Thursday, March 17, 2011

Cardiac Drift

The human heart feels things the eyes cannot see, and knows what the mind cannot understand - Robert Valett
One way to measure fitness is to examine cardiac drift. I'll loosely define this as the tendency of the heart rate to increase as the length of the exercise session increases. If your heart rate doesn't change much over 10 miles then you're in great shape. If it steadily climbs to your maximum after only 5 miles then you may be able to improve your marathon performance by increasing your stamina.

The key to an accurate measurement of cardiac drift are these keys:
1) A sufficient warm-up
2) Consistency during the run (pace, hydration, temperature, elevation, etc.)
3) Distance of the test run

Today I ran 8 miles on the treadmill while I watched the first games of March Madness. I'll count my first two miles as a warm-up -- enough time to let my heart rate fall into a steady state. I kept the pace constant (7:41), the gym temperature didn't vary (although it was warm enough to leave me soaking wet with sweat). I kept the treadmill on a 1% incline the whole time. I did not drink anything over the entire hour run, which may negatively skew my results. Failure to replenish your fluids results in a higher heart rate in large part because the blood becomes more viscous, making it harder to pump. The heart increases the rate in order to maintain an adequate oxygen supply to the muscles.

As far as point 3 goes, I ran six miles after my warm-up. I've read studies that your drift should be under x% for distances of y miles in order to be in shape for races of z distance. I can't remember any of those variables, but I would think that a 6 miles cardiac drift test would be a good indicator of half marathon fitness.

This is how it played out, with each line representing an average heart rate for that mile:
7:41 pace throughout, 1% incline
124 BMP

I'm not really sure what to do with this, but for simplicity sake I'll subtract the average of mile 3-5 from the average of mile 6-8 to get about 6 beats per minute. if I take that number and divide it by the average of mile 3-8 then I get a 4% cardiac drift. If I factor in my resting heart rate (about 45?) then the drift is about 6%.

(144-138)/(141.167 - 45) = 5.67%

The thing is, I don't know if 4% is good, or if 6% is bad. And if I say that my warm up was four miles instead, then those numbers go down to 2% and 2.5%. And I also don't know the effect of not drinking during the run.

I guess the answer is not so much the absolute number so much as how these numbers change when/if I ever do this same exact test again.

Wednesday, March 16, 2011

The Power of Mathematics

Life is the art of drawing sufficient conclusions from insufficient premises. –Samuel Butler

At one point in my life I thought I might want to be an actuary. I am a firm believer that mathematics can be used to explain (and predict) events. Take for instance the heart rate as it correlates to fitness and ultimately race performance.

Theoretically one could collect enough data in order to accurately predict a marathon time. Gather a history of the following training data: pace, course conditions (hills, wind, surface), distance, human conditions (health, fatigue, diet, weight, hydration, sleep, resting heart rate, running heart rate). Develop an equation or some artificial intelligence algorithms based on those factors, and then predict your race given the environment.

One key is to note that most models do much better "interpolating" results as opposed to "extrapolating" results. In other words, if all of the data input distances range between 6 miles and 13 miles then my model will best estimate times between those distances. If I use the model to predict a 20 mile race then I am extrapolating and it's likely to be less accurate. This applies not only to distance but also to heart rate and every other factor for that matter.

There's the rub. Since we so seldom work out at race pace, and never for race pace at race distances, the model will almost always be forced to extrapolate. Of course there are elegant mathematical methods to reduce this limitation, but they can only be so good. I think perhaps the biggest flaw in this approach is probably the general lack of data. If you ran every day for 100 years you probably wouldn't generate enough data to generate a comprehensive set that produced high r squared values. Which brings us to Mr. Butler's quote above. We all go through life making decisions aimed at returning the highest payout (however you choose to measure "payout"), with data sets far too small to be able to know definitively that our choice is correct. In short, we take risks based on our best knowledge. It's the same thing with our race predictions -- I'm going to pick a race goal pace at the beginning of the OKC marathon and hope I can hold on to it for 26 miles. It's risky, and I've almost always crashed in marathons, but I'm hoping this one will be different.

Of all those factors I mentioned above I tend to believe that the heart rate (both resting and running) is the most significant variable that drives predicted performance. To that extent I'm fairly happy with results like I recorded today.

8.29 miles, 1:04:48, 7:48 pace, 130 HR avg

Tuesday, March 15, 2011

In Sickness and in Health

Health is not valued till sickness comes.
Thomas Fuller

I try to be keenly appreciative of my health. I consider it a blessing and a gift that I am nearing 40 with no major health issues yet.

That being said, I often fail in my attempt to offer thanks for my health until I find myself sick. Like today. Right now I'm not feeling 100%. I don't know if it's allergies or a virus, but my throat hurts and I'm generally achy. It's just a speed bump compared to more serious diseases, but if you ask my wife I'm sure she would tell you that I'm unbearable when I'm feeling this way.

So I looked forward to my lunchtime run for a different reason than normal today. I expected the achy feelings to ease after a warm-up and the heart rate to be generally higher at the same pace as non-sick runs. I wanted to analyze the correlation between sickness and heart rate during a run.

My hypothesis of a slower pace for the same HR followed through 3.5 miles -- an 8:03 pace at a HR of 135 BPM. And then something happened like a switch flipping, and I felt perfectly fine. I ran the next 4 miles at 7:41 with the same HR. I'm not sure what to make of that except that perhaps increasing my HR over my resting rate helped to temporarily flush out whatever was causing my ailment.

Overall: 7.38 M, 58:12, 7:53 pace, 135 avg HR

Sunday, March 13, 2011

Stinky Face

6.01M, 46:27, 7:43 pace, 134 Avg HR
No noticable residual effects from yesterday's long hill run.

I saw a skunk today about fifty yards short of my normal turnaround point. He was running away from me. A friend told me he stepped on a dead skunk while doing some night running and the stink was so bad that he had to throw away his shoes despite several attempts at cleaning them. No thanks. I made a 180 and got out of there.

If you have a child then I'd recommend this book:
I Love You Stinky Face

Our copy was a gift from my fellow Tornados.

Saturday, March 12, 2011

The Hills of Conroe

24M, 2:50:41, 7:44 pace, 135 avg HR

I went to Conroe with The Kenyan Way today. It's as close to hills as Houston gets. Sean Wade (KW coach and olympic marathoner) said the route had more hills than Boston. I think I'll join them again in a couple of weeks when they go back.

The legs feel great and the heart rate stayed really low . . . not really sure why, but don't look a gift horse in the mouth.

Friday, March 11, 2011

What a day

"And in the end, it's not the years in your life that count. It's the life in your years." --Abraham Lincoln

Although the majority of my waking hours today will be spent at work, I feel as though today is a vacation day. It's one of those days I like to call a "top 10 day". My lunch time run was as good as it gets -- no clouds, a gentle breeze and the perfect temperature, 6M, appx 7:35 pace. My outdoor companions included canoeists, cyclists, Segway riders, dogs and pedestrians/runners. We collectively soaked in the ideal conditions. Perhaps this is what Abraham Lincoln had in mind when he spoke of having "life" in our years.

Thursday, March 10, 2011

Lenten Reflections

I stumbled upon a treasure trove of quotes at
I'll try to post a few here and there during this Lenten season.

In this life
Be kinder than necessary,
for everyone you meet is
fighting some kind of battle.

derivation of this quote:
Author James M. Barrie, of Peter Pan fame, said “Be kinder than necessary.” But his advice stops there. Plato is quoted as saying “Be kind, for everyone you meet is fighting a hard battle.”

One time I was running two abreast along a narrow path and an older lady (50s?) approaching from the other direction stuck out her elbow and hit me in the rib cage, despite my attempt to make room as she passed. Unfortunately I'm too quick to anger so I got upset. After a while I was able to see that she was fighting her battle with the end of a long run. We've all been there -- everything stinks and you just want it to be over. And ultimately I was ok being the target for some of her frustration, because I probably was taking more than my fair share of the path.

My training is going well right now. I ran a 24M long run yesterday (an easy 7:52 pace) and my normal 6M lunch time run today without any residual effect.

I won't attempt to catch up from the last time I posted a blog, but I will say that right now I'm training for the Oklahoma City Marathon on May 1, 2011. If all goes well I'll post a Boston qualifying time in order to run Boston in 2012. I'm also training for the NYC 2011 marathon. If (big "if") the next three marathons go according to plan (OKC, NYC, Boston) then it's likely that I'll hang up my marathon shoes. Only time will tell.