Explain Glucose/Sugar Levels, Insulin, and effects on Muscle Gain...

[Emevas]

I dunno, I've never had any issue with whey, and have seen a great deal of studies supporting it over milk as well.

I've gotten to the point where I've done enough research to find studies that justify anything I do.

[partyboy]

I've gotten to the point where I've done enough research to find studies that justify anything I do.

yeah, that's the beauty about life these days

[Angry-Monkey]

why chocolate milk over regular milk?

And I'm cheap so I buy powdered skim milk to drink after workouts, am I a terrible person?

[Quikfeet509]

I dunno, I've never had any issue with whey, and have seen a great deal of studies supporting it over milk as well.

I've gotten to the point where I've done enough research to find studies that justify anything I do.

True dat.


As for Phrost's original query, I do have a book that explains it all. It even has references, for what it's worth:

http://www.bodyrecomposition.com/lylemcdonald-the.html


The font drives me crazy and there is too much spacing between the lines...breath...but so far, the information seems well-researched...although I must confuse that it might seem more interesting to me than it really is because I am spending time reading it instead of prepping for my MCAT part deux

[Judah Maccabee]

why chocolate milk over regular milk?

And I'm cheap so I buy powdered skim milk to drink after workouts, am I a terrible person?

Better carb:protein ratio - 4:1, typically.

[Raining_Blood]

The short answer is that insulin prevents catabolism in muscles. It also increase glucose uptake at a celluar level, increases protein synthesis and decreased protein breakdown.

[TheRuss]

This post is a reminder for me to get back to this thread. I've got some notes somewhere on insulin and the hormone cascade, glycemic/insulin index, cortisol, etc. that might be helpful if I can find them.

[TheRuss]

Okay, first off, a quick overview (read: gross oversimplification) of how muscles work.

Your central nervous system (read: brain) sends the signal to your muscle to contract by sending an action potential (read: electrical signal) down a nerve, which connects to the muscle fibers in question at the neuromuscular junction. When the action potential reaches this junction, a series of reactions take place.

Inside muscle fibers, there are myofibrils, which are the "motor" that actually pulls the tips of the fiber towards each other. Each myofibril is made up of a bunch of sarcomeres, which are in turn made up of overlapping strands of actin and myosin (chains of protein). When the above reaction takes place, calcium ions bind to the actin chains, and the myosin chains "twist" along the actin chains, pulling the ends of the sarcomere (and thus the myofibril, and thus the muscle fiber) closer together. This movement is tiny (read: just one link of a long chain), and to disconnect the myosin from the actin to move up to the next link requires energy. It gets the energy to do this from a molecule known as adenosine triphosphate, or ATP.

And now, a bit of physics:

power = work / time
work = force * distance
therefore, power = force * distance / time

This means:
-The more ATP that is available to a sarcomere, the more twists the actin and myosin can perform.
-The more calcium ions the sarcomere is exposed to, the faster the actin and myosin can twist.
-The more twists the actin and myosin can perform in a given time, the more power* the sarcomere can generate
-The more sarcomeres there are pulling in parallel, the more power** the muscle fiber can generate.
-The more muscle fibers there are pulling in parallel, the more power** the muscle can generate.

* increased distance per time
** increased force

So in an egghead sort of way, there are our goals.
More released calcium = muscle can contract faster.***
More available ATP = muscle can contract for longer.
More sarcomeres and muscle fibers in parallel = muscle can produce more force when contracting.

Insulin has important effects on the latter two.

*** I'm not totally sure on this one. A higher calcium concentration may be a necessary but not sufficient condition for faster sarcomere contraction.

[Kaoz]

edit: I learn read

[TheRuss]

All this Krebs-cycle stuff is giving me a headache, so I'm going to switch gears a bit and talk about simple/complex carbs, glycemic index, and insulin index (with some bonus whey talk for Emevas).

-Glucose is the body's ready-to-use carbohydrate. It gets shipped around in the bloodstream, and once in a cell, gets changed into pyruvate by glycolysis. Pyruvate is decarboxylated into acetyl-CoA, which is broken down further in the Krebs cycle. Each of these processes results in more available ATP.
-Dextrose and glucose are the same thing. Supplement companies have made a lot of money off of confusion over the different names.

-The "old-style" grouping of carbohydrates was into monosaccharides (glucose, fructose), disaccharides (sucrose, lactose), and polysaccharides (amylose, amylopectin, glycogen).
-The more modern categorization of carbohydrates is along the spectrum of how much and how quickly they raise blood sugar levels, commonly known as the glycemic index.
-There's a commonly-held belief in a correlation between old and new categorization - specifically, that monosaccharides and disaccharides ("simple carbohydrates") raise one's blood sugar level faster than polysaccharides ("complex carbohydrates"). This is inaccurate.
-For example, the best available data indicates that lactose (milk sugar), a simple carbohydrate, has a dramatically lower glycemic index than potato starch, a mix of complex carbohydrates (about 1:3 amylose:amylopectin ratio). My best guess as to why is that the amylase in saliva breaks the amylopectin down to glucose almost immediately, whereas lactose isn't split by lactase into glucose and galactose until the small intestine, and the galactose isn't metabolized into glucose until it reaches the liver.
-On the other hand, dietary fiber (polysaccharide cellulose, amongst others) has no glycemic impact, as the human digestive tract lacks the cellulase to break it down into constituent sugars. Some dietary fiber can be fermented, but the end product of this is fatty acids, not sugars.

-Currently-available values for glycemic indexes are maddeningly inconsistent to the point of contradiction (look at the two values for baked russet potatoes - nearly a 100% margin of error). This makes it very difficult to structure a diet around published GI values.
-Furthermore, it's not just sloppy experimental procedures. I would expect a fair bit of variation from person to person, depending on the proportions of their enzymes, their hormonal balances, and the structure of their digestive tract.
-Fortunately, if you can handle needles and have some time and money to spare, you can take your own measurements with a glucometer and a battery of test strips. It looks like you should be able to switch fingers between tests, so long as you don't switch meters.
-If anyone actually tries this, please let me know how it goes.

-It is also commonly assumed that since the pancreas' output of insulin is sensitive to blood glucose levels, the magnitude and duration of insulin response (insulin index) will correspond to the magnitude and duration of blood glucose change. This is imprecise. I know of at least two cases where insulin response differs significantly from glucose response:
-Several strains of rice have been shown to have a significantly smaller insulin response (off by a third) than glucose response.
-Milk has a significantly larger insulin response than its lactose component alone. The researchers found that whey protein, despite not being a carbohydrate and thus having no glycemic response, stimulated the release of insulin. This is another benefit to consuming whey (and products that contain whey, like milk) immediately after workouts, as the increased insulin levels should counteract the catabolic effects of cortisol (which I'll get to eventually if y'all are interested).




On a fast-vs-slow-protein aside: In either this study or one like it, they basically found that whey protein caused a large, short spike in blood amino acid levels and stimulated protein synthesis, whereas casein caused a lower, longer increase and inhibited protein breakdown. I'm of the opinion that this is mostly a product of casein gelling upon contact with stomach acid and thus digesting more slowly.

Edit: I found the study that talked about hormone response to different proteins - it's this one.