We’ve been seeing lots of questions about un-training and muscle loss lately… on reddit, social media, in our DMs. Not sure why. But it’s one of those things where the stars have aligned to point an arrow at this topic, so let’s get fuckin’ nerd. Un-training: what is it, how does it apply to you, and how do you prevent it? Ssgo!


First of all, the formal name is “principle of use/disuse.” We’ll call it “disuse” for short. FYI: If you Google “un-training,” you’re gonna find a wide assortment of things that have nothing to do with fitness. We will use the terms interchangeably today, just so you know. 

  1. The Principle of Use/Disuse says that when it comes to fitness, you do actually  “use it or lose it.” This means that your muscles hypertrophy with use and atrophy with disuse. This also explains why we decondition or can lose muscle when we stop exercising.
    • Disuse of muscles can lead to atrophy and muscle wasting, if you’ve ever been in a cast, you know all about this. Remember how shrively that body part looked after being immobilized?
    • Physical inactivity also leads to nervous system changes: slower mental processing, problems with memory and concentration, depression, and anxiety. This is why fitness is so good for your brain.


There are two departments your gains can depreciate: strength and cardio. 

  1. Strength – first let’s talk about what happens in the first two months of lifting weights, you think you’re having amazing gains but it’s nothing more than your central nervous system fine tuning itself, there are no real muscular adaptations that have taken place yet… this process can take 2-8 weeks to get into full swing.
    • Your body has two types of muscle fibers, slow twitch and fast twitch. We’ve talked about them quite a few times, so we aren’t gonna dig into them right now, hit the search bar at meathead test kitchen dot com to find those show notes.
    • It can take years for muscles to build, and this is why people get so scared when talking about disuse… nobody wants to watch their gains diminish, but sometimes it be like that so here’s what happens.
      • It takes about sixteen to twenty sessions (depending on who you ask) for hypertrophy to start if you’re new to lifting.
      • On the flipside of hypertrophy there is atrophy, and it starts happening when you show your body it doesn’t need those muscles anymore (you quit lifting). If you’re eating well, your body won’t make all your muscles disappear.
      • If you have surgery or an injury, you will have accelerated levels of muscle atrophy due to immobilization.
    • Let’s look at the numbers, some athletes will start to see 5-6% loss in muscle density after three weeks. If you’re a powerlifter or olympic lifter, you could see as much as 35% muscle loss in 7-8 months. 
      • Let’s talk about this quick, because it sounds super drastic and it is. Let’s look at how these athletes train though, they have very detailed and aggressive training plans based on pushing up their 1RM for the competition platform. It makes sense when you think about it, but seeing that large of a percentage definitely is startling.
    • The longer you go without, the more you lose… but the fitter you are, the longer they last. So again, if you’re dealing with an injury or illness, please don’t stress it too terribly much. If you have some foundation of fitness before the disuse happens, you will have less mountain to climb. 
  2. Cardiovascular – cardio works your muscles too, just not as much as strength training does. So like, when you start running, at first you’ll see gains in your legs, but they’ll drop off to a plateau pretty quickly because cardio works on energy production, the anaerobic and aerobic systems.
    • The first question people ask is “how fast does it go away?” and the answer to that is, “it depends.”
      • If you’re just getting into fitness and drop off for a while, your gains will go away quicker than someone who has been consistently training for 5 years that took a month off from lifting.

Let’s talk about what happens when you stop training after years of doing it, you’re going to lose your endurance and VO2max pretty quick… if you’re a runner that’ll equate to minutes off of your usual times within a few weeks.

  1. Why is this happening? Your body is dialing back red blood cell production because it doesn’t need as much currently. Our bodies, when functioning properly and excluding fat cells, generally don’t make extras of stuff just to have it lying around.
    • Your body makes millions of red blood cells every day, so it’ll get back to it’s pre-training levels in around a week.

There are other ways that disuse can fuck you up, and it’s something that really needs to be talked about in a conscious way with some empathy… chronic pain and inactivity.

  1. This is rough territory to navigate, because chronic pain is fucking miserable. While it sounds counterintuitive to want to move your body when everything hurts, training your muscles helps SO MUCH in reducing chronic pain.
    • Personal experience: I used to have really bad back pain because I have boobs, lots of people with boobs experience this garbage every day, it makes your lower back so angry.
      • I started weight training, and within the first year… not only did my boobs start to shrink (bonus!), but my posture improved dramatically, and my back pain was gone.
      • Now I’m not saying this is going to be the exact scenario for everyone, your mileage may vary… BUT if you have a solution to your pain problem that doesn’t avoid medication or surgery, why wouldn’t you wanna give it a shot?
  2. Someone listening totally just scoffed at everything Sadie said and that’s fine, we have receipts in the show notes at meathead test kitchen dot com… if you suffer from chronic pain and the idea of fitness literally makes you want to cry, talk to your doctor and/or physical therapist, and they can get you headed in the right direction.


There’s no big showy payoff for an answer here. You already know. You prevent un-training by being consistently active. 

  1. Find a hypertrophy plan you enjoy and dig into it. We’ve got a few at meathead athletics dot com if you’re shopping for a new training plan.
    • We didn’t mention it earlier, but we’ve mentioned it many times before… lifting weights increases your bone density, and if you’ve got ovaries and are in your 20s-30s, start lifting. Osteoporosis is a ho you don’t wanna fuck with.
  2. Get active if you aren’t already. It doesn’t matter WHAT you do. Go for a walk, work in the yard, play with your kids, take your dog to the park… just go move. You GET to move every day, please don’t take that shit for granted.






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