Wednesday, January 28, 2009

Some words about numbers

I love words, playing with sentence structures, teasing semantic overtones, reveling in the subtle shades of meaning from choosing one word over another. I can spend hours obsessing about the phrasing of a single sentence. My more serious posts to this blog can sometimes take days to complete. I've even one that's months old still siting in the queue, unposted, unfinished. No doubt, I've been accused of exhibiting a certain pedantry.

Numbers as well. With numbers my tendencies tend towards a sort of compulsiveness. I've been logging my runs since around 2000. Before that I wasn't consistent (or confident) enough in my running to track it because once its recorded, it's later reviewed then manipulated, analyzed and, ultimately, judged. Time, distance, pace, elevation, calories. Splits, averages, fastest, longest, most, best...worst.

The first few years I maintained written logbooks, but eventually moved to an electronic one. I was always meticulous about recording my runs. If I didn't have my log with me on a trip, I would record the time and distance on some random scrap of paper. Miles would be calculated from maps or estimated (roughly) in their absence. Online mapping software was my best friend. Before a run I'd use it to explore possible routes and alternatives; afterward, I'd retrace the precise path I had taken. I was actually fairly resistant about getting a Garmin for some time. I always said it was just one more thing over which to obsess. But, secretly, I think I really enjoyed the process of adding miles up on the map--mentally re-living the run along the way.

Eventually, I gave in to the GPS. After all, I am a gadget lover as well. Simplicity of recording meant more time for post-run analysis. With programs like SportsTracks, I could review trends: daily, weekly, monthly. I could even generate custom reports; my obsessive nature delighting in the minutiae. With such tools, I can now figure out the difference between my average pace on Wednesday afternoon versus Thursday evening runs over the course of a given year! What more could I as for?

I, similarly, had an initial aversion to using a heart rate monitor (HRM for the initiated). If I already spent way too much time checking the watch for my current pace, distance and accumulated time, I would likely become downright rediculous wirh yet another number to track while out on my training runs. Then there's the whole bio-feedback angle where the very act of worrying about my HR can make it go up. But, alas, I committed to follow the Maffetone equation and keep my heart from beating more than 145 times every 60 seconds during my base building phase. There was pretty much no way to avoid adding yet another electronic device to this normally simple sport, further feeding my obsession with a constant stream of numbers.

So, I've been monitoring my heart rate, trying to keep it below 145 bpm while maintaining a consistent (but, hopefully, increasing) pace. At least in these initial weeks, my pace and average HR vary quite a bit based on a number of factors that I can't always identify. Basically there are good days and bad. I've been looking for a way to compare workouts so I can look for a general trend. My idea was to simply multiply HR in beats per minute (bpm) by pace in minutes per mile (mpm) to come up with the metric of beats per mile. I could then compare the results of this function from one run to another as a sort of index.

The problem with this function is that HR doesn't necessarily rise linearly with pace. So, for example, if my average HR at 10-mpm is 140 and at 9-mpm its 150 then the I get values of 1400 and 1350, respectively. Further, the reality is even more dramatic as my HR seems to go up more slowly as my speed increases, at least to a certain point. After that I, need to work much harder for increases in pace. However, this point, the functional minimum (or the point where the first derivative equals zero for the mathematically inclined), is well above the 145 recommended max HR. I could conclude that I should just try to run as close to 145-bpm as possible in order to optimize this function within the limit. However, this is not only difficult to acheive in practice, but probably goes against the spirit of Maffetone. The idea is to keep all your running below a certain effort level, not to target a particular average while pushing the pace.

I suppose I could just try to minimize my total heart beats over a week, but then my distance is pretty variable so perhaps I could just look at the average per mile. However, even here, weeks with longer runs will tend to skew the data as my HR is higher for a given pace late in a very long run and, therefore, not comparible to the measure added up from a few shorter runs. There are also runs with my wife where I go at her pace so my HR will tend to be much lower overal than if I were just running at my own pace within the zone. No, the only thing to I can do is compare workouts where my HR is at near the same average and see if pace is increasing over the weeks (or conversely compare runs where the pace is similar and see if HR is decreasing). There's no need for my beats per mile metric if HR (or pace) is kept constant.

Oh well, at least I can have some new useless facts with which to waste time. My heart beat 98,560 times while running the last week. Fascinating. This does bring me to one last thought which is the concept of "lifetime heartbeats". As runners, we are often confronted by sedentary people who offer up some dubious criticism of our sport generally as a rationalization for their own lack of fitness. Usually its something about ruining our knees, being hit by cars or eaten by wild animals. However, chief among these absurd claims has to be the assertion that "we only get a certain number of heart beats in our lifetime." The idea being that we runners are going to die sooner because we are using up our heart beats at a faster rate.

Let's enter the couch potato's fantasy land and grant this claim at face value. The average male human resting heart rate is around 70-bpm. Mine is about 48. Let's assume that when not sleeping our fictional sloth manages a modicum of exertion--getting up to go to the fridge, walking to the car, moving between cubicle and elevator, etc.--and manages a weekly average of 75-bpm (we'll put mine at 55). A week has 24*7=168 hours. On a good week (when not racing a 100 miler), I will get in 11 or so hours of running. Let's say that I work pretty hard and have an average HR of 150-bpm for my runs. That would be 11*60*150=99,000 beats while running. The rest of the week would total 157*60*55=518,100 beats for a total of 617,100 beats for the week. Now, our sedantary man in that same week will have accumulated a total of 168*60*75=756,000 beats. Even on a week where I ran a 30hr 100-miler with an average HR of 140 (no way I could keep that high in a 100), my total would still be just over 700K.

Now, tell me, who is going to use up their heart faster?

After all this data gathering and post-data gathering analysis, there is really only one inexorable conclusion. I am, quite likely, borderline OCD about certain things (I can hear you laughing, honey, but its a big border, OK?) The only cure I've found is to lose myself in a very long run on a remote trail somewhere with the GPS serving only its most vital function of reminding me that I do, eventually, need to return home (and letting me know just which way that might be if I need it).

1 comment:

Drs. Cynthia and David said...

Charming entry Steve. I had a similar argument regarding lifetime heart beats with a professor when I was in grad school. (I won)

I think the Maffetone training is complicated by running on hills. Hills get my heart rate up there fast- so I might range from 150/160's on the uphill to 110/120's on the downhill. It seems almost like interval training. Are you seeing anything that looks like a change with your training? I find HR is higher when I am well rested but also when lactate is accumulating at higher paces. It could make a difference whether you are stressed, fed, what you've eaten or whether you've been running every day. Oops, just gave you more suggestions to obsess over (but it's fun right?).

Are you joining Adam's Fat Ass this Sunday? It sounds like fun (though I'm still having troubles).