Calorie vs kJ

[no calves]

Been cycling for numerous years so not new to the energy expenditure on my garmin.

 

After a race last week someone told me i should take the calorie count on my garmin and x4 it for kJ (because drinks bars and gels have kJ listed on them)

 

I was under the assumption that our devices display a reading in Calories but that figure translates directly into kJ??

The question is thus do i change my garmin to kJ (530 has the option) but what about the garmin app, strava etc? i just want workalbe data without having to convert in my head the whole time 

[DieselnDust]

Calorie is metric

kilojoule is SI

calorie x4.2 = kilojoule

what you decide to use is entirely dependent on how you want to track your expenditure vs intake

Edited September 21, 2021 by DieselnDust
to fast with the fingers

[Dexter-morgan]

Quick question, so what is Kcal? not 1000 cal?

[bleedToWin]

35 minutes ago, Dexter-morgan said:

Quick question, so what is Kcal? not 1000 cal?

Kcal is scientific term whereas Cal (capital C) is food calorie. Kcal = Cal. This was adopted for convenience and not at all to confuse anyone. ????

[bleedToWin]

Here's some more interesting formulas:

Energy as you know it for your house is measured in kWh, but the actual unit is Joule.
1 J = 1 Ws (Watt.second)
3600 seconds in an hour so:
3.6 kJ = 1 Wh

If we are working towards energy burned (not just energy pumped into the pedals) there's a crux. You are not an efficient machine. Your mechanical efficiency is somewhere between 20-25% so you have to multiply this value by something between 4 and 5. To get to food calories you would then divide this again by 4.2. Let's assume 4.667 as your efficiency then we have:

1Wh (into the pedals) = 4 Cal (energy required)

Carbohydrates come in at 4 Cal/gram, so:

1Wh (into the pedals) = 1 gram of carbs required.

If you don't like the guess of efficiency, the answer would be 0.86 - 1.07 grams of carbs.
This gets quite interesting. Power along at 200W and you need a whopping 200 grams of carbs every hour! Even gut trained pro's can't get up to 100, so what gives? Well, at lower intensities your body will burn some fat, and if you are well rested you should have around 100g of glycogen stores in your liver, and another 400g in your muscles.

How I use this info on race day:
Let's assume a 4 hour race with average power in the upper 200s. There will be some fat metabolisation, but generally not a high percentage as the intensity is mostly too high. There is also some energy still coming in from my giant breakfast at the start, so I'm comfortable assuming that I'm burning about 800g carbs during this race. This means I need to consume 300g, or 75g/h to avoid the bonk. With some minor gut training and using multiple sources of carbs (with different absorption mechanisms) this is quite attainable. I generally go a bit higher to be safe, but I make sure to count every carb I'm taking with me.

I see folks doing one bottle of drink mix (50g) and one bottle of water with 2 or 3 gels (50g/75g) wondering why they run out of steam 3 hours into intense rides. Eat more folks.

[no calves]

Ok so as far as my knowledge goes as soon as you use a PM you ger your expenditure more accurately because its derived from HR. my question is in the picture below. do i still need to x4 that number to EAT/Drink for or is that = kJ??

[bleedToWin]

10 minutes ago, no calves said:

Ok so as far as my knowledge goes as soon as you use a PM you ger your expenditure more accurately because its derived from HR. my question is in the picture below. do i still need to x4 that number to EAT/Drink for or is that = kJ??

Those are food Calories, so yes multiply by 4.2 to get kJ.

[no calves]

4 minutes ago, bleedToWin said:

Those are food Calories, so yes multiply by 4.2 to get kJ.

So feeding for that would be 2x bottles at 700kJ ea with a bar and a gel for instance?

[W@nted]

So I am trying the single bottle feed system from 32GI. Using the racepro you basically add your whole race/ride carbs requirement in a single bottle. This mixture does get a bit thick (up to 12 scoops in a single 750ml bottle) but it is actually still drinkable (Choc flavour). The other bottles is just a hydration drink with electrolytes and no carbs which is consumed according to thirst.

 

This method is more simple for me, as I do not have to keep count of all the bars and gels and bottles I need to consume each hour. 
 

Main reason for trying this, is that I was really struggling with the gut training to absorb all the different types of carbs. Especially during high intensity rides. I always had a burning stomach towards the end of my rides.

Anyway, i am tying this method and hope it works. In no way sponsored or affiliated to 32GI.

[ChrisF]

17 minutes ago, no calves said:

So feeding for that would be 2x bottles at 700kJ ea with a bar and a gel for instance?

IF you started without any breakfast ....

 

You start with a certain amount of energy "in reserve", the drinks and gels are for "topping up" after that.

 

 

Then again, I got it wrong during a long ride  two weeks ago, so what do I know ...

[The Ouzo]

6 minutes ago, W@nted said:

So I am trying the single bottle feed system from 32GI. Using the racepro you basically add your whole race/ride carbs requirement in a single bottle. This mixture does get a bit thick (up to 12 scoops in a single 750ml bottle) but it is actually still drinkable (Choc flavour). The other bottles is just a hydration drink with electrolytes and no carbs which is consumed according to thirst.

 

This method is more simple for me, as I do not have to keep count of all the bars and gels and bottles I need to consume each hour. 
 

Main reason for trying this, is that I was really struggling with the gut training to absorb all the different types of carbs. Especially during high intensity rides. I always had a burning stomach towards the end of my rides.

Anyway, i am tying this method and hope it works. In no way sponsored or affiliated to 32GI.

I've been using 32gi for a number of years. I ride with the Endure drink and was using their gels and g-shot.

then at the beginning of this year my sister mentioned she was using products from Pace and Power for her running. Back in the late 90's i used to use their products and then switched to 32gi along the way. My sis then gave me a bottle of GT Gel, basically Gel in bottle form that you decant into a smaller squeeze bottle for on the ride gel consumption.

I've been using this gel this year and what I'm really enjoying about it is that I can take small sips whenever the opportunity presents itself rather than having to crack open a gel sachet and having to consume the entire messy thing in one shot.

It gives me better sustained energy, does not hurt the gut and is just cleaner for me and the environment.

Edited September 21, 2021 by ouzo

[Titleist]

3 hours ago, bleedToWin said:

Here's some more interesting formulas:

Energy as you know it for your house is measured in kWh, but the actual unit is Joule.
1 J = 1 Ws (Watt.second)
3600 seconds in an hour so:
3.6 kJ = 1 Wh

If we are working towards energy burned (not just energy pumped into the pedals) there's a crux. You are not an efficient machine. Your mechanical efficiency is somewhere between 20-25% so you have to multiply this value by something between 4 and 5. To get to food calories you would then divide this again by 4.2. Let's assume 4.667 as your efficiency then we have:

1Wh (into the pedals) = 4 Cal (energy required)

Carbohydrates come in at 4 Cal/gram, so:

1Wh (into the pedals) = 1 gram of carbs required.

If you don't like the guess of efficiency, the answer would be 0.86 - 1.07 grams of carbs.
This gets quite interesting. Power along at 200W and you need a whopping 200 grams of carbs every hour! Even gut trained pro's can't get up to 100, so what gives? Well, at lower intensities your body will burn some fat, and if you are well rested you should have around 100g of glycogen stores in your liver, and another 400g in your muscles.

How I use this info on race day:
Let's assume a 4 hour race with average power in the upper 200s. There will be some fat metabolisation, but generally not a high percentage as the intensity is mostly too high. There is also some energy still coming in from my giant breakfast at the start, so I'm comfortable assuming that I'm burning about 800g carbs during this race. This means I need to consume 300g, or 75g/h to avoid the bonk. With some minor gut training and using multiple sources of carbs (with different absorption mechanisms) this is quite attainable. I generally go a bit higher to be safe, but I make sure to count every carb I'm taking with me.

I see folks doing one bottle of drink mix (50g) and one bottle of water with 2 or 3 gels (50g/75g) wondering why they run out of steam 3 hours into intense rides. Eat more folks.

Interesting, thanks. I've learned something today.

[bleedToWin]

58 minutes ago, no calves said:

So feeding for that would be 2x bottles at 700kJ ea with a bar and a gel for instance?

You might be pushing the limits of what your gut can handle. That sounds like 150g of carbs. Untrained I wouldn't go over 60g/h.
Also, with 2000Cal worth of glycogen stores (assuming you are not starting in a depleted state) you could do this 1h46 ride on just water if you wanted to. It's about what you did yesterday and what you are doing tomorrow and if you are trying to run a caloric deficit etc...

[no calves]

7 minutes ago, bleedToWin said:

You might be pushing the limits of what your gut can handle. That sounds like 150g of carbs. Untrained I wouldn't go over 60g/h.
Also, with 2000Cal worth of glycogen stores (assuming you are not starting in a depleted state) you could do this 1h46 ride on just water if you wanted to. It's about what you did yesterday and what you are doing tomorrow and if you are trying to run a caloric deficit etc...

Training rides just got a whole lot more expensive!!!

 

im on the heavy side (108kg) so very much traying for the calorie deficit but its a fine line then between calorie deficit and bonking. Most weekday rides are on the IDT after a day on the farm. 

[bleedToWin]

Eat a carby snack before you ride, and eat fresh fruit when you're done. You shouldn't need much more than water on the bike unless you go over 3 hours. For those I would experiment to figure out where that line is, but likely 500-700 kJ / h should be good.

[DieselnDust]

1000Calories = 1Kcal = 4,2KJ