I did 4 miles on the W&OD rail-trail this morning, but looking at the forecast, I was afraid that it would be pouring rain all day tomorrow and I wouldn't want to run in that. So I went out just before sunset and did another 3 miles on the track to complete my personally-assigned weekly minimum mileage this week. Both times I was averaging a comfortable 12 min/mile pace (or .0833 miles/min).I did something new - counted my right footfalls for one minute to determine my comfortable running cadence. I repeated it four times - so counts of 86, 84, 83, and 83 average out to a stride frequency of 84 strides per minute.
Now since velocity (.0833 miles/min) equals stride length (in ? miles/stride) times stride frequency (84 strides/min) , then stride length equals velocity divided by stride frequency.
Doing the math, and converting to feet, gives me a calculated average stride length of 5.23 feet per stride when I'm running comfortably at that velocity. Cool!
Of course, any time I increase speed, either stride length or stride frequency, or both, must increase, by definition, so these will vary depending on how fast I'm running.
Additionally, this tells me that my lowest optimal cycling cadence is somewhere about 84 cycles/minute. Or slightly higher, since your leg is somewhat shorter when it's bent when cycling, making a shorter pendulum with a higher natural frequency.
Or maybe not. I may possibly have had a teensy bit too much of the excellent Riesling that we had tonight with the tuna steaks that I grilled for dinner. Yum!
10 comments:
Hmmm, just checking to see if Blogspot is buggered up again like it was last night....
Nope.
Ya know I love math Nancy, but that more than I can think about during a run...lol.
It was just counting strides! Not doing math. I can't do math during a run either!!
Doesn't everyone do math when they run? I always have.
I can barely run and chew gum... Nancy - I think you are taking this exercise thing to a whole new level!!!
Since velocity = stride length * stride frequency, in most cases a low stride frequency means nothing more than ... you're running more slowly than someone using a higher stride frequency!
So sure, if I was running faster, or as fast as the "optimal" elite runners Dr. Daniels probably is referring to, I'd be running with a higher stride frequency.
To compare apples with apples, you have to compare runners (or with yourself) moving at the *exact same* velocity.
Well, Nancy, using your math then, if you decrease the stride length, but increase the frenquency, you have the same velocity, yes? I think the point of most coaches is to get you to increase your frequency (turn over rate) and that then, eventually, your stride length will naturally lengthen, resulting in greater velocity. Does that make sense?
I only mention it because my coach has me counting my foot strikes on some of my runs and we are currently aiming for 22 in 15 seconds. To do this, I must shorten my stride because, like you, I want to stretch it out. However, at this point, doing so makes me slower rather than faster.
I'm also not sure their is a direct correlation between foot strikes and RPM on the bike. I can easily do a ride with a 95 RPM but I think I'd trip if I did that while running. Also, by training my body to cycle faster (cadences of 95-105 rpm), I will train my body to run faster. Well, at least so my coach keeps telling me. She says my cycling will help my running more than my running will help my cycling. Hey, if she gets me through IMC this year, I'll be a believer! :-D
Yes, if you both decrease stride length and increase frequency, you stay about the same velocity. Those are interesting aspects, though, Puddy! And you're right, I don't think there's a direct translation to cycling. And when people start talking about "efficiency" usually they're getting onto thin ice, because running faster almost certainly means expending more energy. Unless I lose a lot of weight (fingers crossed!) that is!!
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