It makes absolutely zero sense to practice making yourself sick. You also don’t benefit from ingesting carbs during exercise unless the duration is well over an hour. The logical cost:benefit analysis is therefore to stop cramming stuff down your throat all the time when your body clearly neither wants it nor needs it.
No mentions here of weight-based dosing?
I saw 110lb weight and 80g of carbs per hour specified.
Let’s say the 60-80g carb target applies to an average male. 75kg is the traditional weight estimated for a man.
Does this same experience happen with less carbs, like 40g? Almost there with a banana.
It’s hard for me to imagine that someone with a healthy pancreas can get symptomatic rebound hypoglycemia from consuming simple carbs in setting of exercise.
But that’s what she’s here for help with. She is asking for help to make herself not sick. I think we can all agree that if she can’t avoid disaster pants it’s a bad idea but tweaking things can have a big impact.
She is going to need it for longer rides, so now is the perfect time to find something that works for her. Do you recommend never going on longer rides or waiting until she is hours from home for GI issues to start? Seems like those are the only other alternatives. It might be she can tolerate something lower like 50g/hour or more sodium helps but she can’t nail her nutrition on a 5 hour ride until she can tolerate it on a 1 hour ride.
It’s not at all uncommon for plasma glucose to drop below normal during exercise if the latter is initiated when insulin levels are elevated. In some cases, the dip is enough to cause symptoms of neuroglucopenia. If somebody is susceptible to this, the safe bet is to simply not eat anything too close to the start of exercise, and instead wait until you are 15-30 minutes in.
She’s not doing 5 hour rides, only 2-3. That’s long enough for performance to benefit from taking in carbs, but unless you haven’t eaten in quite a while, short enough that supplementation isn’t absolutely critical, at least during routine training.
So again, for someone who is apparently struggling so the safe bet is to err on the side of less, not more… just ask Sam Bennett.
You seem to really enjoy being contrarian. OP stated above she wants to go on longer rides and work on her nutrition for those rides. She acknowledges she does not need this much for shorter rides. She is asking for tips from people who may have ideas. A PHD in sport physiology gave her some tips. So again, now seems like the perfect time to try a few things.
Haven’t done a deep dive, but I’m genuinely curious/skeptical.
This 1980 JAMA publication shows blood glucose dropped below initial value only after 3-5 hrs into the 1g/kg oral glucose tolerance test. Subjects reach their peak blood glucose 1hr after taking in the glucose load.
Not exactly true is it? You’re sending signals to the body and replenishing those that are being used etc.
This - training for 15h p.w., even at lower intensities, stores are gradually being eroded.
For such a short duration I wouldn’t eat. It doesn’t really benefit what you need over long duration. What you can tolerate and consume over short duration is vastly different over long duration. Just be sure to eat once you’ve finished your exercise.
Gastric distress as you are experience is shoving in more than your body can ingest at the intensity you are riding. It ends up just sitting in your stomach. It builds up till eventually you throw up.
I was out on a ride of 9 hours 45 mins yesterday. First 4 hours I just had a shortbread finger once an hour. That is 20g of carbs an hour. For the second half I had 57g of carbs an hour. If you take in too much sugar at once you release insulin and fat burning is suppressed for anything up to 90 mins. You become more dependent on sugar to fuel your ride. It’s a viscous circle. Then a snack just after I’d finished, then a meal an hour later.
From my ultra distance rides I know all about gastric distress and eating less and improving my ability to run on my fat stores was the solution. Keep any eating light and don’t cram it in.
We seem to be discussing different things. I’m talking about reactive hypoglycemia when carbs are ingested before exercise. It is the combination of insulin and muscle contractions that can exceed the body’s ability to precisely glucoregulate, resulting in a rapid decrease in plasma glucose levels, occasionally to the point of being symptomatic.
ETA. Here’s a now classic study of the phenomenon.
Look at the research. There are a couple suggesting that simply rinsing your mouth with a sweet solution can improve performance during something like a 25 mile TT, but by and large there doesn’t seem to be any benefit to performance unless you are exercising long enough to deplete liver glycogen stores. (You are going to use your muscle glycogen first/primarily, regardless of how much carbohydrate you ingest.)
Great post, as usual. Please correct me but with regard to fuelling up to 1 hour sessions, this largely depends on how you manage calorie intake during the day - ie. are you maintaining/building/cutting calories. Lots of studies evidencing reduced RPE when consuming carbs during exercise regardless of length so I guess why make your training feel harder than it is by not eating even if the workout is less than an hour?
While 80g of carbs per hour during exercise is the current trend in what our bodies’ are supposedly able to absorb and effectively process, bear in mind that that number is highly variable from one individual to the next and how hard an individual is working at the time. It is also important to keep in mind that just because someone can effectively process that amount of food per hour, it does not mean that they actually “need” that much. When our muscles are working, blood is shunted away from the digestive tract to better supply those muscles. The harder we are working, the less blood is available to the digestive tract. If the digestive tract does not have the blood supply to deal with the calories that are being consumed, problems ensue. At 110 pounds, it is not likely that your body can deal with the same amount of caloric intake during exercise as someone who weighs 180 pounds. I’d suggest that you stop eating 2 hours before exercise (to avoid the reactive hypoglycemia that has previously been mentioned) and back your food intake to no more than 40g per hour and see how that works out. Best wishes.
Maybe you are extremely well fat adapted and your body is really efficient at utilizing fat for energy which means you may benefit from consuming things like " trail mix " on a ride. Have you tried fats and proteins yourself during a ride?
From my own personal experience I’ve had a few longer rides which is about 4 hours for me… but on those rides I’ve eating really good chunks of fried chicken breasts. These we not race events but I and we were keeping a pretty heavy effort through out the ride and at the time that food worked well. Ive only done it a couple of times but it made me think why not " protein bars " instead of say a more carb bar ? You can still consume carbs in a bottle but why not more protein or fats during a ride??
My point is, I know its " science " and its talked about all the time about not eating protein during rides but it has helped me before. I dont do it all the time and if we are talking about an all out effort for about an hour like a criterium or short fast group ride then no, I have not eaten greasy chicken in those scenerios but if you’re looking to extend your rides and you are already potentially fat adapted what’s wrong with trying proteins and something like trail mix ? Trail mix has it all, fats, carbs, sugar, salt…
I think the kinetics of the glucose response absent exercise is reassuring.
The journal linked seems to have a limited list of institutions with granted access to read.
I found this review article which mentions 3 arms of counter-regulation against hypoglycemia.
The third mechanism which kicks in around 3 mmol/L in normal individuals is neurogenic with neuroglycopenic symptoms, as if the body is trying to shut you down before you can kill yourself.
Glucagon and epinephrine effects on the liver and tissues, however, are the major counter regulatory pathways and these are triggered at 3.7 mmol/L.
I think it’s important to try to define what dose of exercise is necessary to beat these dominant counter regulatory pathways, as I would expect it would be quite high or I just have too much faith in humans. We should have been selected out of existence if we couldn’t handle eating some sugar before physical activity.
Protein is hard to digest and has the lowest amount of readily available energy of the three (carbs, fats, protein). You also need more water to digest it. If you want to fuel for maximum power, especially for repeated efforts above FTP, carbs are the way to go. If you mainly ride below FTP, food mix can be more variable.
That doesn’t mean you can’t eat chicken during a ride, but it probably does little for fuelling you. However, for up to four hours, I can ride without eating at all, and I wouldn’t think I’m very fat adapted, due to eating very little fat in my general diet. So it doesn’t need to be lots of carbs for rides of that length.
It really depends what your long rides are for - if they are hard training rides or races, eat simple carbs. If you’re just out to enjoy riding your bike, eat whatever you want, and also have a cafe stop with real food.
Suppression of insulin during exercise is a sympathetically mediated response, so the harder you go, the bigger the braking action, and in a non-linear manner linked to FTP.
More relevantly, though, I think you need to distinguish between hypoglycemia and neuroglucopenia. The latter would clearly be problematic when a predator is chasing you, but brief, mild or even moderate hypoglycemia would be unlikely to be. Thus, there would seem to be little evolutionary pressure to prevent it.
For now, I’ll continue to take in carbs before exercise. If there’s more evidence for this phenomenon in the future, I’ll reconsider. I just doubt it’s relevant to what I do as I believe the overall network of regulatory mechanisms can adequately respond to the demands of exercise on a bike.
In my mind, I’d imagine you would need to do something odd like eat couple boxes of donuts before doing the kind of crazy CrossFit activity that causes rhabdo for this to be relevant.
I agree with everything you are saying. My thought is, I think " most " cyclists deal with some kind of fueling issue and even ones who get it right are still going to have to deal with some kind of discomfort during the ride. Even with proper nutrition you still get a general feeling of fatigue or at least a feeling like you just went on a 1.5 hr or a 2 hr or a 5 hour ride.
She is mentioning having trouble with carb intake and trying to increase her ride for over an hour. She’s trying to eat carbs before rides, she’s trying to eat them during her rides, and sounds like she has a pretty sensitive stomach. So my thought is… try some proteins and or trail mix.
Im not big on all the science stuff, and I’ve done long 4 hour rides without much nutrients as well. And my normal 1.5 to 2 hour rides are fueled by liquid carbs, the basics.
Im just trying to give her the idea to not rule anything out " just in case " it works for her.
Shes eating a ton of carbs and getting gastric distress, getting dizzy, she’s shitting her pants.
Im saying, switch it up, try the things she pretty much canceled out at the beginning of her post because we are told to cancel those things out.
But in reality it really could be just consuming " less " of what she is already consuming.
Either go less, or go protein and trail mix.