[multirider]

I'm doing races of 1.5-2.5 hours. I'm wondering how to warm-up. I'd like to spare glycogen as much as possible, so it would be helpful to know when the body uses glycogen.

My LT is 169bpm and max around 185bpm. My 1 hour power is about 275w.

My understanding is that if I'm putting out big watts (i.e. 400) at a high HR (i.e. 170), I've gone anaerobic and am using glycogen. But how about if I'm putting out big watts at a low HR?

For example, if I';m spinning fairly easily on a trainer for a few minutes and my HR is at 130, then I start putting out 400w for the start of an interval, would I be using glycogen as my HR climbs from 130 up through 140 and 150 to 160? Or is glycogen only used once above LTHR?

For a 2-3 hour race where I definitely will hit high HRs, is it important to hit high HRs in my warm-up?

Does cadence have any effect on glycogen usage?

Thanks!

 

[bmxhacksaw]

Your theology's all wrong dude

 

[Argentius]

Your theology's all wrong dude

Theology is religion...

 

[bmxhacksaw]

Theology is religion...

Actually, theology is the study of God which is quite different from "religion" but he'll get it :wink:

 

[Gatorback]

hacksaw may be being slightly cryptic, but he may really know what he is talking about.

The problem with your question is that you are kind of mixing apples and oranges. The bottom line is that if you are exercising at a high intensity, i.e. 400 watts with a 275 watt FTP, you are going to be burning a very very high percentage of glycogen and it won't matter whether you are doing it aerobically or anaerobically or whether you are doing it with a high cadence or low cadence.

A summary: Your muscles MUST have glucose available to contract. This is true whether you are producing energy aerobically or anaerobically. Glycogen is just the name given to glucose stored in skeletal muscles. We also have glucose stored in our liver and glucose that our body can tap into through fat cells. Getting glucose from the liver occurs quickly, but we have only a very limited amount stored in our liver (something like 80g I believe). Getting glucose from our skeletcal muscles (glycogen) also occurs very fast, and while we have a lot more energy available there it is still a limited source. On the other hand, for purposes of a 2 hour event, you have WAY more glucose than you would ever need stored in body fat even if you have an extremely low body fat percentage (even just 2-3% body fat). There is a problem, however, in that our bodies can't convert the glucose available in fat very quickly: not even enough to fully fuel very easy efforts.

When you exercise at a low intensity, you burn a higher percentage of glucose that has been converted from fat cells. So a lower percentage is coming from your liver stores and from skeletal muscle (glycogen). When you exercise at a high intensity, you need more glucose very quickly and your body taps more into the limited liver stores and primarily glycogen. You burn mostly if not almost exclusively the glucose stored in your skeletal muscle by necessity.

Here is what I would suggest:

Don't worry about it. If you train well, especially by doing a long ride each week, and you fuel properly before and after exercise through a good diet, then you won't burn up too much glycogen in a 2 hour race. Your warm-up is important to vasodilate your arteries/blood vessels and get your body into race pace mode. That is more important that preserving a little glycogen. Take sips of sports drink during your warm-up and maybe have a quick gel or easily digestable snack on your way to the race line. If you've trained well, you'll be fine. Make sure to try to ingest glucose during the event, to keep restoring your liver glucose supplies, during your event. That will help.

 

[Argentius]

Actually, theology is the study of God which is quite different from "religion" but he'll get it :wink:

It could be the study of clouds but it ain't bike racin'.

 

[sdeeer]

Humans don't have the enzyme to convert fat ingo glucose. They can only use the glycerol from triacylgylcerides to be converted to glucose. So there is no storage of glucose in adipose tissue as anything other than the glycerol head and fatty acids.

The liver has about 100 grams of glycogen ina full liver and muscle glycogen can be much higher depending on the muscle size.

Durring exercise, fat from lypolysis is relased from adipose tissue into the blood for oxidation (to provide energy) in the muscle. At the higher intensities, you are still burning fat, but glycolysis is "faster" than beta-oxidation, so more acytl-CoA's are coming from glucose/glycogen. And lactate production goes up as the TCA/PDH can not keep up with energy demands.

Overall, metabolic pathways aside, eating a carbohydrate containing food will spare muscle glycogen. With glucose alone, absorption is the limiting factor and high doeses can cause gastric problems at high intensity. Glu-fructose mixed drinks have been shown to be the best bet from a performance and sparing of muscle glycogen standpoint.

The addition of caffiene further improves the benefit.

 

[bmxhacksaw]

It could be the study of clouds but it ain't bike racin'.

No, but it is knowing Multirider for the last 5-10 years from another message board of a different sort

 

[Gatorback]

Humans don't have the enzyme to convert fat ingo glucose. They can only use the glycerol from triacylgylcerides to be converted to glucose. So there is no storage of glucose in adipose tissue as anything other than the glycerol head and fatty acids.

.

You are correct, but the bottom line is your body converts fat into glucose. You are just explaining the steps in a little more detail. You could break them down even further if you wanted. (I kind of thought I was provided a little too scientif of a response).

 

[sdeeer]

You are correct, but the bottom line is your body converts fat into glucose. You are just explaining the steps in a little more detail. You could break them down even further if you wanted. (I kind of thought I was provided a little too scientif of a response).

Sorry, but you are still wrong. Fat can not be converted to glucose in any way in the human body. Fat is stored as long carbon chains (typically 16 C long) and when broken down via Beta-oxidation, it is made into acetyl-CoA (2C) which enters the TCA (krebs cycle). Fat can also be made into various hormones, etc, but not glucose or any other carbohydrate.

 

[Alex_Simmons/RST]

so it would be helpful to know when the body uses glycogen.

All the time.

Just sip some CHO drink during warm up and have a good mostly CHO meal 2-3 hours before the race.

 

[151]

I have a feeling this guy is doing off road MC races, like me. SO you guys please quit jerking his chain.

Dude I am sorry all these smarty pants cyclist are trying to confuse you. They all know that it was proven back in 2002 that cycling is not good for dirt bike racers. Also eating carbs, BAD. Warming up, BAD.

The best thing you can do is keep your mind sharp by watching lots of MTV. The one comment about caffiene was spot on so drink LOTS of redbull.

 

[gardenrunner]

???

You are correct, but the bottom line is your body converts fat into glucose. You are just explaining the steps in a little more detail. You could break them down even further if you wanted. (I kind of thought I was provided a little too scientif of a response).

Were you trying to say that the body depends on fat as it would glucose after a certain amount of hours? Otherwise, sdeer would be correct. That's why endurance atheletes are so damn skinny and have hardly any body fat. After training a certain amount of hours(I believe it's 3 +) the body starts to use your fat stores as fuel. This is also why after 2-3ish plus hours of training you need some protein intake or your body will turn to it's own protein(your muscles) and thus leads to muscle cannibalization. Correct, sdeer?

 

[sdeeer]

Were you trying to say that the body depends on fat as it would glucose after a certain amount of hours? Otherwise, sdeer would be correct. That's why endurance atheletes are so damn skinny and have hardly any body fat. After training a certain amount of hours(I believe it's 3 +) the body starts to use your fat stores as fuel. This is also why after 2-3ish plus hours of training you need some protein intake or your body will turn to it's own protein(your muscles) and thus leads to muscle cannibalization. Correct, sdeer?

For those with out an exericse/metabolism background, this gets kind of complicated. But to keep it somewhat simple....

To start out, you are always burning fat, carbs, and a really small amount of protein during exericise. The amount of fat and carbs depends on the intensity, duration, feeding, and a combination of these factors. Your body prefers to burn carbs, as it "likes" to have muscle glycogen available. Training increases the mitochondrial density (size) and blood flow (capilary density) to muscle which allows for greater use of both fat and glucose during exercsie. The more ATP you can produce, the more work you can do.

Your body uses what it has available (CHO or FAT) for energy during exericse, but has a "preference" for glucose. So, if you exercise at moderate intensity (zone 2 -3) after an overnight fast or for more than 1.5 - 2+ hours into an event without eating again, you use quite a bit of fat for energy coming from adipose tisse and IMTG's. However, you are always burning glycogen as it is a perfered source of energy and readiliy available in muscle tissue, but in the absence of exegenous (from the diet) carb intake, glycogen can "run out" making the oxidation of fat "more difficult". This is the bonk, or hiting the wall as glycogen is runing low and the the enzyme that cuts off glucose is not able to further debranch gylcogen. You never truely run out of glycogen until you die, you just get so low that the "branches" are too short for the enzyme to cut off more glucose. Additionally, exericse in the fasted state is not as good from a performance standpoint and typically does not translate into greater "fat loss" as calories are replaced post-exercsie. Energy balance is the driving factor in body weight and to a certain extent, body composition.

If you eat (carbs) before exercise, then you have glucose available in the blood and in the muscle as glycogen. Glucose oxidation is increased as it "competes" (more of it right there) for oxidation with fat (that is coming from IMTGs and adipose tissue). So you burn less absolute fat, but the same amount of "calories".

Absorption of carbs from the gut is limited at high intensity (less blood flow to gut) and increases glycogen and fat use. However, gylcogen and blood glucose are "faster" sources of ATP during exericse and seem to outcompete fat to provide acetyl-CoA's for the TCA. At high intensity, fat is still being used, but a much greater contribution is coming from glucose/gylcogen. Lactate production is increased as pyruvate is "backing up" for entry into the TCA.

As far as protein breakdown in the muscle is concerned, it is relatively constant. Protein provides a small amount (relatively) to energy and/or glucose precursors. Protein synthesis (rebuilding muscle tissue) can not take place during exercise as AMPkinase activity inhibits downstream protein synthetic machinary. The latest data show no benefit of adding protein to CHO drinks other than satiety. But post workout/race protein and adduquate and often CHO/Protein are required for recovery.

Endurance athletes have low fat mass due to a chronic negative energy balance. They burn so many calories during training and racing and then do not replace them all before the next bout (next day) of training. We (athletes) use a high relative and absolute amount of fat to provide energy at rest and after exercise. So the slight negative energy balance over time, leads to less fat in adipose tissue, as energy (calories/CHO/PRO) is used for recovery, glycogen replenishment, and muscle protein synthesis.

 

[Alex_Simmons/RST]

For those with out an exericse/metabolism background, this gets kind of complicated. But to keep it somewhat simple....

Nice. I just hope it was simple enough to debunk in people's minds some of the myths being regurgitated here.

 

[Alex_Simmons/RST]

so drink LOTS of redbull.

The irony of course is that Redbull is a carbohydrate drink (with caffeine).

 

[Gatorback]

Were you trying to say that the body depends on fat as it would glucose after a certain amount of hours? Otherwise, sdeer would be correct. That's why endurance atheletes are so damn skinny and have hardly any body fat. After training a certain amount of hours(I believe it's 3 +) the body starts to use your fat stores as fuel. This is also why after 2-3ish plus hours of training you need some protein intake or your body will turn to it's own protein(your muscles) and thus leads to muscle cannibalization. Correct, sdeer?

I'm saying that the body uses fat for fuel pretty much all the time, in different ratios with both blood glucose and glycogen depending on intensity of exercise, but was doing it in a simple way by just referring to glucose because most people just consider glucose as the fuel source used in exercises. I just didn't realize my attempt at a simple but informational explanation on an internet forum, correctly answering someone's basic question about whether they can avoid burning glycogen during their warm-up, would be subject to peer review as if I was publishing in a scientific journal.

For those of you that want to delve into the intricacies of metabolism, you can listen to sdeeer's explanation. Just don't try to answer someone's question on here with a little extra information less you be dressed down.

Now I'm sure someone will find something technically wrong here as well. But that is o.k. because I've got thick skin.

 

[gardenrunner]

It's okay, Gator.

I'm saying that the body uses fat for fuel pretty much all the time, in different ratios with both blood glucose and glycogen depending on intensity of exercise, but was doing it in a simple way by just referring to glucose because most people just consider glucose as the fuel source used in exercises. I just didn't realize my attempt at a simple but informational explanation on an internet forum, correctly answering someone's basic question about whether they can avoid burning glycogen during their warm-up, would be subject to peer review as if I was publishing in a scientific journal.

For those of you that want to delve into the intricacies of metabolism, you can listen to sdeeer's explanation. Just don't try to answer someone's question on here with a little extra information less you be dressed down.

Now I'm sure someone will find something technically wrong here as well. But that is o.k. because I've got thick skin.

Hey man, I was just trying to clarify what you were saying because it was confusing. No need to get defensive. I wasn't trying to be a smartiepants, either. I just wanted to make sure what you were saying was getting across appropriately. :thumbsup:

 

[multirider]

Your theology's all wrong dude

Hey, BMX, good to see you're alive and kicking! And still riding. Cool!

 

[multirider]

Work has been crazy and I haven't had time to check back. Thanks for the responses!

A little clarification -- I'm racing 2-3 hour events all summer. I'm also doing the Leadville 100 on August 14. That will be 9-10 hours of racing (if all goes well, it will be 8:30-8:59).

My question is primarily related to the shorter events, but greater understanding of fueling will help for Leadville, so all info is welcome.

The races I'm doing are up in the mountains west of Denver. Starting at 9,000 feet and involve a LOT of climbing. Most climbs are fairly short - 5-10 minutes and then some flat or down. Sometimes there are 15-20 minute climbs.

I climb better than I descend, so I relying on climbing to stay with the leaders. I have found that I climb very strongly and stay with the leaders early, but am able to put out less power and sustain it for less time as the race goes on. Specifically, I can put out 500-600 watts for a minute or so at the beginning of a race to get into the lead pack. I can put out 400-450 watts for several minutes early in the race to match accelerations and attacks. But late in the race, I canj't put out 500-600 watts to save my life and am reduced to 300-350 watts for anything over a minute, 250-275w for anything over 5 minutes.

A friend of mine is a USAC coach and does very well in his category. He told me that my problem was I've used up all my glycogen early in the race and don't have any left for the big anaerobic efforts towards the end of the race. So the basis of my question about preserving glycogen during warm-up was the belief that doing so would help me put out bigger watts late in the race so I can stay with the leaders.

Since Z4 and Z5 are labeled "anaerobic", I was wondering if doing 450w in Z2 or Z3 HR would spare my glycogen stores. Thus, I was wondering if hitting Z4 in pre-race warm-up was necessary or desirable, or if keeping my HR down would preserve glycogen.

The above posts contain great info, but I'm not clear on that basic issue - is it possible to preserve glycogen during warm-up by keeping HR down (even if I do some 1 or 2 minute big-watt efforts)? Is that desirable? Or is it better to hit Z4 HRs in warm-up?

From the above, it sounds like consuming CHO during the race helps preserve glycogen. Right?

I guess an even more basic question is this: am I on the right track to improving late-in-the-race performance by trying to preserve glycogen during warm-up and early in the race?

At the risk of opening a different can of worms, I've read multiple times not to consume food within 3 hours of the start of a race. But I get hungry! I typically am up at 5:30am and out the door at 6am to get to the venue by 8am to park/prep/warm up and be ready to race by 10am. I eat breakfast (oatmeal) approx 6am. If I don't eat anything else, my stomach is growling by 9am. So I typically eat a yogurt at 8am. Sometimes raisin toast. But according to what I've read, eating within an hour or two of the start of a race causes insulin to rush into the bloodstream and that opens the floodgates for glycogen consumption. So perhaps that is the problem with my racing. But going to the starting line with a stomach that is growling can't be a good thing, right?

Thanks for advice/info!