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.
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.