I’ve been a long time fanboy of Trainer Road ( since 2012 ) and have generally accepted their advice carte blanche. I’ve followed the podcast through the years of recommending higher and higher on-bike carbs and worked my gut up to handling ~110g/hour.
Then I came across this new study, which was just published:
Which says, at 70% VO2max ( a bit below FTP ) with only 10g of carbs per hour, there is no performance difference between people adapted to a high carb diet, or people adapted to a low carb- high fat diet.
Has this been discussed elsewhere? Would love to hear the coaches dissect this on an episode of the podcast.
PS. Apologies if I’ve missed this being posted elsewhere. A brief search for “Noakes” ( the author ) didn’t bring up anything relevant.
For what I quickly see they talk about a single 90min or so effort till TTE.
You muscles energy storages are big enough to handle that, especially if you rested the days before the efforts. So not very surprising result.
But that’s not what any racer does, who trains daily with a high energy demand. So imo not much to conclude from it.
But maybe I missed something…
A few years ago, I lost a lot of weight going low carb. I have a terrible sweet tooth and can pretty much eat as much sugar as you put in front of me, so this really helped with weightloss.
Having said that, I was fine doing Tempo and below, but once I tried to get into Threshold and above, I didn’t have much in me for longer efforts. I could handle something like 30/30s, but 4x4 @ VO2 was extremely painful.
RPE was up considerably in all zones, even Z2. Once I went back to sugar, RPE dropped and I was absolutely able to do more hard work.
Note: this may have also been at least partially due to general fatigue from running a calorie deficit, but I can definitely say that hard work is easier with sugar in my bottle.
Yes. We were talking about it ad nauseum last week.
Ingestion of carbohydrate during time trial resulted in statistically significant improvement of performance. That was for very, very modest carbohydrate consumption. I would have said that was consistent with what TR has advocated. I say if the study had used more carbohydrate then the difference would only have been bigger, but we can’t say from this study. MORE RESEARCH IS REQUIRED! (always, more research is required)
I think the thing that most people are surprised by is that time to exhaustion in a Time Trial, CHO bolus, Time Trial arrangement, LCHF performs the same as HCLF. Most would expect HCLF to outperform. But I’m not surprised. This has been tangentially discussed on other podcasts. Fat adaptation doesn’t impact glycogen storage or result in glycogen sparing at higher intensities.
This is a really fun paper to kick around/talk/debate, though.
I don’t do triathlons so maybe it’s different, but I don’t think I could find a single racing in my entire racing career where I was only doing 70% of my VO2 max power. Yes, for long road races, I might average that over the entire race, but I’m doing lots of efforts much higher than that, not to mention any final pushes near the finish. For crits, CX, MTB I’ll probably average that for the race and not spend much time below. So it doesn’t really translate much to any real world riding I’m doing.
That and it doesn’t touch day after day efforts like stage races or even back to back training days.
Tim Noakes has done some good work in the past, but he’s gone off the rails a time or two in the past 10 years so it’s tough for me to trust anything that comes out of his mouth or lab
I think this is so critical. I feel like it’s not exactly related but in my head, I somehow see a similarity… On my trainer my FTP intervals are a breeze. Because I can use Zwift to keep my power within 5 W of where I want to be. But on the road as I constantly dip in and out of VO2, it makes it so much more difficult. And I feel like there’s something similar going on with the carbohydrates. So when you’re doing this moderate effort on a trainer and your watts are really quite steady, I definitely feel like that is different than requiring surges of glucose to have a much more variable power yet same average power.
It could be. Something like how normalized power is higher than average power when there are power fluctuations. Going above the average takes more of a toll than going a similar amount below gives back.
I’ve spent a LOT of time at LCHF scientific conferences and have been keto for several years (my wife personally knows many of the scientists working in this field). What I can say is a couple of things: 1) studies that look into LC diets and performance almost always have subjects that have done LC for too short a time for the studies to be valid, (I.e., they are not fat adapted so the results aren’t even based on subjects that are in that physiological state) and 2) I have found that I can do 100 miles races in 4 hours in a pack of 40 riders on a keto diet but doing shorter, faster road races or crits requires some amount of carbs, i.e., to have that punch over and over and over and/or for a final sprint requires more carbs than what one would have with a keto diet. So, I do a “modified” keto where I’m probably in ketosis and fat adapted most of the time but add more carbs for hard intervals or really hard road races. I’m rarely fatigued and, at 64 years old, I’m still doing 10K miles a year in the bike.
Are you saying that on a day to day basis you decide how many carbs to add based on needs for your training and racing? If so, that isn’t what “fat adapted” is. You can’t just go into and out of it day to day.
I can give you my anecdotal experience. I went keto ~2017 to combat systemic neuro-inflammation from chronic fatigue/Gulf War Illness. I worked my way up to doing 4-5 hour training rides on water and Base Salt and felt great. Did Ironman Cattanooga and IM Switzerland using U-can slow release carbs for maybe a total of 1500 kcals for the whole race and felt great on the run. Then I started gravel racing, usually 100km events. Typical scenario - neutral roll out through town, then turn onto first gravel sector and the hammer drops and the race explodes, supra threshold efforts to close the gaps to small groups. And I imploded. Every time. Around the 2 hour mark. So I switched to Maurten mix and gels (now Flow 60/90 and Maurten gels or homemade mix), and performed a lot better. Bottom line, low carb works great for ultra endurance events (Ironman, ultra marathon/trail events etc), but anything that involves high intensity efforts, and you’re going to tank.
I agree. I only up the carbs the day before races. If you burn the carbs during those races you will be back in ketosis in a day or two afterwords (assuming you go back to a keto diet). Also, fat adaption doesn’t just go away in the blink of an eye if you have done it long enough. I want to be clear - I think one does need carbs for hard races so. I’m not evangelical about the whole keto thing.
(always, more research is required)