Ric,

I feel that your main points are being missed about endurance cycling, ie that it is not power dependent and that performance improvement is training specific. Anyway,

I have a few questions for yourself and any others who have expertise/research in these areas.

The first being the 'Lacate Shuttle' concept (I dont want a debate like someone did with J-MAX on a related thred). Would resistance training of the white muscle fibres (typeI) be beneficial to increase the AT/LT (if it even exists, lets call it a threshold of sorts for arguments sake), improving mitochondrial density and physiological characteristics? By this I mean that as more lactate is produced (with the onset of glycolysis) it can be used (shuttled) to adjacent/other muscle cells/organs to be converted back to pyruvate (cori cycle) to then absorb more of the H+ ions which seem to be the reason behind the onset of fatigue (not the debate/question here). However, I can see how it may not be relevant to endurance cyclists (elite or not) as their dependence on the glycoltic pathway is not at a high enough intensity to evoke an efflux into the blood. This theory may be substantiated in studies that have noted higher BL levels in trained cyclists, as fatigue is definitely localised with a high percentage of muscle fibres not performing the same amount of 'work' as others, for example rec fem vs triceps. Therefore, would you expect to see lower BL levels? So back to my question do you think that RT could assist the bodies buffer system in the onset of fatigue?

Sorry for the essay. My final question (quick i promise) is to do with diet. What kind of experiments with nutrition do you experiment with, with your cyclists? (an open question to anyone interested) as well publisised that the BL curve can be shifted to the right (which would benefit endurace performame possibly) with glycogen depletion, as it increases the demand on the Type I fibres and aerobic metabolism to work harder as well as prevent the onset of insulin and result further in more catecholamines to help with the cori cycle and lipid metabolism. To my point, what do you know of a high-fat approach (low carbohydrate) to improving endurance performance and training.

Regards

Lys

No experiments, only modifications of regimes (i.e. eating times before races, different carbohydrate loading regimes, etc.).
Can you provide more information, I don't recall a well publicised shift in the BL response? To pick up on some of your points...
*Glycogen depletion will lead to a decrease in/limited 'exercise capacity' and therefore decrease potential for performance.
*Insulin response is supressed during exercise and remains at low levels at rest and exercise unless food is eaten.
No, low carbohydrate diets are considered negative to performance and recovery during training and racing. High fat diets are potentialy damaging to health (so are very high carbohydrate diets). Best to maintain a balance of carbohydrate, protein and fat (i.e. neither excessively high in fat or carbs or protein).

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Thanks for the reply.

The topic of high fat diets and performance are definitely not well researched, due to the dogma of high carbohydrate and performance. I am not questioning this has been shown to increase performance as you most probably can confirm. However in regards to endurance events and as you quite rightly pointed out, as glycogen depletion is the direct cause of fatigue, the body needs to tap in to both energy systems. With lactate production as a marker of anaerobic metabolism and the LT (or whatever people decide to call it) is the rate at which BL is at a rapidly increasing level, to enhance performance in endurance events wouldn$B!G(Bt it be best to not deplete carbohydrate stores until the end, relying on an increased contribution from the body$B!G(Bs fat stores? By training in a state of glycogen depletion, perhaps the body would learn to utilise the oxidative system optimally?

Can you provide more information, I don't recall a well publicised shift in the BL response? To pick up on some of your points...

As BL is a response to anaerobic metabolism, if there are very little carbohydrates to burn, the body has to look elsewhere. Therefore the use of lactate as an energy source increases and is utilised on production (lactate shuttle theory) as an energy source therefore lowering the BL levels. These are two that show this can happen

Int J Sport Nutr Exerc Metab 2001 Jun;11(2):248-57
The effect of low-carbohydrate diet on the pattern of hormonal changes during incremental, graded exercise in young men. (Not in performance athletes though )

Maughan RJ, Greenhaff PL, Leiper JB, Ball D, Lambert CP, Gleeson M..Diet composition and the performance of high-intensity exercise. J Sports Sci. 1997 Jun;15(3):265-75


Therefore if this is the case, would my question of increasing the mitochondial density of non-anaerobic working muscle (RT or CV) to consume lactate as an energy source decrease BL level?

*Glycogen depletion will lead to a decrease in/limited 'exercise capacity' and therefore decrease potential for performance.

Very good point, therefore $B!F(Bif carbohydrates are completely depleted, how can the athlete perform?$B!G(B I am sure there are elite athletes who are diabetic, so carbohydrate loading is most probably (I am assuming form what I know) dangerous to them. Therefore what do they consume to produce their best performances?

What are your ideas for the comparison of animals energy system to humans? They are considered $B!F(Bsimilar$B!G(B in order to test them or it would not be valid. Here is my questioning of this area. A Cheetah is one of the fastest land animals and can sprint for a long time when hunting (an assumption). But, what carbohydrates do Cheetahs consume, I would guess they ate mainly proteins and fats from its prey. Why could this not be true in humans?


*Insulin response is supressed during exercise and remains at low levels at rest and exercise unless food is eaten.

Extraction from Glucose Ingestion and Performance, Izumi Nishibata

Ingestion of large amount of glucose (simple sugar) before the initiation of endurance exercise may impair performance (Foster, C., D. L. Costill, and W. J. Fink. Effects of preexercise feedings on endurance performance. Med. Sci. Sports 11: 1-5, 1979) Blood glucose concentration increases when glucose is ingested. Then, blood insulin concentration increases to decrease or stabilize blood glucose concentration by increasing uptake and consumption of blood glucose by various organs. Insulin also depresses the mobilization of fat from adipose tissue. If you begin high intensity endurance exercise with high insulin concentration, blood glucose concentration may soon abruptly decrease because the exercising musculature consumes large amount of blood glucose with the stimulation of high insulin concentration. When blood glucose is decreased and fat cannot be used as an energy source because of the prevention by insulin, the exercising musculature can only depend on its muscle glycogen as its energy source. This hastens the muscle glycogen depletion and decreases performance. When you ingest glucose after the initiation of exercise, blood glucose does not increase as rapidly as you ingest it before the initiation of exercise, because exercise decreases gastric emptying and absorption of ingested glucose. Also catecholamine secreted by the stimulation of the stress of exercise prevent insulin secretion. The higher the exercise intensity is, the larger amount of catecholamine is secreted.

No, low carbohydrate diets are considered negative to performance and recovery during training and racing. High fat diets are potentialy damaging to health (so are very high carbohydrate diets). Best to maintain a balance of carbohydrate, protein and fat (i.e. neither excessively high in fat or carbs or protein).

Would you not consider doing a trial on performance after a low-carb, high fat diet as there is a need for such research especially from those who are competing for real and not just testing in the lab?

Also, why are high fat diets damaging to health? Obesity is interchangeable with type II diabetes that is treated with low/no sugar (possibly GI, depending on the severity) and high fats, which reduce serum cholesterol and triglycerides improving their health status. Again it is for this reason that I question the proposal that a high fat diet is so directly linked with health problems. From what I have read, it is now believed that it is a high fat and high carbohydrate (like you stated) that is the main cause.

Final thing have you guys heard of g-push?

PS: I have to be $B!F(Bargumentative$B!G(B for my rationale, I am not contesting the use of high CHO for performance, but trying to find a reasoning for the possible advantages of low-carbohydrate training for health and performance.

Thanks

As you quotes some journals you might like to research these questions yourself (you'll find more reliable and rounded answers than I can generate off the top of my head)....
If high fat diets do not increase performance why do 'performance research' in high fat diets? There are far bigger questions to be answered in scienece (i.e. a cure for cancer) and sport (i.e. what is the optimal carbohydrate loading regime).

As lactate begins life as glucose/glycogen via glycolysis, glycogen depletion results in lower lactate production and lower exercise performance; therefore WORSE PERFORMANCE. You suggest that the rider should race in a depleted state and then supplement at the end; this is not a good option as the rider would 1. be last and/or fatigued by the time it was time to eat carbohydrate and 2. carbohydrate won't be absorb effectivly to increase performance.

Using energy from fat stores (and no energy from glucose due to glycogen depletion) is not a good idea because 1. its bad for your health and 2. energy from fat is supplied at a lower rate (i.e. WORSE PERFORMANCE).

Training in a glycogen depleted state to increase aerobic metabolism is a bad idea because 1. its not specific (you shouldn't be racing in a glycogen depleted state), 2. there may be no transfer of adaptations from a glycogen depleted state to a non glycogen depleted state and 3. increases in aeroboic metabolism (i.e. increased VO2 max) are induced by high intensity efforts that are difficult in a glycogen depleted state.
From what you have written I think you have miss understood the lactate shuttle theory. Also BL is measured because it closely represents what is happening in the muscles (i.e. muscle lactate). It is the concentrations of lactate in the muscle that limit contractions rather than blood lactate. Therefore reducing BL independantly of ML won't inprove performance.
Possibly (but I haven't done any reading on this topic), but given that it won't effect muscle lactate concentrations significantly its unlikely to improve performance. Most cyclists are in a possition where more 'on the bike' training will improve perforance; training spent aerobicaly training the 'non cycling' muscles is therefore wasted time. BL is removed in large part by the liver; perhaps you should be training that !
(A) Athletes can perform in a glycogen depleted state but at a reduced level (i.e. the 'knock' or 'bonk'). Diabetics have carbohydrate and can eat carbohydrate; carbohydrate loading is not dangerous for diabetics (although some will have to monitor their insulin, blood glucose levels and actual intake to remain safe). Diabetics have carbohydrate to produce their best performances; there are no secrets or magic pills!!!!

(B) Comparing animals to humans provides very little value at all!!!!! Cheetah is one of the quickest animals; however has four legs, different muscle fibre composition, only sprints for 10's of sconds (not ride for hours), etc. etc. Why isn't this the case for human's; because many many research studies over decades have shown that during exercise without glucose performance is limited (i.e. protein or fat are not as important).
This is the most basic advice ever, not to eat too soon before a ride. Generaly people recomend that you shouldn't eat high GI in the 2 hours prior to exercise. Your orignial post you implied not eating during exercise for insulin control; this would be bad advice given that insulin is suppressed during exercise and carbohydrate consumption during exercise can imporve performance.
There is nothing to suggest that a high fat diet would improve performance and lots of lab & anecdotal evidence that suggests it would result in WORSE PERFORMANCE. Repeating the test would be a waste of time.
Obesity is a result of excess energy intake (i.e. to many kcals) and independant to the composition of the diet.

High fat diets can be bad for health, immediatly after a fatty meal plasma triglycerides increase proportionatly to the fat load of meal and remain high for up to 10 hours latter. The triglycerides are carried in LDL and chylomicrons, which both have negative effects on cholesterol transport and are considered atherogenic.

Please read the work on postprandial triglyceride response, by Cohn, Patsch, Austin, etc.
No, but I have heared that water and carbohydrate are good ergogenic aids! Why look elsewhere for performance improvements when the basics are done badly.
There is no problem with you being arguementative; however its a little frustrating when people quote books and journals yet haven't done some basic reading.

In all of the books and reading (except the ATKINS book!) you will see that carbohydrate is important in IMPROVING AND MAINTAINING PERFORMANCE.

Also, interms of health, the very early research shows that high fat meals and diets are bad for your health and this remains correct today. However more information is becoming available on carbohydrate, fat and protein metabolism which is being miss interpurted by the public. It is likely (and perhaps obvious that) some carbohydrates are bad and some fats are good; but that doesn't mean that all carbs are bad and all fats are good.

Finaly, dehydration and glycogen depletion present the largest limits on performance; therefore carbohydrate and water are the most important parts of an athletes diet.

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2LAP,

Thanks again for the response. I dont think it is a case of simple reading of such an area, as the commonplace topic of blood lactate, is still interchanged with an oxygen defict.

Like you stated in an earlier thread (similar topic) why do we believe science, in its relationship with real life settings?

Therefore, why dont we question high carbohydrate diets as being the norm? Take the Atkins book, the guy had to defend his theory in congress!!! He was a cardiologist that changed the lives of his obese patients, arguing against the point you made of excess weight is the resultant of excess calories.

Anyway, in terms of my questioning of the area (and you are right in one respect, I have not read around the whole area, who can?). But, research is slipping through the net of plasma FFA improving endurance performance, due to their depression of carbohydrate utilisation (Is this not the ideal situation for an endurance cyclist? To save their glycogen levels until needed). In terms of the BL, yes you are right (until the next Brooks), and lactate will be reduced (what I was refering to as a shift to the right in the BL curve initially).

Anyway from a biochemical standpoint, glyerol released from fat metabolism enters glycolysis at the same level as glycogen (in fact saving an ATP molecule) therefore lactate can be produced.

In terms of effect on performace, am I wrong in thinking that endurance cycling relies heavily also on fat metabolism to conserve carbohydrate use?? Therfore a higher fat intake the morning before competition can conserve carb' due to the elevated FFA. This is associated with the energy system crossover concept.

These are just some reassons why I am challenging the high carbohydrate rationale. My thoughts to glycogen depletion would be during phases of training (off season micro cycles/ pre determined points) before a periodised increase in glycogen closer to events, and then a high fat breakfast?

This is the rationale behind testing into high fat/low carb diets as there is definitly a need, arent we all trying to achieve the best performance times and methods?

Therefore by improving our lipid metabolism system, enzymes, mitochondria etc, carbohydrate stores will be spared leaving the 'extra' for the end of the race?

Regards

PS G-Push is a carbohydrate drink, made from galactose rather than gluccose/fructose which produces a more favorable gastrointestinal environment, shown to improve the gradual usage during exercise, in theory an excellent concept????

I guess that depends on what you describe as high carbohydrate. I often recommend the often quoted 50-60% of kcals from carbs, 10-15% protein and the rest made up by fat (i.e. <30%). Which I consider 'balanced' rather than 'high carbohydrates'.

There are many good cardiologists doing good work, who all give different advice and yet have similar results. Even the maintenance stage of the Atkins diet has a large number of Kcals from carbs; so even Atkins himself disn't think they were all that bad. I'm not sure that he disagreed with the fact that excess calories cause weight gain, yet he argued that the composition of the diet can change weight gain/health.

I have yet to meet a dieter or read a paper that doesn't show that having a negative energy balance causes anything other than weight loss.
If there is such a gap in the research, I think you have found your topic for your Ph.D.

Of course preserving glycogen is the ideal situation for the endurance athlete, as long as energy is supplied at the same rate. In fact, one important response to endurance training is an increase in fat utilization at any given intensity.

Don't you think that consumbing carbohydrates during exercise would be a preferential was of avoiding glycogen depletion rather than eating to increase plasma FFA? Furthermore, most of the fat used during exercise comes from muscle triglyceride stores with plasma and adipose tissue supplying the muscle in the post exercise state (due to changes in lipoprotein lipase activity).
But not at the same rate, hence lower lactate levels, lower ATP resynthesis and lower performance in glycogen depleted states.
Yes, endurance exercise does reply on fat metabolism; hence this is why fat metabolism increases with endurance training.

Any benefit from eating fat in the morning would be significantly less than that of consuming carbohydrate. The value of eating carbs during exercise is one of the least debated issues in sport/exercise science.
Training in a glycogen depleted state is a poor way to go for the two reasons I mentioned before (1) limited specificity and (2) limited intensity. Not to mention the psychological aspects of riding in a glycogen depleted state.
Yes we are; and I'll be interested to find out your results! But from the weight of research, I feel that this will be bad for both health and performance. Do you remember what if felt like and how fast you went lest time you were glycogen depleted? I sometimes halucinate and just want to fall asleep.
Yes, but this can be acheived through simple training, consumbing carbohydrate and through tactics (i.e. pacing, sheltering, correct gearing, etc.). Surely this is better advice to give to an athlete?

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You may to ask Lyle McDonald some of these questions off of his website at http://www.bodyrecomposition.com/ . He's the guru of ketogenic diets (and diets in general) and has this short blurb in his latest book:

"Additionally, current research has shown that following a 5 day low-carbohydrate period with a 1 day carb-load can actually _increase_ performance in some endurence athletes. The low-carb days in crease fat utilization while the carb-loading period increases muscle glycogen for high-intensity efforts."

He'll know what study he pulled that from.

-Scott

1) the existence of the "lactate shuttle" is debatable, as essentially all of the research upon which the idea rests is based on the use of lactate tracers in whole-body experiments. For reasons *FAR* too complex to go into on a forum like this one, such data are essentially uninterpretable.

2) there have, in fact, been quite a few studies of the effects of low carbohdyrate diets on performance in humans, *none* of which has shown any benefit. To help you quickly get up to speed (and at great risk of sounding quite egotistical), I suggest you start with this review:

AR Coggan and LA Mendenhall. Effect of diet on substrate metabolism during exercise. In: Lamb DR and Gisolfi CV, eds. Perspectives in Exercise Science and Sports Medicine, Vol. 5: Energy Metabolism During Exercise and Sport. Dubuque, IA: Brown and Benchmark, 1992: 435-464.

then do a search of PubMed for a series of studies by John Hawley et al. that were published after the above was written. (The quote in the message just prior to this one is undoubtly from one of John's studies, and likely is referring to one or several subjects whose response went the opposite direction of the group means...which could very well have been due to chance, not some hypothetical intra-individual difference.)

You're not going to come off as egotistical to me, Andy - you're the bomb and know 1000x more than me, and you know from rbr I'm just interested in learning, not promulgating a certain viewpoint.

Thanks for the studies - right now I _am_ doing a cyclical low-carb diet, but not because of any training benefit it might offer, but because it's an excellent option for bettering my body composition, which is really my limiting factor for performance right now instead of average watts at lt. :-)

-Scott

Just be careful about doing this when you are training. Glycogen depletion can and will lead to illness and poor recovery. It is very important to have enough carbohydrate to avoid 'the bonk'. I can see the arguments for keeping down your blood insulin levels etc with low GI/atkins (though I don't really agree with them, especially not for athletes), but I promise you, if you train a lot without enough carb, you will not feel well.

Also, that energy drink that uses galactose as a carb source for slow release is a waste of time during exercise - slow utilisation is not an advantage, it's a negative. Galactose, lactose and fructose are not so good during exercise (though still a lot better than nothing). You want the energy on tap as soon as possible.

Liver and muscle glycogen depletion also results in excellent fat loss. Note that I mentioned my diet was cyclical, so all of my high-intensity workouts happen when I have carbs (actually Sat-Sun-Mon), and low-intensity when I don't.

Why do you say this? Negative calorie balance leads to weight loss. Fat substrate utilisation can be increased during exercise by following certain nutritional guidelines. Lipolysis is the primary source of energy at rest, so I don't see why you need to risk illness by getting glycogen deplete. You would probably do well to avoid insulin spikes though, so low GI makes some sense, but this doesn't mean no carb, it means the right sort of carb.

The only reason I can see for getting at all glycogen deplete is in the 'classical' model for carbohydrate loading, where you exhaust your glycogen then eat a lot of carb so muscle and liver glycogen gets very high prior to a target event. This is outdated anyway, although somewhat effective. Go for the moderate supercompensation model anyday...

Great post. People often don't realise that a negative energy balance is the most important factor in weight loss. 1000 kcal is 1000 kcal no matter the source.

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There's no increased risk of illness with glycogen depletion, and it increases CPT (carnitine palmityl transferase) activity, increasing fat loss, and the drop in insulin from lowering carb intake naturally inhibits alpha-2 receptors in the fat cells (a good thing).

Cyclists are constantly terrified they aren't getting enough carbs so many _overeat_ them, which is why we have fat masters syndrome and pros who don't even have a vein running up their biceps and fat covering their kneecaps when they stand up.

I'm not just supercompensating with glycogen to get me through the next hard training block, I'm refeeding to bump up my leptin levels and keep my metabolism from crashing.

Why not drop insulin by consuming low GI carb if you're particularly concerned by that?

Quote:

Cyclists are constantly terrified they aren't getting enough carbs so many _overeat_ them, which is why we have fat masters syndrome and pros who don't even have a vein running up their biceps and fat covering their kneecaps when they stand up.

We have fat masters because they eat more energy than they expand. Pros have quads that cover their kneecaps. It's very impressive. They also have veins in their biceps - otherwise they wouldn't be able to use their arms. Imagine all those floppy armed pros having to ride down the pyrenees with no hands!

It's not that carbs are the only part of a balanced diet cyclists need - they need everything, macro and micronutrients. Cutting out any one (or more) of these things is a bad idea - carbs included.

Quote:

I'm not just supercompensating with glycogen to get me through the next hard training block, I'm refeeding to bump up my leptin levels and keep my metabolism from crashing.

I know you're not following a taper and supercompensating. You are regularly (it seems) running your liver and muscle glycogen to dangerously low levels (or you are actually eating more carb than you realise which is quite possible). That's fine if you want to do it, but there is simply no reason to, and it seems likely it will increase the risk of infection.