If the goal is to challenge muscles and one is dividing their body into, let's say, you know, three or four day a week split or so, or maybe up to six. How do you know when a muscle is ready to be challenged again? I've heard, okay, every 48 hours is, you know, protein synthesis increases and then we'll get into this and then it drops off.

But frankly, if I train my legs hard, I can get stronger from workout to workout, or at least better in some way, workout to workout, leg workout to leg workout, training them once every five to eight days. If I train them more often, I get worse. So whatever that 48 hour to 72 hour thing is, somehow my legs don't obey that, but, you know, or maybe something else is wrong with me, but I'm sure there are many things else wrong with me, but how do you assess recovery at the local level, meaning at the level of the muscles?

So we'll talk about soreness and getting better, stronger, more repetitions, et cetera. And then the systemic level, the level of the nervous system. And I'd love for you to tell us about the tool that, again, I learned from you, which is actually using a physical scale, because it turns out this is that it will let you tell what the tool is, but that tool is also actively being used for assessing cognitive decline and cognitive maintenance and cognitive function in people with Alzheimer's and dementia.

Dr. Justin Marchegiani Makes total sense, makes total sense. I, alright, so regarding the first part of the question, like, you know, how do you, how would you kind of dictate when a muscle's recovered? So I do think that what you're experiencing is totally real, that different muscles recover at different rates.

And I've always been so fascinated by this concept, I've talked about internally with my team, but like, I feel like what we really need, the holy grail to training is going to be when we're able to crack the code on an individual basis when a muscle is recovered, and that is going to dictate its training schedule.

And the fact that you might have a bicep that could be trained, you know, via a pulling workout, a regular bicep dedicated workout, forget the split at the moment. You might have a bicep that's able to be trained that can be trained again the next day, you know, and then the next day, and then maybe you need a day off after that, but like, you know, and that can vary from person to person for sure, and it can vary from muscle to muscle in that person over the course of time, as you mentioned, because the systemic recovery is going to impact all those muscles anyway, but let's say you're systemically recovering, every muscle itself is going to have a, you know, a recovery rate, and I think what's fascinating is that when you talked about before we like to train in this week or we have like the way our mind looks at training, well, if that was the case with the biceps, that bicep is a slave to the rest of your training split, you know, where it's like, why does it have to be also at the end of every eighth day or, you know, or whatever when it might respond better to something much more frequently, and your legs are also being thrown into that mix.

There's a Mike Mencer concept where he's like, you know, training, you know, one set and be done for 14 days. I mean, you know, there's such variability between muscle groups, and you're linking them all together. I think that coming back and using muscle soreness as a guideline for that is one of the only tools we have in terms of the local level, you know.

We don't really have, you know, being able to measure, let's say, CPK levels inside of a muscle would be amazing, you know, at a local level to see how recovered that muscle is, but that becomes fairly invasive, at least to my knowledge, it becomes fairly invasive. So what are our tools?

I mean, I think that at the basic level, that's the one that most people can relate to and easily identify and then use that as a guideline, and if you're training when you're really sore, it's probably not a great idea, and it's probably a good indication that that muscle is not recovered, but at least hearing what you and I are saying here might be a comfort to the person to say, "Yeah, it is possible that it's not recovered, just because 48 hours is the recommendation, and just because research points to muscle protein synthesis needing a restimulation, well, maybe not.

Maybe you're not necessarily there yet, and for that muscle, you're not there yet." So it's all really interesting stuff, but as far as the systemic, you know, recovery, I think there's a lot of ways, you know, people talk about resting heart rate measured in the morning, all different kinds of, you know, core temperature and things like that that might become altered in a state of non-recovery, but grip strength is very, very much tied to performance and recovery, and when I was at the Mets, we used to actually take grip strength measurements as a baseline in spring training all the time.

Now, obviously, as a baseball player, you're gripping a bat, you're a pitcher, you're gripping a ball. You know, having good grip strength is important, so if we've noticed somebody had a very weak grip, it's just a good focal point of a specialized training component for the program. Dr. Justin Marchegiani Would you do this every day with those guys?

Dr. Tim Jackson No. We would do—in spring training, we'd do sort of a baseline entry-level measurement, and then we would measure it throughout the season, maybe once every two weeks or three weeks, and, you know, the idea there was to, you know, manage the recovery, measure the recovery. But I just gave it away, you know, to determine overall recovery, your grip strength is pretty highly correlated, so we have found that with one of those scales, those old-fashioned bathroom scales at like Bed Bath & Beyond or wherever you can get, which, by the way, almost impossible.

I believe Jesse and I were searching for the last scale to put in that video, and we almost couldn't find one because everything is like digital, and everything, you know, it's like this. I'm looking at the old-fashioned dial controls. Dr. Justin Marchegiani It's like old Macintosh computers. There's a huge market for them, and old phones.

Kids, keep your phones now. In 30 years, the lame phone now will be worth a lot of money. So, you know, I wound up, you know, finding one and it's a great tool for just squeezing the scale with your hands and seeing what type of output you could get.

I think we all can relate to this when you just visualize. Imagine the last time you were sick or just try this, you know, the next time you wake up in the morning. When you first wake up in the morning, you're still groggy, try to squeeze your hand. Try to make a fist as hard as you can.

You're going to sit there angry at your fist because it won't contract as hard as you know it can. You don't have the ability to just create the output, and that is because in that state, you're still sleepy. You're still fatigued. You know, you're not even awake at the whole level at this point.

Well, that is still an actual phenomenon that happens that, you know, a lack of recovery or lack of wakefulness or whatever you want to say is going to lead to a decreased output there. So, when you start to measure that on a daily basis, you can get a pretty good sense of where you're at.

I think when people start to see a drop off of 10% or so or even greater of their grip output, you really should skip the gym that day because I don't think there's much you're going to do there that's going to be that beneficial, even if it is the day to train legs or whatever day it is.

I love this tool. It's simple. It's low cost. You can't find such a scale. I guess you could also find one of those grippers that, and you can do this in a very nonquantitative way, but better would be a scale where you could actually measure how hard you can squeeze this thing at a given time of day.

It draws to mind just a little neuroscience factoid. In the world of circadian neurobiology, one of the consistent findings is that in the middle of your nighttime, you know, they'll wake people up and they'll say, "Do this test." In the laboratory, they use a different apparatus, but it's essentially the same thing.

In the middle of the night, grip strength is very, very low. Mid-morning, grip strength is high, and as the body temperature goes up into the afternoon, grip strength goes higher and higher and higher, and then it drops off. There's a circadian rhythm in grip temperature, so you probably want to do this at more or less the same time each day if you're going to use it, but I think it's brilliant in its simplicity and its directness to these upper motor neurons because that's really what it's assessing.

Your ability, again, it's about the ability to contract the muscles hard. If you can't do that, you're not going to get an effective workout. They also, I mean, there certainly are more sophisticated tools, too, as a PT. We have hand-grip dynamometers, and we can measure one side at a time, too.

I'm getting a little bit blinded by the fact that both hands are squeezing into that scale, and I don't get really a left-right comparison, but even at that level, that could give you a little bit more detail, but that comes with a cost. Those are pretty expensive devices, but if it's, listen, if you were an athlete, you know, the 200, 300 bucks it costs to have one of those would be well worth, you know, the added investment.

You know? And I'm sure some of our listeners are going to want one, too, because there are a lot of tech geeks out there. Not tech industry geeks, but people who like tech gear. What's it called again? It's a hand-grip dynamometer. Hand-grip dynamometer. Dynamometer. Dynamometer. Said by Jeff with a great East Coast accent and by me in a terrible botched West Coast version.

Thank you.