Calorie intake during endurance rides

[mikedkelly]

Between getting into better shape, losing 40 lbs, and changing from an HRM to a power meter, the calorie burn rate reported by my Garmin has gone from 600 Cal./hr. to around 350 Cal./hr. I'm trying to figure out how much of that to eat back during endurance rides of 4-6 hrs. I know that if I keep my HR down around 60-70% max, a good portion of those calories will come from fat. But it seems that the calories reported from power are net (effort) calories and may not include RMR calories, so from a nutrition perspective, it may be under-reporting my "calories remaining before bonking." Is there some method I should use to determine how much to eat, or should I just try to max out fueling at 250 Cal/hr like I do when I am climbing?

[kulivontot]

Eat before long rides, eat during long rides, but don't go overboard when you finish. We tend to overestimate the actual number of calories burned and gorge ourselves. I think if my goal was weight loss I would never want to deprive myself of calories on an endurance ride as you will hit fatigue earlier and end up shortening your ride, which in turn will burn fewer calories.
Listened to this podcast earlier today, a lot of good info.
http://www.velonews.com/2017/03/podcast ... gan_433470
I wouldn't stress so much about the exact calorie equation, almost all measures of expended and consumed calories can be off as much as 20%, as well as your RMR, so at the end of the day your net calorie calculations are going to be all messed up. That said, using an app like myFitnessPal to count consumed calories can be very helpful to determine where your calories are coming from and making yourself accountable for snacks and drinks.

[mikedkelly]

Great advice, thanks. I enjoyed the podcast.

[KWalker]

Hunger, Energy, Cravings. Read the book The Endurance Diet by Matt Fitzgerald.

Caloric burn is not straight forward. Temperature, current metabolic rate, EPOC, intensity distribution, and efficiency can change from one ride to the next. My advice after trying everything is to eat within normal recommendations. I have found that, no matter what, fueling on rides drastically lowers my hunger after.

[boots2000]

How much do you currently weigh and what is your average riding speed?
A rider of around 68 kg/150 lb. burns 700-800 calories per hour at 18 mph/29 kph.

Garmin calorie calculation is not at all accurate.

[KWalker]

Even then, how you burn those calories can greatly influence the kj effect.

For example, 1hr at zone 2 might burn about the same as 1hr where you are at zone 1, but include high intensity intervals of any sort.

[mikedkelly]

I weigh 72kg/160lbs and keep my heart rate between 65% and 80% max when I am on endurance rides. When my Garmin is paired with a power meter, it reports kj and calories from power, which does not take into account any rmr calories, which I think it is doing when you are just wearing a heart rate monitor. That is ideal when you are training and just want to see how much effort you are putting in for a given ride, but when I am doing a century, it is more important to know what my energy reserves are. I am thinking about getting an Edge 820 and just building some custom fields that calculate fat cals and carb cals based on my VO2Max/Fatmax test.

[alastairb]

Kilojoules * 95% = calories burnt.

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[kulivontot]

Partially right, but you're over generalizing

Technically the amount of work done is 0.239 kcal / kj. But the body is not perfectly efficient, so the actual metabolic work done is somewhere between 4-6x that. But this range is hugely variable from person to person and heavily dependent on the type of effort. So yes, you can use 0.95 x kj as a guideline, but if you're trying to calorie balance intake vs output to the nearest calorie, the sum of all estimation errors at the end of the day is going to be significant. So to reiterate, it's not an exact science, use some common sense.

[alastairb]

Training Peaks article reckons HE is ~80% accurate, whereas kj is ~95% accurate; could be up, could be down. Go prudent and assume 95% rather than 105%. Probably as good as it's going to get....previous poster is bang on in that we're inneffient (energy converted to heat rather than kinetic etc), so to produce 1 kj at the pedal takes ~ 4 to be burnt.

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[GothicCastle]

First, well done on the weight loss; that isn't easy.

Second, don't ditch the HRM. Tracking heart along with power gives you insight into both cardio fitness and recovery.

Regarding eating, if you are doing a cafe stop during those rides, you might not need additional fueling. If you are going for four hours straight, having a bit of food every hour or so is reasonable. It really depends on intensity (higher intensity depletes glycogen more quickly). I'm a fan of eating real food on the bike (a sandwich cut into quarters, rice cakes with something savory in them) rather than gels. If you are eating, drink water rather than a sugary hydration mix.

[BikeRider22]

Yes yoiu should avoid the last meal after ride. Make is smaller then rest of them and Try it to make it healthy, no fat, sugar, pizza, candies etc. Remeber to drink water instead of fizzy drinks. This is really important. Anyway you don't need big meals, because you will be driving and sitting on your bike so you won't losing lot of calories.

[byron505]

Between getting into better shape, losing 40 lbs, and changing from an HRM to a power meter, the calorie burn rate reported by my Garmin has gone from 600 Cal./hr. to around 350 Cal./hr. I'm trying to figure out how much of that to eat back during endurance rides of 4-6 hrs. I know that if I keep my HR down around 60-70% max, a good portion of those calories will come from fat. But it seems that the calories reported from power are net (effort) calories and may not include RMR calories, so from a nutrition perspective, it may be under-reporting my "calories remaining before bonking." Is there some method I should use to determine how much to eat, or should I just try to max out fueling at 250 Cal/hr like I do when I am climbing?

one of the convo's i remember having with a coach a few years ago was about the guidelines he set for all of his athletes (as far as on the bike fueling).

When i started, he would insist 200-300 calories every hour.
After a few years with him, I noticed that my zones increased pretty dramatically and asked 'well if im outputting more power, im burning more calories...should i be eating more?'

short answer 'nope. keep eating 200-300 calories every hour.'

his level of expertise? he's coached a few world tour guys

[KWalker]

the body has rate limits with about 400-450 being the upper limit. Those Kona nerds spend part of their training having to force this amount down so they can shit themselves better during the run.

[Marin]

There's a limit of how much you can digest.

Unfortunately, the limit is quite a bit lower than what you can burn!