Your Spine Has No Compressive Budget

Added: 2026-05-14

[00:00:00]Is there anything to the claim that compressive spinal loading is independently fatiguing? If my program contains heavy compound lifts, multi-joint exercises, that load the lower back a lot, should I be concerned about adding volume from standing calf raises or barbell shrugs purely due to the load transmitted through the spine?

[00:00:19]An interesting question.

[00:00:21]Um, I don't know that we have like this uh crazy, you know, evidence-based answer, but I will lead with some numbers here.

[00:00:28]In elite powerlifters, this has been measured. The amount of strain, right, on the lumbar spine has been estimated to be up to 36 kilonewtons. So, 36,000 newtons on L3, the lumbar three vertebra, in routine training, no structural failures there. Bone mineral density at that same uh level correlates with training load with a really high R value, 0.82, and we know from our previous question that loading drives adaptation, not necessarily damage, with the caveat being it needs to be within your sort of physiological tolerance.

[00:01:04]And so, we talk about training all the time. I I kind of say uh I anchor my goal as follows.

[00:01:09]I want to introduce the highest training load to the individual that they can tolerate, and the two biggest bottlenecks here one, time, two, what's their physiological tolerance? What can they recover from, for example? And so, I don't view this question as like a unique sort of case, like, well, look, now we're talking about the back.

[00:01:28]I don't I wouldn't feel that way about the knee, the ankle, the wrist, any of these things. It's like, no, what is your sort of global tolerance? And if you wanted to sort of fraction, you know, segregate that into different joints, like, well, what can your back handle? Sure, that seems reasonable to me, but that that level of micromanagement is not something that I do uh when doing program design. What about you, Austin? Do you think about that? Like, you're designing a program and you're like, look, they need to do some squat patterns, some hinge patterns, pressing patterns, pulling patterns.

[00:01:54]I don't want to do too many exercises that load the low back.

[00:01:58]Yeah, of to some extent I have thought about this in certain cases, especially when training powerlifters, and when it comes down to dosing out their overall kind of training load for for the week.

[00:02:09]And I've talked about this before, and I think you and I actually have maybe somewhat divergent opinions on this, but like for competitive powerlifters, especially those who are conventional deadlifters and low bar back squatters, meaning those who are going to be more bent over more of the time, I pretty much don't program bent over rows because I don't think that the juice from that exercise is worth the squeeze in terms of fatigue that I could otherwise spend on squatting and deadlifting or recovering from the squatting and deadlifting that they're already doing.

[00:02:36]And so to the extent I want to program like a row pattern, I might do a chest supported row or you know, a seated cable row or something like that that doesn't actually add add some load to that area that is not being used specifically. But that really is more a question of like how am I allocating my fatigue costs in the context of specificity being of concern.

[00:02:56]If it's more of a general fitness type program where somebody doesn't have a very specific lift that they're trying to improve or set of lift that they're trying to improve, I don't really care about this quite as much and I'm happy to program any of these things. And then I'm just getting a sense of how is this person tolerating the overall program rather than being worried about particular areas of the body getting overdosed.

[00:03:13]>> Yeah. Yeah, I think actually a lot of this comes back to like what is fatigue and like how do we how do we predict the amount of fatigue that somebody's going to get from a specific exercise? And so like you can think about like uh fatigue in a couple different ways. One, just like you know, how tired you are after a session or an exercise or you know, a number of different exercises. You can think about it as like your ability to produce force relative to some sort of baseline that you had in the in recent history. And and there's no right answer. And then there's fatigability like the subjective sense of like how you're feeling.

[00:03:45]There's all sorts of stuff right in in the research world when people try to define these things. It's it gets messy relatively quickly. However, when I think about fatigue from exercise, I'm thinking really more about total training load, right? Which is not only the amount of exercise that you're doing, but the nature of it, right?

[00:04:00]Exercise selection, how close you are to failure, things like things like that, RP, velocity, so on and so forth.

[00:04:07]I think that generally speaking more muscle mass, more range of motion, more degrees of freedom, right? So like a free weight exercise versus machine exercise, all those sort of things, more velocity, generates more fatigue compared to the opposite. And so you know, I don't know that that's particularly groundbreaking, right? But when you talked about a bent over row, a Pendlay row, for example, compared to a chest supported row, I'm like, oh, well there's less muscle mass involved. Yeah.

[00:04:30]And I'm like, okay, so lower fatigue, duh.

[00:04:32]I'm not thinking about the spinal fatigue as its own unique sort of construct. I'm thinking about the total training load. And so by changing in your example, the Pendlay row to chest supported row, I'm like, oh, well I just freed up some training load that I can allocate somewhere else if I want. And that's the same way you just do a different mechanism. So I, you know, yeah, same sort of thing. Um so to answer this person's question uniquely, I'm to my knowledge there's no specific construct for like spinal fatigue and like a particular limit that that exists based on any sort of evidence. It's all kind of vibes. People are like, it just like we talked about, which is just vibes. We're like, well this is what I think about fatigue and here's how I think about what I'm doing exercise prescription.

[00:05:09]But I also think it this question sort of misses one of the big points about exercise prescription is that we're trying to generate an adaptation that not only improves fitness, but also your tolerance to do the work, right?

[00:05:22]And so over time, your ability to tolerate loading of the low back, general training load is going to go up, right? And so you can get down to a very mechanistic level here. You can look at joggers and runners with, you know, five plus years of of experience doing this thing. They get, you know, improved or increases in their disc hydration, the gag content in their in their discs.

[00:05:45]Their discs actually get a little bit bigger compared to individuals who don't run.

[00:05:49]Um you see in young athletes that their um their intervertebral discs also grow.

[00:05:54]Uh we see this in weightlifters, their vertebral end plates thicken. Like these are all features, not bugs of the training. And so, I generally think when it comes to like spinal fatigue, I I don't really use that as a specific thing to to anchor to. I'm more just like, well, what's the total training load, and is this something that the person can handle? And if they can handle it, is it driving the adaptations that I want? Is that kind of fair?

[00:06:16]>> that's totally fair framing. Yeah. Cool.

[00:06:19]So, all right, last question to you, and then we'll kind of move on, and just a little wrap up on this.

[00:06:23]How do you talk to a patient who brings in an MRI showing a disc bulge and wants to know if lifting is safe for them?

[00:06:30]Yeah, I This reminds me of I think our last episode where it was like, somebody comes in with their testosterone lab panel. And my first question's like, what led to this MRI getting done? Give me fill in the backstory. Tell me about your journey so far. Tell me about your story. And then I'll just shut up and listen.

[00:06:43]>> Mhm. And usually by them telling me that story, I can get a sense of what are all their beliefs, what are their experiences, what are their expectations, what are their fears, what are all the things that I'm going to have to kind of reflect back to them in my answer, uh to kind of come together in the same uh kind of landing place. And so, that I I I'm not going to have a stock answer here, cuz so much of it's going to depend on where the person's coming from. But in general, just an isolated disc bulge on an MRI, I don't actually care like who you are.

[00:07:08]You can, you know, participate in essentially any form of physical activity uh unrestricted, including strength training. I just have to figure out what's the right message that's going to land to to get you confident in doing that same thing, because I have no concerns about somebody uh with a disc bulge participating in strength training um in in general.

[00:07:26]>> Yeah. Yeah, and just to just to sort of drive this point home, if you thought about a series of exercises related to how much compressive loading is placed on the spine, right? You'd certainly place powerlifting and Olympic weightlifting above like recreational running.

[00:07:42]And you just go look at the injury rates for powerlifting and Olympic weightlifting is two to four injuries per thousand participation hours. For recreational running it's 7.7. If you're a novice runner not used to doing what you're being asked to do or asking yourself to do, it's 17.8 injuries per thousand participation hours. And so, you know, then you're like, well, look, you know, runners there's there's a lot more duration here. It's like, yeah, but they're not loading themselves with the heavy, you know, barbell and exposing themselves to that, you know, big moment when they bend over, the bottom of a squat or a deadlift. And the majority of back injuries in powerlifters last less than two days.

[00:08:18]90 90 and a 90.5% needed one day off or less to get back to training. So, it's kind of like yeah, we can hem and haw about fatigue and program design and this that and the other, but like at the end of the day, I just don't think this matters.

[00:08:35]To wrap it up, your spine doesn't have this sort of compressive budget. It has a training tolerance just like everything else. That goes up as you get fitter and you progressively load yourself over time to sort of match the training load to your new-found fitness.

[00:08:49]This orthopedic cost narrative gets the direction of the injury causation backwards. The real risk is born from a person who's not prepared to do what they're asking themselves to do, not by the person who has been gradually exposing themselves over time to these sort of things.