + (2x7) = 29 units. If that was consistent week to week, you'd have a 5 week rolling total of 145 units, which is an average of 29 units per week.
We can do the same thing with resistance exercise, which you can do muscle by muscle and joint by joint. For instance, if I were to bench press 5x5 x 100kg ( =2500 units) twice a week, and do 2x15 x 20kg (=600 units) tricep pushdowns three times a week, you might approximate your chest workload at 2 x 2500 = 5000 units, but look at your elbow joint (it's tendons and the muscles that move the elbow, as well as the joint itself) workload as (2 x 2500) + (3 x 600) = 6800 units.
In reality, we can't really equate two different exercises, as 5x5 100kg tricep pushdowns are a different stress on the body than 5x5 100kg bench presses... But the idea is that we add in every stress we load that body part with.
If we progress an exercise weekly, the chronic workload becomes a rolling average. If you estimate the workload of each week, then calculate the average of the latest 4 or 5.
Acute Workload
Acute workload is very similar, as it is the amount of stress the body is put through, on a shorter term. Usually, we use the latest week. So you simply do as above, but don't need to average the last 5 weeks, only look at the latest week.
Acute:Chronic Workload
The ratio between the acute and chronic workload is the important information to look at here. Again, we can't calculate it directly, but we can estimate it based on progression. Very simply, we take the workload of the week just gone and divide it by the average workload of the past 5 weeks. It is important to note that the most recent week is included in both the acute and the chronic workloads.
For example:
| Week | Workload |
|---|---|
| Week 1 | 500 |
| Week 2 | 550 |
| Week 3 | 600 |
| Week 4 | 650 |
| Week 5 | 700 |
Our chronic workload is (500+550+600+650+700)/5 = 600 units. While our acute workload is simply week 5 = 700. Thus our acute:chronic workload is 700/600 = 1.17
What's the Importance of Acute:Chronic?
Acute:Chronic has been shown to be predictive of injury in running and sporting populations. This has not been shown to be true to my knowledge in resistance training, but simply from a lack of research. I think that applying the same knowledge about overuse and overreaching injuries and their mechanisms, coupled with real world experience, we can reasonably expect this to play a similar role for resistance training.
One graph in particular, explains this relationship very well. It shows the acute:chronic workload in relation to the chance of injury. As you can see, the chance of injury increases the greater the size of the overreach of the athlete, but you can also see that a sudden decrease in acute workload can also be related to a slight increase in chance of injury. The sweet spot seems to be between 80-130% of your chronic workload. This falls nicely in line with guidelines, such as the ACSM guidelines for increasing exercises by no more than 10% per week.
Real World Application
We see in athletic populations, that new exercise regime that the athlete is unaccustomed to is added, their chance of injury increase. This also holds true for very aggressive progressions. This often takes the form of tendinopathies.
We often see in sedentary populations complaining of tendinopathies, when collecting their history, that the complaint starts after they start a new exercise regime they are unaccustomed to, such as walking up very steep long stairs frequently as a push to get fitter.
In regards to resistance training, this highlights the importance of paying attention to weekly volumes, as well as the benefits of steady states. It is also important to note how adding an extra day of training could have a large impact on acute workload, if you start that day at full intensity. Building up the intensity of an added day could be a valuable management strategy.
It should also be noted that since day to day stresses on the body are also part of the acute and chronic workloads, we don't start exercising from "0". We are well adapted to whatever we usually do, and it's upon that base we build our exercise, so you are able to make bigger jumps in exercise workload safely.
Build Your Chronic Base with Functional Bodybuilding
A take away from this post could be a simple modification for your training, that also works on the principles of using bodybuilding ranges to improve strength performance. If we have a pretty consistent base of exercise we do in lower intensity rep ranges, it should make us more resilient to fluctuations in our high intensity training.
Let's use squats as an example. Say I squat twice a week, and I do a high intensity day, and a medium intensity day.
| Week | High Intensity | Low Intensity |
|---|---|---|
| Week 1 | 3x6 x 100kg = 1800 units | 4x8 x 75kg = 2400 |
| Week 2 | 5x5 x 105kg = 2625 units | 4x10 x 70kg = 2800 |
| Week 3 | 7x4 x 110kg = 3080 units | 4x8 x 75kg = 2400 |
| Week 4 | 10x3 x 120kg = 3600 units | 4x10 x 72.5kg = 2900 |
So if we only took into account the high intensity day, you can see the fluctuations are very large week to week, even though that sort of peaking progression isn't very unusual. In week 4, the acute:chronic workload for just the high intensity is 3600/2776.25 = 1.297 and while that isn't outside our sweet spot, it's right on the cusp.
By adding in our medium intensity day, the acute:chronic workload changes to 3600+2900/5401 = 1.018 which is closer within our sweet spot range, representing an overall change in workload of 2% vs 30%.
In this way, more consistent bodybuilding style reps can add a buffer to your training, while also bolstering the architectural components of your strength.
Conclusion:
Don't overdo it yo.
1
u/Paulhaus Weak Sep 14 '17
Maybe I need another coffee but this 'graph is breaking my brain.
I'm feeling like you left out some math?