The Good, the Bad, and the Unsure: Stretching
09-12-12, 01:30 PM
#27
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I stretch before going to bed on most nights. It's relaxing and keeps the legs and hips loose, which can be a challenge for a cube dweller.
09-12-12, 03:18 PM
#28
**** that
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I think "Job" is the key word there, as in it doesn't apply to anyone that isn't ride 5-6 hours a day.
Which is not to say I don't love that blog, it's awesome. In fact I posted the same article earlier this thread.
Personally I'm not a big stretcher.
09-12-12, 03:37 PM
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"If You Don’t Like to Stretch, Find Another Job"
I think "Job" is the key word there, as in it doesn't apply to anyone that isn't ride 5-6 hours a day.
Which is not to say I don't love that blog, it's awesome. In fact I posted the same article earlier this thread.
Personally I'm not a big stretcher.
I think "Job" is the key word there, as in it doesn't apply to anyone that isn't ride 5-6 hours a day.
Which is not to say I don't love that blog, it's awesome. In fact I posted the same article earlier this thread.
Personally I'm not a big stretcher.
09-12-12, 03:40 PM
#30
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09-12-12, 03:48 PM
#31
fuggitivo solitario
Not really. Lactic acid is a byproduct of fuel. Burn your fuel (glucose) too hot in the absence of oxygen and you get a lot of waste product (lactate). Give some oxygen and time and the waste product can be converted back into something that can be used as fuel, but it itself is not fuel. Up until that last point it's a lot like charcoal. If you burn wood out in a campfire, it'll pretty much all burn up except a small pile of ash. If you start the fire, but then cover it up so no air gets in, it'll turn into charcoal (over time) after having burned somewhat. The difference is that if you add back oxygen and a new match, the charcoal instantly burns, while if you add back oxygen to your cells they need to convert it back into something that can be used as fuel.
are you trying to say that the only way lactate can be metabolized is by being shunted off to the liver in the Cori cycle and have it returned as glucose?
09-12-12, 04:03 PM
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I wasn't getting into that much detail, I was just saying you can't just start burning lactate as such. At the very least you need to convert it back to pyruvate (with the help of lactic acid dehydrogenase and oxidized NAD+) before you can use it in the citric acid cycle (or it can go to the liver for gluconeogenesis in the Cori cycle as you point out). Was responding to the idea that lactic acid itself was fuel when, in fact, it's a waste product of a less than efficient use of fuel that has to be enzymatically modified before it's able to be used as a fuel source. I'm more of a microbial physiologist than a human one, so my sticking point was on the use of lactic acid as fuel more than the hows and where's of the conversion.
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Last edited by himespau; 09-12-12 at 04:08 PM.
09-13-12, 11:19 AM
#35
fuggitivo solitario
Of course you are right that it has to be oxidized to pyruvate before the energy can be released, but this is an over-simplification. When you label it as a "waste" product, it really isn't, and especially not in the way you originally framed it when you mentioned that only when there's oxygen again could it be used for energy. I have a review article from 2004 (reference 7 in the article to follow) that goes into theories on lactate shuttles, but I think this article https://www.letsrun.com/2012/lactate-0906.php may be better for the general public.
Back when I was in undergrad, we were taught that the Cori Cycle was the only way to remove lactate, or barring that, exercise intensity has to be greatly reduced. The key take home point is that it's not so much that the incoming O2 is an issue as much as much as the site at which pyruvate gets further oxidized is an issue. Isolated, in vitro studies show that lactate can be used as fuel in the absence of glucose.
Back when I was in undergrad, we were taught that the Cori Cycle was the only way to remove lactate, or barring that, exercise intensity has to be greatly reduced. The key take home point is that it's not so much that the incoming O2 is an issue as much as much as the site at which pyruvate gets further oxidized is an issue. Isolated, in vitro studies show that lactate can be used as fuel in the absence of glucose.
