In this video, David Brimacombe explains why people with post‑concussion syndrome (PCS) often experience a crash after exercising and how to prevent it. He identifies two common patterns of exercise intolerance: (1) fear‑based avoidance, where the autonomic nervous system (ANS) flags movement as danger, and (2) “push‑through” behavior, where individuals ignore warning signs until they crash. Brimacombe clarifies that post‑concussion symptoms (brain fog, dizziness, sensitivity) are alarm signals from a hyper‑reactive ANS, not evidence of ongoing brain damage. He proposes a sub‑symptom threshold training approach that first determines each person’s personal symptom‑trigger heart‑rate ceiling using a simple symptom‑rating and heart‑rate check during steady‑state activity (treadmill, bike, or walk). Once the threshold is identified, training proceeds at 80‑85 % of that heart‑rate, keeping symptom increases to no more than 2‑3 points on a 10‑point scale. The protocol emphasizes gradual increases in duration, incline, or resistance, regular retesting every few weeks, and later incorporation of interval or resistance work once tolerance improves. Throughout, Brimacombe stresses active recovery, consistent small steps, and psychological reframing that the brain can rewire away from associating movement with danger.
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If every time you exercise you crash after, you're not doing it wrong. You're simply doing too much too soon. Now understand that exercise intolerance presents in 2 different ways. Now the first way is when someone is so fearful of exercise that they just don't do it at all. They have that fear in the system. Their ANS, their autonomic nervous system, has created alarm bells and stressors that as soon as they do any kind of movement, they stop. The second way is those people who push through all signs and symptoms. Okay? They think, you know, exercise has been great for me in my life, so I'm just going to do what I used to do. I'm going to push through it. And then they crash. In this video, I'm going to go through both of those types of exercise intolerance, and how to prevent it in the future. Let's begin. Let me know if this sounds like your situation. You exercise, whether it's resistance training with weights, it's walking, it's biking, it's swimming, it's hanging out with your friends, but you exercise. You feel okay, and then shortly thereafter you crash, or maybe the next day you feel worse off. And then you think to yourself, why am I doing this? What is the point in putting myself through a greater stress that is going to delay my recovery? Well, understand that exercise is not the problem. It's your tolerance that is causing these symptoms, and your tolerance can be adjusted just like anything else. Now, let's first talk about why this is happening. Why did something that, for many of you, used to be so easy You could walk down the road, you could go for a jog, you could work out, you could swim, you could bike, and all that was simple. You didn't have to think about it. You didn't have to think about, do I have the energy? Do I have the capacity to do it? It just came naturally. Now, understand that the brain has been rewired, in this case, not for good. It now aligns movement with danger, and with danger, it sends off all the alarm signals. Now, What most people get wrong is that those signs and symptoms you feel, okay, that brain fog, that dizziness, that sensitivity that you have in your system, does not mean your brain is broken, and it is not a sign that you're having further damage. What it is, is it's your autonomic nervous system sending off all the alarms. It is like a car that has an ultra-sensitive alarm system. You brush by it, the wind hits it, a leaf hits it, and And all the sirens and alarms go off. After a concussion, your brain acts like this. Your autonomic nervous system is basically telling you that everything is a danger. Movement is a danger. What used to be easy is now difficult. And for a lot of people, when you feel that way, when you have those sensations, those symptoms arise, you think, I have to stop because those symptoms are a sign that I'm causing further damage, that I'm going to delay My recovery. Now, yes, you should avoid being symptomatic all the time, but they are not a sign that you're broken, and they are not a sign that you're going to delay your recovery any further. See, the one thing you need to understand about the brain is it's always trying to make a connection. So what you do and how you respond will tell it something, and it will make that connection. So if you move and feel symptomatic, It makes that link. It rewires in that pathway. Now, if that continues to happen, that rewiring becomes deeper and becomes stronger. Now, you can break that cycle. It is possible. Now, the longer you've had this sensation, this feeling, the harder it is to rewire, the longer it might take, but it is possible. So, we need to start changing the way your body associates with movement. Now, the easiest way to do this is through what's called sub-sensory Symptom threshold training. So what I'm trying to do is I'm going to try and where my threshold is, so that point where if I hit it or go above it, that's when my symptoms start to come. Okay, that's when those alarm bells start ringing and I can't get them to stop. So my goal is to know where that line is and to train just below it. So I'm training just below it. Eventually that line starts to creep up and my capacity increases. And that's what we're going to get into. So for those who have lost that inclination to work out, lost that inclination to move, okay, let me tell you that I was at that point too. I remember sitting in bed, lying in bed, not wanting to even get up because I knew if I sat up, I would start to feel dizzy, feel nauseous. So I just lie down because that was the easy road. That was the path that I thought, hey, my body's healing. If it's not, if I'm not feeling symptoms, it must be improving. That is one of the biggest fallacies in the PCS recovery space. You need to move. Your body needs to increase that blood flow to regulate your autonomic nervous system so that your muscles, your hormones, your body can operate in a functional way. Now, by sitting down, by doing nothing, you are not actually helping your system. You are deconditioning. You're telling it, this is how I want to live. I want to live in a state where I'm just doing nothing. Now, this is not to say that you are at fault for this. Again, I did this for years. I thought this was the way to go. And over time, I was just hoping that maybe my body would regulate on its own. Maybe through some grace, the stars would align and I would somehow miraculously be healed. But you need to put the work in. This is an active recovery that requires an active participant. An active participant needs to know what to do and when to do it. Okay, so sitting and saying, I'm avoiding all activity because that causes symptoms, okay, is what you used to think. After this video, you're going to think differently. For those who are the type that want to push yourself, you are the second category. You are always striving. You can't stop. You need to move. Now, let me tell you this. I agree, movement is essential. Now, movement in moderation is what you need. You can't maximize your movement now because if you do, it's going to take that much longer. Now, I mentioned that symptoms don't mean your brain is broken, but if you're constantly in a symptomatic state, that is also not a good way to recover as well. The goal is to be sub-symptom or have mild symptoms, but we need to work on training For that style. We need to work on how to train so that we actually stay below that symptom threshold and we're not causing unnecessarily our symptoms to provoke. Now, here's what that's going to look like, okay? Really simply, how am I going to test what my capacity, what my threshold is? Okay, simple. If you have a treadmill, if you have a stationary bike, and even if you don't, there's a simple way to do this. If you can check your heart rate, Okay, using maybe it's a smartwatch, maybe 2 fingers on your neck, on your wrist. Okay, you have everything you need. So, what you're going to do at the beginning of this test is you're going to determine what are my symptoms at right now, rate it out of 10, 1 being very, very minimal, 10 being extreme. Now, if you have an extreme, anything in the 8, 9, 10 range, you probably shouldn't be doing this to begin with because you can't have a reliable test. Okay, the second thing you're going to do is you're going to start moving at a very steady pace. So, I'm going to walk, I'm going to slowly bike, I'm going to go on the treadmill, but I'm going to go at a very steady pace. Now, if you're on the treadmill, you can slowly increase the incline or the speed. On a bike, same thing, increase the tension. If you're walking, increase your speed. Now, as you start to increase the speed, you're increasing the stress on the system. Now, here's what I want you to consider. Every minute, I want you to either check your heart rate on your watch. You can check your heart rate by putting 2 fingers on your neck or on your wrist. And I want you to mark down what is the heart rate. So, here's the 3rd thing you're going to do. When your symptoms escalate by 3 or 4, so if I started at a 2, now I'm at a 5, I'm going to stop at that point. So, whatever that is, I've walked now for 7 minutes. I'm now going to stop. I'm stopping my movement. I check my heart rate, okay, and I write that down. So maybe my heart rate is at 130. I know now that 130 is my maximal heart rate for the time being. That is not your physiological max heart rate, but for the time being, that is your threshold. You do not want to exceed that. So moving forward, maybe in a couple days when I want to actually try to train the system, I'm now going to go at probably 80 to 85% of my max heart rate. So maybe I'm going to train at 115 or 120. I'm going to walk for 10, 15 minutes, making sure that my symptoms don't escalate by more than 2 to 3 points. If I started at 2 and I finish at a 3 or a 4, that is perfectly fine. You are going to have maybe a little symptom provocation as you do this exercise, But it shouldn't cause you great stress. Okay? And then over time, every week, add some time, add some incline on the treadmill, some tension on the bike. But what you're trying to do is you're trying to increase your tolerance. When you go to the gym, if you were to lift the exact same weights every single week, you're not going to get stronger because your body adapts to what you give it. So if you are increasing the speed, the incline, the tension You are then telling the system, I need to increase my tolerance. Now, this could take time, so don't feel rushed. Don't feel like if you have a setback one day where you used to be able to walk at 120 and not have those symptoms come up, and for some reason it does, that's okay, right? We know we have other stresses in our life that causes our body to react in different ways, but know that you can go back in a couple days and hopefully you'll be able to do that. Because you know that the brain is malleable, you know that the brain can change, and you have the power to do so. You are a change agent in your recovery. So every few weeks, I want you to go ahead and retest what your maximum tolerance is. So maybe in 3 weeks, I go back and I test, and I do those checks, and I get to a 6, and I stop. And like, my heart rate is now 140. Wow, I've increased by 10 beats per minute for my maximal heart rate. Now I can train at about 125, 130, and And eventually move up, move up, and move up, right? The biggest thing you need to do, and I need to stress this enough, is you need to start with steady-state movement where your heart rate doesn't have to fluctuate. So that doesn't put as much strain on the system. So walking in a steady state, biking, swimming. Once you feel like your tolerance has increased quite a bit, you can then add some interval. So an interval is when you have inconsistencies in the output. So, you're gonna lightly jog and then walk, lightly jog, then walk. Or do resistance training where you're putting stress and strain during your set, you stop and you slow down. Okay, those are examples of interval training. Now, you can expand that intervals and have more intensity in them as you become more successful. But again, don't start by going and doing sprint intervals and expect that your body can handle that. This is all about making small steps. Your small steps now will be big leaps later on, but if you try to make a big leap now, you're going to crash. So keep it simple, okay? But be consistent to convince your system that this is who I am, this is the new me. I can tolerate these small stresses because they're making me a stronger person in the long term. I hope this video resonated. Understand that you need to build safety in the system by starting small before you can build your fitness. The goal isn't to be a Mr. Olympia or a marathon winner in your first few weeks, months, or even years of recovery. The goal is to slowly move back to the person who can be functional, can, can move about their days and not have the stresses and the strains and the fears that you're going to become symptomatic. Okay? Again, I hope this landed with you. You have the power to change your situation. I hope you have yourself a great day.
