Carb intake based upon intensity

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  • #15046

    I’ve been trying to dial in Carb intake for fat adaption and weight loss. Out of curiosity I made a program that is able to take in a HR csv as well as data on hr vs Calories burned and fat vs carb utilization.

    I wasn’t able to use my own data because I haven’t had an official test for these measures. I used a approximation based upon my pseudo AeT and Ant test along with another individuals results and the graphs in TfNA. I wish I had my data, but cannot afford a test right now.

    I’m using this as a approximation. From this I’m looking to try to vary my carbohydrate intake based upon the duration and intensity. I haven’t found any resources that dive into using HR/intensity to dial in Carb intake. I’m going to be messing with carb ratios and recover using the data. I attached the output of a 2.5 hour session.

    Also has anyone here used Highly Branched Chain Dextrin intra workout. I’ve seen some studies that have shown increased endurance using them vs normal sugar or dextrin. It’s also something I’m going to experiment with on my really long days. I’m going to try to use this data to figure out around the time when I should try to take in carbs. Does anyone know of a study on Glycogen replenishment rate during exercise?

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    Anonymous on #15079

    As with most things training, there are no hard-and-fast rules; just general principles that need to be tailored to the individual. Regardless of what any studies say, you’ll need to do some experimenting to find what works for you.

    Here’s a great infographic that summarizes some general principles:

    Fuel for the Work, by YLM

    Rebecca Dent on #15139

    Hi Curriespencer,

    I’m the Dietitian for Uphill athlete and will try to give you an answer to your questions. What you will discover is, that when it comes to nutrition there is never a straight forward answer. I would tend to agree with Scott above, advise needs to be tailored to the individual and you will need to practice using the guidance to find what works best for you, your goals for body composition, training adaptations and the main event/s you are training for.

    Firstly here are a couple of science papers to get your teeth stuck into;

    ‘Fuel for the work required’
    Carbohydrate requirements during sport

    ‘Carbohydrate intake for training and competition’

    ‘Toward a Common Understanding of Diet–Exercise Strategies to Manipulate Fuel Availability for Training and Competition Preparation in Endurance Sport’

    ‘Carbohydrate availability and exercise training adaptation: Too much of a good thing?’

    What you have proposed is 3 different nutrition goals you are trying to achieve which will all impact nutrition intake/requirements; *body weight loss, fat adaptation and understanding your own carbohydrate needs to support training adaptations (*weight loss is not the same as fat adaptation).

    Looking at your data you have presented, you are utilising approx. 98g of carbohydrate per hour. When it comes to standard guidelines re carbohydrate intake per hour, the recommendations are 30g-90g per hour. You can absorb 1g of glucose per min but with glucose/fructose combined you can absorb approx. 1.26g/min because glucose and fructose have two separate absorption pathways. However it is not a direct translation of what you have used during training to what is required to ingest per hour. As your endurance training continues, what you would hope to see in your figures is a reduction in carbohydrate utilisation during an endurance session and an increase in fat usage (this is fat adaptation).

    To enhance fat adaptation endurance training per se will aid this, but also carrying out zone 1 & zone 2 sessions fasted will optimise fat adaptation. You will find a great article on how to introduce fasted sessions on the uphill athlete website, I would advize reading these before you set out to do any fasted sessions. For high intensity sessions, zones 3 & 4 it is best to consume carbohydrate during these sessions because of the intensity you are training, depending on the intensity and duration on these sessions will influence carbohydrate requirements per hour. Zones 1 & 2 sessions not carried out fasted I would aim to introduce carbohydrate intake around 60-90mins into the session and start with 30g carbohydrate per hour, experiment with the recommended values and see how you get on.

    To answer your question on Highly Branched Dextrin, it is a form of maltodextrin. The research on this shows that it has been shown to prolong blood glucose levels, it may reduce perceived rate of exertion during endurance training, it is faster absorbed by the gut and can also be better tolerated by those who may experience GI upset during training/event.

    I hope this has answered your questions?

    curriespencer on #15189

    Thanks you for the links to studies. Some good information there!

    I’ve been following IF and fasted training for the better part of 5 years now. I did it with BCAA’s when my focus was on weightlifting and since starting mountaineering training I’ve pretty much solely carried out fasted training. My biggest day so far was 12 hours in the mountains with no food.

    So far I haven’t had to really introduce carbs at all to my low intensity days. I’ve done some Z3 work with and without carbs and haven’t noticed much of a difference. I’m not sure if this has to do with the fact I use to do multiple hour oly lifting sessions without any calories except for the BCAA’s.

    My main concern is figuring out a good method for determining my post-workout carb consumption and how it relates to recovery. I’m going to experiment with different percents of carbs based upon estimated utilization. Right now I’m looking to loose about 20lbs so I’m looking to try to find the minimum dose of carbs where I feel recovered.

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