I’ll be racing this one hard. I figure about 400 calories for the swim, about 2100 calories for the bike, and about 1700 cals for the run, for about 4200 calories total. Figure about 75% of that is from CHO (first assumption), for a burn of about 3100 calories. Figure about 1500 calories from storage (I never seem to have that “full tank”), plus about 700 in the pipeline from pre-race fuel, for about 2200 calories. That leaves me with about 1000 calories to be taken in during the race. If I can do ~400 cal/hour on the bike, should I not worry about many calories on the run?
Ken … seems pretty reasonable but i wouldn’t go with a blank sheet on the run. Not sure what you prefer for fuel but a mouthful of calories every (or every other) aid station will keep the fire burning. If you are a gel type person you could do one at :15 - :45 - 1:15 & ??? … not sure how long you expect to be cycling/running. Personally i’d take 3-4 gels in flask, thinned with water, then chased w/ water from the aid stations OR maybe coke if the aid stations have it. Depends on the race and/or my stomach.
If you are well fueled getting off the bike you should not need alot on the run. Stick to what has been working on your training rides. If you have not done so, do a ride that mimicks your race (maybe do the 2nd half of it at perceived race effort) and practice the nutrition content and timing as well. Simply try to simulate the ride and maybe include a short 30min run after to see how it all plays out.
Best wishes!
I have my best races for half-IM on minimal calories (on fumes as they say). Racing a lot faster than IM means more lactic acid, and more possibility of stomach upset.
That means… all liquid (gel or sports drink). I go 200-300cals/hr on the bike, then try to get some sugar every couple miles on the run… just enough to keep my blood sugar from dropping.
I my best HIM, finishing off the majority of my cals about 3/4 of the way through the bike. I sucked down amost 3 flasks of hammergel ( I weigh 200lbs) on the bike and then only took in some fluid and a gel or two on the run. I had tried more of an even distribution before but ended up carrying gels to the finish line when I didn’t have the stomach for them on the run.
How do you figure 400Cal for swim, 2100Cal for bike and 1700Cal for run. Just curious.
Also when you say 75% comes from CHO. 1500Cal from storage.I assume you refer to glycogen stores, as everybody has much more energy than 1500Cal stored when we take lipids into consideration. You do store CHO in muscle and liver. And you can be smart about pre race meals and workouts to maximize glycogen storage.
I really don’t have time right now. The reason I replied was simply to say that you assume way too much.
How do you figure 400Cal for swim, 2100Cal for bike and 1700Cal for run. Just curious.
Also when you say 75% comes from CHO. 1500Cal from storage.I assume you refer to glycogen stores, as everybody has much more energy than 1500Cal stored when we take lipids into consideration. You do store CHO in muscle and liver. And you can be smart about pre race meals and workouts to maximize glycogen storage.
I really don’t have time right now. The reason I replied was simply to say that you assume way too much.
The 400 for the swim is a guess; 30 minutes of swimming has gotta burn less than 30 minutes of biking or running, right?
I did a TT workout on Wednesday, and my PT energy readout indicated, at that power level (which is about the power level I want to race at), I would use about 2100Kj, which means pretty much 2100 calories. Could be a bit less.
According to the treadmills I run on, a person who weighs about 78kg burns about 135 calories/mile. For 13 miles, that’s about 1700 calories.
Yes, the 1500 figure comes from glycogen stores. I gather that the max is about 2000, so I’ll conservatively assume I have less than that at the line.
Ken,
Nice post - one of the things I’ve been interested in. I weigh a bit less at about 68 kg but I figured:
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30 min swim = 300 cals. Wetsuit - not too hard a pace…
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Bike based on PT also - 2000 cals for a bout a 2:45.
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Run I use 100/mile as that what I’ve heard. I’ve also heard that elites can go as low as 50/mile though those are 120 pound/effecient runners. You and me? I don’t have a good range here but if I’m running about a 1:40 I bet I do burn about 1300 calories though thats a flat out guess.
So for me thats about 3600 calories. The big question is what percent carbs/fat are we burning? I have no idea. Even at LT pace we are burning some fat I beleive so at half IM pace I’d guess at least 25-40% fat? Thats a really really flat out guess. If its 75 carbs/25 fat - then our stores will give us 1500 +500 = 2000 cals if we go with the conservative 1500 calorie glycogen. If its more like 60/40 then we have about 2500 cals…
Then there’s breakfast.
Then there’s what you eat on the bike/run…
Too many guesses to calculate it out in my opinion. If one of our assumptions is off by a bit - we’ll blow…
So what I do is copy everyone else - aim for 300 cals/hour over the race - more on the bike/less on the run. If I get bloated, vomit…- then maybe too much. If I bonk - maybe I need more. Practice and see what works. I figure as long as you do not have GI issues overeating a bit can’t hurt - can it?
My plan:
Breakie 3 hours prior. With coke.
gel/water 15 mins out.
Bike - I go for about 1000 calories or a bit under 400/hour
Run - spread 3-4 gels out depedning on how my heart rate is, my stomach is, my pace is…= another 300-400.
So I eat about 1500 cals if you count my pre-race gel at T-15 min. I race in about 5 hours = 300 cals/hour. I could likely get by with less but if it aint broken - don’t fix it.
Dave
I did a TT workout on Wednesday, and my PT energy readout indicated, at that power level (which is about the power level I want to race at), I would use about 2100Kj, which means pretty much 2100 calories. Could be a bit less.
Whoa Whoa Whoa. What do you mean that 2100 kJ is the same as 2100 food calories (k-cal)? 1 calorie is about 4.19 joules. Perhaps you should change the settings on the PT from joules to calories.
-Colin
Ken,
If you haven’t already checked it out, Slowman wrote a great article a couple of years ago about the ‘mathmatics of race fueling.’
http://www.slowtwitch.com/mainheadings/coachcorn/racefuel.html
I still base my nutrition plan for Half IMs and IMs off of what I learned from that article. Generally speaking, 300 cal/hr and a couple of electrolyte tabs/hr does the trick for me. Pre race: I try to eat a good breakfast a couple of hours before the race with lots of good calories (bagel w/PB, yogurt, banana, etc). Swim: I’ll eat one gel within a half hour of my swim wave start to top off the tank. Bike: Then I’ll take down ~ 1000 cals of Carbo Pro mixed in diluted gatorade (to keep in from being too sweet) while on the bike. Run: A gel flask with 2-3 gels diluted w/ water gets me through the run and sometimes I don’t need all of it (if it’s a good day)
I did a TT workout on Wednesday, and my PT energy readout indicated, at that power level (which is about the power level I want to race at), I would use about 2100Kj, which means pretty much 2100 calories. Could be a bit less.
Whoa Whoa Whoa. What do you mean that 2100 kJ is the same as 2100 food calories (k-cal)? 1 calorie is about 4.19 joules. Perhaps you should change the settings on the PT from joules to calories.
-Colin
True. It is also true that bicycle riding is about 25% efficient, so one actually burns about 4 calories for each joule transmitted to the road. Convenient, yes? (Note that I didn’t say 2100kJ is the same as 2100kCal: I said that using 2100kJ on a bike means I burned about 2100kCal: (2100kJ/4.19kJ *kCal-1) / .25 ~= 2100kCal)
The April 14, 2005 Outside magazine (online?) has a Q&A with Chris Carmichael in which he compares the calories burned in swimming, biking and running. For a 170 lb male, it appears you burn about 20-25 kcals per minute when swimming at a 1:15/hundred pace, biking at 20mph, or running at a 7:00/mile pace. The article suggests that more calories are burned when swimming (due to use of more muscle groups) than when biking or running.
Hmm, interesting. I had never heard about those calculations with bicycle efficiency.
-C
Hickory -
20-25 cals/min = 1200-1500 calories per hour. That seems like an aweful lot. Anyone know how many calories its possible to burn in an hour? Anyone with a power meter or calculation for calories for a 1 hour 40K TT? Elite runners can run 13.1 in a bit over an hour and I bet they’re burning less than 100 cls/hour - but again I’m just making stuff up.
Swimming - I highly doubt it burns more calories than running or swimming. You might use more muscles but they are tiny muscles compared to running or biking. Who kicks in a wetsuit?
I really think running burns more than cycling which is more than biking - but some of it may depend on individual differences. I know I burn more running 7’s than biking 20 or swimming 1:15’s… An elite swimmer may be able to burn more swimming than running…
Anyway - does anyone know how they measure this stuff? I assume you could measure O2/CO2 and calculate calories and % carbs/fat but I haven’t looked for the info…where’s AC when you need him?
Dave
and what about effficiency and the individuals muscle fiber composition? those are variables that shouldn’t be ignored. Yes, it is very complex but that the reason I said that there is too much guess-work involved.
I suggest you practice your nutrition in training. This gives you a very good idea on how many Calories an hour your stomach can handle. The digestive absorption rate of CHO is limited as well. Nutrition, especially race nutrition is a very individual.
In an endurance race it comes down to who can sustain the fastest pace over the entire course. That simple, the one with the fastest pace is the one crossing the finish line first. Variables that influence the pace you can sustain include:
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technique/aerodynamics
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Carbohydrate availability
Your body can oxidize lipids and carbohydrates. Although lipids have more calories per weight unit, the rate differs. You can sustain a higher power when CHO are the source of energy production compared to lipids. Ask anybody that bonked in a race and they can tell you.
Now, the question is what can you do to prevent bonking. Consume CHO during the race to spare some muscle/liver glycogen. But that is limited to ~300-400Cal per hour. The key to endurance racing success is having the ability to oxidize lipids. The greater of a percentage of lipids you oxidize during races, the more you spare the valuable glycogen stores. What can you do to spare those valuable glycogen stores? Your muscle composition influences substrate utilization. Genetics is definitely one variable that influences muscle composition, training the other. Muscle tissue is very plastic and can adopt.
(gotta go on my ride soon, already starts sprinkling :(…)
Increase in mitochondial & capillary density, oxidative enzymes, % of slowtwitch fibers, etc. all influence substrate oxidation.
does training change those variables. Yes, scientifically proven.
This will be my last post to this thread as I am trying to spend less time on slowtitch (btw. how much does slowtwitch cost the US economy??)
Training can change some or all of the above mentioned physiological variables. This will help you oxidize more lipids during a race and spare the glycogen stores. All I wanted to initially say was that when it comes down to race nutrition you cannot do the guesswork. You have to go out there and see for yourself what your body can handle and what it needs.
Here’s the link to the article: http://outside.away.com/outside/bodywork/carmichael-20050414.html
I’ve never found the nutrition element to be too critical in a half-IM: gu or gatoraid every 20 minutes on the bike is generally sufficient, assuming you’re starting with a full tank.