Caffeinated GU's and bonking

I’ve had two interesting experiences with caffeinated GU’s (Cliff Shot Mocha).

  • A few weeks ago, hard hilly run. Felt very strong through 9 miles, 4 left. Started feeling a bit weak, then really started thinking about food. Still was able to maintain speed and focus.
    Then I ate the GU. Within seconds, I stopped running. Completely shot. Walked nearly a mile then hobbled back the last 3.
  • Yesterday, very hard ride. Lots of PRs along the way. Was eating bars, keeping fueled. At 45 miles, ate another of these GUs. Started to feel immediately sluggish. So I ate the other one. Came to a favorite “Strava segment” and could not muster any effort. Struggled through, cross eyed. Limped the last 5 miles home.

What gives? Have any other had similar issues with caffeinated gu? It’s obviously time to switch, but I’ve taken them for years without really noticing this bonk after eating.

Not sure if it is related to the caffeine, but perhaps you’re waiting too long and the bonk was already coming. It can take 15-30 minutes for your body to get energy from food, so I’d have a hard time thinking that the Gu caused a bonk “within seconds”. That said, you may have developed a sensitivity to something in it that caused a reaction.

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Curious about this. Suppose you did develop a sensitivity to something such as these GU’s. What would be the best method to test this? Nutritionist? Blood testing from a Physician?

It’s probably not the energy gel causing the problem. Energy gels just don’t cause problems (or help anything) “within seconds” or “immediately”

You probably were about to have the problems, and just coincidentally took the gels right before the problems happened.

So I just chatted with the owner of the local Fleet Feet. His hypothesis is that I was likely on the verge of bonking and that the sudden intake sends resources from the body straight to the stomach, actually reducing blood sugar levels. Suggested not eating the entire gu (let alone 2) at once and maybe trying cliff blocks/equivalent.

Pretty good hypothesis IMO.

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Cliff Shot is not GU.

Your whole post is kind of confusing to me, and I think it’s because you’re generalizing a Clif Shot as a “Gu” instead of as a “gel.”
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So I just chatted with the owner of the local Fleet Feet. His hypothesis is that I was likely on the verge of bonking and that the sudden intake sends resources from the body straight to the stomach, actually reducing blood sugar levels. Suggested not eating the entire gu (let alone 2) at once and maybe trying cliff blocks/equivalent.

Pretty good hypothesis IMO.

& one can only hope he knows more about shoes than he does about how the digestive system operates. The statement… *“the sudden intake sends resources from the body straight to the stomach, actually reducing blood sugar levels” *is not even remotely accurate.


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Ok, yes, it was a GEL, not GU. What difference does that make?
Regarding
*“the sudden intake sends resources from the body straight to the stomach, actually reducing blood sugar levels” *

That’s my interpretation

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Photocopier. Xerox.
Gelatin dessert. Jell-O.
Gel. GU.

One is a generic term, the other is a brand. Fairly big distinction.

Your stomach problem may or may not relate to gels (generically), or perhaps to the specific brand of gel. There are certain ingredients (say, milk solids or fruit puree) in some brands which can cause sensitivity or illness in particular people. So you might want to experiment to see if you are reacting to (a) specific ingredients (i.e., caffeine) or (b) energy products in general.

Also, if you are already in need of food / fluid…it is too late. Eat before you are hungry, drink before you are thirsty.

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I would take his word for it Fleet Feet owners go through extensive training and defense of their lease of the building before they are allowed to open it.

Not that ST is any more of a credible source, but I just hope you don’t jump to conclusions so quickly based solely on word of mouth. What he’s talking about is “Exercise induced hypoglycemia” and it’s relatively uncommon. Given that is has happened after a good amount of time into a workout - it’s even more unlikely.

You should look that up and see if the “no-no’s” are and if they are similar to what you have been doing. If not you should delve into the ingredients more and control for each of them to decide whether it’s the caffeine or the sugar that’s the culprit.

Or you should just forget about it because it happened twice out of what 10 workouts? Unless you can honestly kid your self into thinking that that’s the only thing that you changed between the two days, then continue the witch hunt.

Learned the magic ingredient this past weekend: protein.
85 mile ride, continuously fueled with bars that had protein as well as Accelerade gels which have protein as well.
Felt strong all day; no bonk feelings at all.

I can’t believe I’ve been racing 27 years and only now figured it out.

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Glad you found it.
Yes, 10-20% of calories should be consumed as protein on longer endurance sessions (2 hours or more or something like that).
Lots of decent studies on this if you care to look them up.
Otherwise, just read the sales literature on some of the products that have a portion of protein in them.

Photocopier. Xerox.

Gelatin dessert. Jell-O.
Gel. GU.

One is a generic term, the other is a brand. Fairly big distinction.

And kind of easy for anybody with an ounce of intelligence to interpret what he was referring too.

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Read Brian PBN’s post above, and then if you have time search some of his other post’s and race reports from some of the people who win IM’s under his guidance/advice.

Then take a look at what he has to say about protein, or some products which contain protein.

I would argue that your bonk was situational, i.e. low calories. Protein is not needed during work outs. Some people may like the taste, or how it is easier on their stomach, but totally not required for longer events or work outs.

Maurice

I wouldn’t celebrate just yet, one ride is not enough to determine that it’s fixed, IMO.

Thanks for your astute reply. I assume you only read the first part of my post, and not the latter, which tied in to the observation that not all brands are created equally. That was, for those intelligent enough to get the analogy, the point of the Xerox comment.

You’re not supposed to eat the wrapper!
.

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I think the answer lies in you overall diet 24-48 hours before these workouts and how you refueling after a session. 9 miles shouldn’t require any nutrition, and unless it’s screaming hot or your really slow, you don’t even need water, or at most you carry a bottle for 2 miles, drop it and drink it on the return or a out & back. A higher paced 9 miles run is what, 60-80 minutes? No nutrition needed. No way you should Bonk at anything under 2 hours unless it’s race level intensity if your training at a descent volume.