There are 4 reasons you should be going outside your house during this pandemic: essential work or study, to buy essentials, to care for yourself or for others and to exercise. Since exercise is the only real voluntary one on that list, people who have not run for years are dusting off their gear and representing their favourite sports brand every day. Now this is awesome for their health, increasing your exercise load is going to have far reaching benefits for your muscles, bones, heart, brain and mind which are so numerous I couldn't even list them here for fear of overloading the internet. If it is done correctly. If you increase your exercise load suddenly there is a possibility of exceeding how much your body can tolerate which leads to injuries and ultimately that leads to a myriad of negative consequences not least of which is a decreased capacity to exercise! Luckily for you, you're reading an exercise professional's blog which is going to give you an inside view of how to build your exercise load without causing injury.
Let's start off with a little bit of theory.
Dye's envelope of function is the idea that everybody has a certain amount of exercise that their body can tolerate without causing damage to the system (as shown by the area in the graph under manageable). When we go above this manageable load we get excessive forces on our body which causes damage to the structures under load which can lead to our body getting injured.
I've covered in a previous article that you don't want to train too easy or too hard, there is a sweet spot in the middle which allows for maximum adaptation without excessive fatigue (or to be relevant to today's article: without excessive risk of injury). The following graph is just another way to show a similar idea. However, what I didn't mention in the previous article is that with proper training we can move this sweet spot to be higher up on the graph or that the opposite can happen if we don't train.
These graphs include example exercises to help you visualise where each exercise would go but is not to scale, this graph is just to help you grasp the concept. Also, just in case the nicely drawn lines didn't give it away, the run being measured in miles might have made it obvious that I didn't draw this graph. Credit. 2 miles = 3.2kms if you were curious.
The graph on the left represents someone who has not trained and the graph on the right shows a highly trained individual. You'll notice that the trained individual can manage a much higher volume of exercise than the untrained individual (measured by the area under the manageable curve). This means that if these 2 people both did a 3.2km run the trained person would be fine but the untrained person would have exceeded their limits and would likely pick up an injury for their troubles. But more relevant than that, our upper limits are constantly changing over time as our training does so if you haven't been running for months and then suddenly you're running every day, you could exceed your envelope of function, even if you've run that distance before.
So with all these untrained, newbie runners out clogging up our parks to keep from going insane from isolation my concern is that they won't be working within their envelope of function and in a month's time we're going to see an increase in over-training related injuries. And an increase of insane people...
So now that you've got this theoretical knowledge of your envelope how can you put it into practice to make sure you'll still be moving pain free once this is all over?
Well there are a couple tools I can equip you with to empower your decision making on how much is too much.
Acute to chronic workload ratio
Put simply: how much exercise have you done this week compared to how much exercise you have usually done in the past 4 weeks. The idea of this is to find the amount of fatigue (exercise done this week) compared to the level of fitness (exercise done past month).
To find the ratio you divide the acute workload by the chronic workload. If the ratio is < 0.80 you are probably under training and are not developing the strength to resist injuries.
If the ratio is between 80 and 1.30 you are probably working at an optimal workload and are at the lowest relative injury risk - The Sweet Spot. If ratio is > 1.50 you're on the highway to the "danger zone” and are at the highest risk of injury due to over working the structures in the body.
For example if my previous 4 weeks I ran 4km, 5km, 3km and 4.5 km my chronic workload is 4.125km (4 + 5 + 3 + 4.5 / 4 = 4.125). If I run 5km this week that is my acute workload. You divide 5 by 4.125 to find that my acute:chronic workload ratio is 1.21, landing me in the sweet spot, nice one! But if I were to go for a run with my runner friend who does 10km runs all of a sudden my acute:chronic workload ratio skyrockets to 2.4 and even Kenny Loggins would be worried because I've skipped the highway and I'm in the danger zone now meaning I'll almost certainly be picking up an injury for my troubles. Every time you go for a run make a quick note of how far you ran. From there make sure you don't increase it by more than 30% at a time and you should be sitting pretty in the sweet spot. This may take a little bit of effort to set up but it doesn't need to be super complicated, just write a quick note in your phone and every week punch it into your calculator. This can also be done by measuring total time running, amount of runs per week or even heart rate.
PRS scale - Like an RPE scale but for recovery
A perceived recovery status scale is a simple tool where you rate how well recovered you feel before a bout of exercise out of 10. Whether you feel well recovered (PRS>5) or not (PRS<5) will affect the ensuing exercise session with the accuracy of these feelings on subsequent performance being greater than 75%. That means all you have to do is look at this graph and point to a number to get a good idea of whether or not you will train well today.
If you score less than 5 don't expect to be beating any personal records that day and you also might consider looking at your recovery methods to find why you scored so low.
If you score 8 or above you have recovered well and are ready to smash out a solid workout at a high intensity.
How you feel - Like a PRS scale but even easier!
If even that is too much effort, forget about the scale, just take a moment before you begin your workout to see how you feel. If you're feeling sore and lethargic it might be a good idea to go easy today. This is just your body's way of saying "hey remember that envelope of function thing? I'm getting kinda close to the danger zone so give me a chance to repair myself pleeease!". It's even easier than using the scale (but less accurate).
There has been a large area of research looking into how good your perceived feelings are at guiding training and it has been very positive so far. I've seen things like RPE-based training popping up in the literature which feels like we've come full circle because really it was the way we were guided before any fancy programs were put forth. When we all first started at the gym we probably just picked up a weight we thought looked right and if it was too heavy we went down and if it was too light we went up. Listen to your body! It is honestly one of the most accurate markers we have of recovery, increases in fitness or injury. Don't listen to that "no pain, no gain" nonsense you might as well say "no corona, no Sharona" because it makes about the same amount of sense.
Oh and one last thing:
Give yourself rest days
I've seen a lot of people exercising multiple times per day now that they have the time. Not only that but because they're limited on what heavy weights they can lift, they offset that by increasing the frequency that they lift, great idea! You're going to be super fit, I love your work, keep it up. But don't forget your body needs rest days to recover. Now rest days don't mean "no movement" days, rest days just mean "light movement to encourage recovery" days (and we all remember how important recovery is after my new years eve this year!). So if you're an elite marathon runner who has been training twice a day for the past 10 years a rest day could just mean a slow 5km bike ride instead. Conversely if your hardest training day yet was a 2km jog then a rest day might look like some gentle yoga and slow walks. This comes back to that envelope of function that I covered at the start of the article, you've got to find out what is manageable for you and that can slowly increase (or decrease) over time. Whatever your level of fitness, don't forget to give your body the chance to recover by decreasing the intensity to a light level and changing up the stimulus.
So if you don't want to be one of those people who picked up runnning (or any other form of exercise) for 2 weeks during quarantine and then decided it's not for you because of an injury, follow my advice. Stay within your envelope of function. Gently push the boundaries but always take care of your body. You can measure your acute:chronic workload, your PRS score or just how you feel that day to stay on top of how you are tracking. And always listen to your body. Pain means something is not right. A rest day here and there will do wonders for your overall fitness.
Remember staying injury free means you can keep yourself from going Covinsane (Covid-razy? iso-sane? Hey I'm an exercise scientist not a comedian, I thought it was clever)
Keep your distance, stay safe! Keep your movement, stay fit!