The “Science” behind “Bonking”

It has long been “common knowledge” that endurance exercise is fuel-limited. This is most familiar to general populations as a commonly observed limitation on foot races that says that you will run out of energy, “hit the wall,” or “bonk” at around 20 miles. For common race distances, the effect is most frequently observed in the marathon (26.2 miles). The standard explanation is that you can only store a limited amount of carbohydrate fuel in the form of muscle and liver glycogen, and that you will bonk when the supplies run out. Management of the “problem” is variously accomplished by “carb-loading” before the race to super-fill (“super-compensate”) the glycogen stores, and by various refueling strategies during the race (which support a large industry that provides special drinks, gels, bars, and the like).

At the same time, there is a growing body of evidence that there is no reason to depend on stored carbohydrate fuel which is limited in quantity if you can mobilize your fat stores as a source of fuel. The problem seems to be that anyone who is accustomed (adapted) to eating a high-carbohydrate diet tends to preferentially burn carbohydrates as fuel and does not utilize the energy available from fat in a way that spares carbohydrate use during endurance exercise. These are the so-called “sugar burners” as compared to “fat burners.”

There are a few possible strategies to enhance fat burning. The most commonly discussed strategy is to train at slower, more aerobic paces, to train the body to optimize using fat as fuel. This approach was discussed by Alan Couzens. Although carbohydrate was also restricted, the main emphasis was on low intensity training, with pretty amazing results from the combined approach.

A second strategy, perhaps even simpler, is to change to a low-carbohydrate diet. Maintaining glycogen supplies in a partially depleted state encourages the development of aerobic apparatus via the action of AMP Kinase (increased mitochondria and associated fat burning enzymes such as carnitine palmitoyltransferase, necessary to help transport fatty acids across the mitochondrial membrane). People with deficiencies of carnitine palmitoyltransferase are unable to utilize fat for fuel efficiently, and can even suffer damaged muscles and rhabdomyelosis resulting in kidney failure. There is also evidence that people suffering from obesity and diabetes may have impaired mitochondrial function, which inhibits their fat burning and at least partially explains the origins of their condition. Similarly, a deficiency of carnitine can result in impaired mitochondrial function and even lead to symptoms of metabolic syndrome.

There is an adaptation period of a few weeks to lowering carbohydrate intake during which the appropriate metabolic pathways and aerobic enzymes and cofactors are up-regulated to better utilize fat as a substrate, allowing blood glucose levels during exercise to be more easily maintained. As Alan Couzens explains, lower carb intake should result in a 20% increase in fat burning in a few weeks. Numerous scientific studies bear this out. A recent study, for example, concludes that a high fat diet increased the rate of whole-body and muscle fat oxidation while reducing the rate of muscle glycogenolysis during submaximal exercise, even after restoring high carbohydrate intake. In this study, a high fat diet was followed for up to two weeks (which we know is just long enough to see significant adaptation), during which usual training was followed. A high carbohydrate diet was restored for the last few days along with a taper before racing. The athletes were able to maintain the increased fat oxidation even after reinstating high carbohydrate intake.

There is at least one supplement (Vespa) which is alleged to improve fat-burning during exercise. There is also some evidence that, all else being equal, the athlete that has the most efficient fat-burning ability can consistently beat the athlete with the higher raw power output (higher VO_{2 max}) in endurance competition.

An article in Running Times last year discussed the strategy of carb cutting to increase endurance, though the article suggests mainly forgoing carb supplementation on training runs, not going low carb in the training diet. The Ethiopian runners again are cited as evidence that a high carb diet is necessary to fuel runs, and there is speculation that they are somehow training themselves not to use glycogen as the predominant fuel by not consuming carbs while actually training. This conclusion seems unlikely to us, since it is well known that exercise causes an increase in blood sugar (due to action of epinephrine and glucagon), effectively mimicking the result of taking in supplemental carbohydrate while exercising. A marathoner does not “hit the wall” until they have run ~20 miles at race pace anyway, a condition not likely encountered during routine training runs for most of us.

Despite all that is known about “the wall,” people persist in believing that a high carbohydrate diet is necessary if you hope to be a good runner. A high carbohydrate diet may work well for Ethiopian runners, who are known for running prodigious mileage and training three times per day. At this training intensity, we seriously doubt their glycogen stores are ever completely full, and they may effectively be training in a perpetually glycogen depleted state, which would upregulate the same enzyme systems that occurs in the low carbohydrate condition. Perhaps what they are mainly training is the rapid replenishment of glycogen stores. However, for most of us amateur or older runners, we’re only fooling ourselves if we think we need to fuel exercise with a high carb diet. David does quite well on very minimal carbs (less than 50 g/day), while Cynthia prefers closer to 100 g/day. Since we generally only run once per day and even then usually less than 10 miles, there is no reason to consume any more carbs to fuel our exercise habits.

David has been a low-carb runner for more than two years now, keeping carbohydrate consumption low before, during, and after endurance exercise. While he won’t brag about his speed and has no plans to challenge any course records, he consistently finds that he has even energy levels and rapid post-event recovery with minimal muscle aches and pains. Fat fueling works for him! However, until very recently, while he refueled less often than is typical, he did routinely refuel using protein and fat for any event of more than 3–4 hours.

He was prompted to revisit the issue when he heard about a recent study (“Metabolic Factors Limiting Performance in Marathon Runners”) by Ben Rapoport when he had his fifteen minutes of fame on NPR in October 2010. Ben was attempting to model bonking in the context of marathon runners. David subsequently exchanged e-mail with Ben whose initial reaction was to interpret David’s personal experience as simply confirming Ben’s model, arguing that fat-fueling works, and that you don’t bonk as long as you run sufficiently slowly. David pointed out some flaws in Ben’s interpretation of the scientific data he analyzed and challenged him to define a performance that David might personally be able to achieve that he might consider sufficient to disprove his model, but he never responded to the challenge. We summarize here both a couple of the criticisms of Ben’s model and analysis and some more recent personal experience and experiments.

A key part of the experimental data that Ben used in building his model came from Romijn AJ, Coyle EF, Sidossis LS, Gastaldelli A, Horowitz JF, et al. (1993) “Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration,” Am J Physiol 265: E380–E391. That paper shows (in Fig. 8) the relative amount of particular substrates which are used in short-term exercise at three different intensities. The subject’s dietary habits were not identified, and any changes that might take place over more than a few minutes were ignored. The data show that more intense efforts use primarily muscle glycogen as fuel. They do not show the pathways that feed the muscle glycogen. Glycogen and glucose are rapidly interconverted, and over longer periods of exercise, new supplies of glucose are made by the liver. The liver, in turn, is capable of using any available fuel source via gluconeogenesis to keep blood glucose levels up. These fuel sources include ingested carbohydrates, protein, and fat as well as lactate, glycerol from liver and adipose tissue fat stores, and even body protein stores such as in muscle tissue. Which source predominates depends on availability. Some of the necessary up- and down-regulation of different metabolic pathways can take place on a short time scale to respond to instantaneous demand for fuel from the muscles and other bodily functions. However, there are also some key adjustments that respond more to average demand and supply to deal with changing diet, exercise demand, starvation, and the like, and these are events that tend to have time constants measured in days or weeks, not minutes or hours. The adaptation processes may be numerous and complex (or at least, we fully admit that we don’t understand all of them) and likely include adaptations in the skeletal muscles as well as in the liver. However, we think it is clear that the data extracted from Romijn do not actually show the underlying consumed fuel source for various levels of endurance exercise, and the data cannot reasonably be extrapolated to model and predict bonking.

One factor which Ben cites in favor of the importance of carbohydrate and fueling is the relative stoichiometry of oxygen consumption for each substrate. He states that carbohydrate oxidation typically generates approximately 120 kcal per mole of respired oxygen, whereas fatty acid oxidation typically generates only approximately 100 kcal per mole of oxygen. We would argue that this, while probably correct, is irrelevant in that the difference is relatively small, and the availability of oxygen is never a limiting factor at a typical aerobic marathon pace. There is always an excess of oxygen available. In any case, regardless of the underlying fuel used to generate blood glucose/glycogen, the immediate muscle activity (except for very short term bursts of power) is fueled by glucose.

Notwithstanding the possible flaws, Ben’s model does make predictions as to whether one is likely to bonk in a marathon. In particular, he has provided a calculator for the marathon. Putting in the best estimates David has for his personal situation, the calculator predicts that he should not bonk for finishing times over about 3 hrs. Since he can only sustain a 3-hour marathon pace for about 1 mile or so, he may never be able to really challenge the model experimentally using himself as a test subject.

However, David was inspired to test his need for refueling during running, and now has a significant number of test results that, if not sufficient to explicitly challenge Ben’s model, are at least startling to many people. For some time now, David routinely runs training runs of up to 4–5 hrs without refueling (water alone). This is still true when he runs with his son at faster speeds who typically chooses to refuel using at least a couple of energy bars or gels. David first pushed the envelope a bit on what was supposed to be a planned 18-mile run that stretched to about 26 miles when the route was blocked by an impassable rain-swollen river crossing. That run extended over about 7 hours including some significant rest breaks, so it was not at a strenuous pace, although it did include some significant elevation change. David consumed only water. The next experience was a 50K (31-mile), mostly flat run, again at a very modest pace, finishing in 6:50, again on water alone. Two weeks later, he completed a much more strenuous 50K on rough rocky trails with about 6000 ft of elevation gain (and loss) in 7:28 on water alone. In all three of these runs, David started with a breakfast of a two-egg cheese omelet and bacon about two hours beforehand. He felt some minor hunger around normal lunch time, but otherwise did not experience any significant fluctuations in energy level, and he certainly did not bonk. His overall weight was down about 3–4 lbs at the end of the day compared to the beginning, but looking at beginning-of-day weights across several days, any weight change was pretty much lost in the noise. Of course, it only takes about a pound of fat to fuel a 50K run, anyway. Another week later David ran yet another moderately hilly 50K event which was slower (8:04) due to snowy trail conditions. Due to a late start (10 am), he chose to eat a little at around the 6-hour mark, mostly because it was a long time since breakfast. However, the ability to do three 50K runs in four weekends, certainly confirms that post-event recovery was rapid.

So what’s the take-away message from all this? It’s interesting to compare our reaction and the experiments that David decided to try to others. Greg Crowther also blogged on Ben’s article. Greg’s big concern was inter- and intra-personal variability, and he questioned the validity of extrapolating from some sort of average measurement of performance to the needs of one individual on one particular day. He didn’t ask (as we did) if too many runners are needlessly afraid of bonking but rather, “if ingesting extra carbohydrates before and during a marathon might help you avoid ‘hitting the wall,’ why wouldn’t you do it? Especially after investing all of that time and effort in training, traveling to the race, etc.?” Hey, we’ll even go further: if ingesting fuel (whether carbohydrate, protein, or fat) during a race might help you maintain a faster pace for whatever reason and for whatever limited portion of the race, even it’s just a placebo effect (or tricking your Central Governor), then by all means go for it! But we also stand by our basic conclusions that (1) carbohydrates are simply not necessary before, during, or after endurance exercise, (2) they’re probably not even particularly beneficial, at least if you are suitably adapted to efficient fat-burning (and may be harmful to your long-term health) and not logging very high miles at high intensity, and (3) unless you’re able and motivated to run, say, an entire marathon at a high percentage of your VO_{2 max}, consuming much of any food immediately before, during, or after the event is entirely optional. Moreover, there may be some benefit to having the stomach completely empty while racing, in order to avoid stomach upset, intestinal discomfort/diarrhea or nausea when running at high intensity. (David does continue to believe in significant protein consumption sometime in the 12 hours or so following strenuous exercise as an aid to muscle repair and recovery, but the timing of even that refueling does not appear to be nearly as critical as some authors suggest.) David will probably resume modest consumption of fat and protein on longer events, just because he’s not big on skipping meals entirely, anyway, but it’s reassuring to know that he can easily keep going without any fuel if for any reason he needs to.

SF Marathon Part II: So why so much slower after 26 years?

I was actually pretty happy with my performance, since my trail ultra times have been much slower, and I wasn’t too confident how I would hold up to all that pavement running. I was also very happy just to be able to do the event, grateful that my 53-year old body, despite its nagging aches and pains, is holding up as well as it is. But why am I slower than I was 26- 27 years ago? Well aging is the obvious excuse, but what does that mean, and is it in any way correctable? Does that mean I have less muscle mass, less strength to work with? Does that mean that my heart is weaker, or just slower? Does that mean my muscles and limbs have lost elasticity and/or I have reduced running economy now? Is my higher blood pressure putting too much load on my heart? Do I have endothelial dysfunction and the muscles are being starved (relatively) of the blood flow they need? Or can it all be attributed to increased weight?

I subsequently ran several other marathons during that time period: Summit Marathon- from Los Gatos to Soquel (across the Santa Cruz mountains, another 3:45 - it was tough!), Oakland and Avenue of the Giants. I tried (and failed) to qualify for Boston at Oakland (the qualifying time was 3:20 at the time, but my calf froze up so badly during the cold rain of that race that I had to back off the pace) for a 3:27. Avenue of the Giants was a 3:34, perhaps still overly cautious with the calf muscle. Still, I was at the point in my mid twenties where sub 3:30 was quite doable. I suppose the other piece of evidence I have is that a couple of years later, after starting grad school, I talked a bunch of other students into trying a marathon (Shamrock Marathon at Virginia Beach). I thought I had prepared much the same as before, training in the hills of Charlottesville, but only managed a 4:15. Maybe there was something magical about that early training on the Bay Area hills…

It’s possible that I stumbled upon a useful training program back in 1981-82, where my usual run was about 5.5 miles on some flat but also some pretty tough hills (the Dish loop). It’s possible that I was just lucky and managed to train hard enough without injury long enough to make good progress. It was all very intuitive- I just trained by how I felt on any given day. It’s possible that the bicycle commuting I did added some extra fitness. It’s all still a mystery to me. It’s also possible that I was still significantly undertrained if I wanted to know what my real potential could be. Given what I know about my training at the time in comparison with what I read about now, it seems that I should have been able to progress even further, perhaps to 3:15, maybe less, though I doubt that I had the potential to do much better than 3 hours.

A very rough calculation/guesstimate of my VO2max based on performances from my mid-twenties is 45 ml/min/kg (based on a 7:57 minute per mile marathon pace), with the caveats that 1) this is not the correct way to determine VO2max of course, 2) I could probably have gone at a faster pace had I trained better and not gotten injured, and 3) my VO2max in 2009 could be very different from my estimated VO2 max from 1983, but this is the best data I have at the moment. In other words, I haven’t sprung for a proper test, so this estimate will have to do for now. This number is not merely imagined, but is based on a chart in Noakes’ book "Lore of Running" where various paces are correlated with weight normalized VO2max values. Having a good VO2max is helpful in achieving good running performance, but it is well known that being able to sustain a higher percentage of your VO2max effort is more influential on running performance than VO2max itself. Superior running economy and other nebulous factors are also important in determining who is actually faster. Noakes discusses these quite a bit in his book. See also Lyle McDonald's post for more discussion about predictors of endurance performance, and VO2 max in particular, or the extensive writings on Alan Couzen's blog .

A correlation to of this VO2max chart with marathon paces to my current values would look something like this: as of race day, I weighed about 144* lbs (65.5 kg); in my marathon running mid-twenties I (think I) weighed about 125 lbs (56.8 kg). Assuming nothing else fundamental has changed, in absolute terms, I should have the heart and lungs and leg muscles etc for a VO2max of 2556.8 ml/min (multiplying by the 56.8 kg). Dividing by my now increased mass, that yields a VO2max of 39.0 ml/min/kg and a predicted marathon pace of 9:08 per mile, or about 4 hours. This happens to be closer to my predicted Yasso 800 marathon time of 4:10 than what I actually did in July (4:31), but still seems to indicate I should be able to do close to a 4 hour marathon if the only adjustment to VO2max was added weight. My 2009 performance (10:13 minute per mile marathon pace) would suggest a VO2max of ~34 ml/min/kg. Maybe this wasn’t a best effort due to not being able to stretch out a bit more in the first half, and also by the fact that I had no muscle soreness the days after, that would seem to suggest I didn’t push the pace as much as I maybe could have. Of course, VO2max doesn’t tell the whole story- there are many accounts of people being faster without having a higher VO2max. It’s also possible that I have less lung capacity due to past bouts with pneumonia- the x-rays do show some scarring.

Of course the most likely explanation is that I’m just poorly trained/more cautious now. According to “Hadd’s Take on Distance Training” (skip ahead to part 6 if you want to see how to calculate marathon heart rate (HR) and training HR), marathon HR should be 15 – 20 bpm slower than max HR. In other words, if properly trained and motivated, you should be able to maintain an effort for marathon distance at 15 – 20 bpm slower than max HR, but it shouldn’t feel uncomfortable. According to this calculation, my marathon HR should be more like 155 than 145. That HR for me right now translates into about a 9:00 – 9:10 pace- much closer to the Yasso 800 predicted time, and in good agreement with my estimates from VO2max calculations, but still pretty difficult to maintain.

So why didn’t I run nearer 155? Good question, don’t really know. Some of it is a sense of cautiousness, that I maybe shouldn’t overstress myself, at least not pushing too much. Running at a HR of 155 feels pretty hard to me these days- it’s not hard enough to be reduced to frantic panting, but it feels too hard to maintain for more than a few miles. Perhaps I need to follow more of Hadd’s suggested training and develop my aerobic potential as far as I can and then see how it goes. It’s surprisingly hard to do though- the natural inclination is to run at a pace that feels good- that pace tends to be slightly anaerobic though, especially when rested and feeling good, but not really sustainable for miles and miles.

Another posting on Chuckie V’s site addresses this further. This post basically says that lots of mileage is what makes for superior runners, and points out that the qualifying times for Boston have been eased up over the years because people are training differently, relying on “quality” higher intensity workouts rather than higher mileage. Alan Couzens also addressed this recently, pointing out that research supports the idea that aerobic adaptation in slow twitch fibers is linear with increasing exercise stimulus, suggesting that easier training for several hours per day could provide further increases in training effectiveness. This is not true for threshold/”high intensity” training, the improvements from which maxed out in some studies at about 1 hour. The good news is that you don’t have to kill yourself with exhausting stressful training to see the benefit, and it also accrues over years, even decades! Of course, there is a place for higher intensity training, to increase lactate threshold and sharpen up your speed, or for fun. Anyone who runs on hilly terrain can hardly avoid some higher intensity work on occasion anyway, but the bulk of the training does not have to be “hard.” This training philosophy is not currently fashionable, and I may not be able to manage much more mileage than I currently do anyway (40-65 miles per week), but I can try.

There is a pretty clear correlation of age with heart rate, and it seems that a slowed heart rate should have an effect on my slower performance as well. At this point it’s hard to know since I don’t know what HR numbers I was dealing with in my youth (though I'm sure they were much higher than now), and since my resting HR (and max HR) keeps dropping now. But according to the calculation above, the real limitation resulting in my slower performance is my excess weight, i.e., if I could maintain my marathon HR (a big IF) I would perform at a level that is scaled down by my greater mass. So theoretically, if I lost down to 125 lbs again, I should be able to perform as well as I could in my twenties? This seems unlikely, but worth the experiment. I’ll keep working on it.

*Currently at 139! Yea!

SF Marathon Part I: SF Marathon Revisited

As a birthday present to myself, I decided to run the SF Marathon again after 27 years. This race has a special place in my heart since it was the first marathon I ever ran (back in 1982!), and because it was such a wonderful experience then. I thought if I really wanted to judge my fitness now, I should try it again so I can compare the then with the now. But first, let’s talk about why it was so wonderful back in 1982.

In July of 1982, I had only been running regularly for about 10 months. I had been a sprinter in high school and early college, and then crewed for Duke and Stanford, all of which are largely strength/fast twitch or strength/endurance sports. I always hated the two mile timed runs we had to do for crew to judge our fitness, just as I had always hated the warm up for sprint practice. But when I went through some big hiccups in my personal life, I coped with the emotional trauma by running long and hard, mostly at the Dish loop at Stanford, which was convenient because I worked as a research assistant there after graduating from college. I also ran some with friends, most of whom were faster than me. One was running the SF marathon, and I went along as an unofficial runner at the last minute. I didn’t know how to train, and hadn’t in fact done much specifically to train. I had obviously done some longer runs- maybe 8-12 miles, and the weekend before the race, I went out for ~18 miles on the roads from Stanford out through Portola Valley and back. That went ok so I decided I was ready to try the distance. But I was certainly not expecting much, and just hoping to finish. My running partner went out fast and I didn’t expect to see him again until the finish. I sauntered along for a few miles at what felt like a very slow pace. After ducking into a restaurant to use their bathroom (no portapotties at this event!), I figured it was time to see what would happen if I sped up, so I slowly increased the effort level and kept on speeding up until I couldn’t anymore. This worked surprisingly well, and before I knew it, I was steadily passing people, including my running partner (reduced to a painful walk by that stage)! I don’t know why it worked so well (this is all relative of course- real speedy people will laugh at my pitiful accomplishment), but I was thrilled to finish in 3:45, and especially to pass the guy who always made me feel so slow. I still have the medal to this day, which they gave me even though I was an unofficial runner.

So on to 2009. I’ve been running pretty regularly, albeit with injuries of one sort or another for the past year. Last summer it was a piriformis problem, and this past winter, it was hip flexor tightness, along with more piriformis and glut medius problems (opposite hip this time), not to mention sore gluts and hamstrings when I finally got other parts working properly. In trail ultras, there can be a fair amount of hiking due to steep hills and rough terrain, and trails are rough enough that speed isn’t really an option (for me anyway), so these injuries were not debilitating. More recently, I’ve managed to get past those particular problems, and train more or less regularly, and work on pace as well. So I thought it might be time for a comparison with those earlier days. Also, after David injured his knee last May (he’s mostly recovered and faster than before it seems!), I did more road running, starting from home running alone and heading up into the hills, or up to the Dish, while still doing trails some of the time. My usual training was pretty slow, with easy efforts at relatively low average heart rates (~130’s- I can be very lazy, but justify this by saying that it is low stress :) ). I threw in some faster tempo runs and Yasso 800’s starting in June to help raise lactate threshold, and these predicted a marathon time of ~4:10. So I felt like my legs and feet were reasonably acclimated to pavement and my conditioning should be good enough to get me through a marathon in a not too disappointing time.

The Expo: I’ve only done trail races since starting to run and/or train (if what I do can be called training) more consistently in the past year. So the Expo was a first for me and I was eager to see what it was all about. There were lots of samples of drinks and snacks to try, and clothes that looked like fun. But all I bought was shoes- there was a $50 per pair bargain booth, and I got my first Mizunos and a pair of Brooks. I don’t have much in the way of road running shoes (I ran the race in a cheap pair of Adidas from Costco!), so I thought this would be a good plan. We’ll have to see how these shoes work out.

On race morning, David dropped me off a few blocks from the start with only minutes to spare from my wave 6 start time of 6:17. The line for the portapotties was so long, I just gave up and headed to the start. This probably explains the unexpected mix of running speeds in the pack- all those faster people who were delayed for half an hour at the start! Our wave began, and I loped along at about a 10 minute pace, hoping things would thin out soon so I could get up a little more speed. That never really happened though. The pack was very thick all the way out and back across the Golden Gate Bridge. People could never really get their stride due to bobbing and weaving between faster and slower people all the way up to about mile 10. I blame this partly on the portapotty situation at the start, but also we really needed more space! Many people were taking walking breaks, which made it hard for those of us trying to keep a consistent pace. I felt great though, light on my feet (unusual!)- nothing like adrenaline and a crowd of happy people running in cool SF fog! Returning across the bridge, I yelled a loud “Go Julianne” to Julianne , the only other person I knew who was running (she was pacing the 4:45 group). When they offered Gu at the aid station, I obliged and had a couple (the caffeine was a good idea for this night person), downing them somewhere between miles 8 and 13. There was more Gu at mile 16, and I took another. All during this time, my heart rate was running about 145. It rose on the hills, but apparently I made up for any increase on the downhills. I felt like I was fading a bit between miles 13 and 16, but soon thereafter (maybe it was the double caffeinated espresso gel!) realized that if I was going to have any hope of a strong second half, I’d better get moving. I pushed into a heart rate zone of 150+ through Golden Gate Park and down toward the Embarcadero again. I kept pushing and pushing, but unfortunately, there were plenty of hills that kept pushing back. Then there were the diversions- it was very disconcerting to arrive at an intersection and have them pull caution tape right in front of you and send you a different way! Presumably, this trick allowed them to keep some traffic moving across the race route. I still felt ok though, except for cramping calves. The cramping got bad enough that I had to stop and walk a few times, or pull over to the curb and stretch out my legs- they were very very stiff! I met an older man during one of my stretching interludes who seemed concerned I might quit (he was 71, so I can still say he was older, right? ). He was wearing a complicated looking knee brace. When I asked him what the brace was for, he explained that he had arthritis and when his Dr. said he couldn’t run anymore, he said that was not an option. He said his knee actually feels better after he runs! He also explained that he runs at a level of effort to keep his heart rate below 130 (must be nice!). We ran together for a bit, then I went on ahead while I could, trying to get mine back up to 150 or so. Of course, the last few miles of a marathon just suck no matter what- everything was stiff and hurting by that point and I could barely climb up and down over curbs! And it was warming up in the now sunny city! But drag into the finish I did, in a sparkling 4:31!

The post-race food was disappointing, and not on par with post-ultra refeedings. There was carbs and more carbs in the form of bananas, snacks and more sugary drinks, but nothing more substantial, not that I saw anyway. They were very eager to replace our glycogen stores the moment we stopped running, but I wasn’t eager to replace my glycogen stores immediately- I planned on taking at least one rest day to recuperate. It’s not like a multi-day event where you need to be diligent about getting fuel stores replenished right away. After a grueling event as long as a marathon, you need protein to start the process of rebuilding and repairing muscles, not empty carbs! See the very interesting posts by Robb Wolf here and here. We left the food behind quickly, as there was really nothing there of any use to me. We found a gyro place instead, where at least there was mix of protein, veggies and carbs. It was hard to leave behind the massage tables though. They were quite tempting! Fortunately, David gives a good massage too, and I enjoyed his generosity very much once we got home.

I also thought it was interesting that they put water or cytomax into tiny little cups, holding usually no more than 2 ounces! After the race, I was very thirsty and drank the entire bottle of water they handed out at the end almost immediately. Do you suppose they were concerned about hyponatremia, and trying to keep people from over-hydrating?

I made no effort to “Carb-load” for the race. I may have eaten slightly more carbs than usual (maybe 150 g vs 100 g?), but nothing dramatic. The night before, we had plenty of protein and veggies, but also some birthday cake (a spectacular nut torte made by my in-laws). I was pretty happy that there was no outright crash into the “wall” and in fact I felt quite strong through the usual “wall” territory. Whether this was because I used a few gels (75 g worth of carbs), ample caffeine, or pacing so that I burned plenty of fat and didn’t prematurely deplete my glycogen stores, I don’t really know. I never used gels (they didn’t exist!) back in the 80’s when I was faster, and barely drank any of the Gatorade they offered at water stops anyway. Marathons just aren’t that long, and with proper training, you shouldn’t need carb supplementation anyway. But that’s not fashionable now either. Still, I try to keep an open mind and test these theories as best I can.

I wore drymax socks, and despite no blisters on the left foot, ended up with 3 on the right! The odd thing is that these blisters were in different places than I’ve ever had them before. I think an important part of blister avoidance is acclimating the feet to both the shoes you’ll be running in and the running conditions. I could have had tougher skin on those parts of my feet if I’d trained more in those particular shoes and with longer runs on those types of roads. Since I put in only a few longer runs on roads at all, and often in different shoes, my feet just weren’t prepared for the particular stresses of that event. You’d think I would know this by now. Well, live and learn, maybe…

Surprisingly, the Garmin says I averaged a heart rate (HR) of 147 for the first half (at a pace of 10:05) and 145 for the second (at 10:20). All the effort to get the HR up didn’t do much to increase speed overall, but perhaps the problem was the cramping and the heat due to the warming city streets. I certainly tried to pick up the pace, but the hills between miles 15 and 21 made sure the effort went largely to making it up and over them, not speediness. I don’t really think I could have gone much faster, except maybe in the earlier miles if there had been less crowding. By the end, I was pretty beat and going on inertia and will power.

I knew going into the event that I would probably be disappointed, and it was not likely I would have another surprisingly fast run. I wondered if maybe I hadn’t trained adequately, since I ran considerably slower than I had hoped. I mean the Yasso 800’s predicted a 4:10 after all! Perhaps they’re not so accurate. On the other hand, where was the muscle soreness? I had none of the usual post-race muscle soreness! Walking up and down stairs was just normal the days after the race. My body acted as if this was just a hard training run, and I went running again after resting only one day! This argues the effort was not all out. Perhaps I’m too used to ultras and doling the energy out more evenly over a longer period of time. Then there is that laziness factor…

All in all, this was a nice event. There were cute signs all along the race course asking questions about SF history (but it would have been nice to see some answers to those questions too). I saw parts of Golden Gate Park that I didn't even know existed before. The music stations were enjoyable too, if spaced a bit far apart. It was just a nice place to run on a foggy morning with 20,000 other like-minded people.

That said, I think trail ultras are a lot easier, at least for me. There is more variability in the terrain, allowing you to use different gaits, paces and muscles depending on what the trails throw at you at any given moment. At my level, I walk some, stretch more and generally don’t get quite as stiff and depleted as in a road marathon. So more trail ultras are in the plans, but possibly another road marathon. I should be able to run one faster, shouldn’t I? (see Part II, coming up)

Slowing with Age?

We started our current diet 10 months ago in an attempt to regain our health and vitality and lose some of the weight that had crept on over the last few years. We appeared to be developing signs of metabolic syndrome despite our frequent hikes, and it was time for more drastic measures. We love the outdoors and hiking, so it was natural to combine hiking/jogging with the low carb diet we began last January. Initially, we did much the same routes as we’d been doing on our casual hikes for the last two years. We gradually increased the challenge of our outings, trying to find ways to connect different parks, no longer being satisfied with the ~8–11 miles available in most parks. At first, these longer outings seemed long and took a lot of time: 12, 15, 18 miles. I experienced my first nausea during and after an 18-mile run/hike (with a couple of thousand feet of elevation change). That just made me mad and I wanted to tackle it again, this time with a bit of food to see if the nausea could be prevented (it worked). Then on a whim, we did our first 50K (Headlands 50K—cool but very hilly), and got seriously addicted to ultra events and pursuit of improved fitness. The first was slow (8.5 hr), which again made me mad and determined to do better. The second (Stevens Creek 50K—see Mark Tanaka’s race report) was worse for me at least (9.5 hr, but very hot and hilly, very low finish rate), though David tolerated the heat much better and did quite well (~7 hr). The third was getting better, but still unacceptably slow (Skyline-to-the-Sea: 7 hr, and net downhill. See Scott Dunlap’s race report). Our fourth ultra was the Firetrails 50-miler which took 12 hours (at least, not a slower pace than previous races; see Jean Pommier’s race report ). Undeterred, a couple of weeks later I ran 49 miles (again in 12 hours at the SF One Day—another painful story).

So why so slow? I’m 52 years old, and seem to have lost much of whatever speed I ever had (a middle of the pack sprinter in high school and college). I was on track for a 3:20 marathon before a calf injury slowed me down—PR of 3:27), now 25 years ago. Just how slow must I be now? Is it possible for a person to regain the health and vigor they had when they were younger? This is the grand experiment, and may fail badly, but that’s the question. Can I get back what I once had? Can I get better? Do I have to be resigned to being old and slow? Can I improve my health while I do it?

So it seems it’s time for some more serious training. We’ve started doing small interval workouts on the track (a few 200s, 400s and 800s) and some tempo runs, just to try to jog the memory of those quiescent fast twitch muscles (no pun intended). I was dismayed to realize that I’ve lost all sprint speed, and running up on my toes feels like I’m going to spazz out and fall on my face. Just doing 400s at an 8-minute-mile pace seems fast at this point. I’m hoping that will change, but how to improve?

Recently, I came across a link to a blog I haven’t discovered before, with an interview with Dr. Maffetone about training for endurance events that was quite interesting. He’s the inventor of the 180 rule (basically subtract your age from 180 to calculate your maximum aerobic heart rate [HR]). According to this method, you train at a level that achieves the desired HR, and you naturally speed up even though you maintain this level of effort, as you train your body to use fat as fuel. In the interview, he describes how he discovered this method basically by measuring respiratory quotients to determine at what HR fat burning occurred as opposed to carbohydrate burning. According to Dr. Maffetone, anaerobic training can be implemented after base aerobic training, in interval workouts or races, then followed by more base training.

I was intrigued and read some of the other advice on his website (sign up for a free membership). His nutrition advice really surprised me as well—another low carber of sorts! He advocates cutting out all refined carbohydrates, much the same advice of the cardiologist Dr. William Davis who is working hard with his patients to prevent and reverse their atherosclerotic disease.

It’s possible that we’ve already achieved a good grounding in aerobic (fat burning) ability, and that now would be a good time to work on speed. Maybe a good test would be to run a regular road marathon to at least get a good baseline number on my starting point. We’ll have to see how it goes…