Thnx. I appreicate the time you took to get me those citations.

So i read the abstracts for these articles and I have read Jack Daniel's Book. Jack Daniels seems to observe that 90 is what good runners do but has not established this from a normative perspective. The articles seems to suggest that running economy is important but does not establish that 90 is a magic number. Am I missing something?

But it's pretty convincing that fast people with slow cadences are very rare.

I don't tell someone to run a race at 90 if they have trained at 80.

Scott

Quote

  One of the reasons is that to run fast basically there are only 2 variables you can adjust: stride length and stride frequency. You can modify your stride length to a certain extent, but frequency has a larger range.

no, stride legnth has a much larger range. at various speeds stride frequency will only vary by about 4%, stride length will vary by 28%. most speed in gained by increased stride length.

In Reply To

 
There are lots of other little things you can adjust - the biomechanics of running is extremely complex. There are things like where you land your foot, heel vs. mid-foot strike, forward lean vs. upright, etc.

Cavanagh PR, Kram R (1989). Stride length in distance running: velocity, body dimensions, and added mass effects. Med Sci Sports Exerc 21(4):467-79.
The preferred stride frequency (SF) and stride length (SL) of male recreational distance runners were measured on a level treadmill under a variety of conditions over the typical distance running speed range of 3.15-4.12 m.s-1. At a given speed, the correlation coefficients between the subjects' anthropometric variables (APV) (such as stature, leg length, and limb segment mass) and their preferred stride variables were consistently low (less than or equal to 0.36) and not significantly different from zero. As speed increased through the experimental range, SF remained nearly constant (only a 4% increase) while SL increased by 28%. The use of dimensionless velocity was shown to be no more effective than conventional methods in the prediction of a SL vs velocity relationship, but the dimensionless form of the relationship was remarkably similar to those observed for other animal species and other forms of gait. The addition of masses up to 1.1 kg at each ankle produced no significant change in SF or SL. The results indicate that factors other than APV are the primary determinants of preferred SF and SL. Since it has been shown previously that the preferred SL is usually the most economical, APV cannot be used to accurately predict or prescribe SF or SL on an individual basis.

+/- 90 is what people have observed in elite distance runners. They, however, got there by running lots and that is where their body and mechanics just end up.

"Forcing" yourself into a cadence is just silly in my opinion. If a runner is obviously overstriding and landing in front of their centerline (it makes no difference which part of the foot they land on, just where the foot lands in relation to the center of gravity of the body), then they will usually have a lower cadence and adjustments should be made to get them landing underneath their body. But in contrast, having a lower turnover is NOT an indicator that someone is overstriding. It is just where their body naturally wants to be.

Same idea with cycling.

thanks.
i think 'everybody' likes to think that they (recreational level) should do what the big dogs do and then they will get faster more quickly. but they don't. if one is not an elite then maybe one should look at the training/technique of people at the same level and then build on that base over time. like people who come into tri biking with an advanced bike position. maybe you should start with something more practical and develop into the uber biker. with running maybe a 3:30+ IM marathoner should not try to run like an elite marathoner right away. JMHO.

"Recreational runners aren't great to do that kind of a study, as they (probably) have never consciously tried to work on their running stride, they just run at what feels comfortable, and to go faster, they lengthen their stride, rather than increasing their turnover."
i expect that 'what feels comfortable' is probably better, faster, healthier and that is why they do it. that is what their body and mind are comfortable with. fighting that to increase turnover instead is not the best approach.
regards