New to the forum here, so apologies if this has already been discussed. I’ve been using TrainerRoad for just over six weeks now and I’m really enjoying it—definitely noticing some fitness gains already.
My question is around fuelling during workouts and how that affects replenishment afterwards. For example, today I did a 1.5-hour group ride outdoors. During the ride, I took in about 120 g of carbs (80 g in the first hour and 40 g in the last 30 minutes) in the form of sugar water. My head unit showed I burned 726 kJ.
From what I’ve read, 120 g of sugar is roughly 2040 kJ. So my question is: does the on-bike fuelling “count” toward replenishment, or should I still aim to replace the 726 kJ afterwards with protein and carbs (around a 3:1 ratio)?
Did you burn 726 kJ, or did you produce 726 kJ of work? Burning 726 kJ i 90 minutes roughly translates to an average power of 30 Watts. If that was what you did, 80 g carbs an hour is a bit excessive.
I think you’re likely confusing units from your computer with caloric expenditure
Putting 726 kJ of work into the bike actually burns more calories because the body is so inefficient (mostly all heat loss). Haven’t looked recently but it’s roughly the same conversion from kJ you put into your bike to calories burned
So your caloric expenditure would be 725ish - of which you fueled 480 (120g of carbs) on the bike, leaving a deficit of 250ish
Yes, and as pointed out it roughly translates to 726 kcal of work (or Cal, where writing it with a capital C means kcal as TR does).
So you can either look at your intake in kcal as suggested, meaning that you took in 480 kcal, or you have to multiply that number with 4.2, meaning that you burned about 3000 kJ.
Regardless, to answer your initial question. Yes, on bike fueling counts towards replenishment. You also have to account for your BMR during your ride so the total intake, on the bike and recovery, should be higher than what TR shows you burned during the ride.
Ha. Back to back responses with one saying it’s calories and another saying it’s kj’s of work. I’ve always found this confusing too. It would be good for someone from TR to clarify.
Can you please clarify? Are you saying that kilojoules of work and Calories burned are identical? I don’t think you are, because above I think you said you need to multiply Calories by 4.2 to get the kj? If that’s the case, then the number can only be one or the other, right?
They are considered approximately identical yes. The reason is that the conversion from kJ to Cals is multiplying by 4.2, which roughly matches with the normal efficiency of a human which is 20-25 %.
Put another way. You can go from work performed to energy expenditure by multiplying with 4.2. (regardless if you measure in kJ or Cals), but since it is common in many countries to measure work in kJ and energy expenditure in Cals you can also just switch units which also translates to multiplying by 4.2.
Correct up until the last line. You are calculating in kJ which means that dividing by 4.2 gives you Cal’s not g of carbs. Your deficit in this instance is 1033.2/17= 60.8 g of carbs.
