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  1. #1
    Twincities MN kuan's Avatar
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    What is Base Really?

    Before anyone asks, yes, I'm serious. You start thinking things when you're out there at 6am and you're trying to keep your mind off the cold until you've warmed up.

    From what I've read, building a base is building muscles, tendons/ligaments, and bones.

    I also know that ligaments take a long time to heal.

    I also know that "building" means tearing down and repairing.

    Is this what we're doing when building a base, or building anything at all? How about bones?

    I know when we do weight bearing exercise we're building bone density, but how does it happen? Are we simply adding calcium to the bone or are we making small cracks in the bones and building them up again?

    Just wondering, dissertations not necessary but good explanations welcome.

    Thanks all, Koffee, Danno, Terry Morse, etc. You've all been great!

  2. #2
    Killing Rabbits
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    Base is considered zones 1 and 2; refer to the table as to the changes taking place.

    As for bones they go through phases of growth and decay depending on blood Ca levels (ostoclasts and ostoblasts do the work) but cyling is not all that great for bone strength (not load bearing).

    Enjoy.

  3. #3
    Killing Rabbits
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    Clear image here.

  4. #4
    Senior Member DannoXYZ's Avatar
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    Excellent! Seemingly simple questions of "why" always seems to expose the underlying structures of things. I'll tackle the mechanisms behind bone-building and density. Bones do build in density and strength in response to external loads and stresses. The results are similar to building muscle-strength, but the mechanism is different. Rather than tears in the fibres that leaks out cell cytoplasm; some components of which trigger rebuilding, bones actually don't crack.

    Unlike the bones you see outside of the body, like chicken-bones or a T-bone steak, living bone is more flexible and is actually living tissue. There are actual cells in the pores of the calcium skeleton that give bones their structural strength. Under skeletal loading, these cells are squeezed and the rubbing on their membranes triggers receptors on their surface called integrins. The integrins changes a cascading pathway of the Wnt10b protein that determine whether mesenchymal stem cells differentiate into adipose fat cells in the narrow or into osteoblasts. The final stage of IGF-I hormone binding to the receptors of osteoblast eventually develops them into bone cells with a calcium framework.

    So in short, bones respond to stress and they build up to a certain amount of density and strength based upon the stress. The more integrins you stress on the surface of existing cells, the more you stimulate... up to a point....

    In essence, bone-strength is only partially stimulated by base. The primary benefit is aerobic and energy-system development (fat-burning efficiency), along with ligaments and tendons; which responds to repetition and builds slowly. Also pedaling-form, body-positioning and comfort are less tangible benefits of the base/LSD phase. Once you get all those down, then you can effectively work on the muscle and bone-strength, which responds best to higher levels of stress.

    Which is where the weight/strength-training in the gym comes in. Due to the inertia and movement of the bike+rider through the drivetrain, it's really hard to apply a lot of skeletal loading to the bones; the bike moves! Even in the highest gears or climbing the steepest hills, the highest amounds of stress you can apply to the bones is really about 100kg maximum. This will only build them up to a certain density and strength. With weight-training in the gym you can apply loads of 200-300kg easily (and safely) to the bones and build them up to even higher density and strengths. Then when you go out on the bike, you've got bones that can withstand 2-3x as much load as you'll ever apply on the bike... a wide safety margin...

    Here's a good article on the background of structural modeling of bones: Computational Modeling of Bone Adaptation
    Last edited by DannoXYZ; 10-14-05 at 03:01 PM.

  5. #5
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    Quote Originally Posted by DannoXYZ
    Excellent! Seemingly simple questions of "why" always seems to expose the underlying structures of things. I'll tackle the mechanisms behind bone-building and density. Bones do build in density and strength in response to external loads and stresses. The results are similar to building muscle-strength, but the mechanism is different. Rather than tears in the fibres that leaks out cell cytoplasm; some components of which trigger rebuilding, bones actually don't crack.

    Unlike the bones you see outside of the body, like chicken-bones or a T-bone steak, living bone is more flexible and is actually living tissue. There are actual cells in the pores of the calcium skeleton that give bones their structural strength. Under skeletal loading, these cells are squeezed and the rubbing on their membranes triggers receptors on their surface called integrins. The integrins changes a cascading pathway of the Wnt10b protein that determine whether mesenchymal stem cells differentiate into adipose fat cells in the narrow or into osteoblasts. The final stage of IGF-I hormone binding to the receptors of osteoblast eventually develops them into bone cells with a calcium framework.

    So in short, bones respond to stress and they build up to a certain amount of density and strength based upon the stress. The more integrins you stress on the surface of existing cells, the more you stimulate... up to a point....

    In essence, bone-strength is only partially stimulated by base. The primary benefit is aerobic and energy-system development, along with ligaments and tendons; which responds to repetition and builds slowly. Also pedaling-form, body-positioning and comfort are less tangible benefits of the base/LSD phase. Once you get all those down, then you can effectively work on the muscle and bone-strength, which responds best to high levels of stress.

    You sound just like the A&P class I had on Monday, it is a very simplified version of bone growth, and your theory is different from the theory I was taught about excersize induced bone growth, in that osteoblasts are stimulated by electrical activity. You forgot to mention the effect that parathyroid hormone and growth hormone has the ability to stimulate osteoclast and osteoblast activity in the creation of bone matrix. The fact is that bone is constantly being remoddeled, and when osteoblast activity surpasses osteoclast activity bone is made denser, and vice versa, and the bigger you make the muscle attaching to the bone, the bigger the condyles and tuberosities will have to be to accomodate the larger muscle.

    This is a very interesting subject for me, and the great thing is that I have a mid term on this on Monday, so I would like to thank you all for helping me study.

    I thought that it was the combination of the calcium salts and collagen fibers that gave bone its strength, simmilar to the structure of re-enforced concrete.


    I am curious Danno about your educational background, you seem to have much more knowledge of physiology than most car guys I know.

  6. #6
    Senior Member Dieter's Avatar
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    Here is a good article on the subject:

    http://www.trinewbies.com/Article.asp?ArticleID=153

  7. #7
    more ape than man timmhaan's Avatar
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    Quote Originally Posted by Someday_RN
    I am curious Danno about your educational background, you seem to have much more knowledge of physiology than most car guys I know.
    danno has a good working knowledge of a lot of stuff. a good scientific mind. it's people like danno who make me come back to this forum.

  8. #8
    Senior Member DannoXYZ's Avatar
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    Thanks timm, encouragement from folks like you keep me coming back.

    Quote Originally Posted by Someday_RN
    You sound just like the A&P class I had on Monday, it is a very simplified version of bone growth, and your theory is different from the theory I was taught about excersize induced bone growth, in that osteoblasts are stimulated by electrical activity. You forgot to mention the effect that parathyroid hormone and growth hormone has the ability to stimulate osteoclast and osteoblast activity in the creation of bone matrix. The fact is that bone is constantly being remoddeled, and when osteoblast activity surpasses osteoclast activity bone is made denser, and vice versa, and the bigger you make the muscle attaching to the bone, the bigger the condyles and tuberosities will have to be to accomodate the larger muscle.
    I think we're talking about the same mechanisms, just different parts of it. There are easily hundreds of hormones and intermediate compounds involved in the cyclical formation/resorption of bones. It's interesting to study the apparent conflict between PTH anabolics vs. anti-resorptive SERMs (estrogen) or bisphosphonates (alendronate). The medical establishment is firmly entrenced in opposing camps with one firmly believing in building up bone and the other with preventing bone-loss. Personally, I think they're both static models that can't work without incorporating a more cyclical view of the mechanisms involved. You can't build strength without disassembly and by keeping bones static, you can't build more strength. The trick is figuring out how to tip the balance between the hormones just slightly towards the build-up phase. I found a cool video showing osteoblast vs. osteoclast activity:
    OneBMU.gif
    TurnOver.gif

    By "electricity" do you mean therapeutic external stimulation with TENS devices? Or with the piezo-sensors on the bone itself? It appears the electrical triggers of the integrins are ionic chemicals, like nerve-synapses, rather than pure electrons flowing like in a light-bulb circuit; bones have a nervous system... heh, heh...


    Quote Originally Posted by Someday_RN
    This is a very interesting subject for me, and the great thing is that I have a mid term on this on Monday, so I would like to thank you all for helping me study.

    I thought that it was the combination of the calcium and collagen fibers that gave bone its strength, simmilar to the structure of re-enforced concrete.
    Yes, it's a combination. I think it's the actual calcium/phosphorus hydroxyapatite crystals that take the load. The collagen serves as a mold to pour in the crystals. Rather than being like rebar which takes the load in concrete, the collagen's more like plywood facing on the outside that's the mold. You then pour in the concrete and it takes the form of the mold. Or we can look at it as a carbon-fibre matrix with the calcium being the fibre and the collagen is the binder resin that holds it all together on the outside. The denser and stronger bones seem to have about the same amount of collagen matrix, but more slighly more calcium density. The combined structures are also thicker with a higher ratio of matrix to non-structural space.


    Quote Originally Posted by Someday_RN
    I am curious Danno about your educational background, you seem to have much more knowledge of physiology than most car guys I know.
    I studied Microbiology at UCSB with an emphasis in exercise-physiology. I was doing a lot of bike-racing at the time and was intensely interested in maximizing performance. I realized after volunteering at Cottage Hospital that I really didn't want to be a doctor, but took my MCATs anyway just in case. The way the healthcare system is set is full of power-struggles, egos, and corporate bureaucracy, not something I'd want to be a part of. Although being an EMT was fun.
    Last edited by DannoXYZ; 10-15-05 at 12:17 PM.

  9. #9
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    QUOTE=DannoXYZ][/url]

    By "electricity" do you mean therapeutic external stimulation with TENS devices? Or with the piezo-sensors on the bone itself? It appears the electrical triggers of the integrins are ionic chemicals, like nerve-synapses, rather than pure electrons flowing like in a light-bulb circuit; bones have a nervous system... heh, heh...


    [/QUOTE]

    I believe what I was just taught is that the electrical signals that communicate with the CNS are what cause bone to be thickened, although from what I understand this is just one of many theories as to why bone responds the way it does to stress.

    I also did not use my developing critical thinking when responding to your post, I still have much to learn. I realized after, that something like bone growth is much to complicated to to go into exact details in a forum such as this, and if one was to attemps many chapters could be written about it. I will say although you did not mention some things it is because you probably have better things to do than spen the next 2 days typing and explaining bone growth.

    Anyways I enjoy hearing others knowledge, and I hope to hear alot more so I can continue to learn.
    Long live the periostium

    Thank you

  10. #10
    Twincities MN kuan's Avatar
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    Alright thanks for the explanations and food for thought. I wonder if bones ache after a hard workout. Sometimes I feel a deep ache. Are those my bones aching and building?

  11. #11
    Senior Member DannoXYZ's Avatar
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    Nah, I bet it's mostly muscles deep down. Perhaps a tendon or even a ligament...

    Dull deep aches are usually a sign of widespread minor muscle damage. Such as doing a long endurance ride at speed. The large number of repetitions at medium intensity will cause smaller tears in the muscles, but more of them. The pain tends to be dull and deep feeling.

    Sharp pains, feel more like sprains, are usually a smaller amount of bigger tears. Such as doing sprints and to a lesser extent, intervals. If you do a lot of running, especially sprinting, you'll get these sharper pains due to the higher peak loads involved in running.

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