How should people think about systemic damage and recovery? Because obviously the nervous system and the way it interacts with the neuromuscular system is the site of all the action here, or at least a lot of the action. And the nervous system can in fact become fatigued. It has a great capacity, but the whole system that we're talking about can be worked to the extent that even if a muscle group, like the biceps or the back, is being allowed to rest while you're training legs and other muscle groups, that your whole neuromuscular system needs rest.

How does one determine whether or not your entire body needs complete rest, or low-level active rest, or exercise of a different kind? Yeah, yeah, sure. So I want to actually tackle this because we're on the topic of hypertrophy. I'm assuming that that's the goal in mind here. Yes, here I'm asking specifically within the context of hypertrophy.

I realize that for other training goals the answer to this question could be quite different. Yeah, okay. So we actually do this in a couple of different ways. Let's start local and work back to systemic, right? Because number one, what you're really concerned about is at the local muscle level is am I going to create excessive damage?

And I don't necessarily mean muscle damage here, I mean injury, right? So the kind of rule of thumb we use is like three out of ten in terms of soreness. If you're more than three out of ten in terms of soreness, we're going to start asking questions. If you're six out of ten, we're probably not training.

This is a subjective measure. Total subjective measure, right? And you'll know very quickly, right? If you can barely graze your pec with your fingertip and then you're like, "Ah, I don't care what you score that, we're not training. There's just no damage." If you're three out of ten, if you're just like, "Oh, I'm kind of like a little bit stiff here," but once you get warmed up you start feeling okay, you're probably okay to proceed there.

So that is a very easy way to just think about soreness. You're going to be a little bit tight depending on your training frequency. Now zooming out to systemic, we use a whole host of things. So we actually have a whole host of biomarkers we use. You can get a lot of these from blood.

So you can look at things like creatine kinase, that's the very common one marker of muscle damage. We'll actually look at LDH, we'll look at myoglobulin. That's just like—if you think about hemoglobin is the molecule that carries oxygen throughout your blood. The myoglobin is the part of that that's actually in muscle.

So when muscle gets broken down, that gets leaked out and put in your blood. That's one of the markers actually that's going to be associated with things like rhabdo, which is like you're going to see your urine is purple and it's extremely dark because you've got so much muscle breakdown that happens and kidneys can have a problem and you put a bunch of stuff in there.

So we use those biomarkers. We'll actually also look at probably a couple of things you're familiar with, ALT and ASD. These are excellent biomarkers of muscle breakdown. So if we are actually suspecting that this is a chronic problem, we're going to actually go in and pull some blood. If it's just like I'm super sore today, we're going to use that subjective marker.

But if we're seeing this as constant, like man, are we really pushing you way too much, is there some sort of systemic problem, we're going to blood and we're going to look at all those different things. Now, AST to ALT is really specific and I don't want to take us too far off track here, but the ratio to those things is actually very important as well.

So if you look at the AST to ALT ratio, typically the number we'll look at is like 1.67. As that ratio is like higher than that, you have a pretty high risk of muscle damage. But really between, you know, me and you and a few of these listeners, any time we start seeing AST outkick ALT, we're immediately thinking, as in the ratio being higher than 1, we're immediately thinking like there's something happening muscle damage-wise.

So that's actually a sneaky good indicator of just total muscle mass, because the vast majority of that's going to be in muscle. So those are actually some markers that we like a lot if muscle damage is the thing we're concerned with. If we are more concerned with things like total training volume, systemic overload, then we may turn to something more like sleep.

There's a lot of information we can actually glean from changes in sleep behavior and function. You can also look at things like HRV, heart rate variability, which is a very classic marker and much more sensitive to changes with training than something like a resting heart rate, which is one thing you can actually do that's totally cost-free.

Just look at your changes and any elevation resting heart rate over time, especially more than three to five consecutive days is an indicator. But HRV is much more sensitive to things like training-induced overload. So that's a quick version of stuff that we're going to pay attention to. The last one I would add there is simply motivation.

So if you're really training hard and you like training hard and you just like cannot force yourself to go anymore, that in and of itself can be a good indication of it's maybe not the day, maybe not the week. With all of these things, you want to be careful about overreacting to a single day measure.

Again, we need to look at at least a trend of more than three days. Honestly, I'm looking at more than five days. I'm going to pull back from that and think about what phase of training we're in, what part of the year we're in, typically whether it's in-season, pre-season, post-season, off-season, et cetera, to make our decision about what we're going to do about it.

Are we canning the entire workout? Are we doing a modified, lower version, lower intensity? My default generally, if hypertrophy is the goal, remember, volume is the driver there. So if I can, like can we get in, can we go real light, let's go to six out of ten RPE.

So relative perceived exertion. Maybe we'll reduce the range of motion. Maybe we'll make it a little bit easier. Maybe go to machines or instead of going to squat, we'll just do leg extension or something like that. But I want to still get enough volume in there. That will keep you on target, and again, even going at 50%, not to high repetition, 50% for a set of ten, three sets.

Just get a nice blood flow in there, get it in, get it out, aid in recovery, and then move on and come back the next day. That's probably what I would do rather than canning the entire session.