"There's only one hard and fast rule in running: sometimes you have to run one hard and fast."








Monday, April 28, 2008

Heart Rate Monitor Training (plus new note)

I bought a heart rate monitor less than a year ago, more as a toy than a training tool. Back in my mind was the idea that it might be useful for comparing runs on trails and I might use it to control my tendency to go out too fast in ultras - I bought it shortly after I crashed at FANS - but I don't care for the gadgetry so many runners feel necessary. There are a few books one can buy about training with a monitor and they all seem like so much fluff. I had low expectations, yet I still use a monitor for tough runs. This post is all that I've learned.

You can't increase your maximum heart rate with training. Except, I sort of did. Maximum heart rate decreases with age (it's a function of synapse firing; it slows with one's reflexes and ability to recall facts from memory) and varies a lot from person to person. I measured mine by sprinting up the toughest hill available until I was forced to stop, then pushing on again... and again. I got to 179 beats per minute. Testing several times, I always got to 179 (or 178). Six months later, I got to 180. Last month, 181. I may not have increased my maximum, but got used to running long periods of time at near maximum, allowing me to occasionally get closer to my true maximum. Regardless, it seems to be a measurable improvement. I just can't advocate "run 'til you puke and cry" intervals for a 1% improvement, particularly for ultrarunners who don't ever run anywhere near maximum.

I'd always been awful running downhill on trails. To change that, over the winter I trained on hills, trying to keep my heart rate constant on both the uphill and downhill. This required slowing, even walking at times, on the uphill, but speeding downhill, sometimes just short of out of control. Monitors come with alarms that will tell you if you're above or below a target heart range (finding the right range is an art) and one gets to feel a slave to the monitor at times. One does, however, develop a feel for when the alarm will start sounding.

Generally, people use monitors on a course they do often, either measuring progress by seeing if one's average heart rate slows when running the same speed (treadmill runners especially do this) or set a monitor for a given heart rate and see if their speed improves. It was all too qualitative for me. I wondered if one could do more.

I ran the Nerstrand Big Woods 1/2-marathon with a monitor, averaging 174 beats per minute (with a peak of 180, the first time I reached that maximum). No one, ncluding me, thought a runner could run at 97% of maximum for 93 minutes, so I was going to have to create some new math. For a while, I considered a "phantom" maximum, a number to function as a maximum, even if it were unrealistic.

Here's where the post devolves into technicality. [Sorry.]

According to Tim Noakes, whose sources seem credible, top 5K runners compete at 89-100% of their VO2max, marathoners at 76-87%, 85K runners at 53-76% and 24 hour runners at about 45-50%. There seems to be a reasonable correlation between heart rate and oxygen uptake: %VO2max= % heart rate reserve, or %HRmax=0.64%VO2max+37 (give or take 8%). This should allow one to find what average heart rate one can maintain for various times.

I thought I'd need to run several races with a monitor to come up with a formula, but decided to try piecing together what others had already tried. I found that log(minutes)+Alog(HR-B)=C.
For me, A=4.38, B=66.6 and at maximum, C=10.863. One could determine the constants for other runners with three race results and better than average math skills. The value of A, I expect, is nearly the same for all runners. B might be one's resting heart rate, though mine is currently 35; 67 is just below what I usually get as a minimum during training runs where I do some extended stopping. C would vary with effort, so I may have inadvertently stumbled on a way to compare difficulty of workouts. I've tested the formula at Chippewa and Trail Mix and the average heart rates came out exactly right. It suggests that I could run FANS at 124 beats per minute (49% VO2max), higher than I'd expect.

Lest anyone take this too seriously, it should be pointed out that last year's Superior Trail 50K was won in four hours, or 153 bpm and last place was 8:13, or 140 bpm and I can't seem to stay between those numbers on any hill, no matter how I try.

Still, I think I'll keep my toy.
.....................
My economic stimulus check

I just got my economic stimulus check direct deposited. Yes, for those of you who doubt, that means I actually had earned income over the minimum $3000 last year (for the uninitiated, how I manage to survive financially is a subject of much speculation). I got the $300 minimum.

Here's the checks I wrote the same day: Runnin' in the Ruff 10K ($17), FANS 24-hour ($125), Sour Grapes 1/2-Marathon ($25), Afton 50K ($40), Voyageur 50M ($35), Ice Age 50M ($75). I got comp'ed entry to the Superior 50K [Thanks Gretchen!].

My economic stimulus supplied money to an inner-city educational charity and the economies of small cities in Minnesota and Wisconsin. That's more than the current administration did.

4 comments:

keith said...

Is there a reliable field test to find your VO2 max? Or does one just have to get real friendly with some exercise physiologists in order to score free tests?

Steve said...

I've been always curious about using a heart rate monitor for training, but for now, I'll just focus on getting some miles in. Maybe when I decide to be "competitive" I'll think about it. Very interesting theory though, Steve. I would really like to see some more testing and data on this one. It's funny how small thoughts can turn into theories and in-depth case studies. Gotta love the engineering mindset!!

Runner Brewer said...

by the way, i am pretty much done with using my monitor for the year. I did not use it Sat during our run.

The only times I use it now is for feedback, not to tell me what to do.

Keep in mind, Steve, you have a history of "high competition.".... dare i call you elite....

Most of us hacks don't have that in their physiological base. So, the low hr can be one way to develop a stronger base.

I bought mine 6 years ago, and only used it for speed work. I did not use it for 3 years.

Diane said...

I think some/most of my check will go towards entry fees as well, although some might argue it should go to the t.v. that I bought in February with my, umm, stimulus money?!