Fat Base Pace (FBP)

[Jeff Linger]

I'm starting a new thread on this because its a very interesting concept and I think many people will be interested in this discussion. Sasha said to me in another thread that I had not yet "developed what [he] calls fat base pace (FBP), the pace you run when your primary source of fuel is fats. With a good FBP you can take risks because if you crash you are still running respectably.  If your FBP is not good, you have to pace yourself right or you pay dearly.

I should note that Sasha indicated that he wasn't quite sure how to improve FBP except just be consistent, get your base mileage in, eat healthy, and wait. While investigating this concept I came across a couple interesting tid-bits and would like to share them. I'm including a link before the tidbit for those interested in the entire article.

1.  (http://www.runnersworld.com/article/0,7120,sss6-242-304--10586-1-1X2-3,00.html) -- "To lose one pound, you need to burn 3,500 more calories than you eat. And running burns about 100 calories per mile. Running also keeps your metabolism elevated for hours after your workout, meaning you burn more calories even while you're sitting at your desk at work or on the living room couch recovering from your run." Huh? You mean to burn 1 pound of fat I need to run 35 miles assuming that my diet is optimally established such that I'm eating ONLY the exact amount of calories I need to maintain daily functions besides running? This simply doesn't seem right. It seems to simplistic, and believe that its an inaccurate assessment of what's really going on for a runner. Additionally, when I get on a treadmill and bang out 8 miles at a pace of 7:30 or so the monitor usually says something like "1250 calories/hour" under my burn rate. So I kept looking and found this next interesting chart.

2. (http://www.trifuel.com/forums/archive/index.php/t-4436.html) -- Now, this is from some message board thread and the posting person didn't credit the source, so I don't know the accuracy of it. However, here's the post and chart. It should be noted that this chart pertains to cycling, not running, but I would assume there's a close correlation as it pertains to HR.

"It's not quite so simplistic. There's a ratio of fat-to-carb calories that's burnt. People often confuse the percentage of fat-burning with total-calories of fat burned. In general, the higher the intensity up to your LT, the higher the total calories burned from both fat and carbs. Fat-calories also goes up with intensity, just not as much as glycogen. It really depends upon your level of fitness and condition. Let's compare a beginning-rider vs. an elite athlete:"

BEGINNER RIDER
50% max-HR = 500 Cal/hr = 75/25% fat/carbs = 375 fat-calories/hour
65% max-HR = 650 Cal/hr = 60/40% fat/carbs = 390 fat-calories/hour
80% max-HR = 800 Cal/hr = 25/75% fat/carbs = 160 fat-calories/hour

ELITE FIT ATHLETE
50% max-HR = 750 Cal/hr = 80/20% fat/carbs = 600 fat-calories/hour
65% max-HR = 1000 Cal/hr = 75/25% fat/carbs = 750 fat-calories/hour
80% max-HR = 1250 Cal/hr = 65/35% fat/carbs = 813 fat-calories/hour
90% max-HR = 1400 Cal/hr = 25/75% fat/carbs = 350 fat-calories/hour

"Basically, the more fit you are, the more fat/hour you can burn at a higher pace. Your energy and cardiovascular systen becomes more efficient at converting fat to ATP for burning, without resorting to anaerobic fermentation and phospho-creatine at high-effort levels. So the more fit you become, the more total fat-calories you burn at a higher-intensity, even though the percentage is lower compared to a lower effort.

The latest studies appear to show that total-weight loss is more related to total-calories burnt in the workout regardless of whether it's fat or carbs. If you burn off 3000 calories in a workout and eat only 2500 calories a day, you'll lose about 1-lb fat/week regardless of the intensity. You can ride easy for 6-hours a day or ride really hard for 2-hours. The weight-loss will end up being the same. What happens is that after the ride, your body will convert fats into glycogen to replenish your energy stores. So it doesn't matter if you burned up that fat during the ride, or if it's converted later to be used on the next ride, it's still gonna be used up at one point or another to make up the calorie deficit."

If we consider this chart to be accurate, it appears that the best way to burn fat is to work around the 80% of max HR. However, most consistant runners know that its not simply a question of running at a particular HR, but for how long we run there as well. I assume that its fairly accurate to say that when we burn fat we're also working on our FBP. The problem is that we can never really truly work on simply 1 energy system at a time. We're always burning both carbs (sugars) and fats. But different paces will burn a higher percentage of one over the other. Most people store about 1500-2000 calories of glycogen in their muscles as fuel. Generally speaking, most people burn about 100 calories of sugar/mile. So to come close to depleting these storages we need to run 15-20 miles, at which point our bodies switch over to fat. Again this is somewhat simplistic as we're never really burning just sugars or just fats. But theoretically the concept would seem to hold true, deplete the glycogen, keep going, burn fat, teach your body to become more efficient at burning fat. Well, this means a whole lot of running! Probably more running than most non-elites have time for. And it would take years to get to this point.... thus Sasha's comment to "be consistent, get your base mileage in, eat healthy, and wait".

I wonder if there is another way? Note, I'm not suggesting skipping the Long Slow Run. But I'm wondering if there's a modification to the Long Slow Run to get past the sugar burn faster and get into the fat burn sooner, such that for those of us who don't consistently bang out 20+ milers each week can get in more miles in the highly fat burning stage (after 15-20 miles). It should also be noted that the more fit we get the more miles we probably need to run to get into the glycogen deplete state.

A couple things on this. First, its a bad idea to continuously deplete your glycogen stores. Glycogen is needed to maintain neural balances. Deplete them often and over time you'll weaken your nervous system and make yourself susceptible to injury and illness. Second, glycogen replenishment usually occurs within 22-24 hours of a workout and is sped up through carbohydrate intake, especially when done within 2 hours of a workout.

Ah-hah! Here we go. We come full circle to a post I submitted 6 months ago about not taking a day of rest after the long run! If we proceed normally with our glycogen replenishment we've still got about 22 hours where we can do a run in a relatively highly glycogen deplete state. The perfect time for a 'short slow run'. I haven't done any investigating, but I'm suspecting that running the day after a long run, prior to 22 hours, at a slower pace will improve our FBP? I'm also wondering what happens if we were to warm up, run hard, and then enter a prolonged cool-down. I believe that when we go out hard our brain sends messages much like, "uh-oh we need a lot of energy fast ... empty out the glycogen stores" (one reason you shouldn't start a marathon out fast, you'll cycle through more glycogen than your body needs immediately and drain it for what it needs later). But shouldn't this hold true if we're training our FBP? Drain it and get into fat burning?

Sorry about the long post here. And I'm not suggesting a tricking mechnamism that skips the tried and true workout programs. I'm just wondering if we can increase our FBP more efficiently if we were to tweak our long runs here and there away from the singular LSD workout, as well as follow such workouts up with an easy run within 22 hours. I'll now allow the experts on such matters to step up to the plate.

[David S]

   I have read that one way to get your body better at this is to run long runs without any supplementary fuel sources, such as GU's or carb drinks.  The best description that I have read about this is on McMillian's site.  Full article:  http://www.mcmillanrunning.com/marathonlongrun.htm

Main points highlighted here:

Long, Steady Distance

The key aims of the long, steady distance long run are to increase your ability to burn fat, store more glycogen and to challenge the body and mind to continue running even when fatigued. From physiology, we know that the body uses fats and carbohydrates while running - the portion of each is determined by the pace. Run fast and the reliance shifts to more carbohydrates, less fats. Run slowly and the muscles rely more on fat and less on carbohydrate. Therefore, it is very important that in this type of long run - the long, steady long run, you don't run fast. You'll rely more on fats at an easy pace, possibly improving your ability to burn fat. When I say steady or easy or even slowly, I mean a conversational pace. Use my calculator and stay in the "long run" training pace range.

Another aspect of the long, slow run is duration. While running slowly increases fat burning for fuel, another way to really increase fat burning is to run when the carbohydrate stores are lowered. When the carbohydrate stores (muscle glycogen) are lowered, fat burning really goes up since there is little carbohydrate available. We know that the carbohydrate stores are lowered after 90 to 120 minutes of running so you want to do 30-60 minutes of running "after" this to maximize fat burning and to help stimulate the body to store more muscle glycogen for future runs (and races). When running (and racing) for this long, the blood glucose level also lowers. Ingesting carbohydrates (either through a sports drink or energy gels) before and during the run, maintains your blood glucose level. However, as you see below, we may also want to challenge the body to run with a lowered blood glucose level and to adapt to be better at handling a lowered blood glucose level. Therefore, the long, steady runs must last at least two hours and the longer the better and you may want to try to slowly reduce your carbohydrate ingestion before and during this type of long run. Except for a few exceptions, you should try to gradually increase your long run above two hours and I find that long, steady runs of two and a half to three and a half hours are ideal for most competitive marathoners.
Running for this long also helps us accomplish two of the other goals for this type of long run. First, with these runs your legs will get very tired but will become stronger and better able to tolerate running for such long periods. Second, you will experience fatigue and have to be mentally strong to simply keep going, knowing that you are going to continue to feel tired. However, it's important to remember that feeling tired is what training is about. You receive many benefits in marathon training only after you're tired. So the goal is to run beyond to the point of being tired so that the body is stimulated to grow stronger and more resistance to tiredness.

Finally, (and this is optional) a great way to ensure that you will deplete your carbohydrate stores on these long, steady runs is to not eat any carbohydrates immediately before or during the run. Any carbohydrates ingested will be used by the body for fuel, and we don't want this. We want to deny the body carbohydrates in these runs so that the muscles will become better at sparing the carbohydrate stores, more efficient at burning fat and used to running with lowered blood glucose levels. Now, many people think I'm crazy when I say this, but it works. It takes time to get adjusted to it if you have always been carbing up before and during your long runs, but with time and practice you can do it. I will note, however, that it is important to drink water and electrolytes throughout these runs so that you don't get dehydrated. I also recommend carrying an energy gel with you just in case you run into trouble (like taking a wrong turn, having to run longer than expected and getting a little woozy).

[David S]

One more thing - consider this statement "Most people store about 1500-2000 calories of glycogen in their muscles as fuel."
Now, if we eat our last meal at 6pm the night before a long run, and do not eat anything else before or during the run, we must consider the calories spent during the 12 hours (if one begins the long run at 6am) between the last meal and long run.  Let's say one is mildly active unitl 10pm - so (100 calories * 4 hours) + (8 hours * sleeping (60 calories an hour)) = 400 + 480 = 880.  That leaves 920 calories to burn during the long run (880 - 2000) before reaching a depleted state.  This is very simplistic but it does illustrate that one must consider the calories expended in the hours before a run.

[adam]

Remember that your body is working off of fuel from a number of different sources (carbohydrate, protein, fats) and systems, and that ALL of these are in play at the same time on a consistent basis, though the proportions are all different.

The trick is making that source and system your predominate fuel source during exercise (ie, 100m repeats taxing ATP-Pcr system, 15 mile runs taxing fat sources).

[Dallen]

A couple things were brought up. The easy one first. It doesn't matter if you burn fat or carbs, the weight loss is the same, assuming an equal calorie loss. Our bodies are pretty smart and will redistribute things as needed.

As for improving the speed at which we can run off of only burning fat, that is more difficult. For most of us the real question is how do we best survive in the last few miles of the marathon when we should theoretically run out of glycogen stores. If there was a good answer you wouldn't be asking the questions. I think that the best way to teach our bodies to burn fat is to force them to burn fat.  Long runs. Lots of good long runs. I agree with David that taking in carbs during the long run is somewhat counterproductive. I also personally dislike the traditional LSD, long slow distance. This might teach us to be on our feet for a long time, but it doesn't teach us how to run out of carbs. I prefer to go harder on the long runs (therefor burning more carbs) so that by the end of the run the body is in a similar state to how it will feel in the latter stages of a race.

[adam]

Another way to run off of decreased carbs- run long and early in the morning before breakfast while your body has been in a fasting state for 8-12 hours.

[Fredrick Teichert]

Let me play devil's advocate: If I start a marathon with 2000 calories in my tank, I should be able to run 20 miles before I bonk. I only need an additional 610 calories before I collapse at the finish. That's 1 1/2 quarts of Gatorade, or a couple of Gu's and maybe a banana. I can get them all along the way, so what's the big deal? Besides, my body is converting fat to sugar during the entire race, so in reality, I may never run out of fuel. That goes for my LSR's, too. If my body is supplementing glycogen stores through fat conversion, I might be able to run well past 2 hours before I'm running only on fat. So, in an aided race does FBP really matter? (I'm sure it does. I just want to understand the basis a little better... and forgive me in advance if this sounds rude.)

[Jeff Linger]

Let me play devil's advocate to your devil's advocate: What if you only start a race with 1600 calories in the tank (A well-conditioned [athlete -- he 's actually talking about cycling, but its basically the same] can store roughly 400 - 500 grams [1,600 to 2,000 calories] of glycogen. His or her endurance is limited by this store of fuel as well as the supply of the specific enzymes necessary to metabolize glycogen aerobically. The supply of enzymes can be increased through aerobic training and, of course, the store of glycogen can be replenished by consuming carbohydrates while [performing])  -- John Hughes. That's leaves you at about mile 16 and needing to come up with an additional 1010 calories.

1. Where and when will you come up with this extra 1000+ calories? At some point, usually in the later stages, your digestive system isn't working optimally (http://www.cobr.co.uk/e-cobr_information/t_and_r_section/sections/nutrition/Effects%20of%20exercise%20on%20the%20digestive%20tract.shtml). I'm sure that many of us have experienced this effect in the very late stages of a marathon where we're passing up the last couple aid stations as we simply can't put anything else in the tank. But at the same time, if we overload those 1000+ calories early on we also develop GI issues.

2. The better we've trained our aerobic system (FBP) the more we've increased the supply of enzymes necessary to metabolize the glycogen.

3.  Even if we assume that we've trained optimally in terms of our glycogen storage and usage, a marathon will burn both fat and glycogen simultaneously. The problem, especially the more inexperienced at this we are, is that we may struggle with an accurate riding of the AT line. In earlier stages of the race dipping just below the AT line doesn't feel all that bad. In fact, we may not even recognize that we've dipped into the anaerobic zone. But if we have and continue to maintain this pace then we're going to have to eventually switch over to our fat-burning mechanisms. "A byproduct of burning glycogen without oxygen is lactic acid or lactate. The production of lactate is what causes a burning sensation and the level of lactate is an indication if not a cause of the onset of fatigue.(http://homepage.mac.com/hopbailey/Swimming/Articles/Energy_and_fuel.html) The faster our FBP, the faster we'll be able to run when we do make the switch over, or back, as it were.


Theoretically speaking, if you've got enough glycogen to burn efficiently through 26.2 miles and you don't cross the line too terribly much into anaerobic energy systems, you should be fine. The goal of training is simple. Improve the pace before which your fat-burning mechanisms shut down and improve the pace before which lactate begins to build up in the muscles. That's it.

[dave rockness]

Jeff, first of all, nice job in Boston.  Here's my 2 cents.  Having bonked terribly in my first marathon, I took to heart Sasha's formula advertised on this blog.  Get yourself to the point where you are consistently averaging 10 miles per day then start using tempos/speedwork/etc.  Having observed hundreds of blogs on this site as well as other sites, I have noticed those who consistently average over 70mpw of training rarely hit a wall.  And for those who do hit "the wall", they seem to maintain a fairly descent pace (6 min/pace becomes 6:45 or 7 becomes 7:45).  I've also heard a formula (I can't confirm exactly where) that suggests multiplying your average daily mileage by 3 to predict where you may "bonk" in a marathon run.  For example, if you average 8 miles per day, expect to struggle after mile 24.  On my first marathon, I averaged 50 mile weeks for 4-5 months and bonked right about mile 21 (finished in over 4 hours).  Second marathon, gradually worked my way to averaging 70mpw for 2-3 months and finished with a ton of energy left in the tank (pr'd by 62 minutes).  In Boston, my legs went dead around mile 10 (had been averaging about 6:45) and was still able to hold under 8min pace way past the "bonk zone", including the entire set of hills and final stretch (I couldn't walk more than 20 steps at the finish and they carted me to the medical tent).  I attribute running over half a marathon on dead legs at under 7:45 pace to having a stronger base and averaging at least 10 miles per day since January 1st. 

You ran an incredible race (congrats on the pr), yet if you had been averaging 10 miles per day, my prediction is that you would have at least kept a 7:45 pace towards the end.  Your pr is better than mine, so please know I suggest this with modest experience and humility. 

[Jeff Linger]

Dave, some interesting stuff about the average miles/day x's 3. Of course I take everything you said in the most positive light. We're all here to help each other. A couple things. I assume you mean average miles per day over the entire year, not average miles/day divided by 6, if we're running 6 days a week. Counting from my last marathon to this marathon, excluding the 2 months afterwards that I was dealing with an injury due to overtraining.... From July 1 through the end of March (April was a taper month and not exactly an indication of normal training ... and excluding 2 weeks in November/December that I used as a rest cycle between training cycles) I averaged 7.1 miles for that time span, or 8.6 if we're dividing by 6 days per week. Interestingly, 7.1 xs 3 is about where I 'bonked'. The only problem is that it wasn't really a bonk. I've bonked in runs before. This wasn't a bonk. I got to the bottom of heartbreak hill and it was as if someone had taken sledgehammers to my quads and calves. This is not a bonk. I had not run out of energy. Sasha suggests that it was a bonk of sorts in that my muscles became strained as a result of low fuel capacity within them. I just don't know. I know this. If it wasn't Boston. If it wasn't 6 miles of downhill followed by 10 miles of rolling hills, followed by 4 sets of hills, followed by 6 more miles of downhill ... I wouldn't have had any problem maintaining my 6:45 pace. Having said this. My other marathon run last April was on a course with more net uphill and of a steeper grade than the Boston hills. I trained from July 1 of 07 - December 1 of 07 averaging about 4-5 days a week and maybe 40 miles/week before taking 2 weeks off. This was when I began running and couldn't run 3 miles without stopping in July. After 2 weeks off I trained for another 4 months during which time I ran 5-6 days/week and probably 50 miles/week average over the course of the 4 months. Now, mind you my pace was slower as a result of less aerobic base and strength. But hitting off 15 seconds/mile slower on that marathon for an average ... I never bonked. I fell off the pace about 15-25 seconds/mile during the last 5 miles, all of which contained hills in the 300-500 meter range. I averaged 7:19s for that race and ran a nearly perfect race. My goal was to BQ. My splits are straight down the middle after mile 2 between 7:05 and 7:20 through 21 miles and after that 7:32, 7:41, 7:40, 7:44, 7:22. Try to figure that one out. I'm just not convinced this was a bonk at Boston. Something very strange happened that has never happened before. In my opinion it was a strength issue. I simply did not have the muscular development for that course. I greatly underestimated the terrain factor and did not train with enough specificity for that course. Ultimately it is neither here nor there now. After 2 years of running I feel I am in a position to be able to handle 70 mile weeks week-in and week-out and will proceed in that fashion. My goal is to maintain that mileage through the end of 09 and then work towards the 80-90 mile/week range in 2010.

[dave rockness]

You certainly have worked hard and ran an impressive Boston.  Just a thought on my part.  Based on your St. Louis experience maybe it was just the course.  My interpretation of Sasha's response was that a stronger base (more mileage per week over a longer time) may have given you the ability to run more of a 7:30/45 pace at the end once your legs were thrashed.  In the future if you've worked towards 70/80/90 mile weeks, you might still get destroyed by a marathon or two, but then still scrape by at the end well under 9 or 10 minute miles.  You're definitely a sub-3hr guy who's pretty close to breaking out. 

[James Winzenz]

I have been following this thread, and noticed that the comment about 3 x your daily miles being your crash point seems to have applied to me last year at SGM.  I was consistently running 8 miles/day, with some longer runs mixed in there.  I was in the best shape yet for last year's SGM, yet I still completely crashed at mile 25 and had nothing left in the tank - I ended up having to walk a fair part of the last mile, although I somehow still had something in me when one of my buddies passed me up about 200 yards from the finish and called out my name as he was passing me.  So I find this thread very interesting.

[Sasha Pachev]

Crashing at about 3 times your daily mileage is a reasonable rule of thumb, but it is a rule of thumb of course. E.g Jeff McClellan crashed at 16, and really crashed at 18 in spite of  running about 12 miles a day on average for 6 months. That's because he can go fast enough to burn all of his glycogen in 16 miles, and his FBP is still quite a bit behind his glycogen race pace. So you can do the mileage and still crash. In fact, you can do the long runs, and still crash. When Ryan Hall ran 2:06 in London, he crashed in the last mile slowing down to 5:08 from about 4:45. He commented later that he could not imagine he would ever have to work so hard to run a 5:08.

So I would say you crash when your aerobic capacity, neural drive and the muscular power exceeds your fuel capacity. Which can happen at any level of performance or training, and is not necessarily bad from a long term perspective. Being able to hold pace for the first 15 miles is great. It means you can go your average pace in the first 15 for the whole marathon once you fixed the fuel problems. I have more hopes for a runner that can hold pace to 15 and then blows up than for the one that is evenly off pace the entire distance even if he ends up ahead. It is easier to train the former to hold pace all the way than to train the latter to run at a faster pace.

Jeff and I have been trying a new method of pushing the FBP up. The idea is that whenever metabolism switches from a steady state it switches gradually. So if you stabilize it in one state, you have that state for a few minutes even if you are doing something that will eventually cause a shift. So we end our easy runs with what I call a Fat Mile. The easy run must be a true easy, for us no faster than 7:20 for at least a mile or two, ideally no faster than 7:20 the whole way. It needs to be about the pace you would run at the end of a marathon if you were not tapered and never refueled during the race, in other words the FBP. That should put the body into the fat metabolism groove. Then in the last mile we speed up. We do not necessarily try to hit our marathon pace. The focus is more on the feel. The idea is to speed up without fully awakening the carb beast. So the adrenal glands need to be asleep, no getting excited about anything, or the beast will wake up. But you must push enough so that the body will try to dip into fats harder. The feeling is that you are up against a wall, and you do not understand why in the world 6:00 pace, or even 6:05 feels so hard. If that pace feels too easy, or even normal easy, you are not doing it right. It means you got excited, you have some adrenaline going, so the carbs are available. There is a very fine balance.

[Sasha Pachev]

Good reading about carb energy supply at

http://www.unisanet.unisa.edu.au/08366/h&p2carb.htm

Simple enough for me, so must not be too geeky. My biology background is limited to a C+ in Biology 130 at BYU. I must make a disclaimer, though, that I have never cared about the grade as long as it was passing and thus never crammed for tests.

[Jeff Linger]

Interesting concept Sasha. So if I've got this straight. Your marathon pace is somewhere around a 6:00-6:05? You do a 20 miler or so easy, in the 7:20 range and then the last mile you hit M-pace? Do you ease into that mile with some subtle increases of miles over the last 2 or 3 miles? Can you explain the Fat Mile process a bit more?