the aerobic engine (mitochondria) and those nasty fast twitch fibres

Discussion in 'Cycling Training' started by edd, Feb 22, 2013.

  1. edd

    edd New Member

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    Having been away from this forum for a good while, I was kinda weirded out that ten years on the discussions on training are still pretty much the same. I started this thread in the hope that I and others can shed some light on some basic underling principles.

    1) Muscles are really dumb, they learn what you teach them, nothing more. So cross training or gym training to be better on a bike only makes sense if you want to isolate and build a specific atrophying muscle. Otherwise you are better off training on the bike.

    Why ? Because muscle conditioning is extremely activity velocity duration specific.

    2) Road cycling is predominately an aerobic activity. For this you need to condition (train) your heart and lung function, condition (train) your glycogen (fuel) stores as well as the muscles that are conditioned for cycling activity. For this we need to build mitochondria in the muscles. Mitochondria enable the cells in the muscles to work aerobically (with oxygen). To keep this simple and easy to comprehend I will state that mitochondria are generally associated with slow twitch muscle fibres.

    3) Your body builds mitochondria in the muscles when you work (train) for extended periods, as the body wants to be energy efficient The aerobic system is many times more efficient than the anaerobic energy system. When you park your bike and sit in a chair your body will dismantle the mitochondria as they are consuming glycogen that your body wants to conserve.

    4) Fast twitch muscle fibres are anaerobic and work without oxygen, they use up to 70 times more glycogen than the aerobically fuelled muscle fibres and are generally able to produce more power for very short periods (minute or so).

    You are never working only aerobically or anaerobically. The two systems work together. Your body has an active anaerobic system that recycles byproducts and clears toxins that are built up in the muscles when worked hard anaerobically.

    5) When you go to the gym and build a big muscle (hypertrophy) you are thickening up the fast twitch muscle fibres. These are guns that are heavy to carry around and you may only get to fire on the odd occasion. Chances are they will slow you down.
     
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  2. tonyzackery

    tonyzackery Well-Known Member

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    "Nasty" fast-twitch fibers? Regardless of context, I still take umbrage to that./img/vbsmilies/smilies/wink.gif
     
  3. edd

    edd New Member

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    Well it's the context of what is implied by "nasty" when you have worked for hours and had this bod in you slip most of the time and then suddenly just near the crest of a hill they sprint away from you, you may be inclined to curse. There is this slim chance that you may curse "nasty fast twitch fibres"
     
  4. vspa

    vspa Active Member

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    near the crest of the hill wouldn't be fast twitched fibers neccesarily, you could blame those on a flat sprint 200 meters from the finish line, for the hill example is more of a better anaerobic capacity and better overall condition,
     
  5. tonyzackery

    tonyzackery Well-Known Member

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    Ahhh, context - yes, indeed.

    Knowing my preponderance of 'those nasty fast-twitch fibers', that fact alone would've precluded my sign-on for this race thereby negating any and all cresting of hills. I think Cav, Greipel, Bos, et. al know something of this 'allergy to hills' situation. LOL!

    Still doesn't make them "nasty" though./img/vbsmilies/smilies/wink.gif
     
  6. edd

    edd New Member

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    Now we get into some complexity as there are various types of fast twitch (FT) muscle fibres.

    Depending on how fresh the bod in the slip is and how short and fast the sprint is will determine the extent of aerobic/anaerobic, slow twitch/fast twitch (ST/FT) contribution. As I said previously we are never all aerobic or anaerobic - pretty sure though there'd be some fast twitch muscle fibres firing in a sprint regardless of the slope of the road. It's just we don't see this in a race as all the sprinters get dropped or burnt out by the climbers to be able to threaten at a hill finish, still the climber who can sprint away at the line is working some FTs.

    "Blowing up" it's a FT thing,

    "Bonking" is a slow twitch thing".

    However you raise a very good point, that of overall conditioning. To discuss this we need to understand that building thicker FT muscle fibres in a gym can be detrimental to endurance conditioning - Because the stimulus that is needed to cause muscles to grow (thicken FTs) is also conditioning the muscle (and the whole of the body) to perform for 20 seconds or less. If you are in a sport that allows you to recover from you effort every 20 seconds or so, then helpfull, if no then …
     
  7. vspa

    vspa Active Member

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    phillipe gilbert comes to mind, no one can touch him on a hilly finish and still he cannot score a top ten flat finish,
     
  8. tonyzackery

    tonyzackery Well-Known Member

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    Bonking is a running out (or extremely low) of glycogen thing - regardless of muscle type. I've bonked on a number of occasions and I can probably count the number of slow twitch muscle fibers in my body on one hand. LOL!

    Gilbert's got some ridiculous AWC - anaerobic work capacity. He can go longer in the 'red' zone than most.
     
  9. edd

    edd New Member

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    Yes you are correct, bonking is running out/low on glycogen.
     
  10. daveryanwyoming

    daveryanwyoming Well-Known Member

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    I agree with the overall gist of your post but in addition to Tony's comments, the points above are pretty misleading.

    Blowing up is a short term fatigue of key systems things and can happen just as easily by trying to overpace a 40K TT and blowing up before the finish or a five minute bridging effort as it can in a short intense L6/AWC burst. IOW, you can just as easily blow up during primarily slow twitch sections or primarily fast twitch sections and it has a lot more to do with specific fitness for the type of effort and pacing than the muscle fiber type.

    And as you acknowledged above, Bonking is a fuels management, primarily glycogen and blood glucose fuels management issue, I guess you could say it's a slow twitch thing from the standpoint that it's a longer term issue and you can't really bonk in a minute of hard effort unless you were already seriously glycogen depleted, but again tying it to muscle fiber makeup misses the point.

    FWIW, in some sports nutrition circles they further differentiate bonking and hitting the wall. The former being an acute shortage of blood glucose to the brain with the resulting mood shifts, irritability, tunnel vision, sense of doom, etc. The latter being depletion of muscle glycogen and inability to fuel muscle contractions primarily via sugars. They're often but not always connected to one another. IOW, it's possible to bonk with legs that still have plenty of glycogen on board but you're not currently fueling your brain and it's possible to have enough blood glucose and liver glycogen to feed the brain adequately but the legs are depleted. That can happen during periods of frequent hard and long training and racing when the rider isn't keeping up with glycogen resynthesis, blood sugar can be all right since you can get blood sugar up very quickly by eating on the bike but muscle glycogen stores can be depleted from previous work and glycogen synthesis is a slower process. Anyway, interesting take on things and not how I previously thought about bonking on the bike.

    -Dave
     
  11. teebone

    teebone New Member

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    And this really sucks when it happens. A quick story....I was coming home from a ride years back and "hit the wall" with about 10 miles left. With 2 miles to go I was in utter despair. Equal parts of me wanted to pull over and sit on the curb to cry and pull into traffic to end the misery. With more focus and effort than I have used in most anything else cycling related I navigated the last 2 miles (dead-pan flat) home. I arrived to an empty house and desperately searched for food, but oddly could not figure out how to make anything. Nothing made sense. What the heck do I do with bread and peanut butter and nutella? Thankfully my neighbors were having a party. The noise and odors of food called me in. I spent the next 30 minutes setting land-speed records on the consumption of lumpia, chicken wings, and soda.

    Bonking is a serious deal...

    T

    PS: I have not been invited back to the neighbors since my "indulgence". :)
     
  12. bgoetz

    bgoetz Member

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    I have heard stories of guys crawling into an apple orchard in spring and eating rotten apples from the ground. I have never been that bad, but did ride for who knows how long with a broken spoke and never notice till I went to move my bike the next day and all the rear wheel would do was drag across the ground.
     
  13. gudujarlson

    gudujarlson New Member

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    I honestly don't know if I have ever "bonked". There were a few times early in my biking "career", before I learned my limits, that I became so tired that I had to lay on the ground every couple miles in order to get home. I'm not sure if I was out of glycogen, dehydrated, just tired or all of the above. But since that time, that has never happened to me again even on 400 TSS in rides in 90F high humidity heat. What stopped me in my tracks on the 400 TSS ride was leg cramps.
     
  14. vspa

    vspa Active Member

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    that sounds like bonking, if, when you finally arrived at home, the first thing you did was to empty the refrigerator in two minutes, then it was bonking for sure !
     
  15. gudujarlson

    gudujarlson New Member

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    I don't remember what I did after I got home that day. heh

    I just remembered another ride on a hot and humid day where I became very tired and noxious somewhat suddenly. I thought I was dehydrated or maybe bonking so I stopped at a coffee shop and ordered some food and a fruit smoothy. What's weird is that I found I had no appetite or thirst and could not get anything down. I rested for a bit and then limped home. After resting at home I was fine.

    Does anyone else ever weigh themselves before and after a ride? I have done this sometimes in the summer and the most difference I ever measured was -7 pounds between pre-ride and post-ride weight. I weigh between 160-170 pounds year round so that was about a 4% loss in weight in ~4 hours. I proceeded to eat and drink ~5 pounds of food and water and then pee for several hours. Eventually I came back to homeostasis.
     
  16. daveryanwyoming

    daveryanwyoming Well-Known Member

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    Sure I weigh myself before and after some long and hard rides but mostly for sweaty trainer sessions. You'll have to ride ~5 hours at 200 watts AP to. Actually burn a pound of fat so the majority of those 7 pounds were almost certainly water weight. Your description of no appetite is a common symptom of bonking. -Dave
     
  17. vspa

    vspa Active Member

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    ok, bonking is more like the " eating rotten apples from the ground " story
     
  18. danfoz

    danfoz Well-Known Member

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    I bonked bad on a ride far from home after getting separated from my riding partner and realizing I'd left my wallet in his car. I crawled (literally) into the parking lot hallucinating mildly, eyes rolling in my head, a frothing, pleading mess, begging the parking lot attendant for money for a coke and candy bar from the vending machine. I believe I may even have clutched his shirt in my desparation. I do remember a look of horror on his face as he threw money at me while struggling to get away, but that could have been partly hallucination.

    If there had been any rotten apples on the ground I would have been all over them. Two hours at redline without refueling and it can (meaning it will) happen to you. Nowadays I never leave home without an emergency energy gel in the kit.
     
  19. James SA

    James SA New Member

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    Two weeks ago I was in a 110km road race. It was a long uphill start and I went off too hard. It was a low priority race and hadn't tapered or rested adequately in the build up. I'm not sure entirely what happened but about 1.5hrs in I was shattered. Not that I had to slow down a little but rather that just riding at all was a massive effort. I tried to GU and drink my carb drink but the taste of the sugar in my mouth became so intense that I thought I was going to throw up. I found someone who gave me some plain water and somehow managed to get to the finish. When I got back to my car I couldn't even load my bike. I sat in the car and didn't have the strength to drive. I put the experience down to too much training in that week (that my body is not accustomed to). Too harder start (overconfidence) not enough good quality carbs in the day before and the morning of the race. Interestingly my NP for the first portion of the race was not higher than I have achieved in previous races but there were two distinct differences. 1. I started with a empty tank (no carbs and spent glycogen from the training) 2. Frequent high level anaerobic bursts as I tried to catch faster groups that were ahead of my own starting group. It wasn't like I just slowed down it was like I just "stopped". It took all the will I could muster just to limp home. At no time did I experience hunger and the thought of apples would have made me sick. Only ice cold water helped a little. At the time I would have gladly traded my bike for a lift back to my car. Unfortunately it damages your confidence. I have another race next week.
     
  20. vspa

    vspa Active Member

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    it seems that everybody reacts a bit differently, so it could be helpful to discard things. First, if the race lasts for 4 hours and you have never done that duration in training then you are just undertrained. Second, if you have done the distance but never in a club ride or at least doing tempo, then you are also undertrained. The appetite comes after you bonk really, once you sit down, refresh with water, bite a fruit or a gel, the body will ask you for real nutrition, i have bonked a number of times and i am the kind of guy that goes directly to food to feel better,
     
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