Should we increase our calorie intake as FTP/VDOT increase?

mancona

In reading a thread over at slowtwitch it just dawned on me that I had my nutrition very dialed in 3-4 years ago, but since then it seems to be slowly getting worse as I get faster.  For example, in 2007 I did a 12 hour ironman with zero nutrition or bonking issues on 225 calories per hour on the bike.

The tread made me realize that time my FTP was 209, but now my FTP is 290 and I'm still using the same nutrition plan before because it worked before.  However over the last two years I've struggled in some longer races.

Therefore I'm thinking now that I'm putting out more power (i.e. using more kJ of energy) I should also start to try to take more calories in on the bike.  Make sense?

I have a feeling the same is true on the run as well, but that one I think is a little harder because of ability to digest while running and we don't have power meters to tell use how many kJ we used up during the run.

Any thoughts on if this is true and ways to use the kJ from our power meters to get our nurtition right?

Steven Ford

At first glance to me that makes sense, a high performace vehicle uses more gas than a compact car. Have you tried dialing up the calories a bit to see how you feel?

Shaughn Simmons

Matt, can u process more calories/hour pushing those higher intensities? Maybe your HR is the same however and you are just pushing higher watts? Good opportunity to experiment during training.................

HayesSanborn

This is an issue, I have book marked to study. This was my starting point:

http://sweatscience.com/how-many-carbs-can-a-super-carb-absorber-absorb-during-a-triathlon/

We're dealing with digestion and ingestion, from my limited understanding. If you find other good sources of information let me know!

Good topic to discuss. I'm always followed the calories per body weight and its worked well for me.

 

 

 

mancona

Posted By Hayes Sanborn on 04 Mar 2011 09:53 AM

Good topic to discuss. I'm always followed the calories per body weight and its worked well for me.

 

 

 

@Hayes.  Thanks for the link, I'll check it out this weekend and do some more research.  The calories per body weight worked great for me 3 years ago when I was putting out less significantly less power (i.e. buring less calories).  Of course I weighted 20lbs more then. 

@Shaughn.  Correct, because my fitness has increased my heart rate is the same or lower at higher watts or faster pace.  In otherwords, 3 years ago my IM bike watts were 145 and now I target 205, but my heart rate is the same or lower at 205 watts and I have no problem taking in the same amount of calories at 205 watts, my question is should I now be taking in more at 205 because I'm burning much more.  I'll definitely try it in training before racing and report back.

mgraffeo

Matt, within a small error, the kJ reported by the PT is pretty accurate. So, if you are going from putting out 145 watts to 205, you should definitely expect to be accumulating a higher caloric deficit. How much you can replenish is a different story, but I think your hypothesis absolutely has merit.

BTW, I had no idea how far you had come on the bike. Continues to give me hope!

Dave Campbell

I suppose one could argue that to get a set mass around a course would require the same work(kj) whether you go @ 205 watts or at 145 watts. The difference would be the amount of time it takes. I'm sure your on the bike course a shorter time now. Would be interesting to compare kj from past and present races on same course and see if the kj difference relates to the watts difference. Also not so sure how direct a relationship it is to compare Hr's for these watts differences. I would think muscles working at 205 watts would require more blood volume than 145 watts muscles, therefore if the Hr is the same, its because the stroke volume has increased as the hearts pumping capacity/stroke, has increased proportionately to the increased FTP. Not sure I'd assume that the same amount of blood is therefore available for the stomach to do its digestion work. Also not sure that just because your Hr hasn't changed that the % fat/glycogen being burned hasn't changed. Could be during the past races, you were burning more fat and had more to burn than now. You ask a great question Matt and I'm very interested in the answer, as I will be facing this same question this summer as I prep for LP. Did 1 IM in 2004 with avg watts of 155. Will probably be targeting 185 this year. In between, I've raced 14 1/2's and had to totally re-do the nutrition plan on those.

kurshing

Your hypothesis is true I would think...however, there are two other factors two consider:

1. You are probably processing each calorie a little more efficiently...so that would absorb a little of the extra required nutrition.
2. If you are only on the course 9:30 now vs. 12:00 then, you can probably operate more off of reserves and 'survive' the race instead of having to eat for the duration. Hopefully that sounds as i intended. I other words, Macca probably can get away with lower kcal/HR simply because he just isn't out there as long as most people.

So, yeah, maybe you need more, but I bet it isn't too much more...maybe 275/HR. Also, as mentioned, how much you might need and how much you can actually process are entirely different matters. It could be that you simply need to expedient with different forms of nutrition for more easily usable nutrition at higher levels of energy expenditure.

Just some thoughts...

Shaughn Simmons

I tend to lean toward Stephen's line of thought.  If your HR is relatively the same while producing higher watts, I agree that you have become more efficient.  Does your body consume more calories at the same HR when producing more watts, probably not a material amount more than before.  I think caloric requirements correlate more with HR than with Kj or watts output.

Again, best advice is to practice the hell out this in training, everybody is different.

Good luck Matt!

mancona

Thanks for the tips guys. I agree that I am probably more efficent now. At least as far as training goes I have definitely notices that my body can still opporate on much less now, so I have to be more efficient now than before. For example, I used to have to take in someting if I was running over 90 minutes and not I can routinely run 2 hours and not bring anything at all with me.

I'll definitely start to try taking more calories in during training and see what happens...but racing is allways a little different for me. Good thing I have a 70.3 coming up that I'm not too worried about as I can give this a shot then as well and see what happens.

@Stephen - I totally agree with you for a Marathon or Olympic as I can fake my way through either with a gel or maybe two. HIM and up though I think it catches up with all of us. I don't doubt that it is even harder for someone that is out there for 15-17 hours.

Matt Samojeden

I agree with Mike G that the kj readings from a watt meter “during a steady ride” are a consistent proxy for calories spent during a ride. For a quick discussion on this topic take a look at the following quick read. http://www.cadencecycling.com/CMSFiles/Kilojoules.pdf

@ Matt, I agree with your theme that riding at higher watts requires a greater production of energy per unit of time and thus consumes more calories per unit time. 

Let’s look at some data (you know my love for numbers) Here is 3 example 112 mile rides for me. 

112 Miles	Avg watts	% Change	kj total	Time	hours	% Change	kj / Hr	% Change	HR Avg
Ride 1	155	base	3299	5:54:00	5.9	Base	559	Base	134
Ride 2	166	107%	3390	5:39:00	5.7	96%	600	107%	134
Ride 3	191	123%	3601	5:14:00	5.2	89%	688	123%	128

 

Note I use average watts as this is the real amount of work being done. NP watts indicated the physiological fatigue impact of the work.

Looking at ride 1 and ride 3 we see the kj per hour rate increases from 559 to 688 per hour or 23 % increase. This is a direct result of the average watts increasing 23%. We see that the time decreases 11% which is in line with the square relationship of wind resistance.

Ok so on average I am producing 688-599 = 129 more kj per hour. Assuming kj is close to Kcal consumed, yes my calorie needs are higher and if I rode all 3 rides consuming the same 250 cal per hour I would have a 5.2 hr X 129 = 670 Kcal grater deficit in the third ride.

At the end of the day it all comes down to what level of nutrition can a body absorb at a given level if work intensity. The higher the intensity level the more difficult it is for the system to process nutrition yet more is needed. @ Matt you may want to try a 275 to 300 level on some long training rides and see how the system deals with the added calories. I am good with those levels but we are all different.

Matt

Shaughn Simmons

Matt S.  could you add avg HR to your data set?  I would also agree that if HR is higher more calories are required, but what happens if HR is the same due to fitness gains reflecting greater efficiencies?  If HR is the same is your body working harder requiring more calories though watts are higher?

Matt Samojeden

Posted By Shaughn Simmons on 04 Mar 2011 07:55 PM

Matt S.  could you add avg HR to your data set?  I would also agree that if HR is higher more calories are required, but what happens if HR is the same due to fitness gains reflecting greater efficiencies?  If HR is the same is your body working harder requiring more calories though watts are higher?

 

Shaughn,

I added my avg HR for the 3 rides. 

My view is that HR is an indication of relative fitness and the impact many factors including climate -- HEAT. From everything I have seen HR does not correlate well to calories expended. A simple example is if I get all amped up on caffeine and my resting HR can be 30% higher sitting still in my chair. Yes when keeping many things constant: climactic conditions / fitness / levels of fatigue / sleep / nutrition …. then yes a higher HR indicates greater work load and higher calories consumed.

Shaughn Simmons

Matt S., thanks for adding the information and commenting.  By the way, look at that improvement on Ride 3 with a 5:14 and 128 avg HR for 112 miles.  Looks great!

While I am most likely the least experienced on this thread, it feels like the higher my HR the more calories I burn over time because my body is simply working harder.  Sometimes it is working harder due to the elements or more work or both.

I am sure, overtime, things will work themselves through however.......

mancona

@Matt S - As usual, thanks for sharing the data Matt! Very helpful.

I will definitely give uping my calories a shot and see what happens. I've never tried more than 250 per hour and infact many times I have been closer to 200-225 based on left over in my bottle.

Matt Samojeden

Shaughn, you comment that “it feels like the higher my HR the more calories I burn over time because my body is simply working harder”.

My thoughts, HR is a function of many factors, with 2 of the most significant in endurance activities being supplying oxygen to the muscles and pumping blood to the skin to cool the body to eliminate the heat the muscles are producing. Remember we at best are only 25% efficient, the rest of the energy we produce is heat which must be eliminated from the body by blood getting the heat to the skin. At exertion levels on my rides O2 was not a significant factor, heat was.

Data may not always tell the full story. My ride number 2 was actually with slightly better fitness than the fast ride number 3. The big difference was ride 2 was 105 heat index and ride 3 was ~85.

Shaughn Simmons

Great thread and great thoughts everyone!  Let me know how those extra calories pan out for you guys during those training runs.  I am sure I can learn a great deal as we journey through this together.

 

Brenda Ross

Great thread. Learning alot here.

penlynwilson

Just wanted to add . . . We can look at watts, Kj, speed, HR, etc. However, what really matters, IMHO, is the adaptations that take place at the cellular level in the body. It is those adaptations that impact how many calories our body needs, can absorb, etc. You need to play with it and see how you feel, adjust, tinker, etc until you have your ideal fueling. Just my $0.02.

gsadleriii

I'm wondering if Matt A's recent struggles at faster paces has more to do with body comp than work/hr. He mentioned that he was 20lbs lighter now. I would expect that his body has less body fat as well as less muscle mass in which to store muscle glycogen. It may be that he has less total glycogen in his body now than he did 3 years ago. I know you can train your body to be more efficient at both storing muscle glycogen and at optimizing the mix of fats/glycogen it uses during aerobic exercise. This would compensate for any reduced ability to store them. Maybe in Matt's case, compensation hasn't been enough. Perhaps trying to carbo load before a race might help, especially if he's hit his limit on how much fuel he can take in per hour?

William Jenks

Matt S's examples are inarguable on the base physics here...you have a non-linear function (power >1) of power requirement over a fixed distance, so it's going to require more kJ to get there faster... but does anyone know about physiological efficiency as a function of fitness level? (Mike G?)

For example, we make the round approximation that kJ expended is roughly equivalent to the kCal physiologically consumed because the efficiency is between 20 and 25%. Being a "better cyclist" undoubtedly has at least a small efficiency increase due to technique, but what about the part due to the muscular work. Is anything known about this? e.g., do you go from (say) 20% to 24% efficiency in turning metabolic energy into muscular energy? Or is that response flat or backwards?

Coach Patrick

Great points all. I think Matt's changes are so drastic that he needs to consider this...few have jumped like that ever. But that said, you should always be tweaking your nutrition to see what makes you feel better in your workouts and race simulations. Thanks for digging in on this.