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FT Muscle and Free Fatty Acid Uptake

June 24, 2005 10:15 AM

This sounds imposing, but it is a relatively little known property of FT fiber that it increases its rate of uptake of free fatty acids during fasting. During the non-fasting state it is usually the ST fibers that take up the free fatty acids (FFA) that are reesterfied in the liver.

No wonder it is so easy for me to stay lean. I have a lot of FT fiber volume relative to ST volume because of my training and, perhaps, some genetics too. When I do my intermittent fasting, it turns out that the FT fibers take up more FFA than they do in the fed state. So, I take in and burn fat as the energy substrate to my FT fibers. I burn more fat than someone who has less FT fiber. Another triumph of Evolutionary Fitness technology.

The evolutionary rationale for this is harder to spot. I don't want to go too far out this limb until I learn more about the mechanisms. But, we know that for every mechanism such as, FT fiber takes up FFA but only during fasting, there is a deeper adaptive reason. One could see it as preparation for the high intensity of the hunt, which requires more FT energy. Starvation would motivate the hunt and the uptake of FFA in the FT fibers would be preparation. The ST fibers already carry their energy supply, but are less important relative to the FT in the high intensity of the hunt. So, there is a slight shift of energy substrate between the fiber types. [This is probably too clever by half as one of my early bosses used to tell me about my explanations.] It is known that fighters are more effective if they fast mildly before the fight. This is consistent with the relative shift of substrate between the fiber types.

As you read this remember that the nonoxidative muscles are the FTx and, to some measure, the FTa because they are both glycolitic and oxidative.

It is known that the total uptake of FFA in the body exceeds what can be accounted for by the liver. Now, it appears that the heretofore undiscovered FT fibers are responsible, at least to a significant degree.

Some enclosed comments are my clarifying remarks. The bottom line: FT fibers carry low levels of lipids (IMCLs) when you are well fed, but they take up fats from the blood stream at a high rate and reach high levels during fasting. And, we have always been told that aerobic exercise and ST muscle fiber burns fat. Maybe in the fed state, but not in the caloric deficit induced by fasting or heavy exercise.

How do you fast? Try an overnight 15 hour period of not eating. Skip dinner on any day you like, random is best, so long as you are active and hit your FT fibers on that day.

The following extract is from Muscle-type specific intramyocellular and hepatic lipid metabolism during starvation in Wistar rats in Diabetes (March 2004) by too many authors to list.

"...IMCL values in tibialis anterior and EDL (FT muscles) rose significantly and rapidly during starvation, reflecting an increased FFA reesterification in these muscles in parallel to an increased lipolysis in adipocytes. Recently, it was concluded from systemic and regional glycerol and FFA kinetic studies (studies of how things move through the body and along metabolic pathways) that FFAs must be reesterified in tissues other than liver after a 60-h fast in men, and muscle tissue was suggested as an important site of FFA reesterification (41). In fact, our study in rats also demonstrates increasing IMCL levels, which would support the concept of FFA reesterification in muscle during fasting, but only in muscles with nonoxidative fiber (FT) composition (tibialis anterior, EDL). During refeeding, after 72 h of starvation, the elevated IMCLs in tibialis anterior and EDL returned within 24 h to the very low values observed on day 1 before fasting, thus indicating the rapid physiological dynamics of this lipid pool."

· Evolutionary Fitness

Comments

Posted by: Flower Online [TypeKey Profile Page] at September 12, 2006 3:04 AM

A couple of questions/comments.

Do you have the references for the ST/FT and FAs? Someone I brought this to the attention of mentioned that he thought the studies were done on rats and not humans.

Also, I'm curious if the calories you consume the day after your fast are low or do you compensate by eating more the next day? In other words is it more a consequence of you consuming less calories that makes you leaner rather than the muscle fiber composition?

I find the evolution aspect of diet/exercise to be extreemly facinating. Any other forums/sites/books that might go into more detail? I have lots of questions that I'm sure have been answered.

Thanks,
Mike

Posted by: MikeE at June 28, 2005 1:24 PM

Tabata trained the Japanese speed skating team in a manner not too far from what the JAP article Dave sent describes.

As my elbow heals I have been using something like this sprint training, as I mentioned in an earlier post on trying to see what max I could generate in watts. I found, by the way, that with the machine set at full resistance I could pedal at full speed and barely keep my feet from flying off the pedals. The reading was only 600 watts.

Years and years ago when I was doing motocross racing I ran a bit. But I always pushed the last mile as hard as I could. When I ran with other people who jogged regularly I would just go off and leave them. They never ran hard enough to toughen up and get strong.

Posted by: Arthur De Vany at June 27, 2005 2:27 PM

Daily sprint training? Seems excessive to train a max level for the same exercise every day. And 2 weeks seems barely long enough to see an adaptive response. Nonetheless, good results in such a brief time with less than optimal workout design shows how powerful high intensity training can be.

Fred Hatfield's name has been brought up. I read his training of Hollyfield (used to be free on the web). I've read his stuff. His zig zag diet is for those who need to manipulate caloric intake to lose weight. Little different than an evolutionary perspective where if you live and eat correctly, your body comp will take care of itself. Also, dr Squat used a workout similar to the ascending sets method only Hatfield did the reverse. Heavy for 3-5 reps, immediately to 8-12 reps, and light for 40 reps. He said the FT fatigue faster so you burn them out early with the heavy weights and keep working.

Posted by: Woody at June 27, 2005 11:52 AM

this is actually back to the "creating diseases" piece from a few weeks ago:

http://news.bbc.co.uk/1/hi/health/4122692.stm

"Doctors say thresholds for "normal" blood pressure and cholesterol levels have been set so low healthy people might be put on unnecessary medication......."

Posted by: Chris H at June 27, 2005 9:56 AM

Dear Art
Your comment on sleep was very interesting.Your
right the sleep doctors claim solid continuous
sleep is what people need.
Also I'm reading "Younger Next Year" sorry I bought the book before I heard your comment
Clarence Bass recommended it.These guys recommend
45 minutes of areobics walking would count on some days as manditory for staying young.
They also talk about low level cardio{walking}
as the way to burn fat.nothing about fasting so
far in the book.
Fred Hatfield for years has recommended over eating and undereating as a way to build muscle.
Any comments?
Barry

Posted by: barry bocchieri at June 27, 2005 8:39 AM

Art, great stuff. Read everyday. Your comment on sleep is very interesting. I would be interested in hearing more comments on how to optimize sleep. I've heard many things but one of the most interesting was on the importance of body temperature variation during the day. Your body temperature rises during the day and falls at night. The higher the range the better. The main recommendations were:
1. Get lots of bright light in the day. It regulates hormones and helps raise body temp.
2. Raise your body temperature through exercise.

Its "common knowledge" that setting a regular (ie rigid) sleep cycle is best, however, this seems contridictory to the random patterns of evolution and thus, what our bodies best respond to. More elaboration would be appreciated.

Posted by: Woody at June 26, 2005 10:44 PM

I agree with Jeffrey, any late meal is going to alter the amino acids that get through the blood/brain barrier, particularly one that is high in protein.

Second, if you cut the late meal and still wake up hungry, then I suspect you may be insulin resistant. Check your insulin.

Third, you didn't say what your snack was. It may be carbs, which many people find relaxing because they increase serotonin. This would add evidence to the hypothesis of insulin resistance.

Fourth, big deal if you wake up. People take sleep too seriously. You should get enough, but you can't make it happen. Wild animals are known to spend hours during the night in a kind of wakeful sleep or even wide awake.

I don't think our ancestors got the 8 square hours with no interruptions or awakenings that popular versions of professional sleep advice are apt to summarize their research as saying. It doesn't.

No research on the boxing thing; it is one of those things they don't understand, nobody did until the research I cited came out. But, the serious trainers do it. Evander Holloway was trained by Fred Hatfield (the semi-famous Dr. Squat) and part of the pre fight routine was to eat well before the fight and to enter the ring in a slightly fasting state.

Simon's question/hypothesis has never been researched in quite that form and the research would be extremely difficult to do. None the less, my post to the brief, but high intensity research and to Arthur Jone's theories support that point.

Many would agree that as you round into great condition, you are capable of doing so much that you should do less. That is to say, if you are strong enough it is easy to overtrain. So, train hard but briefly. Those who are in bad shape can barely do enough to overtrain even though their limit for overtraining is low.

Posted by: Arthur De Vany at June 26, 2005 4:27 PM

Anybody please have any info /knowledgey on anything akin to the hypothesis that the more sensitive the system becomes the more one gets from less anaerobic exercise; less meaning time spent, albeit very frequently done or is this gibberish, please ?

Fanks

Posted by: simon fellows at June 26, 2005 10:19 AM

Tom,
Sorry, I tend toward extreme brevity.
It was also my experience to awaken at 0300 or so if I ate anything late. Since skipping the late meal/snack I rarely awaken during the night.

Posted by: Jeffrey Budewitz at June 25, 2005 9:54 AM

Tom,
I would suspect you awake because of the late meal, not despite it.

Posted by: Jeffrey Budewitz at June 25, 2005 8:27 AM

Art: How do you sleep when hungry? As it is, I bounce awake most every night around 3 or 4--even after having eaten a moderate low carb/glycemic meal late, and have to eat something before I can fall back asleep.

Posted by: Tom Traynor at June 24, 2005 4:35 PM

Art,

Can you comment on Ketosis. I've seen conflicting statements regarding it being a natural and desireable mechanism VS dangerous and to be avoided. How does it compare to FFA uptake as you describe it. Thanks.

Posted by: Mike Stima at June 24, 2005 4:00 PM

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