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How much does someone’s LT change in relation to fitness level?? I was under the impression that it did change, but not by much. Comments??

JB
 

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JBergland said:
How much does someone’s LT change in relation to fitness level?? I was under the impression that it did change, but not by much. Comments??

JB
Your LT HR will probably go up as your fitness increases, but not a lot.

More importantly, your power at a given HR will increase dramatically.

Silas
 

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JBergland said:
How much does someone’s LT change in relation to fitness level?? I was under the impression that it did change, but not by much. Comments??

JB
I went from low 170s to low 180s on HR. But like Silas says, HR is really meaningless. Watts wise, last year I was at about 280w FT, but after two months off in the fall, that number went down to 250-ish. Now I'm back on the bike and feeling good again and I'd say I'm at least where I was last year vis-a-vis power.
 

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JBergland said:
How much does someone’s LT change in relation to fitness level?? I was under the impression that it did change, but not by much. Comments??

JB
I think you have LT confused with VO2max. LT is probably the most sensitive physiological variable relating to fitness level.
 

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a lot of gurus talk now about sustainable output, recognizing not only that LT is mutable, but that there is little consistency in what people mean when they discuss LT and that LT is not what people assumed that it was -- the presence of lactic acid does not cause your muscles to fail. This hypothesis came from a series of questionable experiments and more questionable conclusions from the 1920's, I think, that has persisted. The evidence is that cells bathing in lactic acid likely increases endurance. What training is about is getting your body to use the lactic acid more efficiently.
 

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"What training is about is getting your body to use the lactic acid more efficiently."

There's that ugly word again (efficiently)! Training is primarily about increasing your CAPACITY to use oxygen to produce energy whether the substrate is fat or carbs. I don't believe efficiency changes much if at all. By increasing your capacity to produce energy oxidatively you can oxidize fats and pyruvate at a greater rate meaning that more ATP can be produced with oxygen thereby avoiding the converstion of pyruvate to lactic acid. This is why with training you can perform more work before reaching your LT.

And while the role of Lactic acid in fatigue has come into question recently it nonetheless remains true that once lactic acid is accumulating in the blood you're getting near your maximum sustainable work rate.
 

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you obviously know more about this than I do, but I thought that the most recent research (came out within the last year) suggested that bathing cells in lactic acid -- did something beneficial. Am I completely out in left field?
I got that the more energy you can create using aerobic metabolism, the better, that these other forms of energy are available short term, in limited supply compared to aerobically generated energy. But I thought that the bodies ability to -- well we used to think of it as tolerating -- tolerate lactic acid had something to do with endurance.
 

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bill said:
you obviously know more about this than I do, but I thought that the most recent research (came out within the last year) suggested that bathing cells in lactic acid -- did something beneficial. Am I completely out in left field?
I got that the more energy you can create using aerobic metabolism, the better, that these other forms of energy are available short term, in limited supply compared to aerobically generated energy. But I thought that the bodies ability to -- well we used to think of it as tolerating -- tolerate lactic acid had something to do with endurance.
Think about it as an assembly line. Step 1 makes energy(ATP), with a byproduct being lactic acid. Step 2 uses oxygen to clear the lactic acid out. As step one makes more and more energy, more and more lactic acid is produced. As long as your body can supply the necessary oxygen, it never builds up very much. At some point, there is build up. When there is enough build up, Step 1 can no longer take place. The mind and body refuse.

Being able to tolerate the pain associated with this build up is definitely a good thing for racing. If you give up right around threshold, you're not going to win many races. I have never heard of an actual benefit from going above threshold though, aside from providing a training stimulus.

Silas
 

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SilasCL said:
Think about it as an assembly line. Step 1 makes energy(ATP), with a byproduct being lactic acid. Step 2 uses oxygen to clear the lactic acid out. As step one makes more and more energy, more and more lactic acid is produced. As long as your body can supply the necessary oxygen, it never builds up very much. At some point, there is build up. When there is enough build up, Step 1 can no longer take place. The mind and body refuse.
Silas
To be accurate glycolysis (your step 1) "ends" in ATP and pyruvate. Pyruvate is then transported into the mitochondria and oxidized to yield more ATP. When the rate of pyruvate production exceeds the rate it can be transported into the mitochondria then it is converted to lactate which accomulates in the muscle. It's not really about oxygen supply per se since your LT occurs below VO2max (~90% in well-trained persons). There is some evidence that when acidosis occurs glycolysis is inhibited but it certainly continues to take place. There is a whole separate debate as to whether the acidosis that occurs with high-intensity exercise is caused by lactate production or ATP breakdown. It's not clear why the "mind and body refuse". We know that the inability to continue exercising at a high-intensity is correlated with acidosis and lactic acid accumulation but in the past 10 years there has been research that indicates that at least the latter is not causitive.
 

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AT vs VO2max

AT vs VO2max

Hi im new here but have read all off the comments regarding the LT and fitness above.

If you can get your heart rate at anaerobic threashold closer to your max heart rate or if you can increase your VO2max at your maximum heart rate then you have increased your fitness. Or if you can increase the METs at your AT or Max HR you have increased fitness. In order to do this it takes a lot of quality training. I think the most efficient way to do this is through using a HR monitor. The best way to determine your fitness is to have it clinically tested by VO2max. but this can be expensive. I use a polar s625x which has the ability to check your VO2max. I found it to be spot on accurate. I used the polar monitor to check my VO2max the next day i had it tested in the exercise lab and they were identical. So it seems to work well.

Another things is how many METs of work you can do at any heart rate but that is another discussion entirely.
 
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