Replacing Calories By Using KiloJoules As A Guide

morpheus

As I spend the next 5-6 weeks on my 'ReIntegration Plan', I think I'm going to get a little more aggressive with my calorie intake on the bike.  I'm going to experiment a little bit.  Currently, I'm using Skratch Labs Secret Drink Mix for hydration and the rice cakes for calories and energy.  My problem with this is that it's hard to know exactly where I'm at with the numbers.  

So, I want to compare that style with a more calculated approach.

On my Joule, I can watch the KJ tick up and up.  Is it crazy to set intervals of say 30', like we do when compartmentalizing Watts, and attack my cals based on KJ burned?

Surely, it can't be a 1:1 replacement, right?  That would be 700 to 1000 to whatever number of calories per hour!  

And, then, I gotta factor in the max amount of carbs that can be absorbed, 70-90 g Carbs is the standard.  And, everything I'm looking at (presently...CarboPro) has roughly 30g carbs.  So, the problem is...if I load up on the calories, I'm going to OVERLOAD on the carbs?  Not sure how that plays out over 3,4,5,6, etc hours of effort.

Do you have any experience with this?

benvanmarcke

Look in the wiki for nutrition guidelines but using 90g of carbs is very high (360), probably OK for low intensity training but not once you start hitting z3 or higher.

Looking at kJ, it is the mechanical energy used to push the bike forward. The correlation with kcal is that 1 kcal is approx 4.2 kJ. However, the energy used by the body doesn't just go towards propelling the bike, 75% is used to maintain temperature and keep other vital functions going, meaning the efficiency is only about 1/4. So the rule is that, in order to put 1 kJ towards propelling the bike, the body needs 1 kcal of energy.

Now if you race steady, your kJ as function of time will also be steady, so yes, you can drink based on kJ measured but it's exactly the same as drinking. at preset time intervals.

morpheus

Is the listing of the # of calories on a label, in reality, kilocalories?

If so, and I do 500 kJ of work, am I correct in saying that it took 500 calories ( due to convenience for the manufacturers, when it would be more accurate to say kilocalories ) to do that 500 kJ of work?

Yes, I've done the homework and read about the inefficiency of the system, but it just seems like logic to be more aggressive at replacing the 'coal' that burns the 'fire'.

So, my other question would be....how could I be more aggressive replacing these calories without going severely overboard on the carbs (let's just say 90g per hour max)? Using CarboPro as an example, 112 cals and 28g carbs per scoop. If I shot for, just say, 560 cal per hour replacement of 560 kJ worked, then I'm also getting 140g carbs! What happens to those extra carbs if I can only digest/use 90 of them?

John Withrow

I think those extra carbs that you can't digest will simply sit in your stomach and make you sick. I personally think the limiter isn't knowing how many calories you are burning to do the work on the bike. The limiter is how many calories your body can absorb in a given time-frame while putting out a certain effort. The lower the intensity, the more you can absorb, but also the less you theoretically need. I think it is likely impossible to do intense bike workouts and not run a calorie deficit.

So there are 3 different approaches to attempt to address it the way I see it:
1) keep taking in the "normal" 200-300 calories per hour with the proper amount of carbs for your weight and run the deficit that you make up after your workout
2) Take the "Coach P (IMTX)/Core Diet" approach and train your body to take in many more calories on the fly (some people can take in 400-500 cal/hr with the right practice)
3) Train your body to burn fat instead of blood sugar (through fasting workouts, etc).
Each of the above have their own believers and their own haters... Probably a good time for you to experiment and figure out what works for you.

Personally in the past I usually did #1 above with an attempt to push it higher a bit (towards #2). This yr, I have experimented with #3 a lot with shockingly good results. I'll need to try to move back to a more normal nutrition plan however as the race season gets closer. Good luck with your experiment and keep us posted.

Peter Greagg

I have just found out that even with a big breakfast, I need much more than 250 cals per hour on my long run.

I have just raised it to 330 cals per hour and will try even more next week (on Coach P's suggestion).
Based on that, I would see how much you can tolerate rather than seeing how little you you go.
Just saying!

mgraffeo

+1 on John's comments. Most folks at IM intensity would max out their calorie absorption at 300-400 kcal. The only way to absorb more calories is to go slower. You need to find that balance, and then rely on your body's ~2000kcal of muscle glycogen you already have on board, plus the relative contribution of fat burning, to get you to the end.

What's the rationale behind wanting to up the kcal / carbs? Is this to improve performance / help you ride longer and/or harder?

Coach Rich

Posted By Mike Graffeo on 28 Mar 2013 07:54 AM


+1 on John's comments. Most folks at IM intensity would max out their calorie absorption at 300-400 kcal. The only way to absorb more calories is to go slower. You need to find that balance, and then rely on your body's ~2000kcal of muscle glycogen you already have on board, plus the relative contribution of fat burning, to get you to the end.



What's the rationale behind wanting to up the kcal / carbs? Is this to improve performance / help you ride longer and/or harder?

^This^

Your energy during exercise comes from:

• Glycogen, stored in the muscles and liver, about 2000 cals worth
• Fat stores. 1lb of fat is about 3600cals so even the leanest of us have a virtually unlimited supply of fat cals, at least from the perspective of fueling a training session.
• Food eaten during the session.

As Mike and John have said, the limiter is how many calories per hour your body can process at your chosen intensity. For example sitt on the couch and doing Z5 intervals on bike are very different intensity levels with very different calorie consumption potentials (lg pizza vs nutin').

If you're talking about tracking calories burned for the purpose of aiding weight loss, I just use KJ from the ride: enter that in LoseIt, track my calories eaten against that number, done. It works.

morpheus

I'm hearing you guys.

And, here's what I'm gonna try, more calories than I used to shoot for. Now, I won't go all stupid (which is how I started this thread) and try to replace 1cal for every 1kJ, but I am going to try to see where my own limit is. If it's 300cal/70g per hour, I'll find it. If I can hold 500cal/110g, I'll find it.

I'm going to experiment with this now, sooner rather than later. And, I am referring to the longer weekend rides, which will include intervals of harder efforts mixed into longer z3 time.

Gonna start on the high side and work it down as needed over the next several weeks.

A glorious experiment, n of 1, that may include vomit and bile...who doesn't like doing that?!?!