Discussion: 24 hour nutrition

I've been reading about long race nutrition, and have come to the (uninformed) conclusion that the best preparation and nutrition is as follows:

Ensure a modest fat base.
Eat exactly 240 calories per hour.

The concepts I've understood are that the fat base is the best source of energy, but that it can be supplemented by energy from the bloodstream (i.e. food eaten). I have heard that there is a limit to the usable energy from food via the liver and bloodstream of 240-ish calories per hour.

Do people agree with this view?

I would also like to learn about long term nutrition requirements, and recommendations.

From 'training/preparing for a 24 hour event' point of view your goal should be teaching your body to use more fat for energy. You do this by training with HR in your lower aerobic zone (usually 120 - 135). This way your body could keep up with the energy requirements and use the most fat (percentage wise) for your energy needs.
Increasing the intensity increases the use of carbs, as it is much easier for the body to process and deliver to your muscle cells. One practical way to find out the "sweet spot" for most fat utilization is to find out at what HR level from a range of 110 - 140 your breathing rate and depth increases. The reason is that fat utilization requires much higher oxigen levels than carbs.

I don't think you need to eat anywhere near that much. Start with the assumption that you'll be burning around 500Kcal/hr. That's 12,000Kcal.

You have around 2500Kcal in glycogen stores (more if you carbo-load, but that's not really necessary).

Your body can burn around 2 pounds of fat (7000Kcal) in a day.

You can store another 500Kcal in your stomach/intestines by eating a modest meal shortly before the start.

That only leaves you short 2000Kcal. Because you're already burning fat at close to maximum rate, all that extra needs to come from protien and/or carbs. Therefore, I eat around 100Kcal of carbs per hour in a 24-hour event. My total intake is somewhat higher because I do eat things that contain fats as well (but not a lot). I've never run into problems with bonking at that level except in one event that was much colder than expected. The extra fuel required to stay warm was enough to throw off the equation. From that, I deduce that the formula is pretty close to correct for normal situations. Of course, YMMV. Test it out in training.

If you are doing races longer than 24, you need to up your intake considerably because your glycogen stores will be depleted after the first day.

i wasn't going to respond but ebuckley's advice is contrary to everything i've read or experienced. your glycogen stores are gone after about 90 minutes. to test this go for a run. don't take any food and see how long you can go before you bonk. could be 60-120 min but won't be much longert than that. at 135bpm, well below AT i burn 600 cals per hour. but i can't eat 600 cals/hr while racing, if i did and tried to race hard, i'd get sick (yes i've tried).

as a coach i suggest my clients eat from 200-300 cals/hr during races. it's individual how many you need and how many you can process while racing. you have to figure it out during your training... everyone is different.

if you try to race on 100 cals/hr as ebuckley suggests - you will not last long... even at a snails pace.

your glycogen stores are gone after about 90 minutes.

Only if you're going fast enough to do that.

At a slower (24 hour) pace, your body is getting most of its energy from fat stores. As Eric pointed out, your body will need some glucose to burn, but it doesn't all have to come from your glycogen stores, and it's not going to be used at nearly the rate it would be in a shorter race.

For what it's worth:
There was a recent thread on fueling in the Boulder Tri Club group and I am posting a quote from Neal Henderson of the Boulder Center for Sports Medicine here:
"Fortunately, for those of you still reading there is a way that you can actually establish your actual energy expenditure rate while riding and running is through testing in a physiology lab. The specific procedure is called indirect calorimetry where we measure the amount and percentages of oxygen and carbon dioxide in your breath while progressively working hard. At BCSM, we call this a FUEL test- Fuel Use Evaluation with Lactates. Basically you do a lactate profile test (for more info watch the following video from Active Cities USA), and we also measure your oxygen consumption (and carbon dioxide production). In doing this test, you receive training zones based on your lactate threshold and also recommendations on pacing for Ironman, 1/2 and Olympic distance races based on power, RPE, and heart rate. And of course, you'll also receive your energy expenditure values in terms of kcal of carbohydrate and fat at the range of intensities. Attached is an example of my data from a FUEL test (as well as VO2 max). I used this information in training for riding the 24 Hours of Moab (solo). Based on this information, I intended to average an intensity of about 175 watts (or HR of 120 - which I averaged 122 beats/min for 25 hours and 9 minutes in the race) and to intake 450-500 kcal of carbohdrate per hour (which I did). Now, there are old exercise physiology texts that say the most carbohydrate that can be taken up in 80 grams per hour (or 320 kcal), but unfortunately it's old information. New research (and about 20+ years of experience in ultra-distance physiology assessments performed in conjunction with races and training) show that athletes taking in between 450 and 550 kcal of CHO end up being able to use about 420 kcal per hour. In doing this, a blend of carbohydrate sources is ideal. Bob Seebohar has a nice article on this topic on page 15 of the Inside Triathlon June 2007 issue (yes, the sex issue with at least one BTC member profiled ; ) Another article that I've co-authored for First Endurance summarizes some of this information. This is the link for that article: http://www.firstendurance.com/newsletter_carbs.htm... So, hopefully this helps! It is important to train with exactly what you plan on using on race day to ensure that all of the kinks get worked out. Something that goes down fine in training might not work for you at race effort, or after swimming, etc. Remember, all BTC members receive discounts on physiology tests at BCSM. You can contact Avery Marzulla, Cc'd above, or give her a ring at (303) 441-2285 if you have any questions about the tests. Also, Karrie Bach is our dietitian who can also help you with fueling needs - she goes over the energy expenditure part of the FUEL tests while I explaing the lactate profile (and VO2 max portion if done) results. Happy training & racing, Neal

Neal Henderson, MS CSCS
Sport Science Manager, Boulder Center for Sports Medicine
www.bch.org/ sportsmedicine"

so how does this graph define the different exercise levels? Granted when I am doing a 1hr mtn bike race I am at my threshold most of the time and completely spent at the end. But in a 24 hr race i am at 70-75% of maximum heart rate.

If I don't eat contiuously, I bonk after a couple of hours. Maybe if a person does a 24 hr race at a walking pace they don't need to eat. But I don't think that I have ever done one that hasn't started as a gut buster.

As for eating and filling your stomach right before an event, I would highly advise against it unless you want to increase your chances of gastric distress.

Just my 2 cents

Even at relatively fast paces, you've got a lot more glycogen reserve than 90 minutes if you've trained yourself to use it. I ran negative splits at the Pensacola Marathon this year and the only thing I took in (other than water) was a single Gu packet (100 calories) at 20 miles. That's about three thousand calories burned in three hours (and 15 seconds, damn!) with no dropoff in pace. I was tired at the end, but nowhere near bonking.

I will concede that there's no way I could go on that level of intake when I was in my 20's. It seems that your body gets much better at fuel management as you get older. Many ultrarunners have noted the same thing (and that's a lot of why the best ultra guys are in their 40's).

ok maybe it's a pace thing then.

ebuckley we are talking about 24hrs of racing! you "got away with" very little fuel for a marathon. have you ever performed well on 100 calories/hour for a 24hr event? i won't believe you if you say yes. =) it's not possible, unless maybe you are at 50% your max.. but that isn't racing, and i thought we were talking about fueling for a race.

i challenge you to find me an ultrarunning or 24hr mtn bike champ/winner who eats 100 calories per hour.

the answer to the question in my opinion is somewhere in the 200-350 cal/hour range and it's up to the individual to figure you exactly where their calorie needs falls in this (as far as i'm concerned) well accepted range.

At my first 50K race (5.5 hours) I drank and ate about 300 calories per hour. Since than I have always tried to stay in that range. The sport drink I use contains 100 cal. per 8oz, so I drink it to stay hydrated and energized. I try to drink about a quart an hour, but am usually abit short. In races this is easier than in ROGAINES because of the re supply problem in ROGAINEs.
It also depends on how you want to feel. As you use fat, it is pretty uncomfortable for many people. YOu may feel pretty bad and your muscles will hurt as the supply of glucose is not idea from fat stores.
In 100 mile and 12 hour races I have been in, most competitors are eating a lot, whole sandwiches and soup , not those wimpy and bad tasting gooey packets.

I think Eric's numbers are not too far from what we have experimentally figured out for 24 hr ROGAINE's - between me and Bernard (me - 150 Lbs and Bernie ~ 160+ Lbs) we consume 18 to 20 GU each, and allowed ~ 2 hours of rest (total cumulative number), supplemented by low calorie electrolyte drink and base camp dinner ~ 800-1000 cal, I have to mention that 24 HR ROGAINE is different from 24Hr trail or road race - at night energy consumption drops due to navigation difficulties. We do feel wasted after such ROGAINE, but I want to see who does not :)

ebuckley we are talking about 24hrs of racing! you "got away with" very little fuel for a marathon. have you ever performed well on 100 calories/hour for a 24hr event? i won't believe you if you say yes. =) it's not possible, unless maybe you are at 50% your max.. but that isn't racing, and i thought we were talking about fueling for a race.


50% for 24 hours is racing pretty hard. My max is around 1200 Kcal for one hour (I run 10 miles in about 63 minutes). I don't think I could hold 600 Kcal/hour for a 24. If you think I'm dogging it, you're entitled to that, but my "relaxed" pace has resulted in a few notable finishes:

4th, USARA National Championships 2004 (elite division)
2nd, US 24-hour O (ROGIANE) Championships 2002 (open division)

And several wins in lesser 24-hour events.

I agree with Coach that the Gu packs don't cut it in the long events - solid food is the way to go. We've also found that drier is better. That is, don't carry water in your food - you can find water on the course, but you won't likely find any food. Only carry what you have to.

mcdonalds double cheeseburgers. 440 cal and 1150 mg sodium. .99$ each. 4 per 24 hour race.

I would go for Whoppers, do not get quality in McDonalds anymore, but I have to try Joe's recepie :), but not this ROGAINE

FWIW, David Frei did a considerable amount of research trying to find the lightest source of calories. His result: Cheetos. Sure, they take up a lot of room in the pack, but you don't feel volume (in another paradox, we found that some of the lightest packs were bigger than some of the really small ones, so we both have plenty of room). I find the cheesy flavor a bit of a pickup around 4AM, too.

One final clarification before I get off this thread: I'm really just talking about fuel intake that you have to carry it with you. If you have transition areas, drop points, or feed zones where you can get more to eat without carrying it, by all means do so. But if you have to carry it, don't carry more than you have to. Based on considerable experience and that of other successful Adventure Racers, I've found the lower limit of food intake to be about 100Kcal per hour (not counting the fat calories, because that just offsets what you'd burn out of your own stores). I usually take closer to 150 just to be safe.

As you use fat, it is pretty uncomfortable for many people

I believe carbohydrate metabolism is the more entropic one, with more waste products and more heat generated. I feel fine burning fat. I eat almost nothing during a typical trail 50 km if I stay slower than 6 hr pace.

FWIW, I burn about 750 kCal/hr in events longer than 12 hours (moving just a bit slower than gtrogers). I burn this much because I'm heavy (80 kg, 18% body fat). I can perform OK without eating, but with eating it is better. I think we consumed about 300 kCal/hr each at Big Muddy IV (Roschi did all the calculations).