For the sciency people, here are the science notes mentioned in the video:

As mentioned, your vagus nerve innervates your organs and viscera and plays a big role in the functioning of your immune system. The vagus nerve connects to the insular lobe of the brain where a lot of this information is processed. A portion of nerve endings in your musculature and fascia communicate to the insula and other parts of the brain via C-Fibers and this vagus nerve pathway.

0:01 - Intro

Hello again, I'm Shane from MATRIX. I'm back again with another stress-relieving, immune-supportive tip for you during this COVID-19 outbreak.

0:11 – Muscle Squeeze & Vagus Nerve

As I mentioned yesterday, we're switching our perspective a little bit, and focusing more on the immune system and working on the immune system via the vagus nerve -- which is a big long nerve that innervates most of our gut. The interesting part of that, is the part of the brain that the vagus nerve connects to the most is something called your Insula. It lives deep in the middle of your brain and we are able to affect that by using our muscles. Now, I'm going to put the details of how all this anatomy works in the text below so you don't have to listen to me tell all to you. But what it means is that we're going to be working on strengthening our muscles today to affect our insula, to affect the vagus nerve, to help our immune function. We'll be doing this today and tomorrow.

1:03 – Contraindications

Today's workout is for the major muscles of the upper body. Tomorrow will be for the arms and the legs. I hope you enjoy that. What you need to know about doing these exercises is that they should be very, very safe for everybody to do. But if you do have any open wounds, broken bones, those types of things, don't do them. Just use your common sense.

1:26 – How to do the Workout

You do not need any weights; you just need your body. The way we're going to be going through this is I'm going to show you once on each side how to do the exercise. But, if you're actually going to try and do some of this work and build some strength with it, you want to be thinking about doing three to five repetitions of at least three to five seconds for each [side], on each and every single muscle group that we work through.

1:52 – Why We Squeeze the Muscles

These are called muscle contractions. And what we're working on is creating isometric -- or non-moving -- strength over a full range of motion. So that you can really learn how to recruit all the muscle fibers. So that you can create as much force as possible with your muscles.

2:11 – The Basic Pattern

There's a specific pattern that we're going to go through to do this. For each and every muscle, the first thing we're going to do is open up to a full range of motion. Then we'll come across into a completely closed range of motion for that muscle and squeeze as strong as we can. After we finish the squeeze, we're going to go back open and stretch it out again. That's one repetition. And again, you'll be doing three to five of maybe three to five seconds. But together, we're only going to go through one for each part of the body.

2:44 – Side Notes on the Squeeze

With all that being said, the last piece of information you need to know is that I'm going to give you some specific movements to work on. But it's not important. The goal here is to squeeze your muscle and learn how to squeeze the muscle that you're trying to squeeze. One of the best ways to figure that out is -- while you're squeezing it -- is to feel your own body. Actually feel that the muscle is squeezing. If you notice spots that aren't tightening the way you might like, figure out how to squeeze them more. Alright, so are you ready to give it a shot?!

3:14 – Chest (Pec Major) Squeeze

We're going to start with the chest. The chest [muscle] runs from our inner arm across and into the sternum. The muscle is called our pec. To work this muscle, we're first going to stretch it. Taking the arm as far away as possible. You'll notice that I roll the palm up as I do. Then, as I bring the arm across the body, I'm going to rotate the arm in. And I'm trying to bring my arm bone near the armpit, into the center of my chest. I bring it across and I squeeze. Feel the muscle, make sure that it's getting strong. If it's not, try to tighten it up. And then release and stretch. As you're doing that in the beginning, think about maybe only hitting a squeeze of about a 3, 4, 5 out of 10, so you don't hurt yourself, or get too sore. But as you progress, the whole goal is to work up towards that 8, 9, 10 out of 10 level of squeeze. Let's try it on the other side. We again open the palm up. Stretch out towards the side. You should feel a nice stretch across your chest. And now as you roll the arm back in, you're trying to bring the arm into the sternum. Squeezing strong. And ideally, you're feeling the squeeze just in the chest muscle itself, not in a whole lot of other body parts. And then relax and open it back up. If you are feeling the tension in a whole lot of other body parts, that's okay. It's normal. However, your goal as you practice this is to get better and better and better at isolating.

4:45 – Back (Rhomboids) Squeeze

The counterpart of the chest is the back. It's a muscle that runs from the edge of your shoulder blade, right over and in toward the spine. So, it's the exact same thing we just did, but in reverse order. As we go to stretch, we're going to roll the thumb in and bring the arm around to the front of the body. Think about dropping your shoulder blade down and trying to let it slide out and around the ribs. That should create a nice stretch across the back, here. From there, all you have to think about is the shoulder blade moving into the spine. And then drawing the shoulder blade a little bit up. And you should be feeling the squeeze right through the musculature. Right here. Feel it. And then as you release, the shoulder blade drops and rolls back around the ribcage. Trying that same thing on the other side. Start with your stretch. Shoulder blade moves around the body and drops down. That should create a nice stretch through the upper back. Then from there, draw the shoulder blade in towards the spine. Let it slide up a little bit towards the base of the head. Feel the squeeze, right in through here. Not so much up in here. If you're up there, you've gone a little too high [with the shoulder blade]. And then again, release and stretch.

6:02 – Shoulder Squeezes

From the chest and the mid-back, we're going to move on to the shoulders. Now the shoulders are pretty complicated. They do a lot of different things. And we have one big group it's called the deltoids. But it's broken up into three parts that we're going to work specifically.

6:17 – Front (Anterior Deltoid) Squeeze

So, for this one, we're going to work the front of the shoulder first. You're thinking about taking this little triangular piece at the base of the arm, rolling it to the outside and drawing the arm back. As you do, hopefully, you'll get a little stretch in the front of the shoulder, here. Once you've found the stretch, bring the arm forward. Important! Hold the shoulder blade in place. Roll the bicep in. And if your shoulder blade is held down your arm is probably only going to come up about this high. You're trying to pull this part of the arm right in towards your collarbone. Feel the squeeze. And then release. Opening that back up. Same thing on the other side. Remember, bicep rolls out. Arm pulls back. Feel the stretch through the front of the shoulder. Then coming into our full range of motion the other way. Roll the bicep in. Engage the shoulder blade. Try to lift the arm as high as you can. Try to pull this point close to here. Feel the muscle work. And then release Stretch it out again.

7:20 – Side (Lateral Deltoid) Squeeze

Moving on to the side of the shoulders. It's tough to stretch this one because our body is in the way. So, we're just going to let the arm move across the front just a little bit. That's the stretch position. From here, there's no rotation involved. We're again just holding the shoulder blade in place. Pulling the arm off towards the side. Again, if the shoulder blade is still, the arm can only go so high. When we let it go, that's when we get more height out of it. So hold it still and think about the little triangular piece moving in towards your AC joint -- that little bumpy bone that you have on top there. Feel the squeeze. And let it go. Other side. Arm moves across the body to the stretch position. Shoulder blade in place when you draw towards the side. Feel the squeeze as you bring those two points together. Right through the meat there and release.

8:12 – Rear (Posterior Deltoid) Squeeze

Last one for the shoulder is on the backside. This is going to be the opposite of what we did for the front one, as far as the rotations go. The stretch is your basic shoulder stretch. If somebody said to stretch your shoulder, chances are you would do this. That's the position we're looking for. The bicep rolling in and the arm coming across the body. When we go to squeeze back here, again, hold the shoulder blade in place. Start to roll the bicep up and try to bring that triangular piece back into the shoulder blade itself. Find the squeeze, right in the back of the shoulder. And then release, coming back across. Same thing, other side. Stretch. Roll open. Try to bring those two points together. I like to think that my shoulder blade is moving this way, as the arm is moving that way. That's what gives me the best squeeze. And then release and stretch. All right, you should be feeling some work at this point. And you haven't even been doing three to five sets of each. Hopefully you're starting to experience that.

9:18 – Back #2 (Latissimus Dorsi) Squeeze

The last muscle we're going to do today for the upper body is our lat. This is a very big muscle that runs through the side. And if you think of Arnold Schwarzenegger and his big back, those are the muscles that he developed so nicely. This muscle is tricky. There's a lot of pieces to it. So, I'm really going to simplify it for you to try and get you to feel it. It's also one that will tend to cramp. So stay light, around your level of around a three to a five. You're going to want to definitely stick with that one the first couple times you do this. To stretch the lat, think about having your palm facing you. Bring your arm up and across. And do a side bend. Then, underneath, just tuck the pelvis a little bit as you lean away. Because the lat runs from here all the way down to your hip bone. Once you can feel a stretch through your side doing that, come back up to vertical. As you start to rotate [your arm], roll the bicep in. Bring your arm back behind you. You're trying to bring it across toward the other hip. You should start to feel a squeeze up in the upper part here. But to get the lower part -- what I want you to think about doing -- is taking your armpit and bringing it down into your low-back, as you bring your low-back up into your armpit. And as you do that, you should feel a really big squeeze all along the path of that line. It might start to cramp a little bit. If you feel that, just come out of it. And again, take the stretch. Tucking the tail under. Leaning away and reaching with your arm. Doing that on the other side. Again, remember, it doesn't have to be perfect. You're just trying to get the sensation, the feel of it. We lean away. Tuck the tail and stretch. As we come back up, bring your arm behind. Think about bringing your armpit down towards your low-back. Think about bringing your hip up into your armpit. You're even going to lean back a little bit as you do this. Bring all those three points together. Squeeze it. And then release, tuck and stretch away. Ah... all right!

11:32 - Summary

Pretty simple, right? No equipment. Just using your own muscles. But if you actually try this and are feeling it, it's a pretty effective workout. And remember, it's super, super powerful, because not only is it strengthening -- engaging your muscles -- but it's helping stimulate the part of the brain that works with the vagus nerve to help keep your immune system strong and safe. Again, for any of the science behind that, look below. Or you can, of course, join me later today for the Q&A about this if you want to get into any more of those details.

12:03 - Farewell

I hope you enjoyed and check back in tomorrow. We're going to work the arms and the legs.