How Your Bones Change With Exercise

Summary

This educational video delves into the remarkable adaptability of human bones in response to exercise. It illustrates how bones, composed of compact and spongy tissues, dynamically adjust their density and structure under stress. The video emphasizes the importance of both compressive and tensile forces in bone health, advocating for a mix of weight-bearing and resistance exercises. It also introduces key bone cells like osteoblasts and osteoclasts, hinting at the role of estrogen in bone density, which is a topic for future exploration.

Takeaways

• 🏃 Exercise is crucial for bone health, as it stimulates bone tissue to adapt and increase in density.
• 🚀 Astronauts in zero gravity environments experience a decrease in bone density, demonstrating the importance of gravity and movement for bone maintenance.
• 🦴 Bones are composed of compact and spongy (trabecular) bone tissue, with the latter aligning to support the stress placed on bones.
• 🔬 Bone tissue contains both organic (collagen) and inorganic (hydroxyapatite) substances, which provide tensile and compressive strength respectively.
• 💪 Resistance training and weight-bearing exercises are effective for bone health as they apply both compressive and tensile forces on bones.
• 🏋️‍♂️ Consistency in exercise is key for long-term bone health adaptations, as bones constantly remodel in response to stress.
• 🚴‍♂️ Non-impact exercises like cycling can also contribute to bone health, indicating that high-impact activities are not the only way to stimulate bone density.
• 🏃‍♀️ Running and other weight-bearing activities are beneficial for bone health, especially in the lower limbs.
• 🤸‍♂️ A combination of endurance and strength training is recommended for optimal bone health.
• 🧬 Bone cells like osteoblasts and osteoclasts play a critical role in bone remodeling, with exercise influencing their activity balance.

Q & A

How does exercise affect bone density?

Exercise is crucial for bone health as it causes the bone tissue to adapt by increasing its density, changing its shape, and modifying its internal architecture in response to the stress placed upon it.

What happened to the bone density of early astronauts when they returned from space?

Early astronauts experienced a decrease in bone density by as much as 20 percent upon returning from space due to the zero gravity environment, illustrating that bone tissue is constantly adapting to the stress it undergoes.

What are the two types of bone tissue in the human body?

The two types of bone tissue are compact bone tissue, which is the dense outer portion of bones, and spongy bone tissue, also known as trabecular bone, found internally and resembling a sponge in structure.

What are trabeculae and what is their function in bones?

Trabeculae are the tiny beams of bone found in spongy bone tissue. They are aligned in the direct lines of stress that bones experience daily, providing strength and support in the direction of applied forces.

How do bones adapt to exercise through their internal composition?

Bones adapt to exercise by increasing both the organic and inorganic substances within the bone tissue. The organic substance, collagen, provides tensile strength, while the inorganic substance, hydroxyapatite (composed mainly of calcium and phosphate), provides compressive strength.

What types of exercises are beneficial for bone health?

Exercises that push and pull on the bones, exposing them to both compressive and tensile forces, are beneficial for bone health. This includes activities like walking, running, jumping, resistance training, and weightlifting.

Why is consistency important in exercise for bone health?

Consistency in exercise is vital for bone health because it ensures continuous stimulation of bone tissue, which is necessary for the long-term adaptations that increase and maintain bone density.

How does the body respond to different intensities of resistance training for bone health?

For optimal bone health, resistance training should be of at least moderate intensity, where the weight lifted can be managed for six to twelve repetitions. This intensity stimulates bone density increase more effectively.

Can you maintain bone density without high-impact exercises like running?

Yes, you can maintain bone density without high-impact exercises by engaging in activities that still provide a stimulus to the bones, such as cycling or weight training that targets the lower limbs.

What role do osteoblasts and osteoclasts play in the remodeling of bone tissue?

Osteoblasts are responsible for building up new bone tissue by laying down collagen and hydroxyapatite, while osteoclasts break down old bone tissue. Their balanced activity maintains bone density, but an imbalance, such as increased osteoclast activity with reduced physical activity, can lead to a decrease in bone density.

What is the significance of estrogen in relation to bone health and osteoclasts?

Estrogen tends to inhibit osteoclasts, which break down bone tissue. This suggests that changes in estrogen levels, such as during menopause in women, can affect bone density by potentially allowing osteoclast activity to exceed that of osteoblasts.

Outlines

00:00

🏃‍♂️ Exercise and Bone Health

This paragraph introduces the surprising impact of exercise on bone health. Contrary to common belief that exercise primarily affects muscles and cardiovascular health, it also significantly influences bone density and structure. The script uses the example of astronauts experiencing a decrease in bone density due to zero gravity, highlighting the dynamic nature of bone tissue that adapts to stress. The video promises to explore how bones change in response to exercise and the role of various types of physical activity in maintaining and enhancing bone health.

05:02

🦴 Anatomy of Bones and Adaptation

The script delves into the anatomy of bones, explaining the difference between compact and spongy (trabecular) bone tissue. It emphasizes the structural intelligence of spongy bone, where the trabeculae align with the stress lines to provide support. The paragraph further discusses how bones adapt to exercise by increasing density and altering shape and internal architecture. The focus is on the importance of exercises that apply both compressive and tensile forces on bones, which are crucial for stimulating bone tissue adaptation. The composition of bone tissue, including organic collagen for tensile strength and inorganic hydroxyapatite for compressive strength, is also covered.

10:03

💪 Consistency in Exercise for Bone Health

This paragraph underscores the importance of consistency in exercise for long-term bone health adaptations. It introduces the sponsor, Copilot, a fitness company that emphasizes consistent workouts and quality of life changes. The speaker shares a personal experience with Copilot, highlighting the convenience of customized fitness plans and the benefits of having a real coach for accountability and progress tracking. The paragraph also discusses various exercises that can stimulate bone health, such as walking, running, jumping, resistance training, and how these activities create both compressive and tensile forces on bones. The video concludes with a teaser about the role of estrogen in bone health, hinting at a future discussion on this topic.

Keywords

💡Bone Tissue

Bone tissue is the living, dynamic, and adaptable material that forms the human skeleton. It is composed of both compact and spongy bone tissue. In the video, the importance of bone tissue's adaptability to exercise is highlighted, emphasizing how it can change its density and structure in response to physical stress, such as the decrease in bone density experienced by astronauts in zero gravity environments.

💡Bone Density

Bone density refers to the amount of mineral content in bone tissue, which is a key indicator of bone strength and health. The video script discusses how bone density can decrease significantly in zero gravity, as seen with astronauts, and how exercise can help maintain or increase it by stimulating bone tissue to adapt and build more density.

💡Compact Bone

Compact bone is the dense, hard outer portion of bones that provides structural support and protection. The script mentions that compact bone can be quite thick, especially in the shafts of long bones like the tibia, and it plays a crucial role in the overall strength and shape of bones.

💡Spongy Bone

Spongy bone, also known as trabecular bone, is the inner part of bones that has a porous, sponge-like structure. The script describes how spongy bone contains trabeculae, which are aligned to support the bone under stress, showcasing the bone's ability to adapt to various forces.

💡Trabeculae

Trabeculae are the tiny beams or structural elements found within spongy bone tissue. As explained in the video, they are not randomly oriented but are instead aligned to support the bone under the stress it experiences, demonstrating the bone's sophisticated response to mechanical forces.

💡Exercise

Exercise is portrayed in the video as a critical factor in bone health, as it stimulates both the increase in bone density and the adaptation of bone shape and architecture. The script emphasizes the need for activities that apply both compressive and tensile forces to the bones, such as weightlifting and running.

💡Compressive and Tensile Forces

These forces are the pushing and pulling stresses that bones experience during physical activity. The video explains that bones adapt to these forces by increasing density and altering their internal structure, which is crucial for maintaining bone health and preventing conditions like osteoporosis.

💡Hydroxyapatite

Hydroxyapatite is a hard, crystal-like substance found within bone tissue, primarily composed of calcium and phosphate. The script highlights its importance in giving bones their hardness and resistance to compressive forces, which is why calcium intake is essential for bone health.

💡Collagen

Collagen is the organic component of bone tissue that provides tensile strength. The video describes how collagen fibers resist being pulled apart, similar to a microscopic rope, contributing to bone's flexibility and resistance to tensile forces.

💡Osteoblasts

Osteoblasts are bone-forming cells that play a key role in the bone remodeling process. The script explains that osteoblasts lay down new bone tissue, contributing to the bone's ability to adapt and increase density in response to exercise.

💡Osteoclasts

Osteoclasts are cells that break down bone tissue, counteracting the work of osteoblasts. The video script suggests that when physical activity decreases, osteoclasts can outpace osteoblasts, leading to a decrease in bone density, as seen in the case of astronauts in zero gravity.

Highlights

Bone is dynamic tissue that constantly adapts to stress and physical activity.

Astronauts experienced up to 20% bone density loss due to zero gravity, highlighting the importance of mechanical stress for bone health.

Bone density can be maintained and increased through exercise, as bones adapt by altering their shape and internal architecture.

Bones are made of compact and spongy tissue, with trabeculae (tiny beams) in spongy bone aligning to deal with daily stresses.

Exercise exposes bones to compressive and tensile forces, crucial for strengthening the bone's organic (collagen) and inorganic (hydroxyapatite) components.

Collagen fibers in bone resist tensile forces, while hydroxyapatite provides strength to resist compressive forces.

Consistency in physical activity is key to long-term adaptations in bone tissue, leading to increased strength and density.

Exercises like running and jumping apply compressive forces, while resistance training (e.g., bicep curls) creates tensile forces on bones.

A simple action, such as bending a bone, creates both tensile and compressive forces on different sides of the bone.

Runners generally have good bone density, particularly in their lower limbs, without much weight training.

Weight training stimulates bones with both compressive and tensile forces, which is important for overall bone health.

Osteoblasts build bone tissue, while osteoclasts resorb old bone; exercise helps osteoblasts outpace osteoclasts, increasing bone density.

Lack of exercise, like in space, allows osteoclasts to outpace osteoblasts, leading to bone density loss.

Bone tissue constantly remodels, even without exercise, through the coordinated action of osteoblasts and osteoclasts.

Estrogen inhibits osteoclast activity, playing a role in bone density, particularly during certain stages of a woman’s life.

Transcripts

bone is some of the most amazing living

and dynamic tissue in the human body but

when you exercise and your body adapts

to that exercise bone probably isn't the

first thing that comes to mind often

when we think of exercise we think of it

affecting things like muscle fat and

even things like the heart and

cardiovascular system so in today's

video we're going to talk about just how

important exercise is for your bones and

how that bone tissue will actually

modify and adapt to that exercise it's

ridiculously amazing so let's jump right

into this Pony anatomical awesomeness

foreign

so let's start with an example that will

help illustrate why this is so important

when we first started exploring outer

space the early astronauts would return

home for their physicals only to find

that their bone density had decreased as

much as 20 percent in some cases now

that was obviously quite alarming seeing

as how they were in Prime physical

condition prior to leaving but this

helped us to learn something very

important in regards to Bone tissue bone

is constantly changing and adapting to

the stress placed upon it so if you

spend an extended period of time in a

zero gravity environment that bone is

going to change and adapt by decreasing

its bone density kind of like I use it

or lose it situation but that also means

that exercise and physical activity

plays a huge role in maintaining and

even increasing bone density exercise

doesn't just cause the bone to increase

its density bone will also adapt by

changing its shape and its internal

architecture so let's take a look at

some of these amazing features of Bones

so we can figure out what's actually

happening with with these adaptations

and changes and of course get into how

muscles and the various forms of

exercise play a role in this if we were

to take a look at a bone in the human

body we would see that that bone is made

up of two types of bone tissue compact

bone tissue and spongy bone tissue

compact bone is the dense outer portion

of all bones so everything you're seeing

on the outside of this bone is the

compact bone and that compact bone can

get pretty thick in the shafts of the

long bone especially if you take a look

at where we cut into this tibia or shin

bone here you can see how thick that

compact bone can get but deep to this

compact bone is the spongy bone and just

taking a look at that picture you can

see kind of looks like a sponge but look

how cool the real spongy bone is you can

see all these tiny little beams of bone

and those little beans are called

trabeculae which actually conveniently

translates to little beam but this is

also why spongy bone is known as

trabecular bone as well now these

tropically what's really ridiculously

awesome about them is that at first

glance they may look that their shape

and their orientation is random but that

is not the case the shape the

orientation the architecture of these

trabeculae if you will they are aligned

in the direct lines of stress that your

bones have to deal with on a day-to-day

basis think how amazing that is just

like somebody building a building with

support beams and Scaffolding your bones

do the same thing and Orient these

little beams to deal with the forces

that your bones get to see on a

day-to-day basis so what types of

activities and exercise helps to

increase bone density and maintain this

architecture and really important what

is it that's inside the bone that is

adapting to these activities as far as

activities and exercises we need to do

things that both push and pull on the

bones or in other words expose the bones

to both compressive and tensile forces

now you might be thinking that seems

like a little bit of an

oversimplification I just need to push

and pull on my bones and I'm good well

this is important because of what the

bone tissue is actually made of and how

this stuff's going to adapt there are

two very different substances inside of

bone tissue an organic substance that

gives bone its tensile strength and an

inorganic substance that gives bone its

compressive strength both of these

substances we want the bone to adapt and

increase more of hence this pushing and

pulling so let's talk about what these

two substances are and then how this

would apply to the exercises if we were

to zoom into bone tissue even between

the cells we would see these two

components or substances that make up

the bone tissue the inorganic substance

would be a hard crystal-like substance

called hydroxyapatite now that's kind of

a funny name but this hydroxyapatite is

made up of mostly calcium and phosphate

that's why calcium is so important to

the health of your bones it's used to

make this hydroxyapatite which gives

bone its hard characteristic and its

ability to resist those pushing or

compressive forces the organic component

of bone is actually collagen collagen

will bond and form this intimate

relationship with the hydroxyapatite and

collagen fibers are these string-like

proteins that resist being pulled apart

and so think of it as this microscopic

rope that can bend and be flexible but

resist that tensile force or being

pulled apart and therefore gives bone

its tremendous tensile strength so when

it comes to the exercises for bone

health none of these exercises are going

to mean much without consistency where

you need to be willing to consistently

stimulate the bone tissue in order to

gain and maintain these long-term

adaptations and with all this talk about

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description below so finally back to

these exercises that could stimulate the

bones with both compressive and tensile

forces so usually how I go about this is

I'll ask students can you come up with

some ideas that would put a pushing or a

compressive force on the bones and

usually the students will answer that

pretty quickly they'll say things like

walking running and jumping and those

are definitely correct answers those

would put a pushing or a compressive

force on the boom obviously running and

jumping mean more intense and creating a

greater stimulus and say like walking

but then I'll say what about a pulling

force can you think of activities or

exercises that would create a pulling

force on the muscle they often will

think a little bit longer about that but

usually come up with things like

resistance training maybe like a pull-up

or a biceps curl and so let's use the

biceps curl as an example and we'll use

my biceps forgive me my I'm not a very

big specimen here but this is where my

biceps is and when the biceps muscle

belly contracts the tendon of the biceps

would attach down to the bone and as

that muscle belly contracts that tendon

would Yank on the bone and create a

pulling force on the actual bum and so

you can see those are pretty

straightforward examples but the

interesting thing about that is it's

actually even easier than you think

very creative to put both a compressive

and a tensile force on the bones and let

me explain why so let's say we're all

out together frolicking in the forest

and we're picking up sticks and breaking

and snapping sticks so instead I'll use

cornelius's radius here thank you

Cornelius and I'm going to bend it don't

worry it's not going to snap Cornelius

is a synthetic skeleton although Jeffrey

over here to the left is losing its mind

because his bone would snap if we did

this but I want you guys to look at that

bone the top part of that bone would be

being pulled apart or under a tensile

force if you could see that whereas the

bottom part of that bone would be under

a compressive or being smooshed together

a compressive Force so apply that to a

biceps curl yes that biceps tendon is

going to yank on the bone there but

think about the weight trying to push

downward this would create that bending

or bowing now granted it doesn't really

Bend because the Bone's strong enough to

resist this but the forces would create

a tensile force on the top and a

compressive force on the bottom also

think about that with something like

running we go to our femurs here notice

that the femurs are actually angled

Inward and that's even a little bit more

dramatic on say like a female pelvis but

because of that angling inward the femur

every time you step it would kind of

create that bowing Force again doesn't

bow in real life because the Bone's

strong enough to do deal with that

usually and we're going to have that

outside of the bone dealing with a

tensile force with the inside of the

bone dealing with a compressive Force so

as you can see the majority of the

activities that you would choose to

participate in in an exercise program

would actually do a pretty good job at

stimulating the bones in both ways so

what do we do with all this information

in the details we just talked about well

one it's pretty cool just to learn more

about the human body but I will concede

I'm a little biased to that but two we

pretty much just went over the idea that

the majority of exercises that you can

choose from will stimulate the bones

with both compressive and tensile forces

so do we really need to get lost in the

details of exercise choices like does it

matter if we do a biceps curl versus a

chin up or say like do we have to

actually pound the pavement with running

or are there other ways to stimulate

this and the answer is there are

multiple ways to do this as you're

probably already guessed and so what the

main focus is is these general

principles now granted you can get

nuanced with different type of exercise

choices based upon strength goals and

other type of fitness goals when it

comes to bone health with muscular

training or resistance training you want

to do something that's at least a

moderate level of intensity so like if

you could curl a weight like 25 times

it's probably not intense enough you

could probably increase the intensity a

bit which would mean increase the weight

and this is still a little bit of a wide

range but I kind of live in this area

like say something that's you could lift

six to even up to 12 times obviously if

you pick a weight that you could only

lift it six times you're gonna increase

the intensity and the stimulus and

obviously kind of build more of go into

that strength training realm but six to

twelve reps you would tend to get a

benefit there with increasing and

maintaining bone density the other

question is would you have to actually

pound the pavement and run does running

provide a stimulus absolutely Runners

who don't lift a lot of Weights will

actually have great bone density in

their lower limbs now ideally I think

it's great to have a combination of both

some sort of endurance training mixed

with weight training now if people don't

love running compare that to say like a

cyclist cycling doesn't create a lot of

impact and pounding on the pavement but

you would be hard-pressed to say find a

cyclist that didn't have good bone

density so we're kind of answering our

question here you don't have to pound

the pavement granted it creates a great

stimulus but you could simulate that

through say like squats deadlifts really

Contracting those lower limb muscles to

pull on those lower limb bones as well

as well as also create that kind of

bending and compressive intensile force

that we talked about earlier today now

also keep in mind if you're going to

kind of lean towards the weight training

area I think again this is good for

everybody you want to balance the whole

body you want to train all the muscle

groups of the Upper Limb the lower limb

as well as your trunk and core muscles

so let's wrap this up with some final

cool details as well as a point of

clarification I just want to be clear

that we know that the bones are

constantly being remodeled regardless of

the amount of exercise you're doing the

bones are constantly having old bone

tissue be resorbed and then new bone

tissue being laid down in its place so

constantly turning over the bone tissue

and there's some really cool bone cells

that get involved in this one of the

cells is called an osteoblast and the

osteoblast build up or lay down new bone

tissue essentially prepare that Matrix

of collagen and hydroxyapatite the other

cell called the osteoclast will actually

resorb or break down bone tissue so you

have these two cell types that kind of

oppose each other so if you think about

it this way the osteoblasts and the

osteoclasts if they're pacing each other

or that their activity matches your bone

density will stay the same say somebody

decides to start exercising though and

the osteoblasts start outpacing the

osteoclasts bone density would go up go

back to that example of the astronauts

earlier

no physical activity where they're not

putting a lot of stress and strain on

the bone those osteoclasts would outpace

the osteoblasts and bone density would

go down so kind of interesting to see

those different cell types and how

they're active throughout this whole

process now one thing that's really

interesting kind of a little bit of a

food for thought or a little teaser for

a future video estrogen tends to inhibit

those osteoclasts and so think about

that from the female perspective as far

as what would happen during a certain

time of their life if estrogen levels

were to go down but we'll save that for

another video and touch on that a little

bit later but thanks for watching

everyone if you're interested in

checking out copilot that link is in the

description below as always we love

reading your comments go ahead and throw

some of those comments in about what you

think estrogen in the osteoclasts

relationship might do like and subscribe

if you feel the need and of course we'll

see in the next video

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