Yet Another Cycling Forum
General Category => The Knowledge => Further and Faster => Topic started by: quixoticgeek on 25 January, 2018, 10:39:54 pm
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Been wondering, how much glycogen does the average person carry round with them? I know this isn't exactly an easy thing to quantify as there's no such thing as an average person, and it probably depends on if you had a big breakfast, or large meal the night before. But I'm wondering if there's a way to get a ballpark figure of approximately the right magnitude for how many calories one might reasonably expect to be able to draw upon in terms of glycogen reserves?
Thanks
J
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from google:
"Skeletal muscles store about 400 grams or glycogen, the liver stores 90 to 110 grams of glycogen and your blood circulates roughly 25 grams as glucose. This means your body is capable of storing about 2,000 calories of carbohydrates."
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2000 was the number I had in my head.
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~16 miles at marathon pace or faster, which is likely around 2,000 calories give or take.
If I haven't done any fasted rides, I seem to manage about 45 miles on the bike without food/blowing up. After a few long fasted rides 60 miles is easy, so could presumably go further.
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After a few long fasted rides, you are probably getting better at using the 100,000 calories or so of stored fat
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I found structured training improved my fat burning more effectively than fasted or low intake long rides. I expect I was probably going catabolic and doing more harm than good.
Haven’t had it checked recently but I’m losing body fat while training so I’m burning fat somewhere.
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I read of a study some years ago which showed that if you take a 5-minute rest after an hour's endurance-level exercise you begin burning fat earlier than if you don't rest. I've had some corroboration of this myself, but since I rarely rest without eating a bar or similar it's hard to say that it works.
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sounds like you know what you are doing with this, and being more disciplined than I am with it at the moment
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Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
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^^^ hence the burgeoning middles and John Timpson's League of Pear-Shaped Men.
Re the "60 years", I reckon it goes back a lot further than that, 150 at least to judge from Gladstone's aversion for dentists.
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Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
For the normal, healthy human I'd agree with everything you said, and nutritional ketosis for endurance exercise is definitely achievable for most of us.
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^^^ hence the burgeoning middles and John Timpson's League of Pear-Shaped Men.
Re the "60 years", I reckon it goes back a lot further than that, 150 at least to judge from Gladstone's aversion for dentists.
That being said, potato starch will rot teeth even better than sugar.
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[Random historical musings]
I think tooth decay was observed in Ancient Greeks who ate many figs.
I speculate that Esau sold his birthright to Jacob for a bowl of lentil soup because he was bonked out from a morning's hunting (lots of short, sharp anaerobic sprints).
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[Random historical musings]
I think tooth decay was observed in Ancient Greeks who ate many figs.
I speculate that Esau sold his birthright to Jacob for a bowl of lentil soup because he was bonked out from a morning's hunting (lots of short, sharp anaerobic sprints).
Lentil and goat?
:)
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Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
4 days is impressive!
Is there an easy way based on heart rate to know where the fat burning zone is?
On Saturday I did my first 200k audax. My Wahoo reckons I burned 5200kcal over the 12:54 I was riding. On the day I consumed:
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta.
I'm not sure the exact numbers, but I make that something in the 2000-3000kcal range. I did notice towards the end that I was starting to flag a bit (yay for cadence meter), and even stopped with just 1km to go for a handful of M&M's just to give me a kick to get there.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
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Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
4 days is impressive!
Is there an easy way based on heart rate to know where the fat burning zone is?
On Saturday I did my first 200k audax. My Wahoo reckons I burned 5200kcal over the 12:54 I was riding. On the day I consumed:
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta.
I'm not sure the exact numbers, but I make that something in the 2000-3000kcal range. I did notice towards the end that I was starting to flag a bit (yay for cadence meter), and even stopped with just 1km to go for a handful of M&M's just to give me a kick to get there.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
That last question opens up a whole can of worms
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How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
That last question opens up a whole can of worms
Are canned worms safe to consume as part of a ketogenic diet?
J
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How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
That last question opens up a whole can of worms
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1108558
Are canned worms safe to consume as part of a ketogenic diet?
J
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Audax plus Intermittent fasting trained my body to use fat/ketones effectively.
It's what humans are supposed to do. Burning fat, and metabolising Keytones, is our normal, evolved state, not burning sugars.
It's the last 60 years of cheap, easy-access, Carbs that made us all carb-dependent and "bonked" when the Glycogen burned up after 2 hours (when you still have weeks worth of fat fuel stored).
I've cycled perfectly comfortable after 4 days of zero calories, you just need to make sure you stay in a fat-burning zone. Audax is typically fat-burning cycling.
4 days is impressive!
Is there an easy way based on heart rate to know where the fat burning zone is?
On Saturday I did my first 200k audax. My Wahoo reckons I burned 5200kcal over the 12:54 I was riding. On the day I consumed:
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta.
I'm not sure the exact numbers, but I make that something in the 2000-3000kcal range. I did notice towards the end that I was starting to flag a bit (yay for cadence meter), and even stopped with just 1km to go for a handful of M&M's just to give me a kick to get there.
The answer to the question though is, I think, about 2,000kcals. That's why non-cyclists, on the London-Brighton ride, "bonk" about 2-3 hours in. They've been burning glycogen at 600-1000kcals an hour and it's all gone. They aren't adapted to metabolise fat ...so they bonk. They're on empty. A fat-burning cyclist will cycle 50 miles without any difficulty, without the need for carbs. It just needs time to "train" your metabolism. It hurts at first.
Our snacking culture (which shuts off fat-burning immediately) means that we've generally lost our ability to metabolise the very fuel we spent millions of years evolving to use the most efficiently.
How does one go about training one's metabolism? What are the long term side effects of switching to ketotonic energy production?
J
2 cheese & Ham rolls for breakfast.
Glass of orange juice
mars bar
cheese toastie (CP 1)
M&M's ~100gm
Chocolate digestives ~90gm
Chips (portion size unknown)
400ml coke
500ml fanta.
Sounds more like you attended a 7 year old's birthday party !!
I'm not medically qualified so take this with a pinch of salt (waits for humorous dietary comment)...but..
Almost everything you consumed was a "quick hit" carb fuel and not optimal for a long steady ride.
M&Ms, Coke, Fanta, Fruit Juice..etc will just spike your blood sugars briefly and then leave you to crash afterwards.
Far better to have a bag of Mixed Nuts, simple carbs, Oatmeal porridge..etc. (There are websites for slowburn endurance carbs).
I've used sweets myself* (Jelly Babies are the accepted "help me over the final 20km" emergency fuel) but I wouldn't recommend the amount of refined sugar that you ate.
* Nothing works for me like a pint of Bitter Shandy when there's 20-30k to go.
As for the Fat-Burning Zone, I'd use the rule of thumb that, if you can chat away to a fellow cyclist, without getting out of breath, you're probably in Z2 or thereabouts.
As for adapting to burning fat efficiently there's no real shortcuts to actually riding in the zone, without eating. My first year of Audax was a story of eating, bonking & being starving hungry. That improved over time to the point I could do a summer 200 without much more than a bowl of soup.
The long term side effects of a "fasted" lifestyle are positive. It's how we evolved to live. What we do now (Constant Carbs intake) is a very recent change (see: "Type 2 diabetes" and "epidemic").
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In my experience, consuming carbs while actually exercising fairly hard (as opposed to sitting still) prevents blood sugar spikes. That said, the fitter I am, the less food I need during a brevet.
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There seems to be a bit of a vicious circle with doing long bike rides that have the pace set for you, if that pace is a bit high (doesn't matter if it's an audax where the time limit is a stretch or a group ride where you are slow for the group). To go the distance, you need to be able to burn fat, but to keep up you need to ride hard, and you can't do both.
The healthy alternatives seem: to become fat adapted and able to ride at a higher effort while burning fat, or to train your power upwards such that keeping up exerts less strain on your body. The easy way out (one I have taken before) is to fuel yourself with sugar for the whole ride!
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Going from an untrained state of 25% of energy from fat at moderate pace to a trained state of 70% of energy from fat at a moderate pace makes a huge difference to the amount of energy intake required to keep going.
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Indeed.
Those with a low aerobic capacity will working in a higher zone for a given power output and need a higher carb level despite training.
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In my experience, consuming carbs while actually exercising fairly hard (as opposed to sitting still) prevents blood sugar spikes. That said, the fitter I am, the less food I need during a brevet.
The problem is with how sugars are released into the blood though.
Refined sugars are basically just dumped into the blood quickly whereas unrefined sugars tend to "seep in" over a longer period.
Far better in my experience to keep the fuel trickling in over a long period, so you can keep it topped up, than suddenly bonking.
Far better still not to be totally reliant on Carbs.
Worth noting that the cold winter weather increases your energy requirements significantly. Even in Winter Bib-Tights your legs will be radiating a lot of body heat away unnoticed.
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The gut can only absorb about 60g of sugar per hour.
It's really not an excessive intake when working hard.
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And working muscles take up any rise in blood sugar. For most folk, blood sugar only noticeably rises (with subsequent insulin surges) if at rest.
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And working muscles take up any rise in blood sugar. For most folk, blood sugar only noticeably rises (with subsequent insulin surges) if at rest.
Agreed.
Glycogen synthesis is highest immediately after exercise so it's worth trying to get sugars in early (pudding first?!) when you rest, especially if you'll be on the move short(ish)ly.
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Glass of milk.
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Lovely. Milky milky.
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Sludge'n'custard.
Thursday afternoon tea with Grandma used to set me up for record-breaking Friday morning commutes and good Audax weekends.
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Forcing large amounts of sugar into body tissues takes huge amounts of Insulin, even when exercising - so chronic use of sugars to fuel exercise can still lead to Insulin Resistance, and T2DM. There are plenty of middle-aged triathletes and runners out there with T2DM and metabolic syndrome.
Also - relying on a continual flow of carbohydrates becomes a problem on a long ride if suddenly you can't eat for some reason; gastric distress is pretty common on endurance events, and if you're reliant on a steady intake of food, you'll be in trouble.
When Insulin is elevated, burning stored fat is shut down completely - so once you've taken that step onto the carb roller coaster, you're stuck there for the rest of the event.
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Meh. I've not had such problems.
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Forcing large amounts of sugar into body tissues takes huge amounts of Insulin, even when exercising - so chronic use of sugars to fuel exercise can still lead to Insulin Resistance, and T2DM. There are plenty of middle-aged triathletes and runners out there with T2DM and metabolic syndrome.
Also - relying on a continual flow of carbohydrates becomes a problem on a long ride if suddenly you can't eat for some reason; gastric distress is pretty common on endurance events, and if you're reliant on a steady intake of food, you'll be in trouble.
When Insulin is elevated, burning stored fat is shut down completely - so once you've taken that step onto the carb roller coaster, you're stuck there for the rest of the event.
A comprehensive survey of cardiovascular disease was carried out on 779 persons over 15 yr of age. Carbohydrate provided more than 90 per cent of caloric intake and the consumption of protein and salt were about 25 and 1 g daily, respectively. Drinking water was soft. The population was lean, physically fit and in good nutritional state. There was no increase with age in mean blood pressure, serum cholesterol (average), fasting blood glucose or adiposity. Glucose tolerance was high. The average fasting serum triglyceride level was 142mg/100ml. Serum uric acid levels were not high. Pipe smoking was common. No diabetes or gout were found. There was a low prevalence of diagnosable cardiovascular diseases: hypertension, valvular disease, cardiac decompensation (mostly cor pulmonale) and cerebral and peripheral vascular disease. Ischemic heart diesase was rare if not absent as indicated by resting and post-exercise electrocardiograms. Rates for all codeable ECG items were low except low voltage and T wave changes (commonest in middle aged women). Age-related degenerative changes occurred, such as increasing diameter of the aorta and decreasing creatinine clearance, and the declining ECG voltage with age may be indicative of cardiac disease.
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2 hours' glycogen at moderate speed (brisk but not racing). For rides longer than 2 hours you need to eat (in the saddle is fine), or be good at running on fat.
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Not everyone can eat in the saddle.
I couldn't but agree otherwise with RZ.
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A comprehensive survey of cardiovascular disease was carried out on 779 persons over 15 yr of age. Carbohydrate provided more than 90 per cent of caloric intake and the consumption of protein and salt were about 25 and 1 g daily, respectively. Drinking water was soft. The population was lean, physically fit and in good nutritional state. There was no increase with age in mean blood pressure, serum cholesterol (average), fasting blood glucose or adiposity. Glucose tolerance was high. The average fasting serum triglyceride level was 142mg/100ml. Serum uric acid levels were not high. Pipe smoking was common. No diabetes or gout were found. There was a low prevalence of diagnosable cardiovascular diseases: hypertension, valvular disease, cardiac decompensation (mostly cor pulmonale) and cerebral and peripheral vascular disease. Ischemic heart diesase was rare if not absent as indicated by resting and post-exercise electrocardiograms. Rates for all codeable ECG items were low except low voltage and T wave changes (commonest in middle aged women). Age-related degenerative changes occurred, such as increasing diameter of the aorta and decreasing creatinine clearance, and the declining ECG voltage with age may be indicative of cardiac disease.
I could hazard a guess, but population? Total energy intake?
I suspect hot climate, low food intake
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A comprehensive survey of cardiovascular disease was carried out on 779 persons over 15 yr of age. Carbohydrate provided more than 90 per cent of caloric intake and the consumption of protein and salt were about 25 and 1 g daily, respectively. Drinking water was soft. The population was lean, physically fit and in good nutritional state. There was no increase with age in mean blood pressure, serum cholesterol (average), fasting blood glucose or adiposity. Glucose tolerance was high. The average fasting serum triglyceride level was 142mg/100ml. Serum uric acid levels were not high. Pipe smoking was common. No diabetes or gout were found. There was a low prevalence of diagnosable cardiovascular diseases: hypertension, valvular disease, cardiac decompensation (mostly cor pulmonale) and cerebral and peripheral vascular disease. Ischemic heart diesase was rare if not absent as indicated by resting and post-exercise electrocardiograms. Rates for all codeable ECG items were low except low voltage and T wave changes (commonest in middle aged women). Age-related degenerative changes occurred, such as increasing diameter of the aorta and decreasing creatinine clearance, and the declining ECG voltage with age may be indicative of cardiac disease.
I could hazard a guess, but population? Total energy intake?
I suspect hot climate, low food intake
PNG. About 2300kcal/day for the men. Low by modern western standards, but modern western food intake is way too high. It's about 500kcals more than I aim to eat in a day if not training. They would have been far more active than a typical westerner.
They're not alone in having a traditional diet that's very high in carbohydrate but also having none of the diseases of western lifestyle. When they switch to a western diet, they typically are adding a lot of fat and protein, and in particular frying.
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Carbohydrate provided more than 90 per cent of caloric intake
But what did they eat?
Local foods, such as tubers, fresh fruit, coconut and fish, make up the backbone of the Kitavan diet. The most commonly consumed tubers include yam, cassava (aka yucca or manioc), sweet potato (aka kumara) and taro. Common fruit include banana, papaya, guava, pineapple, mango, and water melon. The consumption of Western food is extremely low, with an average Kitavan spending a meagre 3 US dollars per year on Western foods. The intake of dairy products, tea, coffee and alcohol is close to nil, and salt intake is low by Western standards. Also the consumption of oils, margarine, sugar, grains and cereals is low. The overall fat intake is equally low, and most fat consumed is saturated or marine n-3 polyunsaturated fat (omega-3 fat from seafood).
In summary, the Kitavan diet comprises an abundance of foods that have a low glycemic index rating and that are rich in soluble fiber, magnesium, potassium, and omega-3 fatty acids. All of these characteristics may contribute to the exceptional health benefits associated with the Kitavan diet.
So complex starches and coconut.