omenti

manpo-kei, gold plated teaspoons and home runs

A friend had been struggling to find regular physical activity for a few years.  She complained enough about a lack of motivation that her brother gave her a low-end Fitbit for Christmas.  Somehow the pedometer function clicked for her.  Being able to see the numbers of steps was as motivating for her as filling in circles on an Apple Watch is for other people.  On top of this she'd heard about the magic 10,000 step number.  Initially the goal was beyond her, but she was motivated and within a couple of weeks she was there.  She's kept it up and regularly does 15,000 a day along with increasing her speed.  Her blood pressure is down from last year's number and she feels healthier.

 

In the 60s a Japanese company marketed a pedometer known as the Manpo-kei - which translates to the ten thousand step meter.  The pedometer became a fad and somehow the 10,000 step goal was enshrined in popular culture.  There's no reason why the number means anything other than being something like five miles of walking for most people.  That's over an hour of walking and good exercise. So people who aim for the number are getting a good benefit because the general direction of walking a lot is healthy rather than the number being the "right" target. 

 

The NY Times recently ran an article on some inaccuracies in smart watches.  It doesn't surprise me.  I've been around Olympic programs and athletes for a few years and know some horror stories about the over-reliance of data when you don't know it's accuracy or the context of the measurement or its use.  Like anything else with data, you need to know why, what and how you're measuring, manipulating, and finally interpreting and using the information.  In sport that turns out to be difficult.  There are a number of interesting approaches to deal with the issues, but that's another post. 

 

The NY Times piece and elite training experience suggest broad trends over time are much more important than local accuracy and precision  If you're trying to improve your fitness level or play amateur level sports, the motivation from a smartwatch can make a big difference.  If you're an elite athlete there are many other things to consider and it's likely you're taking advantage of them.

 

The notion of broad trend over local accuracy has utility in many areas.  One that frustrates me is building  carbon dioxide removal technology.  It's something of a delaying tactic being cheerleaded by the petrochemical and coal industries.  In reality it's extremely expensive, requires a large amount of energy and diverts funding from much more effective technologies and behaviors.  Currently four 1 million ton  class plants are on the drawing board.  With luck each could remove a million tons of carbon from the atmosphere by 2030 or so with a projected cost of about a billion dollars each.  So how much of an impact is that?

 

A million tons of carbon dioxide is about 1/40,000 of current yearly emissions.  That's roughly the same ratio as a teaspoon to a bathtub full of water.  Imagine running the tub and in the time it takes to fill it, you can remove a teaspoon of water.  The bathtub keeps running..  in the time another tub of water comes out of the spigot, you can remove a second teaspoon.  And then a third, forth and so on.  

 

We currently have many deployable technologies and behaviors that will turn the tap down much more than a teaspoon worth for far less money.  When we're finally down to the point where we're only putting a gallon or so of water into the tub each year, then it might make sense to deploy a number of teaspoons to make a difference for where it's difficult to turn the tap (aviation and shipping for example) 

 

Spend some money and talent learning how to improve the process, but don't count on it in the near term as it isn't, and will never be,  a silver bullet.  Nothing it.  all we can hope for is silver buckshot and using as much as we can possibly afford.  It makes sense to use the buckshot with the greatest cost/benefit ratio - things like wind, solar, better power grids, efficient transportation (full sized EVs don't count!), and any number of energy thrifty behaviors. 

 

And finally home runs and climate change.  Recently a paper made the major news outlets with projections that climate change will have an impact on Major League Baseball home runs: "Several hundred additional home runs per season are projected due to future warming."  The paper is poorly done .. basically a sensitivity analysis based on a single variable. I won't give it the credibility of a link.  Something that doesn't work in the real world with something as complex as baseball.  I have a some expertise in the fluid dynamics of balls flying through the air and would argue the effect is small.  In fact they note the same thing, but word the conclusion to make it appear there is an effect and climate change impacts everything.  This is pure clickbait for news organizations and probably has the impact of diverting attention from much more serious issues associated with global warming.  It's trivial to see the home run impact is insignificant, but a poorly done analysis can lead to fuzzy thinking and even harm.

 

the other dick fosbury

A few years ago I was having fun of  thinking about the fluid dynamics of a ball moving through the air.  The main focus was  beach volleyball, but also several other sports that use roughly spherical balls. Of these, the two with the most curious motions are table tennis and beach volleyball.   It came as a surprise as soccer (football in most of the world) has dramatic movements and baseball can be tricky, but they're not in the league of these two other sports.  People found it fun so I decided expand it into a college level class - a one semester physics of sport course for non-majors.

 

It was a very interactive affair,.  After a few weeks a few coaches and their assistants turned up,  offering things to think about.  After going through the Fosbury flop, one of the track and field coaches mentioned there had been a similar innovation in long jump, but it had been outlawed as too dangerous.  He pointed out you lose a lot of energy at takeoff by leaning back at takeoff.  The innovation was to halt the loss doing a forward somersault.  He couldn't remember the name of the athlete who did it, but thought it was in the mid 70s with World Athletics quickly banning it.

 

That evening I took pencil to paper and came to the conclusion it could increase distance traveled by as much as ten percent.  Ten percent is a change in sport where people will try crazy things for fractions of a percent.  Eventually around I found the athlete - a student from New Zealand who would have had the world record on his first attempt if he had slightly better form.  There were a few still images, but no video.  

 

With the recent passing and celebration of the life of Dick Fosbury I decided to look again.  Two years ago  an interview with a video of the jump was posted.  Long jump records would probably be over ten meters if it hadn't been banned.  The physics is simple - the leap was realizing you didn't have to lean back.

fairness, inclusivity, safety and social convention

There's so much that isn't fair in this world, but most competitive sports make an attempt to provide a reasonably level playing field through the establishment and enforcement of rules and categories.  Rules vary from sport to sport but some constants are the elimination of performance enhancing drugs, a degree of safety for participants, and the creation of categories.  Some sports allow a certain amount of violence or danger balancing what the fans and athletes want vs modifications to the rules that might make the sport less desirable.  In other words there's a social convention.  Sometimes that social convention changes after serious injuries or deaths.  Positive change has come in world rugby in the past few years, but other sports are more resistant to change.

 

More recently fairness and inclusivity have come into play.  Categories exist to prevent grossly unfair contests.  You don't want a wrestler up against someone half their weight.   Twenty year olds don't compete with ten year olds or seventy year olds. Men and women usually are have categories of their own in most sports.  And para-athletes generally have separate competitions with a dizzying set of subcategories to allow fairness given a wide range of capabilities.  Fairness comes first in these, but it allows inclusivity to play and potentially succeed in a given sport.   But like so much else in the world there's change.

 

South African Oscar Pistorius became a below-the-knee amputee in both legs as a child due to a congenital defect.  Using racing blades, he became a good sprinter - an Olympic class sprinter.  There was controversy about how much of his performance came from him and how much from the blades?  Are blades as good as or better than real lower legs?    He was charismatic and there was a large amount of social pressure that running should be inclusive.   A few calculations were done early on followed by a few real tests with this unusual subject.  Some of the early results indicated the energy return from the carbon-fibre blades was the same as the achilles tendon - in other words no advantage.  That was the message the public received. The more careful work that followed has shown he had a significant advantage from lower contact time with the ground and added leg length - enough that 'he was probably a good, but not elite runner turning in performances well beyond his athleticism.  The blades are performance enhancing prosthetics.  

 

Performance-enhancing blades raise an interesting question.  What if a world class runner adopted them?  Would a 9.30s 100 meter dash be fair?  How about a 1hr 50m marathon?  Would elite runners have to get amputations to compete?  Fortunately the really elite runners are staying away from this, but now we have another very good runner trying to compete.  Sports physiologist Ross Tucker has a great interview with Peter Weyand - one of the best biomechanics physiologists on the science and pseudoscience involved.  If you're interested in these things start at about 26 minutes in this episode. 

 

There will be innovation.  What happens in field sports that demand good court vision with augmented reality glasses?  Will they be banned and in what sports?  Will performance enhancing prosthetics for stick and racket sports come about?  What is pure and fair and where does inclusion fit in?

 

And now to a socially charged issue: transwomen and female sports.  To first order biological sex has two categories while gender is a continuum.  I think that gender should not be a category for discrimination, but that biological sex should be used to establish categories for fairness and, in some sports, safety.  There's a good deal of solid science that shows male puberty results in advantages in size, muscle mass, VO₂ max and a few other metrics.  These advantages are important in most sports and would exclude biological women from the elite and next to elite categories in most sports where men compete.¹ Testosterone is cited as the advantage, but suppressing it later in life only results in a small drop in performance (there are a few poorly done studies that claim otherwise).   This has become a social issue with a rightwing party calling for blanket bans in many activities including sports.  There's been pushback by allies.  In some cases female athletes have been threatened by sponsors to not speak out and go along with inclusion rather than fairness.   Should transathletes compete with men, females, or have their own category?  That seems to be a social decision that only a few sports bodies have addressed at this point. 

 

I'll admit to a bias.²   I believe in solid science and fairness. I think transwomen need to compete with men or have their own category. Politically I'm on the left on most issues and think transpeople should work and live how they want, but that doesn't extend into sport where categories exist for reasons of fairness.  Fairness to women overrides scientifically unsupported inclusion in my mind.

 

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¹ A chart showing the performance difference between biological male and female elite athletes. Longitudinal studies show a drop in male advantage from 5 to 30% after three years of testosterone suppression and a non-longitudinal study showed a similarly small drop after about 15 years. 

 

 

In the real world this means a transwoman swimmer who was poorly ranked as a male was able to easily defeat all of his NCAA female competitors even with a few years of testosterone suppression.  In sprinting it has been shown that biological Olympic gold medal females don't even make it into the top 2,000 for men.  It has been posited man ranked 1,000 could easily beat any women even if he had testosterone suppression that dropped his advantage by 30%.

² I have an involvement with beach volleyball and love both the men's and women's game.  I know a few Olympians on the women's side who sometimes train with amateur men who easily outpower them.  The fact the women are less athletic doesn't make their game less interesting..  it's just that the two styles of play are very different.

 

expectation dislocation

a quick minipost

I was listening to a  training technique discussion sports scientist Ross Tucker was having with a Royal Marines Green Beret.  Royal Marine training consists of a lot of what you might expect and adds a few areas you might not.  Expectation dislocation is considered one of the most important.   How do you psychologically and tactically deal with unexpected change?  How do you train people to handle it?

 

In science dislocation of expectations are considered a good thing, although they can be extremely frustrating at the time.  The overlooked, doing something stupid, being on the wrong track, the holy grail of unexpected discovery, and things mostly out of your control like equipment failures.  These things tend to play out more slowly than the battlefield or in sports.  Early in your career you make a lot of the stupid mistakes, find yourself on the wrong track and tend to overlook the obvious.  You learn with experience, but curveballs aren't uncommon and sometimes there's the taste of discovery.  

 

Sport offers dramatic examples.  I've had conversations with Sarah about preparing for and recognizing these dislocations in her sport.  How do you manage the psychological implications when you're trying to be "in the moment" at the same time?  Covid and the postponement of the Olympics had a huge impact on her.  But there are smaller examples.  Here's one of the most striking ones:

 

Sarah and Melissa face April and Alix in a semifinal in Cagliari.  Both teams are amazing - arguably the best in the world.   It's night with a chilly heavy rain.  At the 6:30 mark in the video Melissa goes down with a seriously dislocated shoulder.  After a doctor looks at it and a physical therapist re-locates it, she decides to go on - playing with one good arm.  The Canadians need to figure out local tactics and find a strategy as they go along. They only have their shared experience and all to brief moments of communication.  At one point a very fast spike targets Melissa's injured arm.  Something lights up in Sarah and she goes into her beast mode.  They win and go on to the gold medal match.  Unfortunately Melissa's arm isn't in great shape the next day and  they only take silver.

 

It's widely applicable.  Your car breaks down on a trip, a bad medical diagnosis ... any number of things ranging from very bad to very good.   How do you handle them in your life or your line of work?  How do you prepare yourself for these events?  These moments that can probe what we're made of.

 

ted lasso?

a minipost

I was listening to a panel discussion of elite sports psychologists, sports scientists, and a sports anthropologist when a question was posed:

 

Could a Ted Lasso exist?

 

If you haven't seen the show, Lasso is an American college football coach who is suddenly hired to coach an English Premier League team.  He had success in his D-II school, but it was clear he was hired to fail.  It turns out he didn't.

 

There was some laughter among audience members, but the panel members took it seriously.  It could work.  You'd need someone who was an incredible learner with success leading a team  of some kind.  Someone great at listening, observing and thinking.  They've need a Beard - a character who happens to be a serious soccer expert (among other things), but would never cut it as a coach.   Creating a bond with the players, listening to them, and be willing to experiment is key.  You'd also need management willing to put up with the time required to create a success.

 

The anthropologist noted some of these qualities are missing in NFL, NBA, MBA, and NHL coaching.  Coaches tend to be extremely confident of themselves and there is pressure to win.  Team culture can suffer and creativity is low compared with some other types of teams.  He pointed out some women's teams - particularly soccer and indoor volleyball -  are extremely innovative with positive team cultures well beyond any men's pro team he's seen. 

 

There was general agreement among those in the panel.  Coaching has a way to go in the big pro leagues, but the types of coaches selected are an issue.  A great women's soccer or indoor volleyball coach (several were mentioned) could be a Ted Lasso if they had a Beard at their side and the time to create change.   As an example a women's volleyball coach was mentioned.  Something of a household name in sports, he's as passionate figuring out how to coach a team of pre-teens as he is his countries national team.  He's experimenting and learning and might make a discovery with some twelve year old kids that works with his olympians.

 

It's culture all the way down at the top.  Maybe some of these multimillion dollar coaches aren't worth it, but it's unlikely the culture that selects them will change. 

 

It's an interesting game to think about the question in teams outside of sports.  

 

skiing!

a minipost

With Beijing approaching I started into a piece on skiing, but the number of drawing needed to illustrate carved turns, sidecut radius, reverse camber, self-turning, plowing and so on was daunting.  Looking around I found a good, not very technical, discussion of downhill skiing. The discussion falls apart on freestyle and ski jumping. I'll save freestyle for later as it's a rich area.  But I know a little about ski jumping.

 

The point of ski jumping is to jump as far down a hill as possible while showing style. Contestants are judged on how far their landing is from a critical line know as the K line (kritisch is critical in German).   The main hill at the PyeongChang Olympics was K98 - the K line was 98 meters from the end of the jump.  The long hill was K125.

 

The first phase is the in-run.  A ski jumper releases from a metal bar at the top of the ramp and begins to turn  gravitational potential energy from the height they're at for kinetic energy.  They crouch to lower the area their body presents to the oncoming air.  Aerodynamic helmets and tight fitting suits are used and their arms are out behind them.   Ski jumps have refrigerated ceramic tracks that form a very slippery layer of ice.  New snow or warm sunlight can dramatically change frictional drag and ski waxes are picked for specific conditions.

 

The ski jumper has a good deal of speed and momentum as they reach the takeoff table at the end of the ramp.  It may look angled up, but that's an illusion. It's still slightly down and the jumper needs to change from the crouch they've been in and physically jump into the air.  You don't just fly off.  The timing and power of the jump are critical elements.

 

 The ski jumper/ski combination is a glider at this point subject to three forces:  gravity, aerodynamic drag, and lift.  They've changed from a minimal aerodynamic profile to something more like an airfoil with greater surface area and the best possible shape. The skis move to form a V shape and  with the ski jumper in control of the angle of each ski (a total of six angles) and their hip and chest angles. Their arms are held slightly apart from the body to add some additional area while keeping aerodynamic drag at a minimum.   The best lift to drag in competition is about 1.6 - for every meter a ski jumper drops, they travel 1.6 meters forward. A common sea gull has a L/D of about 10 and modern airliners are in the 15 to 18 range.  

 

The V ski position revolutionized the sport in the mid 80s. Sorting out all of the angles and learning how to  change them for differing conditions is necessary for winning.  The aerodynamic problem is still very computationally difficult, so large low speed wind tunnels as well as racks on top of vans are used for experimentation and training.

 

You might think that a heavy jumper, coming off the ramp with greater momentum, would have an advantage, but the force of gravity is more important and lighter jumpers fly farther.   There were body mass index requirements, now lighter skiers are penalized with shorter skis that reduce lift.  Ski jumpers still tend to be very thin.

 

The flight is rarely more than four meters above the ground, the flight plath roughly following the hill's downward slope. Landings are highly technical and judged for style.  The transition from the V flying configuration to parallel skis one foot ahead of the other requires timing, strength and balance. 

The longest ski jumping events are on K185 and longer hills - "ski flying"  It's not an Olympic event, but shows off the flying portion:

 

But one of the most memorable performances was that of Eddie the Eagle in the Calgary 88 games.  (it won't embed .. watch at the link) You can place last and be the most celebrated athlete Calgary.  If you've stood at the top of a ramp, you get an appreciation of what it must take to even try it.

 

people beyond the numbers

 

"Track is nothing but numbers. A good mathematician probably could be a good track coach."

 

A quote from the head coach of the University of Oregon's track and field program.   They've picked some metrics that aren't applicable to sport which force young women to endanger themselves mentally and physically.  It turns out to be a way to turn a "fitness goal" into body shaming and performance on the field can suffer.   Here's a good piece on the subject.  Unfortunately Oregon isn't alone. 

 

Just what needs to be measured and how is it analyzed and interpreted.  In this case it's an outdated belief that thin people can run faster and jump higher.  It may be true to a point, but going past that point can reduce performance and lead to Relative Energy Deficiency in Sport.   Sadly RED-S is common among female athletes - often the result of the athletes and their coaches not being aware of the last few decades of health and fitness in sports research.  They may be very good at measuring body fat percentages, but that's barking up the wrong tree.

 

People, it turns out, are complicated.  Traditionally medicine has been based on a biomedical model.  Simply speaking you measure something and react (treat medically or create a fitness goal in sports) based on the number and then repeat the steps.  For many medical conditions measurements and treatments are coarse enough that it works well enough - it's often all there is.  

 

In the past twenty years there's been a recognition that the mind is involved.The mind and body react together to what we forecast might happen in the near future.¹  Sometimes the mental component is small but it's can very large - particularly in competition.   To get a handle on the mental side athletes are often asked to keep detailed training diaries on how they feel at various times of the day .  A coach looks for changes and tries to adjust the training accordingly.   To go deeper here's been explosive growth in the use of sports psychologists in professional and D-I college sports.

 

There's also been an explosion in wearable fitness devices.  They can be great when the simple biomedical model applies.  Using them to improve fitness levels works for many people who aren't at peak performance levels.  Many paths can result in improved fitness and motivation is extremely important.  Professionals find them useful in some areas of training - checking heart rates during aerobics for example,  but don't find them terribly useful outside training.  

 

And back to the amateur.  You may have the twin goals of weight management and improved fitness.  Exercise is almost always great for health and probably worth the price of a wearable if you have motivation issues, but weight management is poorly dependent on exercise.  A device may tell you how many Calories of kilojoules you've used during a session, but sadly it's incorrect to assume that's tied to how much you eat.  Metabolism is very complex and the body and mind adjust it to match new conditions.  So you lose weight at first, but then it comes back even though you're exercising and eating the same.   There are good evolutionary reasons for this that we've abundanced our way out of.

 

Assume you have a device that can measure a few metrics that are well-understood.  How the information is used can be tricky.  We're seeing a lot of amateur mistakes with date analysis in the pandemic - and often by people who should know better.  It's common in fitness training and undoubtedly in many fields.   My friend Greg Blonder put together two pieces of information that presented together are misleading.

 

You plot the amount of ketchup on the horizontal axis, and Tastiness on the vertical.
A hamburger is very desirable with a little ketchup, ever more so slathered. Liver is highly detested, but LOTS of ketchup helps. So more ketchup is better for either meal, but worse overall. The undesirability of liver skews the results when you aggregate data.  

 

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¹ In the literature the mind-body models are sometimes called anticipatory regulation or predictive processing.  Journalist Mike Finch and sports scientists Ross Tucker and John Kiely talk about this and a few other training issues associated with elite sport in episode 26 Tucker's The Real Science of Sport podcast.  If you have any interest in sports science this is one of the best podcasts around. 

 

 

celebrating a friend

Sarah Pavan is a good friend who happens to be a world-class professional beach volleyball player.  In 2019 she and teammate Melissa Humana-Paredes were the world champions.  The video is of the semi-final match against Tokyo gold medalists April Ross and Alix Klineman.  Very high level volleyball in torrential rain for part of the time.  The ball behaves very differently went wet and there were more errors than normal, but also some terrific plays. Melissa injured her left shoulder early in the match, but was able to continue play.  Amazing volleyball from the best players.  There are video dropouts in the first few minutes, but that's before the match is underway.

 

The Canadians went on to silver and the Americans bronze the following day.

__________

 

Sport are an excellent vehicle for getting people engaged in science.  There's also a good deal of serious science involved and some open areas for work.

 

 

on good design for those who need it

Olympian Sarah said she is more impressed by the achievements of Paralympians than Olympians.  She loves events like running with a guide and is particularly taken with goalball.  Goalball was invented after WWII for the blind.  The ball has two bells and the athletes have to use their sense of hearing to sort out where the ball is along with the other players.  It's stunning to watch.  (The first match is the gold medal match between the US and Turkey.)

There's a lot of interesting design in the Paralympics.  Sometimes the type of game, sometimes mechanical devices like special wheelchairs, and perhaps most important is a classification system to keep competition fair,  The amount of thinking that has gone into this puts many conventional sports to shame.  If you haven't watched any of the events go back and marvel at a few.  

 

Building proper access has been an uphill battle and people still fight against the Disabilities Act claiming it's "too expensive" or "just not worth it."  Getting the design right is a journey of its own.  A book that may change how you think about the built world is What Can a Body Do? by Sara Hendren. Solid recommendation!  This kind of design goes beyond physical affiances involving politics, law and sociology with the book addressing that and more.  The Paralympics are a shining example of it being done right in a limited area. 

 

This may seem a bit off topic, but I'd claim otherwise.  I've learned a lot from areas far from what I do.  Thinking about beach volleyball  led to a useful technique for studying neutron stars.   Get interested in something very different and you just might find interesting connections to something else.  Thinking about those with challenges is a rich area and probably useful for even non-designers to spend some time on.  It's a target-rich environment. 

 

 

dancing the parabola

from Radiolab on the history American Football (fans may want to listen)

excerpted from the show:

 

JAD: Which gets us to that game. November 23rd, 1907, Carlisle plays the University of Chicago. Last game of the season. We're in Chicago. And the Chicago team is arguably the best in the nation.

ROBERT: The best. I don't think it's even arguable.

JAD: Well, Carlisle's good at this point, though.

ROBERT: Yeah. But Chicago's like Stagg Field, whoa!

JAD: And there are 27,000 people in the stands.

SALLY JENKINS: Well, what happened was the Chicago players had decided to try to defeat Carlisle's innovative forward passing by just knocking the crap out of their receivers every time they came off the line of scrimmage.

JAD: And so Carlisle's greatest receiver, Albert Exendine, our guy, had been stymied the entire game, because the minute the ball was snapped the Chicago players would ...

SALLY JENKINS: Hit him and try to throw him down or knock him out of bounds. So Pop Warner said to Exendine, here's what we're gonna do. Next time they hit you out of bounds, sneak around the bench and get back on the field.

JAD: By some accounts, this was Exendine's idea. But whoever thought of it, on the next play Albert Exendine as expected ends up out of bounds, but he keeps running.

SALLY JENKINS: He runs around the back of the bench.

JAD: Runs around the spectators, maybe around the band.

SALLY JENKINS: And comes back on the field.

JAD: Right at that moment ...

SALLY JENKINS: Hauser, the quarterback of Carlisle ...

JAD: Lets loose a vicious spiral.

JAD: Can I have you read something?

SALLY JENKINS: Sure.

JAD: Hold on.

JAD: This is Sally's description of that moment from her book The Real All Americans.

SALLY JENKINS: For a moment, it was a frozen scene in a staged drama. The ball hung in the air, a tantalizing possibility. Could Exendine reach it? Would he catch it or drop it? Defenders wheeled and stared down field. Spectators watching from the stands found that the breath had died in their collective throats. The spiraling ball seemed to defy physics. What made it stay up? When would it come down? In that long moment, 27,000 spectators mashed together on benches and crammed on platforms may have felt their loyalty to the home team evaporate in the grip of a powerful new emotion. They may have noticed something they never had before: that a ball traveling through space traces a profoundly elegant path. They may have realized something else. That it was beautiful. The ball struck its human target. Exendine caught the pass all alone and trotted over the Chicago goal line. The stadium exploded in sound and motion. It was the game breaker. The rest was just anti-climax. The final score was 18 to 4 for Carlisle. But the very next year, the Ivy League passes a rule that you can't leave the field and then come back on to it.

JAD: Oh, that's where that rule came from.

SALLY JENKINS: Yes. That's where that rule comes from.

JAD: And I've got to say that that description of the ball in the air is -- is timeless, in a way.

ROBERT: Beautiful.

JAD: That's exactly why football is still beautiful at times.

SALLY JENKINS: That's -- that's when -- Carlisle in 1907 is when American football becomes the sport that you watch today.

 

The parabolic path of a ball in flight.  For many there's something profound and even beautiful about the path.  Physics dictates it.  Throw something in the presence of gravity and you get a parabolic trajectory.  Well - almost parabolic.  Air resistance slows the projectile and change the path anywhere from a little to a lot and some things crafty humans have done can further deviate the path - and sometimes the perception of the path - making sport and art even more interesting.   It's something to watch for as the Olympics unfolds.

 

Jumping is a parabolic motion.  A person launches themselves into the air and their center of mass traces out a parabolic path.  It happens in the long jump, high jump, pole vault, dance, basketball, volleyball and much more.   Athletes often change their shape and orientation around their center of mass to achieve a goal.  A high jumper folds their body around a bar even though their center of gravity passes beneath (the Fosbury Flop).  A ballet dancer appears to hang in the air when executing a grand jeté while their center of mass traces a parabola.   The same illusion of hang time appears in basketball and volleyball.  And gymnasts are masters of dancing their bodies around the parabolas they've created fractions of a second earlier. 

 

Dimples on a golf ball minimize drag and have a large impact on range.  Spin on a golf ball creates a force known as the Magnus effect that changes the ball's path a bit. Backspin, for example, creates lift.  This effect has an impact on most other sport balls giving the athlete some control on the deviation from an expected parabolic path.  In sports like soccer, table tennis and volleyball the effect is pronounced.

 

Some balls pass through interesting speed ranges where the drag on a ball can change dramatically on different parts of the ball adding a bit of chaos to the parabola. The screwball is a good example.  These unpredictable paths are often difficult to master, but have become weaponized in a few other sports than baseball.   

 

I've written about most of these effects in more detail, but it's fun to watch for these deviations from the expected parabolic trajectories.  I started with American football and should mention the spiral.

 

In many sports spin is used to make a ball's path less predictable while in American football it's used to make the path more predictable and easier to catch.  The difference is the odd shape of the ball.  Drag from air resistance depends on the football's orientation.  This is fine when the ball is kicked. The fact it's tumbling makes the path a bit more unpredictable to the opposing team.  

 

A spiral pass is a different matter.   Here the quarterback puts spin on the ball as it's thrown. The higher the spin, the more stable the football.  This turns the ball into a gyroscope of sorts.  If the ball is thrown pointed slightly up, for example, it will retain that orientation throughout its flight.  The coefficient of drag remains constant and deviation from the expected parabola will be constant.  That and the ball won't be tumbling when the receiver catches it. 

 

There is a tradeoff.  A quarterback has a finite amount of energy that can be transferred to the ball.  Putting spin on the ball reduces how fast the ball can be thrown.  Six hundred revolutions per minute is something of a minimal sweet spot.  The ball is stable at that spin rate and it doesn't reduce range as much as a faster spin would.  There's also another constant force from the direction of spin that makes the ball curve a bit to the right or left depending on the handedness of the quarterback, but that's another discussion and something quarterbacks compensate for.