Energy and Power Numbers at the Gym

I spent a few more minutes on the elliptical at Ponds Forge this morning compared to my normal workout.  When I was finished, I snapped a photo of the screen, shown below.

I have written about numbers seen on gym equipment before (click here), but I thought I would revisit the topic.  The power reading was dropping precipitously after I stepped off the pedals.  I had burned 684 Calories.  Note that 1 "big C" calorie is the same as 1 kilocalorie, which is 1000 "little c" calories.  Food calories are always in terms of "big C" calories.

To find average power, I need only divide energy output by exercise time.  I will find the time in seconds first.

\[T=(80\,\mbox{min})\,\left(\frac{60\,\mbox{s}}{1\,\mbox{min}}\right)+4\,\mbox{s}=4804\,\mbox{s}\,.\]

Now find the energy output in joules.

\[E=(684\,\mbox{Calories})\,\left(\frac{4184\,\mbox{J}}{1\,\mbox{Calorie}}\right)=2,861,856\,\mbox{J}\,.\]

Sorry about all the digits!  I will truncate soon.  Now get my power output.

\[P=\frac{E}{T}=\frac{2,861,856\,\mbox{J}}{4804\,\mbox{s}}\simeq 596\,\mbox{W}\,.\]

That looks like an impressive power output, right?  After I stopped the machine, I saw the screen below.

Ignoring the extra second on the clock, that page told me that my average power output was 98 W.  Why such a difference in powers?

The answer lies in the thermodynamic inefficiencies associated with energy conversions in the body.  The laws of thermodynamics tell us not only that we cannot get more energy out than what we put in, we cannot even break even.  The glorious second law of thermodynamics tells us, in a hand-wavy way, that there is always waste energy in the workings of a motor.  My body's efficiency may be found as follows.

\[\eta = \frac{P_{output}}{P_{internal}} \cdot 100\% \simeq \left(\frac{98\,\mbox{W}}{596\,\mbox{W}}\right)\,(100\%) \simeq 16.5\%\,.\]

I have added subscripts to the powers.  My output power was not quite that of a 100-W lightbulb.  If you have never tried to keep a 100-W lightbulb on while biking on a stationary bike, you should try it one day.  It is not as easy as it might seem!  But for me to output power at the rate of 100 W, I need to consume food energy in my body at a rate nearly six times what I am able to output.  The waste energy is why I feel hot while working out.  I have estimated Tour de France cyclists' body efficiency to be 20% in my past work.  That is certainly in the ballpark with what I found above.

The MOVEs number is a bit less well defined.  Technogym, who made the elliptical I used, defines MOVEs as "... the ultimate unit of measurement to objectively assess your lifestyle based on the movement and exercise you do and regardless of your gender, age or level."  Technogym gives some examples, such as 50 MOVEs for taking five flights of stairs, 200 MOVEs for a half-hour walk, and 400 MOVEs for a half-hour run.  Technogym further defines Movergy as "... an index of how active your lifestyle is and represents the average of your daily MOVEs over a 14-day period."  If your Movergy is below 500, you are sedentary.  If your Movergy is above 750, you are moderately active.  And if your Movergy is above 1000, you are considered active.  I am thus happy with my 1629 MOVEs!

Do take numbers on gym machines with a grain of salt.  The machine I used had no idea of my gender, age, height, weight, level of fitness, and so on.  I suspect that a human average efficiency of one-sixth is used to compute energy burned.

So Long, Pete Rose

Just after waking up this morning, my wife told me that Pete Rose had died.  I confessed to her when we left our Sheffield house for the gym that the news she passed on to me was quite a gut shot.  I have written and spoken too many times to count about my love of baseball.  Growing up in West Virginia meant living in a state without a professional baseball team.  I thus followed the Baltimore Orioles, the Pittsburgh Pirates, the Philadelphia Phillies, and, of course, the Cincinnati Reds.

I wrote a '5' on my glove because I was enthralled by the way Brooks Robinson played third base.  But the team I rooted for while growing up in the '70s was baseball's first team, the Reds.  Rooting for the Reds in the '70s meant rooting for one of the greatest assemblages of talent on a single team.  The little kid I once was listened to Marty Brennaman and Joe Nuxhall ("the old left-hander, rounding third and heading for home") on the radio at night as names like Bench, Morgan, Concepción, Pérez, Foster, Gerónimo, Griffey, and Rose became larger than life for me.  Long before the internet, newspaper box scores and backs of baseball cards became the sources of numbers for my fertile brain.  Many of the numbers associated with the players I listed above still dance in my mind.

Books on baseball were how I learned baseball's history.  The story of Pete Rose crashing into Ray Fosse to win the 1970 All-Star game in Cincinnati's Riverfront Stadium was familiar to me as a five-year-old baseball junkie.  But that famous play happened 53 days before I was born.  I once looked up that Pete Rose went 2 for 5 on the day I was born.  He would have been 29 years old then.  Despite his age in 1970, Pete Rose had more than 2500 hits to get, a third batting title to win, an MVP to capture, and three World Series rings to earn.  I was jumping for joy when the Reds won the 1975 World Series, but I recall to this day being told by my dad that I had to turn in before extra innings began for the 6th game.  I missed Fisk's home run, but I stayed up to watch the Reds win the thrilling game 7.

I am far back on the list of people who have made the following observation.  Pete Rose fought, clawed, and scratched to win baseball games.  I admired his grit and determination to no end.  A moment in a department store in the summer of 1978 is one I still recall.  I was not interested in shopping with my family.  The televisions drew my attention.  I wanted to see if Pete Rose could keep the streak going.  He hit one of his trademark line drives for a double and I knew the streak was still alive.  Later that summer, I watched on television as Gene Garber, whose sidearm delivery I occasionally mimicked when I pitched in Little League, got Rose to chase an off-speed pitch to end the game and the streak.

Though I was sad to see Pete Rose leave Cincinnati before the 1979 season, I was happy that he was still close in Philadelphia.  He would get 208 hits that year, his last season of at least 200 hits.  I rooted for the Phillies in the 1980 World Series, and I can still see Pete Rose grabbing the ball that Bob Boone muffed near the Phillies dugout.  Rose looked so happy, especially when he bounced the ball on the turf.

Not long after my 15th birthday, Pete Rose passed Ty Cobb.  At that time, Rose was a lock for the Hall of Fame and a glorious post-baseball life.  But just before I turned 19, Rose accepted the permanent ban.  Maybe I had a "Say it ain't so, Pete!" moment that summer of 1989, echoing an apocryphal statement to another one of baseball's permanently banned greats.

It is wise not to turn people into heroes.  Disappointment is almost always the result of doing so.  To this day, I admired the way Pete Rose played baseball.  He inspired me at an incredibly early age.  He was far from being the most physically gifted player of his era.  But he used a grit and determination unlike any player I have ever observed to become a baseball great.  How did that observation manifest itself into my own life?  Growing up lower middle class in West Virginia meant that I had to work hard just to figure out how to get on the academic path I grew to desire.  I loved Rose's example of simply outworking everyone around him so that he could succeed despite any obstacles facing him at the start of his journey.

I repeat that it is wise not to turn intrinsically flawed human beings into heroes.  For me, I could admire and be inspired by the absolute best of a person like Pete Rose even if the very worst of him disgusted me.  Lying was among his vices, and that is one vice I cannot abide.  Pete Rose spent the last 38 years of his life, nearly half of it, answering questions about gambling and the Hall of Fame.  Being a Hall of Fame pariah for all those years probably brought him more fame and notoriety than if he had been inducted in the early '90s.  His gambling vice is now embraced by sports organizations that have enjoyed the money that has rolled in since sidling up to legalized betting.

On the day after he died, I thank Pete Rose for all the wonderful baseball memories.  I thank him for being an astonishing example of how hard work can pay off.  So long, Pete Rose.  You were not my hero, but I sure did admire the best of you.