ldesfor1@ithaca

Does anyone on this subforum have any experience with doing fasted, AM workouts (typically 60-120' in Z2-Z3) as a method of training the body to prefer fat as fuel? Some refer to this as "Bonk Riding", but that title is misleading, as I'm not suggesting that one actually bonks on purpose.

I'm wondering if anyone has used any protocol of this sort and seen improvements in their long race endurance.

( I dont want to know if this protocol is "good for losing weight", just if it seemed to improve your performance in long races).


I'm curious as it seems like a way to get in some long miles and possibly train the body to spare muscle glycogen.

Thoughts?

mollusk

You can go slower, but I don't think that is the answer you wanted to hear.

Racer Ex 

I do that. No breakfast, no fuel until an hour or more into the ride on some of my non-race weekend rides.

The caveats are that you're going to be flatter during those "full gas" moments if you're on a group ride, you need to keep quick refuel food on hand because you can get pretty far down bonk road pretty quickly (not a good idea), and you need to be really on top of refueling post-ride.

There's some anecdotal info out there but no published studies that I know of. I trend more towards seeing if things work for me in any case, people respond differently to different training stress, even within their own training cycles.

substructure

I've read that nothing 3 hours before a ride really helps fuel you anyway. Is this true?
A friend of mine tested it during a tough ride once. Didn't eat anything that morning and only started fueling during the ride. He finished strong.

YMCA

Scott Price (coach in New Mexico) used to have a website with an article on "aerobic deflection training."

If you google that term you'll find an article on DailyPeloton.com that he did a few years ago.

The premise was that you head out the door completely emptied of food in your stomach (at least 6 hours since your last food), then ride at ~70-80% of max hr, with rpms at 95-115. It was best to start the ride at 70% and slowly move it up as the ride progresses (this will happen naturally sometimes). The goal being able to ride 3-4 hrs on water only (do not dehydrate!). Pros could even get up to 5 hours.

I never followed his outline perfectly, but have used training similar to this many days a week sometimes. I've gone close to 4 hours at good aerobic paces, the key being that I never went into the red, not even for a minute.

I have also done quick paced morning group rides on a weekday, where I had 2 hours by the time I got home and a whole bunch of efforts. If dizziness comes along during the harder sections, then I backed off and cruised home or found sugar asap.

Most of the time, I am bonking only the last 15' of easy riding, so it's never a big deal about recovery from the workout.

Try riding at Z2-3 like you said for a couple hours and see how far you can go as the days progress. In the off-season this type of training could be done a few days a week.

Recovery days should always be ridden this way, even in-season.

mkadam68

Earlier this year, I was doing exactly that. Rode to work, about 2:20 away. Averaged z1 - z2 with some z3's thrown in on the hills. Never had any problems. But, I knew from experience that I could do this without bonking from weekend rides, etc..

Carried a PowerBar w/me just in case, though. Used maybe twice, not out of necessity but because I started getting hungry. Normally, I would eat the bar as soon as I got to work and something else for breakfast.

I was doing it for weight loss, not directly for performance. Although, indirectly, it did benefit, but not with aerobics that I could tell. Can't help you there.

NomadVW 

I'll offer the flip side -

I've felt the bonk closing in on me before heading out on a ride without grabbing breakfast once last winter, something I just never do. I had to pull over, sit down, eat and chill 25 minutes into a ride at 6am. It was a full on nausea, tunnel vision closing in, and a whole body shutdown.

Won't do it again. Ever.

I know I've seen the studies on the "bonk training" for weight loss. I've heard it works for folks. I've also heard that calories in < calories out works.

As far as efficiency goes.... I'd rather carry the extra powerbar than try to train without it. I'm admittedly a crazy bit of paranoia when I'm laying on hard training. I do everything I can to stay fueled, nourished and "full up." I get germaphobic and the works. Doing anything that cheats my body of anything that could put me over the tipping point to illness is not worth the risk.

Speaking of which... damn I'm hungry. Time to go eat.

grolby

When I first started cycling, I had a tendency to bonk, hard, in a short amount of time. I would be starting at around 25 miles or so, and be in a full-on bonk before hitting 30. My solution, rather than to keep riding without food and trying to adapt, was to adapt a policy of "eat early, eat often." When I started training for my first races, over the winter of '07 to '08, I carried a couple Clif bars with me, and I would eat the first one at 10 miles or even sooner. Over the course of all the riding I've done since then, my body has become much better adapted to endurance riding and I don't burn through my glycogen supplies nearly as fast. I can leave for 30 miles without taking food, provided of course that I'm not hungry when I leave. So I trained myself to burn more fat while eating more, not less. Had I tried to ride on less food, I would not have been able to ride as far, and I think that I would probably have received less benefit.

I'm not saying that you can't influence your level of adaptation by riding on an empty stomach or changing your riding diet, but I think that the other side of the equation - the distance - is much more important. Riding long miles at endurance pace is going to do a lot more for training your body to burn fat. Diet changes can probably be influential, but consider this: you are always burning glycogen while you ride, even at an endurance pace, even at a recovery pace! Keeping your glycogen stores low on purpose is just going to make your body hungry; there isn't some ceiling above which glycogen kicks in; hell, your brain runs on the stuff, so that alone is going to draw fuel from the tank.

By the way, why are you planning on doing this? Do you find yourself running out of gas at the end of your road races? Personally, between my much improved endurance metabolism and figuring out nutrition that worked for me, I now know that I can ride a three-hour road race and still have fuel to burn. Add 33% or so for safety; why would you need to run more than four hours in a Cat 3 race? The way I see it, as long as I'm replacing calories fast enough that I'm not hunger-flat after three hours of racing (about the longest my current races last), it's better to run a little hot and be able to access energy quickly than the other way around. Unless you're planning to race 200km weekly in Belgium in March, I don't really see the need for this.

Bobby Lex

From what I understand, your body doesn't "decide" what fuel to burn based on what you have available. It choses what fuel to burn based on the level of intensity of your effort. Friel points out the following interesting information from a 1993 American Journal of Physiology article about fat/carb fuel ratios:

>At low intensity efforts (e.g. walking) about 90% of the fuel you use is fat, 10% is carbs.

>At moderate intensity efforts (e.g. LSD riding) you use fat and carbs equally (50/50). (And you burn roughly 2x the total calories per hour compared to low intensity efforts.)

>At high intensity efforts (race-effort) your fuel use ratio is 1/3 fat to 2/3 carbs. (And you burn roughly 3x the total calories per hour compared to low intensity efforts.)

Clearly, it's the intensity of your effort that determines whether fat or carbs will be used to fuel same.

On the other hand, Friel does point out that endurance training in general (not necessarily bonk training) can improve your ability to use fat as fuel. Friel says: "Research reveals that a well-trained athlete is capable of storing greater amounts of carbohydrates while using it more sparingly than an untrained person."

Note that Friel doesn't say that by restricting carbs you force your body to burn fat. He says that well-trained athletes actually store more carbs than untrained persons, but they burn more fat anyway.

Lastly, keep in mind that your body needs to use carbs in order to be able to burn fat. Carbs are the flame that lights the fat fire.

Bottom line is that I think your idea is ill-advised, either as a weight-loss scheme, or as a means of "teaching" your body to burn fat as fuel.

My .02

Bob

gtmandsager

I had a lactate test done a year ago and was told that my body relies too much on glycogen rather than fat as a fuel source, at any intensity level. I have also read (I'm sorry I don't recall the source) that the main aerobic benefit to long slow distance training that can't be replicated by high-intensity intervals is the increased use of fat as a fuel source.

I plan on incorporating what I refer to as "near bonk" rides during the off-season. These will be fasted AM rides, ~60 mins at z3. I don't want to sacrifice a training day to recovery so I'm not looking to completely bonk but hopefully increase reliance on fat for aerobic efforts.

Bob, doesn't at some point the body have to "decide" what to use for fuel? For example, the reason that dizziness accompanies bonking is because glycogen is the exclusive fuel for the brain. Doesn't it make sense that the body would resort to an alternate fuel source, either fat or protein, in order to protect limited glycogen stores? I understand that there are risks involved, which is why I plan to always do these intervals indoors on a trainer and abandon if I start to feel ill-effects of bonking.

grolby

Riding in Z3 while fasted is a really dumb idea. You will be much better off building endurance by spending a lot of hours in Z2. 60 minutes in Z3 = moderately high demand for glycogen, which means that your principle accomplishment will be starving your engine. That's not how good training works.

Maybe it makes sense. But so what? Are you going to trust your uneducated guesses about physiology, or are you going to look for evidence that this is a good idea before trying it? Does it help clarify things to know that the bonk is the result of your body resorting to an alternate fuel source? Point being: if you run out of glycogen, you run out of gas. Period. End of story. Access to the calories burned in fat is so slow that relying on them alone feels like a bonk. Which makes sense, because that's exactly what a bonk is.

See my earlier post again for an example of how eating MORE during my rides probably did a lot more to help my adaptation to burning more fat than eating less would have by allowing me to stay out there for longer. Again, I'm really skeptical that fasting yourself on rides is the optimal way to improve your adaptation to endurance riding. Sure, it might work, but you really need some scientific evidence on it; after all, if it doesn't work, you'll be actively sabotaging your training. On the other hand, there's absolutely no doubt that riding lots of hours at an endurance pace WILL produce the adaptation you're looking for without any risk of doing more harm than good. That would be my go-to method. Also see my question for Leo, and consider it yourself: why? If you were told after your lactate test that you "burn too much glycogen," but you are able to finish a three-hour race without getting hunger flat, than maybe you do not, in fact, burn too much glycogen. Tests are great and all, but they need to be put into a real-world context. If you've been bonking in your races, and haven't been able to fix the problem by experimenting with nutrition options, that result should probably be taken pretty seriously. But if it's not causing you problems... well, it might be smarter to not worry about it and just race your bike.

ridethecliche

WTF happened to Snuffleupagus?

He used to talk about this stuff all the time! He was famous for his bonk rides.

As far as LT tests go, I had one early this season. I was given an aerobic threshold, and an LT threshold. Aerobic was the point where I was moving from mostly fat-->more glycogen/carbs.

Coach wanted me to do all my LSD rides at/around aerobic threshold. He said training both the Aerobic threshold and LT would allow both to be raised over time, with the advantage of a high aerobic threshold being that you would be chillin' in the pack around there and your body would be consuming fuels no differently than it would if you were sitting on a couch.

Over simplification, but still...

That being said, I went out for a 60 miler the other day and started to bonk on the way home.

I ate 2 poptarts, 2 bottles of drink mix, a granola bar, and a gel. I think that was all. It was about 700-800 calories consumed, I ended up with around 2000 Kj and still managed to finish relatively strong. I think the longer rides will really help me for next season. I really died during the road races this year. Fell apart after the first hour...

Enthalpic

Are you going to trust your uneducated guesses about physiology, or are you going to look for evidence that this is a bad idea before refuting it?

We know that endurance training –with or without diet manipulations- alters substrate utilization towards increase fat metabolism and glycogen sparing. However, we also know that carbohydrate feeding during training somewhat attenuates this training effect. (1)

We know that low carbohydrate / high fat diets –with or without exercise- increases the expression of fat oxidative enzymes, indicating that is is possible to alter gene expression by diet modification.

We know that fasted exercise increase the % of calories burned from fat for that particular workout and recovery period. However, Leo, it is unclear whether fasted exercise will increase your performance during future carbohydrate-fed workouts (e.g. priority workouts / races). (2)

At this time my stance is that athlete reports should drive future research because the method is theoretically sound. I know you didn't mention weight loss but one author (3) found that fasted, hypocaloric rides were a good way to increase P/w ratio.

(1) Glucose ingestion during exercise blunts exercise-induced gene expression of skeletal muscle fat oxidative genes.
https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
In conclusion, glucose ingestion during exercise decreases the expression of genes involved in lipid metabolism rather than increasing genes involved in carbohydrate metabolism.


(2) Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake.
https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
For a given initial glycogen content, F blunted exercise-induced glycogen breakdown when compared with CHO (P = 0.04). Neither IMCL breakdown (P = 0.23) nor fat oxidation rates during exercise were altered by training. Thus short-term training elicits similar adaptations in peak Vo(2) whether carried out in the fasted or carbohydrate-fed state. Although there was a decrease in exercise-induced glycogen breakdown and an increase in proteins involved in fat handling after fasting training, fat oxidation during exercise with carbohydrate intake was not changed.

(3) Effects of caloric restriction and overnight fasting on cycling endurance performance.
https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum
Research has demonstrated body fat-reducing benefits of exercise after fasting overnight. We hypothesized that fasted-state exercise in calorie-restricted trained cyclists would not result in performance decrements and that their PWR would improve significantly....The cyclists' PWR and body composition improved significantly, and their overall weight, fat weight, and body fat percentage decreased. Lean mass was maintained. The cyclists' RPE decreased significantly during 2 hours of submaximal cycling post-CR, and there was no decrement in submaximal or maximal cycling performance after 3 weeks of CR combined with overnight fasting. Caloric restriction (up to 40% for 3 weeks) and exercising after fasting overnight can improve a cyclist's PWR without compromising endurance cycling performance.

ridethecliche

That bit about modification of gene expression is really cool

I guess it just upregulates transcription of the RNA for the enzyme. Makes sense.


Also, the bit about eating carbs while on the bike decreasing fat metabolism is really cool. I guess I should find a balance of rides where I can go with just water and no food for about 1-1.5 hrs or so. Or do 2-3 hr easy rides without food.

Who knew CR would increase performance. That's badass. Maybe diets aren't for wussy, and maybe losing weight/CR is a better method of increasing PWR and P/W. The adage of doing one or the other isn't completely necessary. This is cool. I need to look into what exactly they were doing for training during this point.

Hm.

Fat Boy

That's a lot of eating for 60 miles. Unless it was 60 miles of hard climbing, you need to work on your aerobic base more. I regularly do 75 on water/electrolyte(no calorie) mix, an apple and a small box of raisins. I'm not bragging, I don't think my base is really all that great. I want to be able to ride three hard hours without any food. You have to condition your body to use what it has available to it, and all of us have plenty of fat.

The reason you fell apart after your first hour in road races is that your body is running on almost all carbs. Things like interval training conditions the body to go for the easiest source of fuel, which is carbs. After an hour, in a race, you've burned maybe 800 calories or so and your body is beginning to run out of carbs to use. You haven't trained it to look for fats, so it won't go there. You might have 100,000 potential calories of fat on your body, but because of your training, your body is still looking to use the last 1200 or so carb calories that remain.

Read 'Base Building for Cyclists'. It really goes into detail on this. I think most of us have a lot to learn in this particular area of training.

Enthalpic

Careful they were using p/w ratio not absolute power and this was for sub maximal efforts. The adage has been tested and found to be true for maximal performances.

Effects of sprint interval training and body weight reduction on power to weight ratio in experienced cyclists.
https://www.ncbi.nlm.nih.gov/pubmed/1...ubmed_RVDocSum

The results demonstrate that cyclists can use SIT sessions and body weight reduction as singular training interventions to effect significant increases in anaerobic power to weight ratio, which has been correlated to enhanced aerobic cycling performance. However, the treatments were not effective as combined interventions, as there was no significant change in either PPOan:Wt or APOan:Wt in SIT + WR.


I also want to make sure people don’t take this as an endorsement for fasted exercise. Both fasted and fed exercise have their advantages. Fasted seems to be better for fat burning, improving growth hormone production, possibly weight loss. However, it is worse for high intensity training, post-exercise immune suppression, and endocrinological hunger feedback systems.

ridethecliche

And all these reasons make it perfect for trying out during base.

I wonder how long the effects last for.
I.e if you're upregulating transcription and you start eating while you ride, do you lose all benefits?

ridethecliche

It was a 4 hr ride. 3 sections of hard hills. It was all at tempo though. TSS was 230 with a IF of .8. It wasn't a easy endurance ride.

That being said, when I started riding, I used to bonk after an hour. So being able to ride 2 hours on only drink mix is a pretty big deal for me. I do need need to get better at riding with less fuel on me and that's one of my goals for this base period.

If I can do 40-50 mile rides on water after not having eaten in the morning, then that'll be awesome. Though perhaps I should start by only eating oatmeal and then going out instead of starting out without eating anything and trying not to eat during the ride.

Then again, I can always carry food with me for when I start feeling the bonk coming up.

YMCA

https://www.bikeforums.net/training-nutrition/249215-bonk-training-does-really-work.html

few years ago

Fat Boy

I've been doing this type of training myself. At first, I was hungry at 1 hour almost on the dot. Now I've gone as long as 3 without dying. Not killing myself on the rides, Z2-3, mostly 2... always less than SST. It's helping, but I'm still not where I need to be. It's one of those things where you have to slow down to go faster. Strange, but true.

grolby

I was suggesting that evidence was needed. And lookie there. Evidence. Good on you. In ignorance of the physiology involved (and I was not pretending to have much knowledge here), it's not good to bet on the option that will make you hungry. That's all.

I'm still not clear on why this is such a great idea - the vast majority of riders will be able to develop the endurance they need without fasting during rides. Like I said, I had a major nutrition problem and yet I was able to develop the endurance I needed without starving myself on rides. Again, if you're not finishing your races bonked, there appears to be little incentive to drain your reserves and potentially reduce training effectiveness because of the amount of recovery that's needed after that kind of a workout.

Weight loss, as you suggest, is a whole 'nother ball of wax.

ZeCanon

I haven't tried to do this specifically, but Tom Danielson told me last spring that his coaches were making him do something similar - long rides with not quite enough calorie intake. I guess they probably have a good reason for doing so.

I find that the ability to ride longer and longer without food just comes naturally with normal training, though I still tend to run out of fuel faster than others if I don't eat. Maybe it's because I'm so freakin lean, I don't know. When I'm very fit I can still do a relatively hard 3 hr ride with no fuel if I really need to. When I'm not so fit, 1.5-2 hrs is about my limit without throwing in some calories.

grolby

You're much stronger than I am, but we seem to have similar characteristics (climber's body, sprinter's jump), and I similarly seem to run out of fuel more quickly than other riders if I don't eat. So maybe there's a link between the physiology that affects your abilities as a racer and the physiology that affects your metabolism.

In any case, this is more ammo for the view that fasting rides are probably pointless for most riders. Normal training boosts fat metabolism anyway, as you say, and any further deficit is relatively easy to make up through smart in-race nutrition.

I do remember hearing about Tommy D's bonk riding regimen last winter, but the demands of his races are far more extreme than most of us have to deal with. No doubt there was indeed a good reason to have him do that, given that we wants to finish strong in races that might be five or six, sometimes even seven hours long. Personally, I'm a Cat 4, and none of my races are more than three hours; Cat 3 races are seldom any longer than that, either. Maybe I would be unable to absorb enough nutrition to replace glycogen losses over five or six hours, but so what? I doubt that I'll ever be doing road races that long and that intense.

gtmandsager

First, I appreciate the healthy skepticism and disagreement. I'm more appreciative that Enthalpic did my leg work, but disagreement spurs the best discussion.

Second, you're right, I'm not bonking at the end of my races. But I'm not winning them either, which is the point. The purpose of this specific training goal is to increase the utilization of fat as fuel over glycogen. If I can save x% more intramuscular and liver glycogen stores during aerobic efforts, then I will have a bigger source of quick energy when I needed during intense anaerobic surges/breakaways/etc.

The reason I stay in Z3 is to promote the depletion of liver glycogen at a faster rate than Z2, further promoting the adaptation I'm looking for. The actual physiological stress isn't hard, as far as my muscles are concerned it's an hour of tempo, and I make sure to follow the workout with plenty of food to refuel. I haven't noticed needing any extended recovery after these sessions.

jooaa

Great info, thanks.