The year of running injuriously

Cynthia’s Experience

Ok, silly title, but apt, as you will see. As of late summer of 2009, after running the SF Marathon and wondering why I was so much slower than expected, I intended to increase my mileage and see if I couldn’t improve my running ability. That did not happen as planned obviously, or I would have been happily blogging about my triumphs attempts. For running friends wondering what has happened, here is the sad story of the last year in running.

May 2009 at Quicksilver 50K, I landed badly while jumping across a creek—the embankment was at a steep angle, which I failed to notice until midair. Afterwards, I had swelling and pain in that foot off and on for a couple of months. It never hurt particularly badly and I mostly ignored it, continuing to run on it, even completing Diablo 50K a month later without problem, with my foot at least. Anyone who has done an event at Mt. Diablo knows it will take a lot out of you one way or another. I mentioned this in blog entries in June 2009 and July 2009. I thought I was babying it enough by taking it easy and mostly running uphill, where the foot falls are softer and more controlled. It did feel like there was some structural weakness for a couple of months when I’d try standing on the ball of that foot with my full body weight, but I figured it would pass. Mostly I just congratulated myself on having good recuperative powers, and continued to run as much as I pleased, and never bothered to get any x-ray or medical opinion.

In summer 2009 while training for the SF Marathon, I ran more track workouts and harder road runs, not the varied and softer surfaces of trails. A glimmer of foot pain began, but remained sporadic and mysterious until by August, after the marathon when I got the bright idea to up my mileage, I developed the dreaded plantar fasciitis. I scoured the web for information on treating and training with PF. One of the more useful references I found is from the Sports Medicine Institute, complete with physical therapy recommendations. My symptoms matched those of textbook PF, and I began to treat it as recommended—icing, using arch supports, keeping the fascia stretched, reduced running, using ibuprofen, etc.


When September came around, it was time for Steven’s Creek 50K. This is another charming local race on trails that we often train on, put on by Steve Patt of Steven’s Creek Software, with proceeds to benefit the Audubon Society. In 2008, the first year I ran this event and only my second 50K, I had such a poor time that I was determined to come back and vindicate myself, hurt foot or no. In 2009, the weather was cooperative, cool and even a few sprinkles, and I managed to improve my time by over 2 hours even with the injury! This tells you how terrible I am in the heat. I found myself running slower and scouring the trail ahead for the softest surfaces to run on, but my foot seemed all right afterwards.

So without too much fear, I signed up for a second running of Dick Collins Firetrails 50 Mile. I thought I would be faster since I was fresh from marathon training and significant hillwork and was lighter compared to 2008. Instead, I was slower by 40 minutes (almost a minute per mile slower!). It turned out to be a truly miserable experience, with me fantasizing about using crutches for much of the race, wincing down the long descent to the turnaround and just generally having the motivation sucked out of me by pain. I vowed not to run any other races until it didn’t hurt so much to run.

For the rest of the Fall/early 2010, I was reduced to easy running/rigorous icing, stretching and physical therapy. I could run, but not fast, and not far (nothing new really, but I didn’t enjoy being even slower than usual). There was almost no pain running uphill—this is of course without any kind of energetic bounding, which would likely negate the pain-free aspects. But of course, there is the downhill part to every run, where I would cringe and whimper my way back down. The strange part is how much more it hurt after running than before or during, and more than in the mornings when it is supposed to hurt the most (“first step” pain). On bad days, the arch and entire heel blazed with heat from the resulting inflammation (icing certainly helps with that), and even tingling or buzzing sensations from nerve irritation and entrapment. I also noticed occasional toe numbness and neuroma-like symptoms, but it seemed to be specific to going uphill, and was helped by walking on rocks that would put the pressure on the arch and not the ball of the foot.

During this time, I compared my feet and realized that my injured foot was now noticeably longer than the right (before, the right was larger), and the right calf musculature was better developed. Whatever injury I had sustained caused the foot structure to attempt to adapt and compensate for the weakness. The bone structure in the arch is now noticeably thicker as well, and presumably is stronger. This picture shows the two feet aligned heel to heel (excuse the post-Rio blisters). The plantar fascia can be easily seen when the toes are stretched back, revealing the tautness of the fascia. Unfortunately, the left fascia is still much tauter than the right due to the relative fast growth of the foot. The tautness can be more readily felt than seen, and the right is springier, with more give to it, than the left. Whenever I strain the fascia, such as landing on the toes going downstairs, skipping, running fast, I can feel it yanking on the calcaneus as if it was trying to pull free. In the acute phase, it felt like an ice pick or broken glass in my heel. Now it is merely a dull but persistent pain.

During January, we cut back running in favor of some weight and cross training, but ran the Fremont Fatass 50K anyway. This is a local event organized by Catra Corbett and Mike Palmer, a friendly (mostly) flat run on bike trails between Quarry Lakes and Coyote Hills. My foot wasn’t too bad on the trail part, though the pavement portions were painful. Then we ran the Second Saratoga Fatass 50K in February (where we got lost and only did a marathon) and Adam Blum’s Overgrown Fatass Marathon, where I was feeling better (and won the women’s event—Yea me! I think there were only two of us!). With the rainy winter, the trails were often soft and squishy, and this helped a great deal to soften the impact for my hurt foot.

By March, I was just starting to feel normal again, until I pushed too hard one day. I could feel something in the fascia “ping” and was back to pain and rigorous icing again. It was clear I wasn’t going to race anytime soon. We volunteered at Skyline-to-the-Sea in April, but my foot was killing me just from standing around all day. I went back to track workouts, thinking the soft springy surface would help. I also did running drills, not realizing these would exacerbate the problems. With more PF pain and weird associated pains and numbness, I finally broke down and went to see a podiatrist in an attempt to find out what the heck had happened and whether I had a stress fracture or something serious. Several x-rays and CT scans later, he informed me I had dislocated a bone in my foot nearly a year before! As a consequence, the foot joints had been trying to compensate for the injury by growing larger and stronger, hence the longer left foot. He also said it looked like I was getting some arthritis too. He instructed me to ration my running, run on soft surfaces, use an insole and to take glucosamine/chondroitin sulfate pills. (As an aside, he was also appalled at the looseness of my left ankle ligaments and advised me to run with an ankle brace, which I do- it has saved me from further injuring the ankle at least). So for the next month, I stuck with trails, the softest I could find and ran gently—no more “speed” work!

By May, it was time for Quicksilver 50K again, the scene of the original injury. I was determined to run it again, not sure if it would be the last ultra for a long time. I wanted to look for the offending stream crossing and this time cross it sensibly, but never did find it (I think they put up a bridge). This race was slower than last year by 23 minutes, but my foot didn’t hurt until after 15 miles. The after effects were fine too—less pain if anything. Encouraged, I signed up for the famous and popular Ohlone 50K two weeks later (I got lucky on the wait list), which involved a lot of slow trudging up hills and fast downhills trying to make up time, and I was pleased that my foot wasn’t a limiter, not seriously. We got lucky with a cool spell of weather on this one too. My lack of ability to run those hills was by far the biggest limiter. And again, the after effects were minimal. I was so excited to get through Ohlone without further injury that I went out and injured something else by running too hard (one of the little gemellis or something in the butt—the little bugger still hurts).

David and his son Ethan decided to run the SF Marathon this year. I played “coach,” leading them through a 30 minute time trial to assess training paces, long runs, hills runs, and mile repeats and Yasso 800s on the track. I couldn’t keep up with their pace, but tagged along behind. We did short trail runs at first to keep the impact lighter to help Ethan work up to longer distances without injury, but quickly escalated to 17–25 mile runs (I only did 20 miles that day) when it was clear he was weathering the distance without his previous injuries reappearing. Being injured yet again, I took it pretty slow and used this as a build phase. By marathon day, they were both primed and ready (though as it turns out, David had pushed too hard already and had some limiting injuries), and gave 3:37 and 4:12 performances.

So by August 1st, I was eager for another race, this time Skyline 50K. This race was extremely well organized and fun, with friendly volunteers positioned at trail junctions pointing the right direction frequently during the race, it was not possible to get lost. The course was harder than I expected, even though it is ostensibly completely runnable (just not for me), because some sections are very steep and rugged. I was amazed to read Jean Pommier’s account of running 7 minute miles through the parts that had me picking my way carefully over roots and rocks, averaging 15 minute miles!

Two weeks later marked the August 2010 (instead of September or March) running of the Steven’s Creek 50K. The event was well run this year as well, though our weather was not as considerate and became hot, while last year was unseasonably cool. I met Roger Jensen (“the yo-yo guy”) and Gordy Ansleigh here. Roger planted the seed for running Rio del Lago, saying that he and Barbara Elia would be there. I ended up finishing a little ahead of Roger, and thought Hmmm…

For these races as well, my foot just wasn’t the main limitation—it still hurt sometimes and made me run cautiously and tentatively at times, but after the races seemed better than before, if anything. But by the time the next weekend came around, I had put in 61 miles for the week and everything started to rebel. I had aches at the Achilles insertion into the calcaneus, peroneal brevis (or longus) tendonitis (maybe) in addition to PF (but the buzzing and tingling of nerve entrapment has finally gone for good I think). I blamed running with extra weight for aggravating the ligaments, but I certainly don’t understand what causes it to flare up on occasion still. So, a couple of easy cutback weeks were in order. I watched and pampered the foot during these weeks and then on the last possible day signed up for my first 100 mile race. Stay tuned for this next misadventure!

So the upshot is that over the last year, an impact injury with dislocation resulted in significant remodeling of foot structure, resulting in PF and other aggravations. It’s possible if I had gone to have it checked out right away, all of these problems could have been avoided, although I’ve heard stories about residual effects of injuries in people who were careful to get everything checked out. I now wonder whether PF is generally the result of minor or unnoticed foot remodeling. After all, the fascia is very inflexible, and changes in bone structure in the foot increasing the length of the foot of only a few mm could result in changes in tension in the fascia, possibly in stretching and tearing injuries. I was able to keep running, but not as fast or as far as I wanted. I had to give up my beloved Inov8’s because my feet seemed to hurt more wearing them than my uber-protective Montrail Continental Divides (sadly, no longer available). I also tried La Sportiva Cascadias and Salomon XTs, which are great shoes, but not as easy on my feet. I got into a routine of easy runs with prophylactic ibuprofen, which seemed to help prevent the majority of the inflammation, then I’d have to sit around for several hours icing my foot. It gradually got better so that it no longer hurt after running most of the time, and did not hurt when getting out of bed in the AM, but still requires a lot of maintenance and pampering. I’ve been able to manage mileage of 20 to 50 miles per week throughout the year, but have to be prepared to cut back at signs of aggravation. At various times, the pain has caused me to run with an awkward running gait, twisting of the knee or ankle (trying to avoid direct pressure on the heel), differences in foot falls (midfoot or forefoot on the left while heel strike on the right), all possibly leading to additional injury if not careful. I can really see the difference on potentially fast downhills, where I find myself holding back for fear of re-injury. I am optimistic, but would not be surprised to have to put up with this for another year or more. It’s looking less and less like I will ever run as fast as even a 6:30 (hilly) 50K again, but at least I can still get out there, and I am grateful for that. Luckily for most PF sufferers, their injuries are more minor and will resolve more quickly.

David’s experience

It has been a rough year for both of us in the running area. David strained his popliteus muscle in May 2009 (sprinting on the track in his new VFFs), and shortly thereafter pinched his meniscus, probably as a result of his knee misbehaving due to his first injury (one injury begets another). He ran with a knee brace for months, and as a result of this knee tenderness was not willing to run Steven’s Creek 50K (he volunteered) or Firetrails in 2009, but instead agreed to be my pacer. Sometime in late Fall 2009/early Winter of 2010, David also developed plantar fasciitis, in the same foot as me. We’re not sure why, or if it was related to some adjustments he made due to knee pain he had from the previous injury, or due to excessive strain when adapting to using VFFs. His PF never became as rabid as mine, and he has managed to recover without suffering too much. It didn’t seem to bother him in the Fremont Fatass 50K or the Second Saratoga Fatass 50K, though he was definitely slower at the Overgrown Fatass Marathon because of it (and also something of a real tenderfoot on that rugged trail with his VFFs). So he has spent some of the past year also icing his foot, along with physical therapy exercises too (lots of ankle work and calf raises).

Then while training for the SF Marathon, he injured a psoas muscle and one or two adductors. Though seemingly minor, these became aggravated during the race so that he was unable to run his best pace. Afterwards, we noticed he had a big lump on his Achilles tendon, so he is treating all of these new injuries with caution and easy running. David is convinced that it was speed work that was problematic and led to injuries; he’s never had any problems from the longer, slower distances. I am reminded of one of Gordo Byrn’s posts about how big men (i.e., ≥ 6 ft tall, > 165 lbs) benefit from easier training (“Small women get fast from intensity, big men get fast from volume.”). This certainly seems to be true for David. He seemed indestructible when he first started running with me, but then he never had to strain very hard to keep up with me and was always able to stay within his body’s limits. Avoiding high intensity training doesn’t seem to have prevented him from running faster than me!

Weight Loss Followup

In previous posts, we discussed the first several months of weight loss for Cynthia and David. We’re now about two and a half years into our new eating lifestyle, and it seems like a followup post is overdue.

We have been taking near daily measurements through the period with some more occasional measurements of other parameters, so we have lots of data to misinterpret according to whatever bias or slant you might want to apply. As usual, life is complicated, and the data are subject to a lot of coarse- and fine-grained hypotheses that can be postulated to explain various features. We’ll offer an assortment of hypotheses, some of which are more strongly supported by the data than others. Since it’s all basically post-hoc analysis based on two subjects, none of the hypotheses can really be considered confirmed.

The most striking observation, perhaps, is that the change to lower-carbohydrate consumption continues to be working. (Let’s not call it a “diet” since that seems to mean something that people try to use as a temporary measure that ultimately fails when they revert to “normal” eating habits.) While our weight loss has inevitably slowed and had various “plateaus” and “reversals” or “setbacks,” our weight loss is holding and we are both at or near our lows of recent years some 30 months into our new eating habits. This bodes well for the long term. We are emphatically not counting calories, calorie restricting to the point of gnawing hunger, or otherwise depriving ourselves of the enjoyment of eating. Sure, we are emphasizing some different foods and limiting consumption of sugars of all sorts and simple starches, but, for the most part, we don't crave them and can satisfy what cravings we have with either small portions or satisfactory substitutes. Fortunately, we don’t often share meals with the high-carb/low fat crowd, so we don’t face a lot of peer pressure to “cheat,” and we stay away from the French bakeries. There are some differences between our preferred diets as well. David tends more towards the “Optimal Diet” (lower carb and high in butter and cream) while Cynthia gives in more to carb cravings (more fruit and indulgences such as Chinese dumplings), to which she attributes her various weight stalls and reversals!

And, of course, at least among those who are open-minded enough to have actually investigated the current state of the science, acceptance of the low-carb lifestyle has been increasing steadily. While advertising by the food industry continues to be abysmally misleading, we’ve noticed an increasing number of more positive references to low-carb nutrition in everything from a steadily increasing number of blogs posts, books, and scientific papers to passing references in recent movies (e.g., “She eats CARBS” from The Devil Wears Prada). The mainstream government agencies and medical societies are generally still not recognizing the error of the low fat diet, as seen in the 2010 USDA guidelines. (Quoting from Question 5 in Appendix E-1, “Conclusions”: “No optimal macronutrient proportion was identified for enhancing weight loss or weight maintenance. However, decreasing caloric intake led to increased weight loss and improved weight maintenance. Therefore, diets that are reduced in calories and have macronutrient proportions that are within the ranges recommended in the Dietary References Intakes (IOM, 2002/2005) (protein: 10%-35%; carbohydrate: 45%-65%; fat: 20%-35%) are appropriate for individuals who desire to lose weight or maintain weight loss. Diets that are less than 45 percent carbohydrate or more than 35 percent protein are difficult to adhere to, are not more effective than other calorie-controlled diets for weight loss and weight maintenance, and may pose health risk, and are therefore not recommended for weight loss or maintenance.”) There are, of course, huge entrenched economic interests that will continue to fight the status quo tooth and nail. There is some evidence that they may start to crack in the foreseeable future—for example, the American Diabetes Association now recognizes that a low carb diet may be useful for weight loss in diabetics—but progress continues to be slow.

Then there’s the exercise wild card. We all “know” that increased exercise is a “necessary” part of any “reputable” weight loss program. And yes, we have increased our level of exercise. We were never serious couch potatoes, but we weren’t serious athletes, either. Very roughly, we were running 20–30 mi/wk two and a half years ago, and increased to 30–40 mi/wk, and have often done closer to 50 mi/wk. We also started running ultramarathons of 30–50 mi in one day, averaging more than one such event per month at times. So what did all that exercise do for us? Well, we certainly got stronger and faster. We generally feel good and energetic (aside from the inevitable sore muscles and minor injuries). We also continue to find that more often than not, increased exercise correlates with weight gain, not weight loss! This happens both over the short term
(water weight of up to a few pounds the day after an ultra-marathon that may take a few days to lose), and over the longer term (our weight loss trends reversed for about 4 months after we started doing frequent day runs in excess of about 15 mi). We also tended to see a stalling of any downward trend whenever we increased our weekly mileage significantly. Partly, this is because moderate mileage increases such as this are easily compensated for by eating more. There are exceptions too, for example, during August 2009, Cynthia upped her mileage considerably (>50 mi/wk) and found she could not eat enough to keep her weight stable. However, this amount of mileage was not sustainable (due to an injury in May 2009 that began to cause pain), and eventually she gained it back.

There are, of course, several competing things going on when you exercise a lot. Over the period of the exercise itself, the dominant effect is usually level of hydration, and body weight is often used to monitor endurance athletes for dehydration and/or over-hydration. If you exercise hard enough and long enough, you can also deplete your glycogen stores to account for another pound or so of temporary weight loss (including the accompanying water of hydration). So generally speaking, you usually finish a long, hard bout of exercise down a few pounds. But then, of course, you eat and drink. Your appetite increases, so you may eat more than normal, and there are various reasons why you might retain extra fluid. That’s why we frequently saw a net increase in weight the day after. Interestingly, the size of this effect has generally decreased over time. Probably, as our bodies have become better adapted to the rigors of a long, hard day of exercise, they no longer see it as stressful. This is supported by the evidence of less muscle soreness and edema, as well. In David’s case, there is probably also a nutritional effect. He ran earlier events consuming more than normal carbs during and immediately after the event, and then, in later events, switched to more strict low-carb fueling before, during, and after. Some amount of fluid retention would be expected to be correlated with a temporary increase in carb consumption, and eliminating the carbs apparently eliminates that source of fluid retention. Cynthia tends to push harder into her non-aerobic zone, especially when trying to keep up with David, and chooses to consume more carbs during and after long runs, but she’s been showing smaller post-event weight spikes more recently, too. The effect is a sensitive measure of training, because it is more pronounced when less prepared or perhaps as a response to heat stress. The water retention is most likely due to a complex interplay of hormones that signal the kidneys to retain salt and fluid. Such a response is understandable after the stimulus of long and/or hot conditions.

The increased appetite can generally overcome any predicted weight loss from a purely thermodynamic point of view. The problem is that you have to run on the order of 30 mi or so to burn enough calories to consume a pound of body fat (assuming that you’re actually burning fat for fuel). If you do that over a week, it’s pretty easy to unknowingly increase your daily food Calorie consumption enough to more than offset that burn. It’s not much more than an extra couple of “servings” of something tasty per day. Be careful about rewarding yourself with too many bowls of ice cream or extra double cheesburgers!

An increased level of exercise, if done systematically and with adequate general nutritional support (enough protein, for example), often results in muscle building. This can result in body “recomposition”: loss of body fat and increase in lean muscle mass with no net change in weight. That may explain some of the apparent plateauing of our weights. Running doesn’t build bulky muscles the way, say, weightlifting does, but we have seen some measurable changes in body measurements.



Nevertheless, with a very blurry-eyed look at the weight loss data over 30 months, a simple-minded interpretation and hypothesis is that we both generally lost weight more or less linearly for 8 months until we started seriously increasing our level of exercise and then stalled out, remaining at a more or less constant weight for the following 22 months. (Click on figures to show larger.)



With slightly less blurry eyes, one immediately notices that longer trending period tends to follow more of an exponential curve rather than a straight line. A simple model which can be made to fit the data pretty well is to assume that you are always approaching an asymptote (target weight) exponentially so that your rate of weight loss (gain) gets steadily slower as you approach your target. Fitting such exponentials to the various regions on our graphs gives a pretty good fit (i.e., the data looks like it fits a set of straight line segments on a semi-log plot where an estimated target weight is subtracted out). Measured time constants vary from about half a year to two years. And while our weight loss is now hard to see from day to day or even week to week, we are still losing at an average net rate of about a pound every 2–3 months. We both feel like we should be able to lose another 10–15 pounds, but that could take a few years.


It is interesting to treat the data using some of the technical indicators typically used on financial charts. For example, one can draw upper("resistance") and lower ("support") levels and trend lines. Weight can bounce off or break through these lines as you can see on Cynthia's chart from August 2008 through February 2010. You can also see a downward trending channel or notice triangular patterns with converging oscillations, double bottoms, retracement levels, all very similar to observed price behavior on financial charts.

There are other secondary effects that may also be present in the data. While we have so far explained the weight gain last fall as due to increased exercise, it could also be due, at least in part, to a normal seasonal effect. Some weight gain through the fall and into mid-winter is perhaps genetically programmed to store fuel for the winter. Some of it may also be just increased fluid retention in cooler weather (or just reduced dehydration?—the body probably undergoes larger hydration cycles in hot weather as one sweats and eventually replaces lost fluid—but note that a drop in core body temperature actually has the reverse effect as anyone who dives in cold water can attest: the body naturally sheds excess water when cold).

Cynthia's data also show a pronounced oscillation with an amplitude of 4–6 pounds and a period of 1.5–3 months. We have, so far, been unable to correlate this oscillation with any obvious body cycles, lifestyle cycles, eating, or exercise habits. Being female, one might suspect menstrual cycle effects, but the period is too long and the amplitude is too large. (Menstrual cycles generally result in monthly weight variations with an amplitude of about 2 pounds. In order to see it, you typically have to average several months of data [with the end dates of cycles carefully lined up if the length of the cycle is at all irregular] since the amplitude is comparable to normal day to day fluctuations. It's actually more noticeable as a cyclic change in waist circumference.)

David's data show periods of unexpectedly rapid weight loss (July/August 2008, January/February 2009, May/June 2010). Again, we have not been able to clearly explain these periods, although similar “success” periods seem to be commonly reported anecdotally. Perhaps the body suddenly decides to adjust its natural setpoint in some important way. Fat storage and loss is driven more by hormonal signals than by daily calorie balance anyway.

If you want to keep losing weight, you may need to keep reducing your calorie consumption as well. In principle, this should happen automatically if you basically eat to satiety, but eating habits can often be somewhat independent of satiety if you are in the habit of eating particular portion sizes (e.g., 2 eggs and 2 slices of cheese, etc.). Presumably with a little conscious effort, you should be able to readjust your habits to your new needs as you lose weight, but some portions are a little hard to adjust. (It’s not convenient to cook 1.8 eggs for breakfast…)


Another interesting comparison is to plot David’s weight vs. Cynthia’s weight. This plot is noisier in that David’s and Cynthia’s weight gain and loss have not always been tightly correlated despite similar diet and exercise schedules. Overall, David’s weight is approximately 30% higher than Cynthia’s at any given time, but he has been losing about 1.2 pounds for each pound that Cynthia loses. We're still not sure how much more weight we can (or should) realistically lose. The corresponding weight loss rates are consistent with our college-age weights of about 167/125 pounds respectively, but a more realistic goal may be more like 175/133 pounds.

There are other measures of body composition that are often used to determine “ideal” weights. The most commonly used is the Body Mass Index or BMI. This is based purely on height and weight and does not take skeletal build or musculature into account at all. David is still classed as borderline “overweight” by standard BMI guidelines; Cynthia is “normal” at a BMI of ~23.

However, David is relatively well-muscled and big-boned. At least by current American on-the-street standards, most people would not say he was overweight at this point. Another approach to determining ideal body composition is to estimate percent fat. There are many ways to make this measurement—all approximations based on indirect measurements of one sort or another.
Underwater weighing is the current standard against which other measurements are typically evaluated, but it is imperfect, too. Skin-fold thickness is also popular, because it’s easy, but it can be unreliable. See Lyle McDonald’s post for more in-depth discussion. The two methods that are most readily available to most people (including us) are Bioelectric Impedance Analysis (BIA), a measurement built-in to some digital bathroom scales, and various formulas based on using additional body dimensions such as waist, hip, and neck circumference. Our favorite of these right now is a set of formulas derived by the US Navy based on height, waist, weight, neck, and hip (women only): %Fat=495/(1.0324 - 0.19077(log(waist - neck)) + 0.15456(log(height))) - 450 for men or %Fat=495/(1.29579 - 0.35004(log(waist + hip - neck)) + 0.22100(log(height))) - 450 for women. These give current values of 28.5% fat for Cynthia and 18.5% fat for David. Not surprisingly, these calculations put both of us solidly in the “acceptable” range, but still significantly above the upper end of the target ranges for athletes (presumably based on a young military test population: 20% for women, 13% for men). Just to give you some idea of the uncertainty in these measurements, the BIA method as implemented by a Weight Watchers bathroom scale gives 25.4% for Cynthia and 22.4% for David, showing discrepancies on the order of 3% and in opposite directions for Cynthia and for David.

And finally, just a quick observation about the Weight Watcher brand scale implementation of the BIA measurement: while we have been unable to locate any information on the algorithms implemented in the scale, it is clear that there is more than a little something amiss. First, it tends to report %Water in the mid-50s, while the human body is generally estimated to be closer to 70% water. While the instructions warn you that the data may be inaccurate if you take measurements immediately after heavy exercise or large fluid consumption, it is nevertheless disconcerting that it actually tends to report higher %Water (and lower %Fat) after losing a lot of fluid due to exercise and sweating, and lower %Water after a large drink! Clearly the algorithms and/or measurements fail to accurately account for variations in the distribution of fluid throughout the body. Another anomaly we have noticed is that the scale has reported a slight decrease in %Bone for both of us as we have lost weight, something that is very unlikely to be valid.

So all in all, our way of eating is pretty easy to sustain and requires no weighing or measuring. If we really wanted to lose weight faster, I'm sure it could be done using more discipline, but then we'd have to worry about regaining once the discipline slips. This way the changes are more gradual, and perhaps, more sustainable.

Vibram Five-Fingers, 1200 Miles in

Most reviews of running in Vibram Five-Fingers “shoes” are necessarily based on a few days to a few weeks of experience. Journalists, of course, rarely have any longer time horizon available to them since they need to get something out promptly. My own first review was based on a couple of months of experience; this is a follow-up report now that I’ve been using them for some 8 months and 1200 miles.

“Barefoot” Running?
Do I now consider myself a “habitual barefoot runner”? No! I’ve definitely gotten solidly past a transition period away from conventional running shoes and now run (and do most things where I need shoes and can get by without more complicated foot protection) exclusively in my Five-Fingers. However, my feet don’t have good abrasion resistance yet. I can run 3–4 miles on “good” surfaces such as real or artificial turf, smooth dirt, rubber track surfaces, and the like, and up to about 2 miles on rough surfaces such as gravel or rough asphalt or concrete, but for longer distances, I need to wear something on the bottom of my feet to avoid blisters and hot spots. I have no plans to run any organized events barefoot anytime soon, though I will continue to go barefoot for less strenuous activities whenever I think it is safe to do so.

That said, of course, running in minimalist shoes, whether Five-Fingers, moccasins, sandals, or other commercial attempts to provide a near-barefoot experience, does allow you to mimic a lot of the characteristics of barefoot running with our modern typical fragile foot bottoms. Musculature and fat pads adapt more quickly than abrasion resistance, though these, too, require some real adaptation leading to a lot of early problems for people that try to do too much too soon.

Running Style
Whether running barefoot or in minimalist shoes, you rapidly discover (if no one tells you first), that you probably want to move away from the sort of heel-strike running gait that most shod runners are taught to use or use instinctively for anything beyond short sprint distances. True habitual barefoot runners (such as those who grew up not wearing shoes at all) do not use a heel strike. The high shock associated with landing on your heel without any possibility of shock absorption by the foot causes heel bruises and other unpleasant feelings (such as more strain on the knees) if you don’t have any shoe structure to absorb the shock of heel-strike running. Sprinters run on their forefeet and generally don’t let their heels touch the ground at all. But for longer distances (more than about 30 seconds of running), most runners do allow their heels to touch even if they don’t land on them.

There are many possible variations on the exact gait one can use when running in minimalist shoes. Personally, I strive for efficiency as an endurance runner (I’m definitely not a sprinter), and I find that the gait I use for most routine running keeps my feet low to the ground, and my stride length perhaps a little shorter than it used to be. I land first (just barely) on the inside edge of my forefoot and roll the ground contact across the ball of my foot and then back along the outside edge to my heel which just touches the ground with minimal force and then comes back up to reverse the movement until the foot leaves the ground again. This motion, of course, makes full use of the natural structure of the foot and provides maximum opportunity to use all available ligaments, tendons, and muscles for shock absorption, energy storage and release, and push for the next step. I think this is true regardless of your foot type (within normal variations). I happen to have rather flat arches, but I don’t think my minimalist shoe running style is particularly different from that of someone with very high arches. I haven’t yet seen any data on wear patterns for the soles of minimalist shoe runners. Anecdotally, there is still some variability in the location of maximum wear, though much less so than is observed for “normal” running shoes. I think I am seeing what I think is the most common pattern, finding that the point of greatest wear is on the inside ball of the foot and the big toe.

[Addendum 11 February 2010: (thanks to Tuck for making me look more carefully at Daniel Lieberman’s pressure-plate video) It seems that exactly where you naturally strike on your forefoot depends on your particular foot structure. I have rather flat arches and a tendency to pronate (turn my foot inward) which is manifested in a tendency to wear the inside edge of the heel of shoes when running with a heel-strike gait. In a forefoot gait, I land first on my first metatarsal and then transfer weight to my big toe, then across the rest of my metatarsals. Daniel’s pressure plate video (presumably of himself running) shows initial pressure buildup under the fourth metatarsal with a roll toward the first metatarsal. Presumably he does not tend to pronate and likely has higher arches than I do. If you don’t have access to time-resolved pressure plate data recording equipment and don’t want to wait a few hundred miles to analyze shoe wear patterns, here’s a simple trick I found that should tell you how you should probably land: Stand up (barefoot) with your leg forward. Point your toe (i.e., bend your foot forward), but keep your ankle in a neutral position laterally (don’t consciously turn it either in or out). Now touch your foot to the ground. When I do this test, I touch with my first metatarsal and/or big toe. Cynthia, on the other hand, who has high arches and no tendency to pronate, touches on the fourth metatarsal. While there are some people who try to get everyone to do the “right” thing meaning the same thing they do, it is my belief that there is no right or wrong way to use your foot. You should do what is comfortable and natural for your particular bone and ligament structure. For me, while I could force myself to land on my fourth metatarsal, it would be an unnatural thing to do and likely cause undesirable side effects in the form of muscle strain.]

Landing on your forefoot results in a gentler landing with less force against the ground, less shock on the knees, and less noise. You become the proverbial Indian brave, able to run quietly through the woods in your moccasins (or equivalent). In fact, one of the ways that you can further train yourself to reduce stress is to aim for the quietest running that you can achieve. There is still a range of impact force that can be used with forefront landing, and a good way to aim for lower impact force and greater running efficiency is to listen to your running and try to keep it as quiet as possible. You may need to ramp up the noise a little bit again when you’re out to get maximum speed, but for most routine running, quieter is probably better.

While I am primarily a trail runner by temperament, one surprising (to me) consequence of switching to a forefoot landing habit is that running on hard surfaces such as roads is no longer something that I shun. Since I am now a gentler runner, long distance pavement pounding is just not nearly as stressful as it used to be, and in fact, all else being equal, I now find myself seeking out the smoother harder surfaces rather than running on the adjacent dirt if both are available.

Another aspect of running in minimalist shoes is that you are less constrained to hold your foot in a particular orientation relative to your leg. Most of the time this doesn’t matter all that much. But if you happen to be contouring along a steep hillside or placing your feet on the sides of a deeply rutted trail, you may find yourself needing to adapt to a surface that is far from perpendicular to your leg. In shoes, this can be an unpleasant ankle twisting (and even ankle spraining) experience. But with Five-Fingers shoes you can take up most of the extra bending in the foot rather than the ankle with structures that are much better adapted to the bend than is the ankle. This is an aspect of barefoot/minimalist shoe running about which I’ve seen very little comment. I discovered the phenomenon accidentally one day when I found myself running along the side of a very steep hillside, cutting across an open field. I suddenly realized that the running was much easier and much less stressful on the ankles than I would have expected.

Muscle and other Soft Tissue Development
Any change in running style—whether due to a change in footwear, compensation for injury, change in running surface, distance, or terrain—will stress muscles in new and different ways. Most notably, switching from heel-strike to forefoot running increases the dependence on muscles associated with the feet. The strongest of these muscles are actually located in the lower leg and connected via an elaborate system of ropes and pulleys (a.k.a. tendons, ligaments, and fascia) to the bones of the foot. Runners who transition too rapidly from heel-strike to forefoot running often experience at least pain if not outright injury in their lower leg muscles as well as their Achilles tendons and plantar fascia. As with any transition, the key is to start slowly—less than a mile for the first few days, increasing gradually as muscles allow. Plan on a minimum of 2–3 weeks of gradually increasing distance, speed, and difficulty, and preferably at least twice that long. Back off if you experience any significant pain. If you want to supplement your actual running with other training, then anything that puts you on your toes (calf raises, skipping rope, dance or fencing exercises) can be useful cross training.

How did I fare during my transition? Well enough. I had an enforced reduction in mileage about the same time I made the transition due to an unrelated injury. I’m finally fully recovered from that injury, and I actually think that forefoot running and the associated reduced knee stress helped me recover more quickly and increase mileage again more quickly. I’m presently contending with a mild case of plantar fasciitis in one foot—nothing that is limiting my running at all, but annoying all the same. Again, I find that forefoot running is less stressful on the injured tissues.

Padding
Of course, one of the main things that people wonder about, especially for trail running, is the issue of how you can run on rough surfaces without much cushioning from a shoe. Running on surfaces with a lot of small stones (rocky trails, gravel roads with relatively little actual gravel) is the most challenging. It takes a while to toughen the pads on the balls of your feet, but it does happen. The improvement is gradual and takes easily 3–6 months depending on how you train. Eight months out, I find that surface that used to leave my feet feeling beat-up after a few miles no longer bother me at all. I can run 10+ miles on very challenging trail surfaces and come home feeling unaffected. A recent 50K run that included a lot of gravel trail still left me feeling a bit worked over, but my feet were fine again by the next day.

The older models of Five-Fingers shoes (including the KSO model that I wear) have practically no tread or padding in the sole. In response to customer feedback, newer models incorporate some tread which also provides a little more damping out of the running surface roughness. Since I haven’t had an opportunity to try running in the new models, I can’t comment except to say that, now that I am well-adapted to running with the older thinner soles, I don’t feel any particular desire to have more protection under my feet than what I’ve got now. From a marketing point of view and the usual sort of instant gratification that many customers will want, I’m sure that a bit more sole will be a good thing; for more experienced minimalist runners like me, it doesn’t seem that more sole has any compelling attractions.

I also noted an unexpected pattern to the toughening of the pads on the balls of my feet. There is a transverse arch across the ball of the foot, and I, at least, expected that not much would happen in the middle of the arch (behind the second toe), thinking that the primary stress would be on the outsides of the arch. In actuality, the reverse happened. The most toughening occurred precisely in the middle of the arch, and there even tends to be some slight callous development there! Apparently, the transverse arch flattens completely on impact and the middle experiences as much or more force than the outsides even though the initial contact and maximum sole wear points are on the outside.

Traction
As I just noted, Vibram has recently introduced newer models that include more familiar looking shoe bottoms that have some lugs that provide both more padding and maybe more traction. After 1200 miles of running on varied surfaces including concrete, asphalt, rubber, dirt, mud, sand, rock, turf, fields, etc., I can say that I have almost never felt at a loss for traction in the KSO model soles. These soles are smooth flat rubber with laser-cut zig-zag patterns that increase grip on smooth surfaces. The only surfaces that I have found difficult to deal with are those with thin slippery mud which are challenging in any footwear (though probably respond better to lug soles than smooth soles). Deeper mud and soft sand/ash present no difficulty—the toes work very well to provide good grip and traction. Wet surfaces are generally not a problem—the rubber grips well. I don’t recommend Five-Fingers shoes for snow and ice, but under such conditions you probably want more thermal protection anyway, never mind the traction issues.

Foot Protection
Minimalist shoes clearly provide less protection for the foot against all sorts of insults. You wouldn’t want to wear them anywhere where normal safety practice would dictate steel-toed safety shoes, for example. You won’t get much protection from ankle twists, kicking hard objects (rocks and roots), sharp objects, others stepping on your feet, etc. If you need arch support or ankle support, you won’t get it (though some people who have failed to get much relief from arch-related problems with all kind of expensive orthotics have found that going minimalist instead actually turns out to be more beneficial).

So what’s my track record after 1200 miles? Pretty good and getting better! Early on, I caught one little toe on a root and wrenched it badly enough that it hurt for a couple of weeks, but that’s probably the worst thing that’s happened. I’ve also kicked a handful of rocks and roots, especially running in poor light. I have to consciously work on lifting my feet more when I can’t see the trail surface very well. I’ve poked my feet into an assortment of sharp sticks now and then, enough to do some damage to the shoe uppers, but not enough to break skin. Not surprisingly, the more you run with minimal protection, the more you instinctively avoid problems. Just as I’ve found that my rate of falling (never very high) has gradually decreased over the years, my rate of minor foot trauma has declined to almost zero over the last several months.

One of my most annoying problems as a shod runner was toenail bruising. Long downhill runs where you are constantly jamming your toes against the front of your shoe cause the most trouble. Even with careful shoe sizing for plenty of toe room, careful toenail trimming, and various aids in the form of taping, toecaps, tubes, and the like, I usually found myself losing toenails due to such bruising a few times a year. Hilly ultra-marathons generally did the most damage. This was probably the single most important factor that drove me to try Vibram Five Fingers in the first place. In the last eight months I still lost one toenail, but it was the result of kicking several rocks in a row while running in the dark, so I’d have to argue that it was really my own fault. I just don’t have toenail jamming issues with Five Fingers footwear. You fit the shoes small. I wear at least a size 44 (European) in most running shoes, but only a size 42 in Five Fingers. Your feet don’t slide inside the shoe. The front of your foot between the toes hits fabric and prevents the toes from jamming into anything.

Socks
Five Fingers shoes are usually worn without socks, though they can also be worn with toe socks such as those sold by Injinji. I started out wearing socks more often than not, and especially for runs of more than about an hour and when the weather was warmer (my feet tend to sweat more in hot weather). As time has gone on, I wear socks less and less; I just don’t need them. I almost never wear them for runs of less than two hours now, and I’ve done a full (winter) 50K without socks. One key to running without socks is to remember that the shoes, in effect, become your socks. So just as you wouldn’t wear socks again after a long run without washing them, you need to wash your Five Fingers regularly. You also need to make sure that your feet are really clean before you stick them into your Five Fingers. I regularly use a pumice stone to remove all surface debris from my feet including any sticky dirt and grease. That keeps the inside of the Five Fingers much cleaner and minimizes accumulation of junk that can cause abrasion. I wash my Five Fingers after any long run, any muddy run, and any very dusty run, and at least once a week regardless. After my 50K run, I did have a couple of minor blisters that I hadn’t realized I’d gotten. They were on the inside side of both feet in the arch region at a seam. I’ll probably opt for socks on future 50K+ runs just to protect myself from this particular hazard.

Keeping Stuff Out
The KSO model is named for “keep stuff out.” It has elastic fabric over the top of the foot that fits snuggly. It works! I’ve never had to stop to take my KSOs off to remove debris. I can’t say the same of any other shoes I’ve ever run in. KSOs still don’t keep everything out, though. They don’t keep water out, and they don’t keep fine dust out. After running in dusty conditions, your feet will look like you have dirt socks on. But I’ve never had any trouble either from dust or from wet feet. Neither has caused any harmful chafing. I consider myself fortunate to have ended up with the KSO model; other runners I’ve talked to that have ended up with other models that don’t have fabric over the top of the foot do have problems keeping stuff out.

Durability
Shoe manufactures would like you to believe that you need to replace your running shoes every few months or every few hundred miles whichever comes first. I never really bought into that plan, running happily for many months and miles in nominally worn-out shoes. Nevertheless, I am still impressed by how few signs of wear my Five Fingers show after 8 months and 1200 miles. They should be good for many more miles to come. That’s not to say that they have been completely problem free. There have been a handful of holes and seams to repair particularly wear I’ve poked the fabric with sticks. These are easy repairs to make since the material is just a cloth fabric that is easily sewn. The soles are holding up well. There is visible wear, but since there are no lugs to wear off, the wear is spread over more surface area. I have not yet needed to add any material to the soles and may not need to over the life of the shoes. As yet, I still can’t tell what the ultimate end-of-life failure mode is likely to be.

The most serious design flaw from a durability point of view in the KSO model is the strap and the slot through which the strap passes on each side of the foot. The strap is made from a relatively thin nylon fabric, and the slot is reinforced with a hard plastic resin. The nylon rubs against the edge of the slot and wears through after a while. I have so far dealt with the wear by reinforcing each strap where it goes through the slot with some thin leather. If I ever have to actually replace the strap, I will try to find some heavier duty material to use. But if I were to change one thing in the design of the KSO Five Fingers, it would be the choice of materials for the straps and slots.

Another weak point in most running shoes is the insoles. These often wear out before the rest of the shoe and need to be replaced. However, with my careful cleaning habits (both my feet and the shoes), I see no signs of wear at all yet on the insoles of my KSOs. When I wash them, I am careful to clean the surface of the insoles of any accumulated dirt and grime. I’m sure this helps. In fact, I suspect that the combination of clean practices and the natural tendency of the KSOs to keep stuff out are the primary reasons for my good experience.

The newer models of Five Fingers intended for trail runners have switched to leather uppers. While I haven’t tried these out, I don’t presently view this as a positive change. I like my thin elastic uppers. They have proven to have adequate durability and are easily repaired when damaged, they breath easily to keep my feet cool, and they can be quickly washed and dried. I am skeptical that leather would perform as well.

—David

Bibliography
There is an ever increasing number of articles and blogs about barefoot running, Vibram Five Fingers and the like. A selected bibliography includes:
http://www.nature.com/nature/journal/v463/n7280/full/nature08723.html
http://www.runningandrambling.com/2010/02/vibram-fivefingers-kso-trek-review.html
http://www.runningandrambling.com/2010/01/invisible-shoe-huarache-review.html
http://www.runningandrambling.com/2010/02/barefoot-professor.html
http://www.runningandrambling.com/2010/01/declaration-of-dependence.html
http://www.runningandrambling.com/2010/01/brooks-ceo-jim-weber-on-barefoot.html
http://www.runningandrambling.com/2009/08/barefoot-revolution.html
http://www.sportsscientists.com/2010/01/running-barefoot-vs-shoes.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+blogspot%2FcJKs+%28The+Science+of+Sport%29
http://stevemagness.blogspot.com/2010/01/why-running-shoes-do-not-work-looking.html
http://stevemagness.blogspot.com/2010/01/first-big-study-on-barefoot-running-in.html
http://www.time.com/time/video/player/0,32068,62885933001_1955910,00.html
http://www.time.com/time/magazine/article/0,9171,1955580,00.html
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/09/02/BA1G19FFPH.DTL
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/10/05/DDG419E4P0.DTL
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2009/10/05/DDGB19VSQV.DTL
http://www.nytimes.com/2009/08/30/business/30shoe.html?_r=1&scp=1&sq=vibram&st=cse
http://well.blogs.nytimes.com/2009/09/01/have-you-run-barefoot/?scp=2&sq=vibram&st=cse http://well.blogs.nytimes.com/2009/10/05/the-roving-runner-goes-barefoot/?scp=9&sq=vibram&st=cse

Primal Potatoes—a Contrary View

In a recent blog entry “Primal Potatoes, Part 2” the author tries to make the case that humans are evolutionarily adapted to include starchy foods such as tubers in their diets, and that there would be survival advantage in keeping glycogen stores higher using these sources of starch. We don’t disagree with all of the conclusions he ends up with, but we think that a lot of the “evidence” used is factually incorrect or misleading. Here’s our take:

There is no doubt that the human digestive system has broad adaptability. The fact that humans are “omnivores” who can digest most everything that any animals eat except straight cellulosic materials (grasses and dietary fiber) clearly provides a survival advantage in that it allows humans to survive for at least short periods on whatever food source is available. It does not follow, however, that the ability of humans to digest starches means that they provided a real performance advantage in hunting and/or survival activities and would have been a required part of our diet. Rather, it seems to us that humans are well-adapted to depend predominantly on aerobic exercise (fat-burning) which can be sustained for many hours even in a fasting state if necessary, using the generous fat storage capacity available. Humans have an auxiliary system able to use the much more limited glycogen (carbohydrate) energy stores for primarily short bursts of intense exercise (30 seconds or less at a time) or to supplement for higher intensities than can be sustained by fat burning alone. This auxiliary system is further adapted to replenish/restore itself fairly quickly, again, even without the aid of carbohydrate consumption. While it is possible to create situations in athletic training and competition where the rate of depletion can be faster than can be replenished in steady-state (especially for athletes who normally depend on carbohydrates for much of their calories), it does not follow that such rapid depletion followed by rapid replenishment using dietary carbohydrate sources, was ever important or necessary in evolutionary terms. Note, for example, that athletes in many sports routinely use “reps” or “intervals” of intense activity separated by recovery periods, typically with no consumption of food or drink during the recovery periods. To the extent that fuel stores are being restored during these recovery periods, the process does not depend on any particular external source of calories.

In effect, the body is so effective at conserving and recycling its limited stores of carbohydrate fuels that large dietary replenishment would not have been required to satisfy the needs of hunting and survival activities.

An article by Fournier was cited in “Primal Potatoes, Part 2” to support statements that “whereas typical glycogen stores will support an intense aerobic exercise for a few hours, a single maximal sprint effort will deplete one-third to one-half of glycogen stores,” and “humans can replenish glycogen stores without dietary carbohydrate, and even while fasting.” However, the article link did not work. A PubMed search found this article which appears to match the cited reference. The article describes experiments on rats which were made to engage in moderate exercise (swimming for 30 min with a weight attached to their tails), followed by a 3 min “sprint” (when a much heavier weight was attached to their tails). The main point of the article was to determine if the lactate produced during the sprint was the predominant source of carbon incorporated into newly synthesized glycogen. If you look at Fig. 1, you’ll see that the preceding “moderate” exercise depleted glycogen by at least 50% before the “sprint,” which then further depleted glycogen (down to ~25%). The researchers concluded that the lactate only provided ~50% of the newly synthesized glycogen, which actually is not surprising given that the previous glycogen depleting activity had already reduced the amount of glycogen available, and presumably any lactate that was or could have been produced and therefore recycled into new glycogen had already been oxidized completely and was no longer available. In short, the cited article does not support the first statement, which appears to be an exaggeration. There was no study showing that a single maximal sprint would deplete one third to one half of stored glycogen. Rather, the already ~50% depleted glycogen stores were further depleted by the “sprint,” showing only that the higher intensity the effort, the more rapidly the glycogen was depleted. A “single maximal sprint effort” as we understand it would most certainly not deplete a large fraction of glycogen stores. It may feel like it, but that feeling is not due to glycogen depletion per se, but rather due to acidification due to lactate and carbonic acid accumulation.

There is some confusion as to the meaning of the word “sprint” and how different available fuel sources are used by humans in sprint versus endurance events. True “sprints” (short bursts of maximal effort) do not even depend on glycolysis, which is too slow. There is a third energy storage and release system based on local stores of ATP and phosphocreatine. These are typically sufficient for about 7 sec of peak power output, and are rapidly regenerated during any rest periods using energy from aerobic glycolysis or fat metabolism. (See, for example, Noakes, Lore of Running, p 154.) But even a 100 m sprint by a world-class runner takes longer than 7 sec, and some energy must then come from glycolysis. Perhaps a single clean-and-jerk or other 1 rep maximum weight lift can be completed using primarily this sort of burst of maximal energy, but even a typical set of 10–15 reps in weight training takes longer.

Most people probably think of a “sprint” as something roughly equivalent to a 100 m or maybe as much as a 200 m maximum-speed run. Such efforts typically take about 10–30 sec to complete and, while not possible using only the local ATP and phosphocreatine stores, the effort can be completed mostly anaerobically, fueled by local glycogen stores. The 30-second maximum for this kind of effort is probably limited by the acidification resulting from the rapid production of lactate. What glycogen has been depleted can regenerate rapidly when the maximal effort ends. “Recovery” for a repeat of a similar effort largely consists of clearing enough of the accumulated lactate to relieve the sensation of “burning” in the muscles. Fuel depletion is not a major issue.

Three minutes of a “sprint swim” (or an 800 m run or a flight from a predator) is a much more complex sort of “maximal effort.” It is not a sprint as usually defined for humans. It is a “middle distance” that cannot be completed purely anaerobically. Even an 800 m run (2 min of effort for good runners) is considered an endurance event (requiring stamina), and much of the speed can be developed using aerobic training, though a maximal effort of this length will utilize primarily glycolysis and generate a lot of lactate temporarily. (See http://www.lydiardfoundation.org/news/pdfs/Snellcourirenglish.pdf.)

Clearly the maximum power output that can be maintained for a few seconds cannot be maintained even for 30 sec. A several minute effort is still in the range where a human is capable of power output that exceeds levels that can be sustained for much longer periods of time. The relative contributions of the available metabolic paths to energy generation for an maximal effort of a few minutes can vary widely depending on the individual, the level of normal activity, training or conditioning, dietary habits and adaptations, and the level of actual effort relative to the individual’s maximum capabilities over that distance or time. Anaerobic metabolism of glucose from glycogen is certainly one of the possible contributors. In fact, the limit to how fast any one individual can go for, say 3 min of “maximal effort” is probably still set by acidification caused by lactate accumulation (and carbonic acid from CO₂ produced) due to anaerobic glucose metabolism. As the anaerobic metabolism of glucose is very inefficient and would rapidly deplete stores, additional more efficient metabolic pathways will be tapped, most notably aerobic metabolism of fat and glucose. Another important contribution comes from the aerobic metabolism of the lactate (produced from anaerobic metabolism of glucose mentioned above). If lactate is being overproduced, some of its carbon will be further metabolized in the heart and muscles and converted to CO₂ through the citric acid cycle, and eventually breathed out, with most of the potential ATP from the glucose being realized eventually, even if not in the muscle of origin. At modest production rates, much of the lactate can be used aerobically and directly as fuel by the muscles, and is a preferred fuel of slow twitch and heart muscle. In addition to possibly being used by other muscles, this lactate is also taken up by the liver and converted back into glucose and then glycogen, and thus recycled. In short, it takes a lot more than a 3-minute burst of effort to substantially deplete glycogen stores. In fact, calculations show that the glycogen stores of a well-trained runner are sufficient to last for approximately 2 hours if glycogen is the exclusive fuel (and, incidentally, stored fat would last for about 59 hours [estimates based on glycogen and fat stores present in lean elite athletes]).

Thus, it is simply not true that there would be an urgent need to fully replenish severely depleted glycogen stores after a single episode of high-energy activity. The glycogen stores would not be significantly depleted (e.g., >50%); any of several available replenishment mechanisms would be sufficient to provide necessary restoration; and there is, in any case, no urgent need to provide complete restoration within 24 hours anyway.

This renders meaningless all of speculation in the post about the large amount of protein that would need to be consumed to replace the allegedly depleted glycogen. Let’s consider first, how the body actually uses its glycogen stores. Many authors tend to focus on how much total glycogen can be stored in muscles, how much activity that amount will support, and how much time is required to replace and completely refill the muscle glycogen stores. This way of thinking may be relevant when trying to achieve peak athletic performance for a particular competitive event, but this artificial effort would not be relevant to “normal” life and evolutionary pressures. In "normal" life, maximal effort may be required on occasion, but would be punctuated with adequate rest periods to allow recovery and maintenance of energy stores. Glycogen available to any given muscle for short intense effort is only that stored locally in that muscle—you can’t steal from other muscles. Similarly, once stored in the muscles, it remains there until used—it is not depleted beyond a certain level that is protected and maintained even after extensive exercise.

Even after an exhausting race, a person can still increase their efforts and sprint to the finish. A critical detail to remember is that lactate produced from glycolysis can be used to regenerate glucose and then glycogen, as well as enter the citric acid cycle and be used aerobically. Hence lactate is recyclable—glucose can be used anaerobically for a brief intense effort, then rapidly regenerated from lactate once there is a rest period. Under conditions of carbohydrate restriction or partial glycogen depletion, the body simply intensifies the recycling effort and favors use of fat for most energy needs. Only during periods of long and repeated exhaustive glycogen depletion would glycogen levels be dangerously low, and then the body would attempt to reserve them for emergencies, decreasing intensity of activity to levels supported by fat metabolism.

That said, the amount of glycogen storage for any given muscle is also “trainable” in that the amount of glycogen stored increases with increased use. A well-trained athlete may be able to top out his muscle glycogen stores at as much as three to four times that of a sedentary individual. And presumably, a paleolithic hunter is more similar to a modern athlete than to a couch potato. Further, the “normal” steady state condition for an active individual is probably not with glycogen stores full, but more like half full. This seems to be the condition measured for endurance athletes in steady state (i.e., several hours into a many-hour event or in everyday training. See Noakes, Lore of Running pages 101–102 and references therein). It may take a day or more of resting and relatively high carb eating to fully replenish glycogen stores to maximum capacity, but the half-full steady state can be maintained more or less indefinitely, and is fully capable of supporting most any activity that is needed. Further, at least for individuals adapted to fuel their activity primarily on fat, this steady state can be maintained with little or no carbohydrate consumption, and at levels of protein consumption that are modest compared to any levels that might overwhelm the kidneys.

A further point is that it is possible that this “half full” condition is optimal for health, in that muscles that are not topped out with glycogen are still hungry for more glucose, that is, they still express glucose transporters on their surface that are actively scavenging for glucose. This constant glucose uptake by hungry muscles would tend to keep blood glucose levels low, optimize insulin sensitivity and thereby keep insulin levels low, compared to the condition of the over-fed over-carbed SAD consumers. (See http://ajpendo.physiology.org/cgi/reprint/285/4/E729.)

As soon as liver glycogen starts to decrease, gluconeogenesis kicks in, and if adapted to fat burning, gluconeogenesis enzymes may be up-regulated. One can sustain aerobic activity (presumably using glycogen stores in addition to fat stores) for many hours and still have no measurable depletion of blood glucose levels! In fact, we routinely observe the opposite (elevated blood glucose after hours of running). Glycogen stores can thus be regularly replenished (at least partially- enough to call on in emergencies) as needed even during prolonged aerobic exercise, even when fasting, to support the needs of occasional anaerobic activity. As already noted, data indicates that trained athletes can maintain a steady state level of average glycogen stores that are approximately 50% of their maximum capacity. Put another way, during prolonged periods of inactivity, a trained athlete can store ahead approximately twice the “normal” levels of glycogen stores. (Note that even the “normal” levels are about twice those measured in sedentary humans.)

In the example given of hauling a buffalo carcass out of a ravine, this activity may involve some anaerobic activity, but it will necessarily stretch over an extended period of time and be completed primarily using aerobic metabolism. There may be brief bursts of high intensity effort as needed, and there may even be bursts of extreme effort for particular heavy lifting tasks, but on average the task will necessarily be completed with levels of effort that can be sustained over hours not minutes. We suggest that hauling out a buffalo carcass would not necessarily require a lot of glycogen, and even if it did, would not necessitate gorging on potatoes or other carb food to replenish glycogen stores. Perhaps the one situation outside of athletic competition that could force someone to put out maximum effort for as long as possible (and thus seriously deplete glycogen stores) is a fight (or flight) for life. These events presumably don’t occur in close succession, so the primary evolutionary adaptation would be to provide the capacity to sustain the necessary fight or flight long enough to survive the immediate crisis. An ability to fully recharge is not necessary and would not confer much less of a survival advantage.

In fact, it is often argued that the key characteristic of humans that makes them surprisingly competitive in the predator vs. prey world compared to animals that are nominally bigger, stronger, and faster is that humans don’t depend on their peak power output capabilities but instead on their ability to maintain lesser levels of output for very long times (as, for example, in a “persistence” hunt, where they literally outlast and outrun their nominally faster prey).

Other purported advantages of eating tubers cited in “Primal Potatoes, Part 2”:

1. Lower dietary protein/meat requirement, reducing the pressure for success in hunting large animals, and making it possible to feed more people (offspring) with each kill.

This seems to be a common misconception! Eating less carbohydrate means eating more fat, not more protein. And the hunting of large animals provides increased fat relative to smaller animal sources of protein. It is difficult to eat large amounts of protein, and most people find it almost impossible to eat too much protein. It is true, however, that tubers are easier to store for extended periods than meat (and meat fat) which must be more carefully prepared for long term storage, especially in warmer climates. Agriculture does enable more concentrated population centers and was probably a major driving force for the increasing urbanization of the world. However, it is not at all clear that the sort of monoculture version of agriculture that has come to dominate how we feed large populations is a positive step. In fact it is becoming increasingly recognized that we may be destroying the planet faster with mass agriculture than we ever did by overhunting.

2. Less burden on the liver for ammonia detoxification.

This is nonsense. Again, protein consumption tends to be self-limiting at levels well below anything that would present any significant burden to the liver (or kidneys).

3. Easier to avoid protein poisoning while at the same time maintaining greater glycogen stores.

Again nonsense. Protein poisoning is just not a serious risk. And it is not difficult to maintain more than adequate glycogen stores with very low carbohydrate consumption because glycogen stores do not need to be 100% full in order to provide adequate auxilliary anaerobic energy production.

4. Easier to maintain and increase lean mass in response to the stresses of high intensity activity, with a lower dietary protein requirement.

False! As anyone who has seriously tried a low-carbohydrate diet knows, it is much easier to maintain lean body mass without increasing excess fat storage if carbohydrates are minimized in favor of fats. And carbohydrate consumption always causes blood insulin levels to spike, which has a whole series of negative consequences. Arguably, from a public health point of view, the widespread adoption of higher-carbohydrate diets was the single worst event in human history that is the major cause of most of the so-called “diseases of civilization.” Building lean mass (muscle) is usually easier with adequate protein consumption. The key to maintaining it is to (1) make sure that you maintain sufficient nutrition so as not to catabolize too much of your own protein (which the body will do if other fuel sources are limited) and (2) to consume enough protein for muscle building and rebuilding/repair. (See for example http://www.bodybuilding.com/fun/md92.htm and references cited therein, which provides evidence that excessive carbohydrate consumption post-exercise actually inhibits optimal muscle growth and repair.)

5. Reduced pressure to hunt only the fattest animals by use of carbohydrate instead of fat to dilute the protein content of the diet; which greatly enlarges the pool of potential prey, increasing dramatically the amount of energy available for harvest.

Fat is good anyway! You should always be hunting for your fat needs as well as your protein needs. You just don’t need that much total protein. But you do need some protein, and high quality protein (i.e., the so called “essential” amino acids) is hard to get in sufficient quantity from non-animal sources.

In summary, while we certainly believe that humans likely ate tubers and other starchy vegetables (and eventually the New World potato) when they could be found, we see no evidence that that behavior conveyed any sort of evolutionary advantage beyond survival in times of limited food availability.

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!