Yesterday I took part in the Abu Dhabi International Triathlon (ADIT), racing the Short distance - except there is nothing "short" about it: 1.5km swim, followed by 100km bike, followed by a 10km run.
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| Hello Abu Dhabi! |
This year, however, I went in the complete opposite direction: I wanted to race the event on nothing but water. That's right: no energy gels, no energy bars, no electrolyte tablets, no coke, no gatorade... just good old fashioned water, for a race that typically takes between 4 and 5 hours and coincides with the beginning of the UAE summer heat.
But I'm not an idiot: I didn't just wake up last week and decide to race "on an empty stomach". During the past 2 months or so, I've amended my diet and training to become more fat adapted. In other words, I've been teaching my body to prioritize the use of fat as a primary source of fuel both for exercise as well as for daily living. At the end of this blogpost, I'm outlining some of the main things I've adopted to become more fat adapted.
The purpose of my plan to race ADIT "unfueled" was to determine whether I was fat adapted enough to tap into my fat resources to fuel me through the entire race, without the need to resort to energy gels/bars/sports drinks.
Why am I doing all this? What's the harm in consuming carbohydrate-rich energy gels and drinks? Primarily for health reasons: I have diabetes in my family history, in addition to heart disease, high blood pressure and triglycerides, all linked to high carbohydrate consumption. I talked extensively about all this here.
I also did not make use of any electrolyte supplements (e.g. Saltstick, Nuun, Gu Brew...). These are claimed to replenish electrolytes lost in heavy sweating. All the research I've read in recent months about the topic point to the fact that it's virtually impossible to deplete yourself from electrolytes to the point of causing cramps in a single day event, unless you've had 0 salt/mineral intake with your food in the days leading up to the event (another impossibility).
So water was all there was (with some amino acids, as I explain below).
The X Factor
While my aim was to isolate the "fat adaptation" aspect in my experiment to make it the only "factor" in the race, there was a somewhat significant "X factor": my race fitness, or lack of it to be exact. I honestly haven't trained much in recent months due to a combination of personal and work-related matters. I had enough fitness to carry me through the race, but not enough fitness to "race" the race.
I knew I would have to look at my post-race results with that lens...
Preview and Race Conditions
The race took place on Saturday March 15th. I drove up on Friday morning, checked into the hotel, registered, did the pre-race usual (dropped off bike in transition, etc.). On Friday, conditions were horrible: heavy rain, heat/humidity, and gale force winds to boot. We were all hoping that things would calm down overnight...
and calm down they did...
On Saturday, we woke up to clear skies and no winds. The rain had left something behind though: we were looking at 80% humidity throughout the day, and the air felt thick. We also knew that the winds would pick up over the course of the day, as they always do in this part of the region.
The Race Plan
Nutrition
Breakfast - 2 hours before race-start: Bulletproof Coffee +3g Amino Acids
Bike: water +1g Amino Acids on the hour every hour (so 3g)
Run: water
Some explanations:
Bulletproof Coffee? What the heck is that?: Click here for an explanation. Why? Well the fat content in the Bulletproof Coffee actually triggers the fat burning metabolism (called beta-oxidation) in your body. In other words, it "starts the fat burning engine", thereby allowing you to tap into your fat reserves.
Why Amino Acids? Amino Acids are the basic building blocks of proteins. I take a small amount (6g in total) just to protect my muscles from destroying themselves too much during long endurance events, like a triathlon. I don't get energy from Amino Acids, they're more preventative than anything else (again following the theme of minimize the negative health implications of endurance racing).
Race Execution Plan
In order for me to get through the race without resorting to energy gels/bars/drinks, I would have to stay in my "fat burning" zone of effort. This typically means an effort of around 75% of my maximum effort on the swim, the bike and the run.
Why? Well your body uses 2 sources of fuel primarily: carbohydrates and fats. Fats provide more energy, but they take longer to burn. Carbs produce less energy, but they are "quick".
- So if your effort level is "hard" (e.g. 80% or more), you need energy "quickly", so you will need carbohydrates. You have some stored in your liver and muscles, enough for around 90min of effort. After that, you'll need to eat carbs to replenish and keep going (gels, bars, sports drinks, etc.)
- If you keep your effort level around the 75% mark, you can use "fat" as a source of fuel. You have hours and hours worth of fat stores in your body (no matter how lean you are).
What I've been doing over the last 8 weeks or so is "recondition" my body to learn to burn fat for anything other than a "hard" effort (I describe some of what I did at the bottom of this blogpost).
Swim:
I opted for no wetsuit, even though it was going to mean a slower swim. My lack of swim training meant that going 45sec faster with a wetsuit would not have made any difference. In addition, the air was warm and thick with humidity, conditions I normally struggle with anyway, so I didn't want to risk overheating during the swim by wearing a wetsuit.
Target effort level: 75%, comfortable pace
Bike:
Plan was to bike also at a 75% effort, making use of my Vector power meter and heart rate monitor to gauge my effort and keep it steady throughout the bike course (i.e. avoid spikes which would push me into carb-burning zones, which are typically above 80% effort).
Run:
Same as bike: keep it at 75% effort and use heart rate monitor to maintain a stable pace.
Race Day
Preparation
I woke up at 5am after a good night's sleep. It's funny, I don't get nervous much before races, a big step from a couple of years back when I would spend the night tossing and turning.
I ordered fresh coffee from room service, and while waiting for it, spent 5min doing some breathing exercises. Those have a dual purpose of (i) oxygenating my blood/muscles and (ii) warming up my breathing muscles (diaphragm, rib cage muscles).
When the coffee came, I prepared my bulletproof coffee, and while sipping it, I completed a quick warmup: pushups, burpees, lunges. Nothing crazy: just getting the blood flowing to all muscle groups.
I got my kit ready, took 3g amino acids, and headed downstairs to catch the shuttle bus to the race venue.
I got to the race venue and it was buzzing with activity. The Pros were about to start, music was blaring, and there was this infectious energy in the whole place, which I love and missed since my last big race at Challenge Roth in July.
A bit of a burst bubble happened when I realized that my bike computer (Garmin Edge) was stolen off my bike overnight! I couldn't comprehend it: the only people with access to the bikes were race officials and other athletes. What kind of athlete steals a bike computer!?
Anyway, I had my old trusty Garmin Forerunner 310XT in my bag, and I had charged it overnight as a backup. I put it on my wrist, paired it with my power meter and heart rate strap, and headed down to the beach to warm up before race start.
The Swim (1.5km)
I was in a wave of around 300 other athletes. I started on the side (no point in getting bashed around too much). When the horn went off, I plunged it and tried to settle into a rhythm immediately. I had to deal with kicks and blows for the first 5min or so (typical of a race start), but then things cleared up and I was swimming super comfortably.
Results: at this stage, I experienced the impact of the Bulletproof Coffee for the first time: I had never experienced such mental clarity during the beginning of a race. I was acutely aware of where I was in the water, I was reacting a lot quicker to other swimmers, and I was very much focused on my streamlining, body position and stroke. Certainly the most comfortable swim in any race I've taken part in.
I came out of the water in 32:10. Slow, but expected.
Swim:
I opted for no wetsuit, even though it was going to mean a slower swim. My lack of swim training meant that going 45sec faster with a wetsuit would not have made any difference. In addition, the air was warm and thick with humidity, conditions I normally struggle with anyway, so I didn't want to risk overheating during the swim by wearing a wetsuit.
Target effort level: 75%, comfortable pace
Bike:
Plan was to bike also at a 75% effort, making use of my Vector power meter and heart rate monitor to gauge my effort and keep it steady throughout the bike course (i.e. avoid spikes which would push me into carb-burning zones, which are typically above 80% effort).
Run:
Same as bike: keep it at 75% effort and use heart rate monitor to maintain a stable pace.
Race Day
Preparation
I woke up at 5am after a good night's sleep. It's funny, I don't get nervous much before races, a big step from a couple of years back when I would spend the night tossing and turning.
I ordered fresh coffee from room service, and while waiting for it, spent 5min doing some breathing exercises. Those have a dual purpose of (i) oxygenating my blood/muscles and (ii) warming up my breathing muscles (diaphragm, rib cage muscles).
When the coffee came, I prepared my bulletproof coffee, and while sipping it, I completed a quick warmup: pushups, burpees, lunges. Nothing crazy: just getting the blood flowing to all muscle groups.
I got my kit ready, took 3g amino acids, and headed downstairs to catch the shuttle bus to the race venue.
I got to the race venue and it was buzzing with activity. The Pros were about to start, music was blaring, and there was this infectious energy in the whole place, which I love and missed since my last big race at Challenge Roth in July.
A bit of a burst bubble happened when I realized that my bike computer (Garmin Edge) was stolen off my bike overnight! I couldn't comprehend it: the only people with access to the bikes were race officials and other athletes. What kind of athlete steals a bike computer!?
Anyway, I had my old trusty Garmin Forerunner 310XT in my bag, and I had charged it overnight as a backup. I put it on my wrist, paired it with my power meter and heart rate strap, and headed down to the beach to warm up before race start.
The Swim (1.5km)
I was in a wave of around 300 other athletes. I started on the side (no point in getting bashed around too much). When the horn went off, I plunged it and tried to settle into a rhythm immediately. I had to deal with kicks and blows for the first 5min or so (typical of a race start), but then things cleared up and I was swimming super comfortably.
Results: at this stage, I experienced the impact of the Bulletproof Coffee for the first time: I had never experienced such mental clarity during the beginning of a race. I was acutely aware of where I was in the water, I was reacting a lot quicker to other swimmers, and I was very much focused on my streamlining, body position and stroke. Certainly the most comfortable swim in any race I've taken part in.
I came out of the water in 32:10. Slow, but expected.
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| Thanks Christian for the pic! |
Transition 1
T1 in ADIT is a bit of a long one. You run up the beach, through a fresh water shower, into a changing tent to grab your "bike bag" and change, then out into the large area where all the bikes are.
Grabbed the bike and ran with it to the mounting line. I had left my bike shoes clipped into the pedals, so I ran across the mounting line, hopped on, slipped my feet into the shoes and started pedaling away.
T1: 4.5min. Rusty, lack of practice shows.
Bike (100km)
Since my bike computer was MIA, I had put on my backup Forerunner on my wrist. But when I looked at it on the bike, it was "dead': water had gotten into it during the swim (no idea why) and it just refused to restart.
Switching to Plan C then!
I had 2 choices at that point:
I opted for option 2.
How I executed it was pretty simple: 75% effort means I should be able to breath through my nose. Every time I had to breath through my mouth, I would slow my effort down until I regained control of my breathing. Of course I "let that go" on the bridges somewhat, but just by 10% or so.
The bike ride was otherwise super-smooth. I stayed on the aerobars for pretty much the entire ride (except for tight corners on Yas Marina GP Circuit).
I was grabbing water from every aid station (and nothing else). It was getting hot and very humid very quickly, so I was drinking around 800ml/hour (estimated, I had no watch/bike computer/Garmin!!).
Results
Positives: never ever felt any energy dips or lack of power. Never felt the need to take any energy gels/bars/drinks. Felt super steady and consistent in my effort, and it was very easy to regain control of my breathing after going up bridges and flyovers.
Negatives: none really. The only thing I struggled with was the fact that I was getting passed by so many people in the first 40km or so of the bike.
Switching to Plan C then!
I had 2 choices at that point:
- Throw the experiment out the window, smash the bike segment, grabbing energy gels from the aid stations throughout; or
- Try to estimate what 75% feels like using my breathing and "perceived exertion" and stick to the experiment.
I opted for option 2.
How I executed it was pretty simple: 75% effort means I should be able to breath through my nose. Every time I had to breath through my mouth, I would slow my effort down until I regained control of my breathing. Of course I "let that go" on the bridges somewhat, but just by 10% or so.
The bike ride was otherwise super-smooth. I stayed on the aerobars for pretty much the entire ride (except for tight corners on Yas Marina GP Circuit).
I was grabbing water from every aid station (and nothing else). It was getting hot and very humid very quickly, so I was drinking around 800ml/hour (estimated, I had no watch/bike computer/Garmin!!).
Results
Positives: never ever felt any energy dips or lack of power. Never felt the need to take any energy gels/bars/drinks. Felt super steady and consistent in my effort, and it was very easy to regain control of my breathing after going up bridges and flyovers.
Negatives: none really. The only thing I struggled with was the fact that I was getting passed by so many people in the first 40km or so of the bike.
This is something I'm not used to: the bike normally being my "strength", it's usually the other way around for me.
I took a little pleasure in the last 40km though: I was passing a lot of the people who had passed me earlier, even though I was still putting out a 75% effort. Many people were beginning to fade as the winds picked up during the second half of the bike.
Total time for 100km: 3:12 (avg 31.2km/h)
Transition 2
T2 was uneventful. Got off the bike just before the dismount line, leaving the shoes clipped into the pedals. Dropped off my bike at the first empty spot I could find and jogged to the transition tent feeling very comfortable. Helmet off, shoes on, visor on, and off I went for the 10km run.
Total time for 100km: 3:12 (avg 31.2km/h)
Transition 2
T2 was uneventful. Got off the bike just before the dismount line, leaving the shoes clipped into the pedals. Dropped off my bike at the first empty spot I could find and jogged to the transition tent feeling very comfortable. Helmet off, shoes on, visor on, and off I went for the 10km run.
Saw Christian Berglehner from Race-Me and my club-mate at TriDubai on the way to the changing tent, and he snapped a pic:
Run (10km)
The moment I stepped out of the tent, I realized how hot and humid it was. It was close to mid-day and the sun was blasting, and I already knew that the run course had no shaded areas whatsoever.
Again, I had no heart rate monitor, so I had to gauge my effort by feel to keep it at 75%.
Run (10km)
The moment I stepped out of the tent, I realized how hot and humid it was. It was close to mid-day and the sun was blasting, and I already knew that the run course had no shaded areas whatsoever.
Again, I had no heart rate monitor, so I had to gauge my effort by feel to keep it at 75%.
I already knew what that meant for me (that's how I train myself and others): 75% means I'm able to keep a 4/3 breathing pattern. 3/2 means I'm beginning to go above 80%, and that was a no no for this particular experiment.
Remember what I mentioned earlier: 80%+ effort means you're dipping into stored carbs, and you only have 90min of those in your body. I was already 4 hours into the race, and I certainly did use some of those 90min during the swim (aggressive start) and the bike (bridges and flyovers).
Now the major parameter that influences how fast you go at a particular level of effort is your fitness. For example, someone who can run at 11km/h at 75% effort is fitter than someone who can run at 10km/h at 75% effort.
Things are also negatively affected by heat and humidity: if you normally run at 10km/h at 75%, the heat/humidity will drive your effort to 80% for the same speed of 10km/h. Some people (e.g moi) are more susceptible to hot weather conditions than others.
Results
I started the run feeling ok, and kept my pace very slow to control my breathing and maintain that 4/3 breathing pattern. 2km into the run and I started to lose control: I couldn't maintain a 4/3 breathing pattern anymore, which meant that my effort level was creeping above 80%. I had to slow it down since I still had 8km to go.
But I know myself. This has nothing to do with how "fat adapted" I am. This has to do with how "unfit" I am. Given the lack of training over the past few months, I just was not "capable of staying at 75% at 6min/km", and the only way I could was by slowing down to a walk.
I started a new pattern:
That went on until the 9km mark, when I decided that I still had some of that stored carbs left: I picked up the pace and ran the rest of the way to the finish at 85-90% effort.
Remember what I mentioned earlier: 80%+ effort means you're dipping into stored carbs, and you only have 90min of those in your body. I was already 4 hours into the race, and I certainly did use some of those 90min during the swim (aggressive start) and the bike (bridges and flyovers).
Now the major parameter that influences how fast you go at a particular level of effort is your fitness. For example, someone who can run at 11km/h at 75% effort is fitter than someone who can run at 10km/h at 75% effort.
Things are also negatively affected by heat and humidity: if you normally run at 10km/h at 75%, the heat/humidity will drive your effort to 80% for the same speed of 10km/h. Some people (e.g moi) are more susceptible to hot weather conditions than others.
Results
I started the run feeling ok, and kept my pace very slow to control my breathing and maintain that 4/3 breathing pattern. 2km into the run and I started to lose control: I couldn't maintain a 4/3 breathing pattern anymore, which meant that my effort level was creeping above 80%. I had to slow it down since I still had 8km to go.
But I know myself. This has nothing to do with how "fat adapted" I am. This has to do with how "unfit" I am. Given the lack of training over the past few months, I just was not "capable of staying at 75% at 6min/km", and the only way I could was by slowing down to a walk.
I started a new pattern:
- Run at 75% until I couldn't
- Walk until my breathing recovered
- Restart running at 75%
That went on until the 9km mark, when I decided that I still had some of that stored carbs left: I picked up the pace and ran the rest of the way to the finish at 85-90% effort.
A highlight of the run was seeing TriDubai trisuit after TriDubai trisuit. Such a big presence for our club at such a major race made me immensely proud! Shoutouts from Venny, Johan, Patrice, and countless others were uplifting!
Run time: 1:17 (slow as a snail).
TOTAL TIME: 5:11 (263rd out of 381 in my age group).
I crossed the finish line a little out of breath, but I can honestly say that I finished "fresh". I wasn't tired, no muscle pains, no cramps whatsoever…
But the most important thing of all: as with the swim, my mind was "clear". I had never experienced this mental clarity at the end of a brutal 5hr race. No mental fog, no dizziness, no blurred vision, etc…
Carbs are famous for causing mental fog in the best of conditions, but I always thought that the mental fog at the end of a long-distance triathlon came from the exertion… not this time!
I was chatting to some of the guys at the finish, and I could recall every minute of my race and could tell them what was happening at every one of those minutes. It was an incredible feeling…
Conclusions and Next Steps
In my opinion, the experiment was a resounding success: I never felt out of energy and my level of energy was steady and consistent throughout the whole event.
This is all hypothetical of course, but allow me to run some numbers:
Run time: 1:17 (slow as a snail).
TOTAL TIME: 5:11 (263rd out of 381 in my age group).
I crossed the finish line a little out of breath, but I can honestly say that I finished "fresh". I wasn't tired, no muscle pains, no cramps whatsoever…
But the most important thing of all: as with the swim, my mind was "clear". I had never experienced this mental clarity at the end of a brutal 5hr race. No mental fog, no dizziness, no blurred vision, etc…
Carbs are famous for causing mental fog in the best of conditions, but I always thought that the mental fog at the end of a long-distance triathlon came from the exertion… not this time!
I was chatting to some of the guys at the finish, and I could recall every minute of my race and could tell them what was happening at every one of those minutes. It was an incredible feeling…
Conclusions and Next Steps
In my opinion, the experiment was a resounding success: I never felt out of energy and my level of energy was steady and consistent throughout the whole event.
This is all hypothetical of course, but allow me to run some numbers:
The following were my swim/bike/run paces at 75% a year ago (when I was far more race-ready):
In other words, I'm convinced that this experiment was successful enough to warrant a second attempt after a few months of training.
I'm registered for Norway 70.3 In July. Will I adopt the same there? Probably not. Not because I will stop fat adapting (I won't) but because I don't want to "race" Norway 70.3 at 75% effort. It's my "A" race this season and I'm looking at going hard (85% effort).
Having said that, I will certainly continued to teach my body to tap into its fat resources, because that will make me more efficient at ALL effort levels.
- Swim 1.5km: 29min (vs 32min today)
- Bike 100km: 33km/h (vs 31.5km/h today)
- Run 10km: 55min (vs. 75min today with walks)
In other words, I'm convinced that this experiment was successful enough to warrant a second attempt after a few months of training.
I'm registered for Norway 70.3 In July. Will I adopt the same there? Probably not. Not because I will stop fat adapting (I won't) but because I don't want to "race" Norway 70.3 at 75% effort. It's my "A" race this season and I'm looking at going hard (85% effort).
Having said that, I will certainly continued to teach my body to tap into its fat resources, because that will make me more efficient at ALL effort levels.
This will certainly reduce the amount of carbs I will need to ingest during the race in Norway, which ultimately would be beneficial for my health.
I'm competitive, and all for getting a good result in my races, but not at the expense of increasing my risk of diabetes 10 years down the road…
How did I "fat adapt" over the past few months
I'll start off by admitting that I stuck to this plan around 70% of the time, and "fell off the wagon" around 30% (partially on purpose, partially due to either travel, entertaining, or lack of will power).
On the training side, it was pretty simple:
On the nutrition side, I adopted a high fat, high leafy greens, moderate protein, low carb approach.
You will note that I still had carbs. Carbs at 25% means I was adopting a "low carb" diet and not a "ketogenic diet". I won't get into the details on the differences, but suffice it to say that keeping carbs at 25% consistently is a lot easier than you think.
Note: when I started this fat adaptation around 8 weeks ago, I could barely run for 60min on an empty stomach and without fueling. By last week (pre-race), I could run for almost 2 hours in a fasted state first thing in the morning feeling absolutely fantastic. It works people!
Finally, I have to say that my whole fat adaptation process resulted in a number of positive consequences which were not the reason I embarked on this in the first place:
Tony
I'm competitive, and all for getting a good result in my races, but not at the expense of increasing my risk of diabetes 10 years down the road…
How did I "fat adapt" over the past few months
I'll start off by admitting that I stuck to this plan around 70% of the time, and "fell off the wagon" around 30% (partially on purpose, partially due to either travel, entertaining, or lack of will power).
On the training side, it was pretty simple:
- Unlike what some traditional people recommend, I did not only train at 75% or lower efforts
- I trained like I normally would: a mix of longer endurance sessions (75% effort) and higher intensity efforts (80%-95%)
- My longer sessions lasted from 60-90min on the runs and 90-180min on the bike
- All of my longer endurance sessions were done in a fasted state (water only)
- All of my higher intensity sessions were under 60min and were pre-fueled
On the nutrition side, I adopted a high fat, high leafy greens, moderate protein, low carb approach.
- Fats accounted for around 55% of my diet.
- Proteins accounted for around 20%
- Carbs accounted for around 25%.
You will note that I still had carbs. Carbs at 25% means I was adopting a "low carb" diet and not a "ketogenic diet". I won't get into the details on the differences, but suffice it to say that keeping carbs at 25% consistently is a lot easier than you think.
- Fats included: grass-fed butter, coconut oil, olive oil, avocados, raw nuts, sardines, salmon, eggs, bacon
- Veggies included: spinach, rocca, tomatoes, olives, bell peppers,
- Proteins included: grass-fed beef, lamb, free-range chicken, duck, fish & seafood
- Carbs included: quinoa (also source of protein), potatoes, fruits, rice (rarely).
Note: when I started this fat adaptation around 8 weeks ago, I could barely run for 60min on an empty stomach and without fueling. By last week (pre-race), I could run for almost 2 hours in a fasted state first thing in the morning feeling absolutely fantastic. It works people!
Finally, I have to say that my whole fat adaptation process resulted in a number of positive consequences which were not the reason I embarked on this in the first place:
- My body composition improved dramatically, despite my limited training: I dropped 2.5% of body fat in 6 weeks
- My GI problems all but disappeared (carbs have been proven to be a major cause of GI problems since the "bad bacteria" in your gut only feed on carbs).
And here is a list of "experts" whose knowledge and experience I draw upon a lot in my education about how our bodies work, how best to fuel, and whose experiences and knowledge I've drawn upon for this whole experiment:
Tony
A friend from my tri club asked: did I do a metabolic test before and after fat adaptation, how depleted were my glycogen stores by the end of the race, and how far can you take fat adaptation, is there a limit? My answer: the tests to determine your metabolic efficiency are pricey so I didn't do them, but the empirical data I have stems from my ability to run at a specific intensity for longer and longer periods of time. For example, 2 months ago I could manage 75min at 75% effort. The fact that I couldn't go longer meant that even at 75%, I was burning significant amounts of glycogen, which ultimately limited how long I could keep going.
ReplyDeleteOver time, and at the same intensity, I was going for longer and longer and feeling better and better. This means that glycogen depletion was no longer an issue, and my metabolic efficiency was improving. I would say that I currently burn close to 90-100% fat at that intensity, as evidenced of my ability to go on for 5 hours fasted at that intensity. Please note that I had 0 carbs in the 12 hours preceding the race, so my liver glycogen stores were likely to have been depleted to some extent anyway as I started.
To answer your question about how far you could take fat adaptation: there is a limit in terms of how high you could take intensity before glycolysis kicks in. You see metabolic efficiency (how much and how well you burn fat) is a function of 3 things:
1. the efficiency of your mitochondria (how well they convert fatty acids to ATP),
2. mitochondrial density (how many mitochondria you can create and stuff in a cell) and
3.the speed of beta oxidation:
As you become more efficient, you will be able to burn more fat at every level of intensity, since points 1 and 2 above improve with nutrition as training. But no matter how efficient you become, beta oxidation does take a lot longer than glycolysis to produce ATP, so that's a limiting factor. This means that at some point, you will be dipping more and more into glycogen stores.
There are ways to improve your glycogen storage efficiency too by the way.
To answer your question about how depleted were my glycogen stores at the end: I put the hammer down in the last km at probably 90pct (pure glycogen burn). When I finished, I didn't have any hypoglycemic symptoms. And I didn't eat till almost 3 hours later. So no I don't think I depleted all my glycogen stores in those 5hrs. Hope this helps