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The Injury Buffer: Why So Many Runners are Chronically Injured

70-80% of runners develop a running-related injury every year. This number is staggering and there are numerous contributing factors and potential explanations. However, after years of helping runners of all levels and abilities rehab hundreds of chronic running-related injuries, I believe that a lack of an injury buffer ranks as the number one reason why runners stay or become chronically injured.

For 6 years, I've worked as a physical therapist. During my first 3 years, I worked in a general orthopedic & sports setting in the White Mountains of New Hampshire, occasionally working with runners. In my free time, I consumed running-specific rehab content and familiarized myself with the most up-to-date research. I wanted to combine my lifelong running experience, now totaling 26 years, with my physical therapy experience to become a top running rehab expert.

For the past ~3 years, I've worked mostly with runners in Maine & New England, recognizing numerous patterns and frameworks over this time. I certainly don't have all of the answers, but I know that building an injury buffer is the #1 framework that helps runners stay injury-free. And if you're currently rehabbing a running injury, you should not stop your rehab once you are back to 100%. This is where you should add extra emphasis to your rehab, but where most people stop.

Most running-related injuries are overuse injuries. These include shin splints, stress fractures, tendonitis/tendinopathy, patellofemoral pain syndrome, IT Band issues, plantar fasciitis, joint impingement, and repeated muscle strains. Most of these issues would feel better if we stopped running. Why? Because they are overuse injuries, and when we rest, we stop using our tissues (muscles, tendons, bones) in a challenging way. Most of these issues would also likely still be present when we return to running. This is because resting doesn't increase our tolerance to more running, it likely decreases our tolerance due to underuse.

It's important to recognize how much more challenging running is on our body than most of our other activities. There is a large amount of impact with every running stride - which is generally a good thing for the longevity and strength of our tendons, muscles, and bones.

So, what is an injury buffer?

In order to understand an injury buffer, we must first understand three things: our actual current capacity, our desired current capacity, and our goal capacity.

Current Capacity

I define current capacity as the amount of total physical load that our body can handle in a given day, week, or month, without producing pain or getting injured. If your main activity is running, the majority of your loading will come from running. It's important to recognize all things that contribute to your total load, which does include things like how much you walk throughout the day, any cross-training or strength training that you do, and all of your other activities.

Knowing your total physical load on your body each day and week is vital to understanding your current capacity. But it’s not the only consideration. We also need to deeply understand our recovery. If any recovery aspect is suboptimal, it will negatively impact our tolerance to load, and therefore decrease what our body can currently handle without pain or injury.

Fully understanding our recovery is much more challenging than understanding our total physical load. There are many more contributing factors to our recovery status, and most of them are much less objective to measure than what we do for activity. Recovery factors include sleep quantity & quality, stress levels/management, proper fueling & hydration, our hormone levels, and other blood biomarkers such as vitamin D, iron, etc.

Actual vs. Desired Current Capacity

Where most runner’s issue stems from is a lack of understanding of their actual current capacity compared to their desired current capacity. We often think that we are currently capable of doing more than we actually are, often due to a lack of an understanding of all the contributing factors and how much of an impact they can have on our capacity. 

Understanding our current capacity is so challenging because the status of all of our recovery variables can significantly vary from day to day. This means that your current capacity one day may be vastly different than it is the next day. Did you get 3 hours of sleep one night? Your current capacity plummets for days. Are stress levels rising without management or have you had a recent significant change in life stressors like having a newborn, change in relationship status, death of a loved one? These certainly will decrease your capacity. Did you eat poorly for a weekend, binge drink with friends, or not eat enough calories or protein to support your current activity level? Each one of these independently will decrease your tolerance to physical load, and if you start combining multiple factors - it’ll be surprising if you don’t get a flare up or new injury.

Goal Capacity

Goal capacity is slightly more objective than our current capacity. Typically when discussing goal capacity, we assume that someone’s goal recovery status will be the same as their current recovery status. Then we have a discussion about what their long-term goals are regarding activity level. How much do they want to run? How much of it will be a hard effort? Any significant elevation gain? How many runs per week? What other activities do you want to be doing?

It is perhaps not necessary to point out that our understanding of our current capacity and our goal capacity are always just educated guesses. We can never 100% know exactly what amount of activity we are capable of without getting hurt, but the more educated we are about the above and the more in tune with our body we are, the better we will be at guessing our capacity.

A diagram showing the relationship between Activity Level/Load & Actual Current Capacity, showing when someone would be in pain, pain-free, and have an injury buffer.

(Note on diagram: the green, red, and blue lines are never linear in real life!)


Injury Buffer

Now that you understand current capacity and goal capacity, it's time to delve deeper into what we call an injury buffer. 

An injury buffer is the extra capacity that we have built into our physical system that can absorb unexpected stress or load increases. It's the safety net that allows us to avoid injury if we have a day or week where we increase our load significantly more than expected, or our recovery takes a hit due to unforeseen life stressors. If we have no injury buffer, we are always walking a fine line between health and injury, which is a stressful and non-ideal situation for most runners.

Remember, the more we know about our bodies, the more accurate our estimation of our capacity and the better chance we have of staying healthy and injury-free. 

The theme of the injury buffer is about not limiting yourself. With enough time, dedication, and commitment to progression - you can always do more.

To build an injury buffer, we must make our actual current capacity higher than our desired current capacity, and ultimately have our actual current capacity reach our goal capacity. Our actual capacity can even become higher than our goal capacity - the larger this difference, the larger our injury buffer and the less likely we are to sustain an overuse injury or have a previous injury come back. 

To build a proper injury buffer, you need to combine two things: a slow, specific progression of the duration/frequency/intensity of the activities you want to perform, and targeted strength training. Targeted strength training challenges the specific body parts most loaded by your desired activity.

Passive activities like massage, foam rolling, cupping, scraping, & stretching might help increase your tolerance to activity in the short term, but none of these play a significant role in being able to tolerate a much larger, more sustained load.

A common question remains: an injury buffer is a relatively simple concept - be able to tolerate more than what you are actually going to do. But why is it so common for people to not build an adequate injury buffer? The answer comes down to two reasons.

The first is a lack of education on why this is important. Many healthcare providers don’t understand current capacity, goal capacity, and injury buffers because it isn’t taught in school. They then cannot provide the education to their patients on it’s importance, so many runners don’t ever learn about this concept.

The second reason is that people's priorities shift as they have less pain. As they improve, their dedication to their strength progression typically diminishes as they start spending more time running.

At Steady State we believe strongly in developing an injury buffer. We want to help our clients get to their dream outcome. To create an injury buffer requires commitment from both the client and the PT. What makes Steady State a unique healthcare experience is our commitment to you - beyond the initial injury you come to see us for. We understand how important living an active life is to you, not just now but for the rest of your life.

If you have any questions, I’m always happy to answer them at

Want to work with a running expert for rehab or prehab at Steady State? Contact us at to schedule a free discovery call so that we can learn about your issue and make sure that we are the next best step for you.