omenti

clues to the mind and the mind-body connection

We're all aware of cute optical illusions.  Some play tricks with our perception of color, size, or motion ...   This particularly beautiful example plays with our perception of brightness - both turn out to be equally bright inside and out.

 

 

Optical illusions are an interesting tool to study how our brain puts together sensory input sent by the eye and there have been some major surprises and there have been revelations that address the question of how much of reality do we sample through our senses as we observe the world.  To what degree are we sampling reality?

 

I stumbled across this example in a PNAS paper by Bruno Laeng and Tor Endestad of the University of Norway in Oslo.   The illusion is well known, but they looked at something else - how the pupil responded.  

 

If you look at something bright your pupils constrict to adjust to the new brightness level.  This takes place in about a tenth of a second - reasonably fast on our level of perception - and it was thought to be a pure reflex that helps protect the retina from damage.  Reflex mechanisms should be fast to prevent as much damage as possible and this one was thought to occur in in a few dedicated cells in lower brain structures.¹  What is curious with this illusion is our pupils contract even though there is no real brightness - the reflex is in response to what we think we see rather than what really exists! 

 

This is fantastic.  Perceptual errors behave more liked learned phenomena and may be adaptations.  Perhaps evolution has made us more adroit at encountering our environment.  

 

A lot of visual information is ambivalent and noisy.  Perhaps there is some contextual processing going on to construct a "reality" that is more useful.  Maybe the reality our mind assembles is a bit better for our functioning that what really exists in nature.

 

The same goes for other senses - particularly hearing, but taste also comes to mind.²

 

As I am writing this it occurs to me that there are many other evolutionary tricks that help us to deal with how we relate to the environment.   We read stories of animal athletes - cheetahs that can sprint to 70 mph, our cats and dogs that can make jumps that appear amazing - and sometimes think humans must be unathletic in the scheme of things.  But we are amazingly good at endurance running.  We probably evolved to this as our ancestors may have had to run down prey in order to get close enough to dispatch it, but whatever the reason we are wonderful aerobic machines.³

 

Many people report a "runner's high" after exertion.  I find it around the sixty minute mark with my rowing and, if I make it that far the resulting rush is enough to encourage me to continue for as long as an extra half hour.  It is a feeling of real euphoria.

 

It turns out the body under heavy aerobic load produces endocannabinoids which are substances that act as neurotransmitters.  The name probably rings a bell - endocannabinoids are chemically very similar to the active ingredient in cannabis.  

 

The runner's high is the real thing and the euphoria can be an excellent reward.

 

Recently it has been learned that a few mammals that are good aerobic athletes(humans and dogs) produce serious amounts of endocannabinoids during aerobic exercise while other mammals that aren't aerobic athletes (ferrets) don't.  It may be we have evolved a reward system to encourage this type of activity - I know it is one of the few things that keeps me on the rowing machine for lengthy periods.   Colleen is more geared towards bursts of power, but she notes that she loved the feeling of euphoria that came over her after an hour or so of intense training and the reward was enough to encourage her to go on for several hours more. 

 

My niece Magi is a runner.  A remarkable runner.  She is a single mom with two very little kids and is struggling with raising them, working a couple of jobs and going to nursing school.  A few years ago she took up running and found it came naturally.  She's done several marathons and does respectable three hour times - not bad for someone who can't run every day and rarely more than an hour at a time and also lacks the money to get coaching - shoes are a major expense for her.

 

She lives in the Phoenix area and has always been comfortable in the mountains.  A few races were in the back country and she found she really liked them.  Also she learned that she's good with distance. Her quarter times on the Boston Marathon were all within a minute with the last quarter being the fastest.   About a year ago she started trying the longer distances and did very well in several fifty mile runs.  

 

With those under her belt it was time to get serious.  Last Saturday she ran the Zane Grey - not a race for the faint of heart.  Rather than writing about it, I'll print the email she sent and add a few images.  Do read the links from the race director and another runner for more color...  like

...

The course runs along the base of the Mogollon Rim, constantly dropping in and out of the little canyons and crossing multiple creeks and streams.  The route is entirely single track trail and is extremely rugged.  Despite a ton of work our volunteers have done on the course, entrants will have to navigate over or under fallen trees, through thick wickets of Manzanita bushes, and over very rocky terrain.  There are also sections where the trail just disappears and route finding can be challenging.  The middle section of the course, known as the “burn area” had the trees burned down from the Dude Fire in the early 90’s. Runners are exposed to the heat of the Arizona sun and have to travel as far as 11 miles between some aid stations.  An unprepared runner can sometimes run out of fluids in these long hot stretches.

 Not easy terrain down there. The Mogollon Rim is rough, tough and relentlessly difficult

...

 

with that, Magi's email:

 

Here is my first race report. I apologize in advance if you do not want to read this much about me, nevertheless this was an incredible experience and I am really excited to share it!

 

The Zane Grey 50 has earned a reputation for being one of the most grueling ultras out there. I had spoken with friends who had completed the race and the consensus was I could expect to add about 2 hours onto my avg 50M time (if there is such an avg) prepare to trip, get scratched, sprained, dislocated, lost, broken, etc.,, this all sounds like adventure right?! The race was a bit of a blur so I am sorry for the lack of detailed trail accounts.

 

 April 21st 2012 was the big day of the notorious race, in anticipation of this I had prepared with all sorts of hot, hilly, long, and really fun desert mountain runs. Emmet was prepared to crew for me race day, this made a huge difference. Knowing that someone 100% reliable is waiting for you at designated aid stations on the course with water and nutrition refills, sunblock, an icy towel to wipe down with, words of encouragement, and anything else you may possibly need is beyond words. I say this because when you are running 50 miles through some of the most unpredictable Arizona terrain, your entire life is narrowed down to the steps it takes to get your butt from aid station to aid station. Emmet has accompanied me on many training runs so he knows my pace, my weaknesses, my strengths, and he also knows how to tell me what I need when I may not realize it, this is important. The weather was predicted to be 90 degrees, I wasn't to concerned about this, by default I have to train in the heat and have learned to be very smart about hydration and electrolyte balance. Unfortunately the heat was by far the biggest hazard on the course that day for many of the runners, out of 126 starters only 84 finished.

 

this link is an interview with the race director

 

 

this link is by a runner, he has great pics of the course in his blog

 

 

In the two days prior to the race I have a total of 5 hours sleep, this was the only stimulus for self-doubt weighing in my head. The night of the race I was lying in bed with the "I want to cry but I'm so mad I can't" feeling. The alarm clock went off at 3:15 am and all that nonsense turned into baloney, it was race day, wheee! We arrived at the start 4:30am, just enough time to hit the bathroom, check in with race officials, and stay warm in the car until just before the 5:00am race start. And just like that the race started, off we went into the woods, all 126 of us with our headlamps beaming in the dark. Actually mine was lightly beaming, I think the batteries died just as the sun rose enough to see without it, lucky me! It was 8 miles to the first aid station, I was equipped with all the nutrition and water I would need to get me to the second aid station (mile 17) where Emmet was planned to meet me, the first 8 miles flew by, it took about 3 miles for the runners to spread out and about 40 minutes for the sun to rise. Running with a headlamp is really fun, the small illumination for your footfalls on new terrain makes me feel like a little kid exploring with a flashlight. Admittedly it really slows me down as the few falls I have had in the past all occurred while running in the dark, thus I now go a little slower. The logic is I'd rather be 5 minutes slower than broken. As we came into the 8 mile aid station we were greeted with cheers, and even better Emmet was there to make sure I was doing OK, (I had started the race with a new hydration pack and he wanted to make sure that it wasn't leaking) I ran through the station on my way to mile 17.

 

 

Miles 8-17 were beautiful, the morning was cool and this portion of the trail was through pine forest ascending to views of the Mogollon rim, I was on fresh legs and trying my best to hold back for the many many hills and miles to come. There were numerous river crossings over precarious rocks that really added to the adventure feeling, the course at this point was on an easy to follow single-track trail, well marked with yellow tape and glow sticks. Coming up on mile 17 I could hear the cheers as runners came into the aid station, this was so encouraging I cried a little! Emmet had prepared an area with everything I could possibly need, I quickly toweled off the crusty salt-sweat, exchanged my hydration pack for a freshly packed one, took 2 ibuprofen to help ward off inflammation and set off again----DANG IT! I didn't take my sunglasses, I was running without a visor on purpose as I didn't want to risk missing any trail markers in my periphery, the trail was now becoming more treacherous and it is very easy to get lost. Many experienced ZG runners have lost hours going in the wrong direction.

 

Mile 17-33 was brutal, I was told to expect the worst during this part, the majority of the trail is an old exposed burn area. Tons of direct sunlight (grrr no sunglasses) lots of elevation to climb, and lucky you if you don't get lost as you have to be super aware of trail markers. This part of the trail has to recover from a harsh winter so the area has a ton of dead tree fall, new dry grass/shrubby growth, and lots of crumbly unsteady soft red rock. At mile 23 there is an aid station only assessed by the official race crew, this aid station is an oasis---it's called Hell's Gate from mile 23-33-- as I ascended into the station the volunteer shouted out "Welcome to Hell, how you doin'? I was doing pretty good considering all the runners were in the same hot boat, I was conditioned for the heat so I knew as long as I kept hydrated I would have no problems. I filled up my pack with water, chugged another few cups of water, and threw a handful of ice down the back of my shirt, off I went into Hell. At this point in the race runners were beginning to drop, many people started out to fast, spent their energy, and were not prepared for the heat. I was not really going to fast but I managed to pass many people during this stretch. The race is organized so that there are rescue workers stationed on the course about every 7 miles with radios, their job is to account for each runner as they pass and make sure nobody goes missing. About mile 25 I came up on a man who had passed me around mile 20, he was hunched over on the side of the trail, he was obviously unprepared with not enough water or calories, as I was offering him some of my water he vomited, nothing I could do for this guy except for run on ahead to tell the next rescue crew they had a runner in trouble. There were some pats of trail during this leg where I would think to myself "seriously?? I am supposed to run this?" and other parts where I had to remind myself that I had trained to go faster and harder, hiking was the only option for many parts of the trail, however dragging my feet was not. My head needed to be reminded to move my feet!

 

Whoo-hoo I made it to mile 33 aid station! The delirium sets in completely about this point, as I came into the station Emmet was yelling "go this way, now go this way, now this way" leading me from the check in to the car where all my gear was. This is where it makes a difference for someone who knows your habits to intervene, I was spot-on for nutrition and hydration but with the heat every ones sweat factor was major--Emmet made sure to impose upon me the importance of taking saltstick caps--these are electrolyte tabs to swallow--if you had seen all the salt crusted on my face/shirt/body it's pretty obvious I was depleted, I now swear by these caps! Seriously, all I could tell you at this point was which way is up or down. My brain was only focused on watching my footfall to not trip and keeping a keen eye on trail markers. A funny note here, about a week prior Max had told me in his cutie voice "Good job Mommy" when I pointed out a local peak I ran to during a training run. During the race I had his cute little voice in my head rewarding me with a "Good Job Mommy!" every time I came upon a trail marker!

 

 

So onto miles 33-44, Emmet loaded me up with 2L of water on my back, 32oz in my hands, about 800 calories in my pack (all of which I would use) and I was on my way! This was serious fun, the trail was about 60% run-able so now I know I need to improve my hiking skillz, other than this I was focused on the next 11 miles of adventure. I think my most proud accomplishment for this race was not falling once, I don't fall often but still this terrain is really 'trippy' (funny right?) so now blur blur blur, hill, hill, up , up , up , and I arrive at mile 44!

 

 

The crowd is cheering all the runners as we descend into the station, Emmet leads me to the car and preps me for the last 6 miles. Hmmm 6 miles, how long might this take...try 1 hour and 40 minutes...uuuuuffffff. This last 6 miles was long and exhilarating, and hard. The terrain was pretty pine forest but my legs were shot, there was spot about mile 42 where some thin ice patches were still frozen on the ground, it just made sense to me to come to a stand still stop to look at them and contemplate lying down on one--I chose to keep on trucking but now I was day dreaming of cold pools to dip in and icy drinks. After what seemed like an endless stretch of trail I rounded a corner and was in earshot of the finish, what a rush! I picked up the pace as best I could and finished strong, the 35th finisher and 8th female to be exact. The whole race took me 12:40 minutes and every second was great!

 

 

I will definitely do this race again, it was a total adventure! Thank you so much for all the encouragement

For many reasons I'm very proud of Magi:-)  Today - a week later - she's running a regular marathon "for fun"

She obviously is mostly slow twitch or red muscle.  This comes from both sides of her family, who tend to be gracile and endurance/non-sprinter types.  I'm really slow and a terrible jumper, but I can go for a long time.  In college I would regularly ride "centuries" (100 mile bike rides) on most weekends and never had any exhaustion problems.  Even now when rowing I specialize on going for an hour to an hour and a half rather than intense five minute intervals of burst effort.

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¹ This is similar to what happens when you burn your finger. Your finger touches a red hot burner and a signal races towards the closest area that can make a decision - the spinal cord in the case of the finger.  A response is quickly generated and sent back causing the muscles to jerk your finger out of the way.  This happens "reflexively" - long before signal can be processed by the brain and long before pain is even felt.

² By taste I am referring to flavor which really isn't the conventional five tastes on the tongue, but the mixture of taste, touch and smell that generates "flavor" in our mind.

Also color is generated in the mind as is music.

³ This is one of the reasons why our bodies respond so well to aerobic exercise and why we tend to fall apart when we become sedentary.  At risk of sounding preachy, your body and brain with greatly benefit from regular aerobic exercise so find an excuse to just do it.

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A Very Simple Simple Pea Soup

 

Ingredients

° 2 tbl unsalted butter

° 1 diced medium sweet onion

° 1 clove garlic, sliced

° Kosher salt to taste

° 2 c thawed frozen sweet peas (fresh only if picked on the same day!!)

° 1/2 c lightly packed fresh tarragon leaves

 

Technique

° Melt butter over medium low heat.  When it foams add onion, garlic and salt. Cover and cook until the onions are soft, but don't brown!  Stir frequently - not a walk away and forget it stage

° Add a quart of water and bring to a boil. Add peas and tarragon and cook 'til tender - a few minutes

° take off heat, purée and strain.  

° Reheat if necessary and serve.  I like to garnish with a few whole raw peas and a bit of plain greek yogurt

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bonus non-recipe

After 80 or 90 minutes of hard rowing I'm soaking with perspiration and am in need of something cold with a lot of protein.  Here is my current favorite - not vegan friendly though.  "Shake" is tongue in cheek - I can make a quality milkshakes.  Ask if you visit and we'll do one.

Berry Yogurt "Thickshake" with Nuts and Chocolate

Ingredients

° A good handful (about 100g) of slightly thawed frozen blueberrys or raspberries

° About 200g plain greek yogurt - I like to use 2%

° a half frozen banana - I remove the skins on very ripe bananas and tightly wrap them in plastic wrap and freeze.  A great way to deal with ripe bananas

° 2% or whole milk.  Start with 100g and adjust

° something sweet - maple syrup, honey, sugar

° 15 to 30g of dark chocolate broken into small bits

° 15 g broken pecans

Technique

° Blend banana, fruit, and about 50g of milk.

° Add the yogurt and milk as necessary to get a good enough consistency.  Add sweetner if necessary

° Pour into a serving glass or bowl depending on thickness.  Stir in pecans and chocolate

 

 

from watches to red:white muscle ratios - and a rapidly evolving technology

While reading a recent issue of Science I came across a short article on the metabolic mechanisms invoked during judo.  Now I know nothing about judo, but a fair about about metabolism and that sparked a need to for a short post.  Not one centered on sport or metabolism, but rather it makes sense to move back to my human-computer interface department at AT&T Research in the mid 90s and something completely different...

 

Among other things we were charged with looking at user behavior and began to notice that as people became more comfortable with mobile phones they were beginning to use the watch that came on some of them in place of a watch.  The trend seemed to be larger among groups of young users, but nothing for Swatch to worry about at the time.  

 

We did a bit of work with Swatch - they were convinced the technology trend was more towards a focus on the watch and were busy trying to concoct ways to move some of your personal information to your wrist.  The concept that the phone was the important target was lost on them and those of us who were working along the phone line did not - or at least I did not - have an extremely strong conviction one way or the other.

 

About the same time some of the folks in the lab started working on combining digital cameras and mobile phones. The early attempts were incredibly crude to the point of being unusable and the dog and pony shows would produce a lot of abrasive comments.  But there was a certain amount of magic in it.  

 

A few of us had become fascinated by digital music devices and serious work informed us that quality - at least as measured by the standard measurements found in audio magazines - didn't matter very much.  People were more interested in convenience.  Terrible quality was shunned, but as it increased there was a point ..  around 96 kbps mp3 - where the objections went away.  People might be able to tell, but they didn't care.  Furthermore, when they were isolated from comparisons to a reference, they could put up with cheap reproduction hardware including very cheap headphones.  It was something of an epiphany to me.

 

At the same time we were seeing the same thing with video and video conferencing.  Just make it work and get it to a minimum acceptable level and the vast majority of people don't really care about quality.  This gives you a very different way to think about cameras - use Moore's law and a bit of optics from physics and you could convince yourself that cameras on cellphones would begin to make real sense around 2004 give or take a year or so.  

 

I was thinking a lot about photography at the time as two of us were deep in thought about how people interact with music and were inspired by Susan Sontag's essays in On Photography as a framework.  The real question for digital photography was convenience and cost was a major part of convenience followed by size.  The notion of taking an instant image at no cost and of being able to have a camera with you always was compelling.  It was easy to predict film was going to die and we did.  We also suggested the camera would become part of the phone as an always present ability to capture images was highly desirable.  It was then that I started to see the mobile phone as a small box that could be filled with sensors and that these sensors had a connection, albeit an imperfect one, with the external world.  We got excited about what it meant to attach a real computer and have it disappear into that box.  It all seemed so obvious (Steve, Nancy, and Wayzen are all nodding now).  We did something called Air Graffiti around 1999 to 2001 with bits that would still seem interesting today.  All you needed was something like an iPhone to make it work.

 

I've been thinking about other sensors recently - the urge comes every few years.  The most recent thinking came with noticing the new third generation iPad has BlueTooth 4.  BlueTooth is pretty ugly as a protocol (or pile of protocols), but it works and volumes are high enough to render it approximately free and ubiquitous.  BT4 has some lightweight features that seem tailor-made for talking to external devices that may have a sensor or two, but have very tight power requirements.  You look at the world and begin to imagine what a home with a few hundred - or thousand -  sensors might look like.

 

An obvious use is making measurements of what your body is doing.  Smart shirts and so on start to become very inexpensive.  Up to now a considerable engineering design effort was required to make a system work - you had to source and program a very small computer, worry about communications and do a hundred other tasks that drive the costs high enough to prevent enough volume for them to be affordable.  A lightweight radio link and remote processing and display would vastly decrease costs.  That would only decrease the costs of the tiny computers and radios used by the sensors. They would probably all be integrated into a single chip that could be produced for pennies - plug in an antenna, battery and a sensor or two and you're all ready to go.

 

This, and a few other things, has me thinking more about the science of sport as that is a leading edge for this sort of device (arguably so is the medical world, but that has some strong legal restrictions and I don't know that many medical researchers.

 

Anyway the trigger for writing this was a fascinating paper on metabolism in Judo.  The muscles turn energy into motion using two (three depending on how you count) basic mechanisms - anaerobic and aerobic metabolism.

 

We use two basic forms of anaerobic (without oxygen) metabolic systems - alactic and latic.²   The first is for short intense bursts of exertion using energy stored energy compounds known as phophagens that are present inside the muscle.  Terrific amounts of power can be generated.  World class sprinters like Usain Bolt develop power in the vicinity of 2.5 to 3 kilowatts for about ten seconds - impressive when you consider the electric burner on an electric range uses about 1.5 kilowatts.  For the runners about 80% of that energy is turned into waste heat, which causes their internal body temperatures to soar.  Anything much over fifteen seconds at that level can be fatal, but they have exhausted their store in that period. The second allows muscles to break down sugars anaerobically and is good for a few minutes, but at power levels well under those unleashed by alactic metabolism.

 

Longer term muscle use requires externally supplied oxygen - aerobic metabolism - which basically works as long as there is oxygenated flowing blood and  energy being converted by breaking down food or stored fat.  A world class runner or bike racer can probably manage 350 watts of output indefinitely.   Think of invoking them as shifting gears.  You can get a sense of the power available in this post.

 

There are several muscle types, but they are often categorized at a high level as white and red muscle.¹  Red muscle is optimized towards aerobic metabolism and is best for long duration use.  White muscle excels at getting its power from anaerobic metabolism and is useful when bursts of power are required. People have different muscle compositions based on their genetics.  Sprinters tend to have large percentages of white muscle - up to 70% -allowing them to convert a lot of energy into motion for a short period.  Endurance runners and cyclists can convert a more modest amount of energy over extended periods and have as much of 80% red muscle.  Most of us have about half and half, but most marathon runners are usually at least 60% red muscle.  Even very athletic average people can have serous problems with endurance work and marathoners are notoriously bad at jumping. 

 

Judo is interesting as it is an unpredictable sport with differing output demands. 

 

The judo work informed us that all three metabolism types are important.  Phosphagen metabolism was critical in throwing people and the other class of anaerobic metabolism came into play, but aerobic metabolism was much more important than suspected. Probably enough that conditioning for the sport probably deserves a more critical look.

 

This caught my eye as I've been worried about the energetics of volleyball; another unpredictable sport which is a combination of moving around the court in longish bursts with brief moments of extreme output.  Indoor volleyball, the the elite level, tends to specialize and some extremely good jumpers emerge, but the beach game is too much of a generalists game.  Height is important in both, but tall extremely good jumpers are rare as most people - including tall people - tend to have a 50-50 red:white muscle ratio.  It is spectacular when it occurs, but they tend not to have a lot of endurance.

 

Learning about how the body works in sport means asking questions demands measurement and that may provide novel techniques that are useful in many other areas - perhaps sorting out interesting sensors that naturally pair with smartphones and may be useful far outside of sport.  Spinoff happens all the time - just another form of connecting the dots.

 

Predicting many of the big trends in technology a decade out is certainly possible and it is much more likely among those who are engaged in serious play and connecting with areas beyond technology.  Smartphones were very obvious 10 years out when you started to think more about how people relate to music and photography.   Getting the specifics is probably impossible.  At the same time it is possible to rule out many other technologies.  You need multidisciplinary teams with multidisciplinary - and really curious - people.

 

Oh - and on watches - in 1997 we wrote a paper that the watch industry would have serious problems, but the high end would probably do well as watches are also a form of jewelry and that serves an important function for many people.³  We suggested watches could also house sensors that would talk to small computers housed elsewhere - like in a mobile phone - using very short range radio links.  One of us even developed an unusual pointing device that listened for the acoustic signals caused by rubbing fingers together.  The convenient place to locate it was in a ring.  While it was impractical at the time it was formed the seed of a line of extremely rich inquiry.

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¹ Also fast and slow twitch muscle.  A general comment.  At elite levels genetics and body type are important components of winning, but at lower levels it makes sense to go with your passion.  I see parents moving kids into sports that may be optimal for their genetics when they are nine or ten years old ..  completely silly.  For most of us sport should be recreation and a pathway to lifelong fitness.

² Alactic metabolism is also known as the ATP-PC phosphagen system - a very beautiful piece of biochemistry that is well beyond the time I have to write.  If you haven't been exposed to it I encourage you to read about it.  The other lactic metabolism is as known as anaerobic glycoloysis.  Glucose and glycogen are used anaerobically and one of the by-products is lactic acid, hence the name.  Duration is in the 200 second range at power levels significantly below phosphagen metabolism.  This mechanism is very important in 400 meter to mile long foot races.  

Here is a nice little video from the School of Physical Education and Sport University of Sao Paulo showing how some of these things are measured in sport.

³ Pocket watches are now being embraced by leading edge 20 somethings, although it is too early to identify a real trend.

 

global efficiency and flexibility through local inefficiencies

My sister Corinne has a great love for horses.  Part of it is the beauty of their motion. There are four natural and distinct gaits.  The walk with its left hind, right hind, right front, left front four beat cadence transitions to a two beat gait called the trot as the horse speeds up.  Now its legs are moving in unison in diagonal pairs. It is a very stable gait and the horse’s head is often very steady.  

 

As the horse speeds up the cantor appears.  Now you hear three beats and a pause and then three beats and a pause as one of the rear legs supports the horse as the other three move forward. 

 

As the horse accelerates a four beat gait emerges.  The horse is still pushing off with a rear foot -  for brief moments it has entirely left the ground and is flying.  The full gallop -  as fast as a horse can move.

 

Galloping is not terribly efficient and the horse will tire quickly.  The cantor is more efficient, but not by much.  Walking and trotting, on the other hand, are great paces for a horse if it is to travel long distances.  Horses have very narrow  ranges of optimum speeds.  People can tweak these ranges through breeding altering musculature and leg length, but the horse is a four speed creature with two economy speeds.

 

You might think leg length is an important determinant of the best running speeds in humans, but a look at elite runners - both distance and sprint - show they are mostly of average height.  At six foot five Usain Bolt is a rare exception, but he is the exception in several other metrics.  

 

An examination of the energy used to travel a fixed distance in running is fairly constant over a wide range of speeds - something that is unexpected and very different from horses and other four legged mammals. Adding to the puzzle is the most efficient walking speed.

 

I like to walk and have been on long walks with a variety of people. Most of us are of differing heights, but the average speed we walk at tends to be not that much different from the speed we use when we’re walking along.  Most people walk somewhere between 3.0 and 3.4 miles per hour.  The efficiency of walking is strongly peaked.  If you walk at your own natural cadence you will burn fewer Calories per mile than you would if you were walking at a faster or slower pace.

 

This is very curious as people have very different leg lengths.  At six foot one, but long waisted my 31 inch inseam gives me much shorter legs than six foot seven Colleen’s 40 inch inseam measurement, but her optimal walking speed is only a bit higher than mine and is a small amount lower than another friend who has shorter legs than me.  We give up some efficiency, but it is generally easy for us to adapt our speeds to that of our friends and visa-versa.¹

 

The physics and biology of mammalian location is non-trivial and still under active investigation.  A recent paper that looked into the activity of some skeletal muscles involved in walking and running gives some fascinating insight that paints a picture deeper than the problem at hand.²

 

It turns out it is difficult to directly measure the efficiency of a specific muscle while it is working, but measuring its electrical activity with electromyography is a good proxy and you can estimate efficiency.  Seventeen people were wired up and put on treadmills and asked to move at a variety of paces.  Thirteen muscles were monitored and the muscle activity per distance travel was recorded.

 

 

The results are fascinating.  The plot on the left shows the speed at which a particular muscle was most efficient with walking in black and running in grey.  The plot on the right shows the speed of peak efficiency for each subject for walking and running.

 

Note that the muscle efficiencies don’t peak at the same walking speed - there is quite a bit of variation, particularly in running.  Individually our leg skeletal muscles are not optimally efficient at a single speed. 

 

You might think this is some sort of evolutionary failure, but it is probably the opposite.  We don’t spend our time walking at the same speed even though we do have an optimal walking speed.  We have the need for doing many other activities.  We climb, dance, kick, sprint and have the need to match speeds of others.  These different activities involve each of the muscles in different degrees.  We don’t have the best possible efficiency at our optimal walking speed, but we have a huge amount of flexibility and we have a very wide range of running speeds at ok efficiencies.  Often we are more efficient than the horse - my niece Magi participated in a man vs horse race and dropped all of the horses. 

 

This illustrates something deep.

 

The best general purpose optimization often involves a mixture of non-optimized components.  Making each component as good as it can be by itself and allowing it to operate where it runs best usually results in a larger system that is far from optimal.  This is central to engineering which is the practice of finding and harmonizing a variety of pieces into a whole which is the best compromise.³

 

 

_________

¹ How people communicate the proper walking speed is a fascinating look into the subtle non-verbal ways we communicate with others.

 Note if you are walking for exercise and walk over a fixed distance slowing down or speeding up from your normal pace will burn more energy. Speeding up burns the most and if you are walking for a fixed amount of time - say and hour - the higher speed will usually burn the most energy.  

The relationship between efficiency, performance and physical size is a rich subject area and sport is an excellent lens to illuminate interesting questions.

 

² The musculoskeletal system of humans is not tuned to maximize the economy of locomotion

David R. Carrier, Christoph Anders, and Nadja Shilling

Abstract

Humans are known to have energetically optimal walking and running speeds at which the cost to travel a given distance is minimized. We hypothesized that “optimal” walking and running speeds would also exist at the level of individual locomotor muscles. Additionally, because humans are 60–70% more economical when they walk than when they run, we predicted that the different muscles would exhibit a greater degree of tuning to the energetically optimal speed during walking than during running. To test these hypotheses, we used electromyography to measure the activity of 13 muscles of the back and legs over a range of walking and running speeds in human subjects and calculated the cumulative activity required from each muscle to traverse a kilometer. We found that activity of each of these muscles was minimized at specific walking and running speeds but the different muscles were not tuned to a particular speed in either gait. Although humans are clearly highly specialized for terrestrial locomotion compared with other great apes, the results of this study indicate that our locomotor muscles are not tuned to specific walking or running speeds and, therefore, do not maximize the economy of locomotion. This pattern may have evolved in response to selection to broaden the range of sustainable running speeds, to improve performance in motor behaviors not related to endurance locomotion, or in response to selection for both.

 

 

³ A week or so ago I was in an email conversion where someone noted a Steve Job’s quote and I reacted.  I think Apple is an excellent example of a company that understands not only how to make these engineering compromises, but also that the final product involves more compromises than are possible if you “just” use the discipline of engineering.  Consumer electronics has evolved beyond engineering.

 

[friend quoting Jobs} “When you first start off trying to solve a problem, the first solutions you come up with are very complex, and most people stop there. But if you keep going, and live with the problem and peel more layers of the onion off, you can often times arrive at some very elegant and simple solutions. Most people just don’t put in the time or energy to get there. We believe that customers are smart, and want objects which are well thought through.” - Steve Jobs

 

[me] Absolutely - and this is *so* different from ordinary engineering and product development. 

 

[friend] How so?

 

[me] This is a *very* long subject so I'll try to just hit a few points.  Engineering is all about finding a compromise among various components to create something that makes specifications.  Great engineers are really good at this and I have enormous respect.  The key point is there is an end point - after all, something has to ship on a certain schedule.  When you are doing this you can only work within a fixed domain.  It can happen that you bump into something new as you work on something, but that is rare and certainly not your job description.  In recent years the goals of a product are specifications and hitting price targets.

 Apple certainly does engineering, but it is a different scale.  Other non-engineering disciplines are involved.  During the design phase there is this tendency to keep going deeper.  Occam's razor is a fundamental driving principal.  You need to simplify wherever possible *even* if you didn't think it was possible at first.  There is also a sense of artistic elegance and pride that comes into the optimization.

All of these competing subcomponents and pieces of software have qualities of their own - along with time dependent evolution curves.  You need to be suboptimal on several to make the global result better.   Much of conventional engineering ignores the fact that real consumers also like to see elegance and a simple UX mixed in too … in fact those may be the defining characteristics of a product.  And the product needs to dance properly with other products in addition to the person who uses it.  Getting these details right is an entirely different skill set and Apple has built an organization that understands this deeply.  Artists get it deeply. 

 Jobs once described himself not as a technologist, but rather as an artist who paints with technologies.    

My heritage and way of looking at the world is through the perspective of science.  Here you are trying to figure out how nature works.  There is an absolute you are working towards, but she tends to reveal herself only when questioned properly and then only a bit at a time as you need to find better questions to progress.  I was not attracted to biology or chemistry as they are so complex.  (they are still very beautiful - but it is a preference of mine)  I found physics to be my sport as it is so simple - you only look at the most simple systems, but you want to go in as deeply as possible. The idea is to find the really fundamental questions.  I find the people who have sensibilities most similar to mine are artists and composers.  

Apple is the company with these sensibilities as they are trying to peel the onion back as they progress.  The analogy isn't great - they are probably closer  to biology as they are working in a complex environment -- Jobs, in a different time and if he would have had academic leanings - may have made a great biologist.

As these products that combine art, electronics and computation progress conventional engineering is going to be an increasing failure as a global solution.  It is a piece of what needs to be done, but the integration with other disciplines is central and, I think, a requirement for success in at least the consumer product environment.   There are so many things that need this approach.  It is terrifically exciting. 

 

running

About three years ago I became interested in the fluid dynamics of volleyball and found a nice result that introduced me to the science of sport.  While most of my work has focused on beach and indoor volleyball, I've had contact with folks who puzzle the motion of elite athletes.  Their work deals with the fundamentals of everything from how muscles work, to the efficiency of motion and even neurological and psychological issues.  A fantastic playground working with amazing people at the extreme edge of human performance and a huge question generation machine.

 

Last week one of them noted a paper on age related decline in performance.  The authors looked at a large number of German marathon runners and their analysis led them to a somewhat surprising result that may be of interest to some of you as at least four of you - Jheri, Magi, Pip and Dave - participate in marathons for sport.  

 

The abstract says gets to the gist of the matter:

 

 

Background

Physical performance often declines in middle age, but it is unclear to what extent this is due to biological aging. It can be difficult to determine whether such physical changes are truly age-related, as they might alternatively be explained as the negative consequences of a sedentary lifestyle.

Methods

We assessed the endurance of a physically active subgroup of the population by performing an age- and sex-stratified analysis of over 900 000 running times of marathon and half-marathon participants aged 20 to 79. We also analyzed the responses of 13 171 marathon and half-marathon runners to a questionnaire about sports, lifestyle, and health.

Results

No significant age-related decline in performance appears before age 55. Moreover, only a moderate decline is seen thereafter; in fact, 25% of the 65- to 69-year-old runners were faster than 50% of the 20- to 54-year-old runners. Our survey also revealed that more than 25% of the 50- to 69-year-old runners had started their marathon training only in the past 5 years.

Conclusion

Performance losses in middle age are mainly due to a sedentary lifestyle, rather than biological aging. The large contingent of older “newcomers” among marathon runners demonstrates that, even at an advanced age, non-athletes can achieve high levels of performance through regular training.

 

 Really good news for once!

 

There are some difficult issues to tease apart (self selection and a skewed sample size for example), but the paper appears fairly robust.  It would be interesting to see what others did with the same database as well as similar databases in other countries to see if this is generally true.  

 

For fun I plotted the times for the average marathon runners and then moved the curve for the best runners normalizing it so performance for elite and middle of the pack 25 year olds matched. This is far from a robust numerical technique, but I'm only trying to compare the relative shape of the curves to notice how performance deteriorates with age.  The elite athletes turn out to always be better runners by definition, but the performance of that group deteriorates more quickly with age.  You have no real hope of being an elite performer past the age of 40, but you can certainly have good recreational performances into your mid 50s and beyond.  We won't break records, but those of us in the middle can retain our level of performance for a long time.

 

 _______

 

I have always been terrible at sprinting and jumping, but am not bad at endurance work.  Some foot issues keep me from running, but I row and don't find two hour sessions impossible.  As a student I averaged a few century level bike rides a month and did my share of double centuries.  Both of my nieces are runners and one even runs ultra-marathons in the mountains of Arizona.  The three of us have very similar body types (sadly for them) and it is likely we have a high percentage of slow twitch muscles.

 

It turns out people have several types of muscles.  The skeletal muscles involved in moving our limbs come in two basic flavors - slow and fast twitch¹.  Fast twitch muscles are associated with bursts of power and are sometimes called white muscles.  Their slow twitch counterparts are associated with much lower levels of power, but they can function at those levels for much longer periods of time- often hundreds of times longer - before fatigue occurs.

 

Most people have about a 50-50 mix of slow and fast twitch muscles.  Elite sprinters can have as much as 80% fast twitch and elite marathon runners can have 70 to 80% slow twitch.  Even good recreational distance runners tend to have a much higher percentage of slow twitch muscles than an average person.  

 

When we push ourselves there are a few basic power levels we can produce that depends on the muscle type and fuel supply.  I'll mention the main four.

 

A very short term bust of power can be had for a few seconds from ATP stored inside the muscle, followed by about 10 seconds of a somewhat lower power mode.  Both of these exhaust fuel local to the muscle and neither require externally supplied oxygen.  Fast twitch muscles are ideally suited for this type of power generation.²  As the blood doesn't have to be well oxygenated, these muscles often have a white appearance.

 

For up to about two minutes another form of anaerobic respiration takes place as glycogen breaks down into glucose.  The muscles can convert glycogen into ATP with or without oxygen, but the problem is anaerobic conversion forms lactic acid while leads to extreme fatigue and pain.³  Sports that live in the twenty second to two minute range are dominated by this process.  Running a mile is well beyond the anerobic barrier.

 

The difference in power can be startling.  A world class 100 meter dash specialist or 200 meter bicycle sprinter can develop 2000 to 2500 watts - for about 10 seconds.  Colleen, when she was competing, could develop over 700 watts for 30 seconds and over 550 watts for a minute.  For scale consider that a horsepower is about 750 watts.

 

These bursts come with an enormous cost - you have to get rid of the heat somehow. The ten second sports are that for a reason - any longer and you have to shift gears to the next level of respiration and performance would drop dramatically.  Internal core body temperature soars to the level where a few more seconds would cause a stroke. We're very lucky our muscles don't have enough internal fuel to push the body to that level.  The amount of thermal energy that must be dissipated isn't huge, but the power pulse is great.⁴

 

 

After the local fuel supply runs out fuel and oxygen must be brought in from elsewhere.  Now the body shifts to a mode where glycogen that is circulating in your blood converts to ATP aerobically.⁵  The power levels are low, but the process can go for a long time - theoretically until you run out of fuel from your digesting food and stores of fat.  The slow twitch muscles are centers for this type of aerobic power and the oxygenated blood gives them a red appearance. This is the world of the distance runner.  

 

 

In my recreational rowing I usually plug away at about 150 watts output generated about 600 watts of waste heat in the process.  I can step up my power level for short amount of times, but my performance is very lame compared to average male athletes or an elite female athlete.  I have plotted some power vs time curves for different types of people.⁶   My excuse is that I'm not trying for bursts, but rather just for long durations.  Of course I'm far from an athlete.

 

No matter what your muscle composition is, getting some regular exercise is a good thing and now it appears that we can maintain reasonable performance levels throughout middle age and perhaps give ourselves increasingly difficult goals - for those who are into such things.  The rewards are great.  I've been increasing my fitness level to where it probably was in grad school and during my last physical my doctor's notes described me as a "thin athletic male"...  not terrible for a middle aged guy who had been seriously out of shape.  Vital signs like blood pressure and pulse fall right into line without drugs.  A larger benefit is that the exercise periods are good for clearly the mind.  Highly recommended.

 

And to those of you who are in an upcoming marathon - good luck!!

 

Somewhere down the line I'll go into the physics of volleyball - there are some amazing things are taking place and it is even more interesting in the beach game.

 

_______

¹  There are more types, but for a high level discussion it is fair to use this categorization.

 

²  There are several types of fuels our body can use.  Ultimately muscles use ATP, which is the only fuel they can use to power their contraction.  There are several mechanisms that produce ATP and ultimately all of these come from the food you eat.  Some of these can supply energy immediately in short bursts and others can be used at slower rates over long periods of time. 

 The muscle has two fuels that can be used immediately.  One is a very small reserve of ATP that can supply great bursts of power for a second or two - just the sort of thing if you have to jump or start a sprint.  There is also a substance called phosophocretine (PCr) that can quickly be turned into ATP. Together these are called the phosphagen, but you can think of it as an very high power, but short duration anaerobic fuel supply.

After the stored ATP is gone PCr being turned into ATP, but there is only about ten seconds worth.

 The muscle does not require oxygen to use ATP or to convert PCr to ATP and these processes are anaerobic.  They only generate work and heat.  Immediately available and offering high power, they are the reason why some athletic events that require enormous power - weight lifting or the 100 meter dash for example - take place in about ten seconds or less.

 

³   Our muscles have stores of a glycogen.  Glycogen is a complex carbohydrate that is just a string of glucose molecules.  Cells in the muscles break glycogen into glucose.  Your body can turn the glucose into the ATP you need without or without oxygen, but there is a trade off.  The aerobic process that uses oxygen completely breaks the glucose down with water, heat and carbon dioxide as waste products.  It also happens to be a slower process and although your heart and lungs are starting to work hard , they don’t have their act together yet.

 At this point you need immediate power and that means turning the glucose into ATP anaerobically.  The process isn’t as fast as the phosphagen system and it isn’t terribly efficient, but this is the only good source of energy ten seconds into the run.  

An 80 kilogram person in good physical shape has about a pound - maybe 400 grams - of glycogen stored in the muscles.  Since carbohydrates are about four calories per gram, that is about 1600 calories of stored energy.  But there is a fly in the ointment.

 Converting glucose into ATP anaerobically produces lactic acid as a waste product.  

 Carbohydrates can supply the energy required to go beyond ten seconds of endurance.  These can be simple sugar glucose, glycogen (otherwise known as starch), and a partially metabolized form of starch called lactate.  These fuels can be used in several ways.

 Glucose and glycogen can be used anaerobically producing a lot of power for and leaving lactic acid as a waste product.  The lactic acid buildup is painful and will cause you to fatigue quickly.  Your body can’t remove it quickly enough when you are running hard.  This glycose-lactic acid system is good for about two of three minutes of hard running before you need to shift gears again.

 As you continue your  heart rate is increasing and you is breathing much harder.  You have been running for nearly two minutes and your heart and lungs are now working well.  Rich oxygenated blood is flowing through her body and the oxygen is used with the glucose to produce ATP without the nasty lactic acid buildup.  your muscles are shifting from the anaerobic glycose-lactic acid system to aerobic respiration.

 

⁴  At 20% efficiency a 2500 watt 9.5 second 100 meter dash would generate 10,000 watts of power - or 100,000 watt seconds of thermal energy that must go somewhere.  We radiate some, a bit is conducted away, but the majority makes use of our ability to sweat which relies on some oddities of the physics of water molecules. 

 

⁵  There is fair amount of glycogen in your muscles and glycogen in your liver is being broken down into glucose which goes directly into her blood stream to fuel the muscles.  You're also getting some glucose from food you've been eating as it gets absorbed by the intestine and placed into the blood.

Glucose circulates in the blood along with oxygen and can be turned into ATP slowly, but for as long as there is fuel coming from the digestion of food.  The power levels provided by this aerobic metabolism are much lower than those produced anaerobically, but they are sustainable for hours.

 During aerobic respiration, your muscles can convert ATP to work at about fifty percent efficiency - the rest of the energy is heat.  The aerobic conversion of glucose to ATP is about fifty percent efficient, so the efficiency of turning glucose into work is the product of the two - about twenty five percent.  This is similar to the peak efficiency of the engine in your car.  Specific motions lose a bit more efficiency several common motions people perform get the work done that moves you or propels a ball about a twenty percent efficiency.

 

⁶  The male athletes were from a sample of college athletes in the early 1960s measured by NASA as they were trying to understand human performance.  The average men were about 80 kg.  Colleen weighs 80 kg and this is a fairly average curve for elite 80 kg women these days. The 20 year old male sample was from college non-varsity teams in the early 1960s.  All of these measurements are on calibrated ergometers.  Mine is a Concept2 rowing ergometer.

 

 

 

cheating death and thinking more clearly as an added benefit

Damn it!

 

An email just came that said someone I used to work with died yesterday at age 62.  

 

That makes two in a month - John and George.  George was only 49.  Both died way too early.  Heart attacks.

 

damn it!

 

so sad for their families

 

The last time I saw them both were in terrible physical shape - delightful people, but pure couch potatoes.  Sports meant stretching out on the couch and watching someone else and neither could be convinced to take even a short walk.  It is difficult coming to the realization they are no longer around and I have to wonder what the story would have been if they would have taken better care of themselves.

 

A few nights ago Grant and I were talking about our mutual love of walking.  I've always enjoyed it and find it a place to think.  Some of you share this addiction and I've been lucky enough to have had some great conversations on longish walks.  Mostly I take them to clear my mind and enjoy a bit of nature, but it is impressive how many unsettled problems managed to connect up and solve themselves during these times.  I'd go so far to say that most of the insight I've had so far has managed to manifest itself on walks and bike rides.

 

It turns out there are additional benefits to this modest form of exercise if it is regular and long enough and this is why I mentioned the sad deaths.  Apparently very little exercise is required to increase your likely lifespan.  I'm not terribly surprised by the numbers reported here ... a third of adults get no regular exercise.  Even 15 minutes a day can make a measurable difference, but the recommended levels are at least 150 minutes a week.   Thowing in a bit of more intense aerobic exercise is even better.

 

It is very difficult to encourage exercise without coming off as sanctimonious.  In light of the deaths I feel compelled to write a bit, so take it in that light.

 

Our need for regular exercise is basic.  Most of us have basal metabolic rates that account for about 70% of our energy expenditure - it is generally felt our bodies are made for the 50% to 60% range.  Seriously inactive people may be as high as 80%.  I probably would be a complete couch potato if it weren't for a couple of benefits - the clarity of mind one gets during long walks, the serendipity that sometimes comes with being a bit closer to the natural world (for several months a vulture accompanied me and I've had a fawn back into me),  and a few hours of a good feeling following aerobic exercise.  Those are seriously positive and enough to recommend activity even if no other benefits existed.  Not to mention it is a relatively inexpensive pleasure - I get about 1600 miles from a pair of Asics.¹ 

 

When I started consulting I swore to myself that I'd take an hour off for a walk every day no matter what the weather and no matter where I was.  I've kept that promise at over the 99% level and even take walks during ice storms.  They are often the highpoints of my day - a period where clarity comes easily.

 

Aerobic exercise is great too.  I'm slowly restarting my rowing after my injury in August and am noticing an improvement in how I feel for hours afterwards as well as my mental alertness.  

 

It is sometimes difficult to budget time, but I timeshift enertainment time from the evening to my early morning rowing sessions with an iPod.  An hour of walking seven days a week and an hour of aerobic exercise five times a week seems to agree with me.  Start a program of your own and give yourself an unfair cognitive advantage over your competition.  You're also likely to be more healthy and live longer - assuming you don't walk in front of taxis in NYC (I can hear Juliette laughing now).

 

One of the companies I consult with considers exercise important enough that they match a half hour.  If you put in an hour of exercise, they'll let half of it count as work.  You also get a free lunch as part of the deal.    Their gym facilities are wonderful and trainers regularly visit to help out. I'm told about a third of their workforce uses their gym at least twice a week.  

 

It is inspiring to realize that some go much further - a few of you are much more serious than me.  Dave and Pip run marathons.  My niece Magi is a very serious runner and took first place in a fifty mile marathon a few weeks ago.  She manages to run about an hour a day for training and "several hours" on Saturdays.  

 

Colleen did serious training on the sand - trying sprinting and jumping in the sand some time for a sense of the added difficulty.  Fueling her was a 6,000 Calorie a day propositon.  Imagine doing routines the one in the video five days a week along with everything else an athlete does.

 

 

It is comforting that you don't have to go to the extreme levels that Magi and Colleen chose.  Fortunately simple walking and maybe a bit of low impact aerobics have a very positive impact...  these days Colleen is down to walking the dogs and kickboxing and some regular gym time these days and still feels great. Even with this comparatively light load her BMR probably only accounts for half of her caloric requirement.

 

Note that unless you are into megaexercise you are unlikely to have much success with it by itself for weight control.  In an hour of rowing I do about 150 watt-hours of work and require about 750 watt-hours of energy.  That is equivalent to roughly 650 Calories - about two Snickers.   It helps, but to remove a pound you need to remove about 3500 Calories.  So exercise for other benefits and enjoy the modest benefits of a slightly higher caloric requirement.

 

Make it a game if you can - just start something and give it some time until you get to the point where it is more of a gift than a burden.  The benefits can be amazing.  I don't want to hear about others going before their time.   And if you have kids teach its value to them!

________

¹ inexpensive per hour.  My shoes average $100 a pair so we're looking at six and a quarter cents per mile - a bit more than what I pay for car tires