Hi. Possibly a silly question but a thought that’s been bugging me…
Is there a point during a training session where fuelling becomes pointless?
Specifically, my understanding is that a gel will take 20 mins to get into your system. Therefore if I take one 20 mins or less before the end of the session it’s going to be pointless right?
So is there a maximum time before the end of the session beyond which you no longer fuel?
Not pointless. It is important for recovery.
For me, it depends. If it’s a short workout, I usually quit 20-30 mins before it ends. If it’s a long (3+ hours) one, I’ll fuel right up until the end.
Honestly, I don’t think it matters much as you need to fuel after for recovery anyway, but I mostly do it just to save the money and take in healthier food after instead of pure sugar during.
I’m not an expert, so I’m not sure I gave you a deep enough answer, but when that is said…
Carbs also help you recover. So you’re not only fuelling for the ride, but also for the next.
After I have started to fuel the complete ride, my recovery have ben so much better!
“Take one” of what? Different foods, and even different carbs, take different amounts of time to get into your system. Plus, as others have already said, you are also refueling your body for the following day.
The sentence before that he specifies a gel
I guess that’s what I get for responding before having coffee in the morning. I think I read that post three times and completely missed ‘gel’ each time. ARGH! Might it still depend on the type of gel, though, and what specific carb they are using? 
Ha! Been there! 
For me it also depends on (1) the intensity/duration of the current workout and (2) what I have coming the next day.
But if it’s a hard or long ride then I’ll eat till the end since I probably need the calories and I might as well get in another 100 or so while I can get a more-or-less insulin free carb intake.
When we are fueling during a workout, it can be as much about properly fueling for tomorrow, the next day, etc. as it is about fueling the current workout. For most rides/workouts, you are coming off the bike in a calorie deficit. If you can reduce the deficit coming off the bike, that makes nutrition off the bike more normal and consistent. When on the bike (and ~30 minutes after), the body is particularly well positioned to restore glycogen stores and set yourself up for future work. I try not to miss out on that window, particularly when I’m training a lot.
During hard 60 min sessions I used to be whacked afterwards, brain-fog, not much use for a couple of hours. Then I started fueling during the ride, just a little. Maybe 30-60g carbs depending on the workout and it changed my life! (Not really, but it meant I wasnt a mess post workout and could be a functioning, productive member of society). 
My hands post chemo aren’t the most dextrous so for a ride out door I just tend to fuel with a carb drink and the cafe stop. It seems to more than get me by. My mate though who is undeniably the best in our group, constantly nibbles also.
What I do need to get in the habit of is having a recovery drink post session regardless of brain-fog or not. I’ve a habit of forgetting if I don’t have brain-fog and it seems to help me sleep better so it would have been better if I had.
This is the replies that makes most sense to me but thanks all!
A little besides your point. I don’t know the source of the 20 minutes, but have read similar before. I just wanted to comment that when I am starting to feel like I am dragging, I consistently start to feel better right around 8 minutes after I eat something. I realize that the feel-o-meter is notoriously bad when compared to lab tests. But time and time again, it is about 8 minutes for me.
Same. A maltodextrine gel hits me between 10-15 mins. And, in addition to how long the ride is and what my next workout is going to be, I take into account how I’m feeling and what challenges my ride presents for that last half hour. If my legs are feeling fatigued and I have 7 miles straight into a headwind, I’m eating a gel.
But, I don’t usually weigh the option anymore. I used to think I could save the calories (100 cal?, I can burn that in 10 minutes), and too many times I regretted it.
Pretty much my experience too. Without fueling well I had to limit how much I rode during the week days so I could be productive at work, and on long weekend rides I pretty much rode all morning and laid on the couch the rest of the day nursing headaches, fatigue, etc. Now I get back from week day 2-3 hour rides feeling fine, and even the 4+ hour weekend rides don’t keep me on the couch and zero headaches.
This idea that a gel takes 20 minutes to reach your system is old folks’ tale from the era before modern sport.
It’s like pouring a glass of water on a hot pan that has been on the stove on 10 for 10 minutes, the real consideration is that if you eat it too fast you may see an insulin spike which will reduce your LT1
wut…
Gonna need a source on that claim
Thanks for your question, very interesting field of study
Elite endurance athletes have high metabolic flexibility. They can switch between fat and carbs efficiently without disrupting lactate clearance. They oxidize lactate more efficiently via mitochondrial lactate oxidation complexes. If they eat carbs, their LT1 is unlikely to shift much acutely because their system can handle fuel switching rapidly.
Recreationally trained athletes have weaker metabolic flexibility. They rely more on glycogen due to poorer fat oxidation. Their lactate clearance isn’t as strong. An insulin spike could shift them into glycolysis sooner and push LT1 down acutely.
After a high-carb meal, there is reduced latent aerobic ketosis. If an athlete is in a mild ketogenic state, burning fat at rest, and they consume a high-carb meal, insulin will suppress fat oxidation, increase glycolysis, and cause a more abrupt shift to carb oxidation. This means that at the same intensity, they’ll start producing more lactate sooner, effectively lowering LT1 temporarily.
The acute vs. chronic effects on LT1 differ. Acutely, there is likely a transient shift due to suppressed fat oxidation. Chronically, if this happens daily over time, it could cause metabolic inflexibility, lowering LT1 long term.
Yes, an insulin spike could acutely lower LT1, especially in metabolically inflexible individuals. The effect is likely transient in elite athletes but more noticeable in less-trained ones. If metabolic inflexibility develops over time, then LT1 could be lowered long-term. This is essentially the “early reliance on glycolysis” phenomenon seen in metabolic syndrome patients but applied to athletes in a temporary state.
Assessment of Metabolic Flexibility by Means of Measuring Blood.pdf (1.3 MB)
Generally speaking, taking a gel within 20 minutes of finishing your session won’t provide much benefit for that workout itself. Since gels take roughly 15-20 minutes to kick in, you’d be fueling just as you’re wrapping up.
However, if you’re planning a hard effort near the end of your session or you’re training for back-to-back intense workouts, a late gel might still be helpful for recovery or to avoid a crash