Transcription
Connective tissue is something that we have all heard of, and it is extremely important for your health. Think for a second about how much suffering comes from things like bad knees or back pain or neck pain or arthritis. All of those are related to connective tissue, but I don't think many people have actually looked deeply into connective tissue before.
You already know about tendons and ligaments and bone, maybe even fascia, and maybe you know that they are made mostly of collagen, but what actually is collagen and how is it organized into these different structures like tendons and bone? And if you're dealing with like joint pain or a tendon injury, what might be able to help with that? We're going to get into all of that in this video. I want you to come away from this understanding what connective tissue is and how you can take better care of your connective tissue health.
Connective tissue is one of the four main tissue types along with epithelial tissue, muscle tissue, and nervous tissue. Epithelial tissue covers surfaces and lines cavities like skin, it lines your gut, it lines your blood vessels. Muscle generates force through contraction, and nervous tissue transmits electrical signals around the body. Connective tissue is very important because it provides structural support. It basically makes up the physical architecture of the body. It provides force transmission, so tendons convert muscle force into movement by pulling on bones. It provides shock absorption and load distribution. Cartilage, fat pads, and fascia are what do this. And connective tissue even has metabolic roles, so adipose tissue or fat tissue is a kind of connective tissue and it acts as an endocrine organ. Bone marrow produces blood. Many connective tissues also contain resident immune cells, so there are lots of functions that connective tissue does and different types of connective tissue.
And most sports injuries are not actually muscle injuries, but rather connective tissue injuries. You see guys who are taking steroids, they tend to get injured more often, things like bicep tears and pec tears, because their muscle grows faster than their connective tissue can keep up with. So there is a mismatch, and when they lift really heavy weights, their muscles are capable of it, but their tendons and their ligaments are not necessarily ready yet, so they are more susceptible to tearing. And this is because of the different structural features and like blood supply of muscles compared to tendons.
And besides sports injuries, a huge part of what we subjectively experience as aging is connective tissue degradation, like bad knees, bad hips, back pain, neck pain, a lot of tightness and stiffness. So we really want to keep our connective tissue in good health. And you're going to learn how to do that throughout this video.
Unlike the three other types of tissue that I mentioned, connective tissue is defined more by its extracellular matrix rather than its cells. In epithelial and muscle tissue, cells are quite tightly packed together, and it's the cells themselves that do most of the work, most of the job of those tissues. But in connective tissue, the cells are a bit more sparsely distributed, and most of the tissue's volume is extracellular. It is stuff that is outside of the cell, and the cells' jobs are mainly just to make and maintain and remodel this extracellular material. But connective tissue is made up of both of those two components, cells and extracellular matrix.
In terms of cells, there are many different types of cells in connective tissue like fibroblasts, which are the generalist builders that secrete collagen and ground substance in most soft connective tissues. Chondrocytes maintain the cartilage matrix. Osteocytes, osteoblasts, and osteoclasts build, maintain, and remodel bones. Adipocytes store lipids or fats, and they also secrete hormones like leptin and adiponectin. Tenocytes maintain tendons, and then there are resident immune cells like macrophages and mast cells, which live throughout connective tissue and form part of the body's immune surveillance network.
And then, other than cells, there is the extracellular matrix, which is the real star of the show in connective tissue. And extracellular matrix is made up of two things, ground substance, which is the gel-like medium that fills the space in between cells and fibers. Ground substance is mainly water, and the water in ground substance is what allows connective tissue like cartilage to resist compression. Because of the physical properties of water, it resists compression. Ground substance is also where diffusion happens, so like nutrients and gases and waste products move in between cells and blood vessels through this medium of ground substance. So being hydrated is very very important for ground substance. That is something important I want you to take away, hydration.
And the other part of the extracellular matrix is fibers such as collagen, which is the most abundant protein in the human body, and it provides tensile strength or pulling strength. Collagen has a glycine every third amino acid residue in its structure, and the other two amino acids are usually proline and hydroxyproline, but it can be many other amino acids. The important thing is that every third amino acid is glycine. I will speak a bit more about that later. Collagen has got a triple helix structure, which is assembled into fibrils and then into fibers. And this structure makes it extremely strong in tension. There are at least 28 types of collagen, but the most important ones for us are type 1 collagen, which is found in bone, tendon, skin, type 2 collagen, which is found in cartilage, and and type 3, which is found in reticular fibers, and you see it in early wound healing.
Collagen is not the only fiber, though. Another major type of fiber is elastin, which provides recoil and allows the tissue to deform and then snap back into its original state. It's found in arteries, uh lungs, skin, certain ligaments, tissues that need to deform, stretch, and then come back to normal. So like you can pull on your skin and it will return to its normal shape and position because of elastin. And the third type of fiber is reticular fibers, which are fine type 3 collagen networks and they form the scaffolding of organs like liver, spleen, and lymph nodes. So they're kind of like a mesh uh scaffolding network.
So those are the different key components of connective tissue. There are cells which make the extracellular matrix and the extracellular matrix itself is made up of ground substance and fibers like collagen, elastin, and reticular fibers. And the different types of connective tissue are basically classified by the proportion of ground substance and different fibers and then how they are organized like their orientation. There are loads of different types of connective tissue and it can be very easy to just get lost in the weeds with all of these. So I tried to avoid that and keep it fairly relevant to real-life stuff that you'll be interested in.
There are two big families of connective tissue. There is connective tissue proper, which is generally the soft stuff, and then specialized connective tissue like cartilage, bone, and blood. Starting with connective tissue proper, there is loose connective tissue, which has more sparse fibers, lots of ground substance, and many different cell types. It is soft, it's pliable, and it's well vascularized. And its main job is packing material, acting as a diffusion medium, and immune surveillance. Examples of loose connective tissue are areolar tissue, adipose tissue, and reticular tissue, which, like I said earlier, forms the internal scaffolding of lymph nodes, spleen, bone marrow, and liver.
Then there is dense connective tissue, which is dominated by collagen fibers and it has less ground substance and fewer cells, and it's built more for mechanical load. Dense regular connective tissue is collagen fibers arranged in parallel bundles like tendons and ligaments, and these provide maximum tensile strength along one axis, like one direction. This is the one that most people are probably thinking of when they think about connective tissue. Uh dense regular connective tissue like tendons and ligaments are poorly vascularized. They don't have very good blood flow, and that is why they heal slowly. We'll talk a bit later about how to strengthen and help to heal tendons and ligaments. Dense irregular connective tissue is a meshwork of collagen fibers, which resists tension from multiple angles at once, like in the deep layers of the skin, the joint capsules, and the fibrous coverings of organs. And then elastic connective tissue is a kind of dense connective tissue, which you find in the walls of large arteries, in lungs, and in specific ligaments.
Moving on to specialized connective tissue, there are a few types. Cartilage is type 2 collagen embedded in a proteoglycan-rich matrix that binds huge amounts of water, and this water is what allows cartilage to resist compression. So, like I said earlier, hydration is very important for your cartilage. Cartilage has no blood supply of its own and no nerve supply, so nutrients can only reach cartilage through uh diffusing through the matrix. And this means that cartilage heals very poorly, even worse than tendons and ligaments. There are a few types of cartilage like hyaline cartilage, which makes up the articular surfaces of synovial joints like the inside of your knee, so you obviously want that to be well hydrated and in good working order. Elastic cartilage has lots of elastin as well as collagen, so it's very flexible and springy. This is what like your outer ear is made of, so you can fold your ear like forward or down and it will quickly pop back into place, right? And that's because of elastic cartilage. And then fibrocartilage is what you find in the intervertebral discs, the menisci of the knee, the labrum of the shoulder and the hip is built to handle tension and compression. So, as you can imagine, we want this to be healthy to avoid things like disc degeneration and knee problems.
Another type of specialized connective tissue is bone, which is a type 1 collagen matrix mineralized with hydroxyapatite. You might have seen toothpaste that contains nanohydroxyapatite, and bone is basically made largely of that stuff. So you are remineralizing your teeth when you use that nanohydroxyapatite toothpaste. In bones, collagen provides the tensile strength and the mineral hydroxyapatite provides compressive strength and rigidity. Bone is constantly remodeled throughout life. Compact bone is the dense outer shell of bones, which makes up about 80% of your skeletal mass, and then spongy or trabecular bone is the internal meshwork of bony struts. It's very lightweight, but very strong. Spongy bone also houses red bone marrow, which is where blood cells are made. And then, blood and lymph themselves are also a specialized connective tissue because they are cells suspended in an extracellular matrix. I won't spend any time on those two today.
So, how do we make sure that our connective tissue health is on point? Connective tissue is very much a living tissue, and it can adapt to its environment over time just much more slowly than muscle. The two main inputs that connective tissue responds to are mechanical stimulus and nutrition. And if you can get both of these right consistently for a long time, you can make your connective tissue stronger, healthier, and more resilient. And if you neglect either of these two, you can end up getting injured.
So, let's start with mechanical stimulus. The basic principle is mechanotransduction. So, cells sense mechanical load, and they respond by remodeling their matrix, laying down more collagen, organizing it better, making the tissue more better adapted to the load that's being placed upon it. And without mechanical load, the cell will downregulate collagen synthesis, and the matrix will degrade. So, being sedentary is disastrous for your connective tissue health. You have got to keep moving and keep lifting. Bone remodels in response to the loads placed on it. This is called Wolff's Law. So, the trabeculae in bone align themselves along the line of mechanical stress. And Davis's Law is the soft tissue equivalent. So, connective tissues remodel themselves according to the demands that are imposed upon them. So, connective tissue can adapt to mechanical forces over time, but this happens much more slowly than in muscle, on the scale of months or even years rather than weeks. And this is mostly because collagen turnover is a lot slower than the contractile proteins in muscle. You have to be very patient with like tendon adaptations, for example. And like I said earlier, this is why you see guys on steroids getting injured more often because their muscle growth outpaces their tendon adaptations. So, the tendons just can't keep up, and they snap.
So, what can you actually do in terms of mechanical load to help your connective tissue health? Heavy slow resistance training, first of all. Basic heavy lifting through a full range of motion with very heavy weights, those reps are going to be by nature slow reps, and that is good for connective tissue. Also, long duration isometrics, like 30 to 45 seconds at a high intensity, is good for connective tissue. Heavy eccentrics as well. So, slowly lowering a heavy weight. Progressive overload builds muscle, and it also builds connective tissue adaptations, just much slower. You have to be much more patient with tendon and ligament adaptations. Very small consistent increases in the stress over time. And bone needs impact and axial compression, not just tension. So, heavy compound lifting like squats, deadlifts, and overhead press loads the skeleton axially. That's good. And then, short bouts of impact like sprinting, jumping, and plyometrics also trigger bone growth responses. Ideally, you have both of those things, like heavy lifting and then some kind of impact.
So, what causes connective tissue to actually break? Well, prolonged immobilization, like I said, being sedentary is terrible for your connective tissue. Also, sudden spikes in loading after detraining. This is a classic cause of injury. Guys will take months or years off the gym, and then they'll come back and think that they can just start off where they left off last time, and they end up doing more than their connective tissue is capable of handling. Also, chronically overloading your body without leaving room for recovery uh will increase your risk for injury. Corticosteroid injections weaken your tendon structure if you repeatedly use those. And then, smoking impairs collagen synthesis. Basically, you should lift heavy, do some sprints and jumps and plyometrics, acknowledge the fact that tendon adaptations take longer than muscle, be very patient with it, don't jump straight into like super heavy weights and super hard sprinting and jumping, really high impact stuff. Build up to it gradually. Avoid long gaps in your training, and include both slow tension work for tendons and some impact work for bones.
And the other main thing is nutrition. You can't build your extracellular matrix if you don't have the raw materials to make it with. Connective tissue is largely made of protein, so you need lots of protein and amino acids in your diet, somewhere around 1.6 to 2.2 g of protein per kilogram of body weight every day. That's like 0.7 to 1 g per pound of body weight. And especially, collagen is the most important protein for this. Collagen is made of glycine and are mostly proline and hydroxyproline. So, you need to make sure that you're eating foods that contain those amino acids. And this is where a lot of people go wrong. You shouldn't just be having muscle meats like steak or chicken breast or like whey protein or eggs. Those are great, but you also need to be including more collagenous cuts like lots of stews and broths that are slowly cooked for hours to release those amino acids into the broth. Things like skin, meat on the bone, oxtail, lamb neck, even chicken feet. You might want to take collagen or gelatin to get these amino acids directly. Technically, taking 10 to 15 g of hydrolyzed collagen or gelatin about 30 to 60 minutes before your training will be ideal because when you train, blood flow to those tissues, the tendons and ligaments, is elevated, so you can deliver those amino acids to the target muscles more effectively.
And alongside your sources of collagen, take some source of vitamin C because vitamin C is required for collagen synthesis. This is why sailors got scurvy because they didn't have vitamin C, so they couldn't make collagen, and their connective tissue started to break down. So, they would have weak blood vessels, their skin would start breaking down, wounds wouldn't heal properly, and they'd get gum disease. All of those things require collagen. Virtually everyone today gets enough vitamin C, but if you want to get the most out of your collagen and connective tissue health, take some vitamin C sources with collagen, like citrus fruits, strawberries, or bell pepper. There is the concern of vitamin C blunting the positive adaptations that you get from training. So, I don't recommend taking big doses of isolated vitamin C supplements really close to your training sessions, even though that would maximize collagen synthesis. I think just generally getting a good amount of collagen and vitamin C throughout the day from mostly whole food sources will be fine.
I like to supplement glycine as well. That is, as I said, every third amino acid in collagen is glycine. So, glycine is really good for connective tissue health and also sleep as well. There are some other important minerals involved, like copper, which is required for lysyl oxidase, which is the enzyme that cross-links collagen fibers. Zinc is required for matrix metalloproteinases and general protein synthesis. And manganese is a cofactor for glycosyl transferases involved in proteoglycan synthesis, which is a part of the extracellular matrix. Other important nutrients are vitamin D, which is very important for bone mineralization, and it's also involved in soft tissue health. Vitamin K2 makes sure that calcium gets directed into bones rather than soft tissues like arteries. This is why everyone tells you to take vitamin K2 with vitamin D so that the increased calcium that you get from vitamin D will be directed into your bones rather than hardening your arteries. And of course, calcium and magnesium are part of the bone matrix.
Avoid using nonsteroidal anti-inflammatory drugs around training because they blunt the inflammatory signaling that drives connective tissue adaptation. Inflammation is part of the remodeling process. It is not just a nuisance. And if you block it too much, then you're just not going to get the adaptations in your connective tissue or your muscle that you want. And you need to stay well hydrated because the ground substance is largely water held in place by proteoglycans. Dehydration reduces the mechanical quality of cartilage and intervertebral discs. So, you need to hydrate yourself not just with plain tap water, ideally, more like mineral water, milk, orange juice, broth, juicy fruits, coconut water, things like that.
So, to summarize the nutrients, hit your total protein, get lots of collagen along with vitamin C. Basically, eat a varied whole food diet to cover your minerals. Don't use nonsteroidal anti-inflammatory drugs all of the time, and don't chase exotic supplements before you have got these basics dialed in.
So, a quick practical summary for you to take away and start applying. Lift heavy weights and consider doing some isometrics or heavy eccentrics, and build up to doing some high impact work like jumping and sprinting and plyometrics. Eat more collagenous foods like stews and broths or meat on the bone. Consider taking 10 to 15 g of collagen 30 to 60 minutes before training. Get enough protein overall, and just have a varied nutrient-dense diet, and maybe supplement glycine. And make sure you have vitamin C with your collagen sources.
Hope you enjoyed this video, and you know more about connective tissue now. I will be doing more videos on this topic, like specifically videos for tendons and ligaments, a video on bones, maybe fascia, maybe a more in-depth video specifically about nutrition for connective tissue. So, stay tuned for all of those. In the meantime, I will be writing some emails about this topic over the next few weeks, so subscribe to my email list and keep an eye out for those. You'll also get a free 3-day per week hypertrophy program that is basically the best way to maximize muscle growth in 3 days of full body training per week. The link is in the description to sign up to that email newsletter and get that program and my exclusive email content. Let me know what connective tissue-related topics you want to see in the comments. Thank you for watching, and I will see you in the next one.