Elitetrack: Sport Training & Conditioning

fuzzy math…

Let’s refer to the research as your calculations are not making sense to me.

Limitations to maximum running speed on flat curves- by Chang and Kram (see attached)

Track (m) (steps·s–1) time (s)

Straight 2.07±0.12 3.72±0.19 0.159±0.005

Curved radius (m)
Outside leg
6 1.70±0.10* 3.56±0.12 0.190±0.006
4 1.45±0.05* 3.66±0.18 0.198±0.007
3 1.41±0.07* 3.35±0.10 0.226±0.008*
2 1.18±0.08* 3.30±0.18 0.242±0.010*
1 0.80±0.04* 3.56±0.26 0.261±0.022*
Inside leg
6 1.53±0.02* 3.88±0.13 0.203±0.008
4 1.30±0.03* 4.05±0.11 0.221±0.009*
3 1.21±0.03* 3.78±0.06 0.233±0.008*
2 1.01±0.07* 3.74±0.23 0.263±0.008*
1 0.77±0.02* 3.82±0.12 0.290±0.004*
Values are means ± s.e.m. (N=5).
*Statistically significant different to the straight path condition
(P<0.05).
Symmetry was assumed on the straight path.

note stride length changes and 10.5 guys have longer than 2 meters. Colin Jackson was 2.0 meters for his hurdle strides but was 1.6 off the hurdle.

Cody what are your thoughts now?

Carl,
I will look at the study in more detail in the days to come, but my initial reaction is to notice that the curvature of radius was 6m. What is the curvature of radius for the 100m curve? Some googling give me about 31m for the radius of curvature. Given that fact, you can see from the data posted that with the increase of radius of curvature, the stride length is increasing and approaching the straight-away stride length. I don’t think it will ever reach the stride length of a straight-away, but if at 6m you are already at 82% of your straight-away stride length (outside leg), then a radius of curvature that is more than 5 times greater will increase that percentage a significant amount, bringing it closer to the straight-away stride length.

Cody

Read the research Cody. Read the post data. I showed you that the curve had shorter strides.

Okay, I’ve read the research, and I’ve read the post data. I think that the paper is great and its main focus was on force output changes and time spent on the ground. I won’t argue that the curve has shorter strides; I agree, its just the significance of the shorter stride that is at issue here and whether or not the significance can be used as an effective training tool. Are you going to tell me that the researchers would have seen a stride length of 1.7m around a 100m curve just like the paper showed for the 6m curve? I hope not. It looks to me like the stride length was increasing with each radius of curvature increase. In fact, from 3m to 6m it increased by over 17%; 6m to 12m lets say 10% increase...now the stride length is at 1.87m; 12m to 24m lets say another 5% increase...length of 1.9635m (4.2 inches less) and we aren’t even at the curvature of the track in lane 1 so lets add another 2% increase for a final stride length of 2.003m which means a 2.6 inch difference. Plus, I think I’m being generous with my percent increases, it may even rise faster.

The main point of my original post was that when you are on a curved surface and you take a short enough distance, you are essentially going straight. Think about the earth. We all know it is round, but for short distances do we take into account the curvature of the earth? Not usually. Same case for the track. When I looked at my track and I marked out 2m, it was virtually straight, try it and see. Especially if you go out into lane 8.

Well, I think I’ve beat this horse to death, if I’m way off base then I apologize, but I just don’t think that one can suggest that the fact that a 6 meter radius of curvature showing significant decrease in stride length immediately means that a 30 meter radius of curvature will show the same significant decrease especially when the same research shows stride length increasing towards straight-away length with increasing radius of curvature.

Conclusion from the paper: “In summary, we have shown that maximum sprint velocity
on curves is not only limited by a physiological limit to axial leg force since: (1) direct evidence indicates that maximal physiological force generation is not achieved during maximal effort sprinting at all radii; (2) externally supplying centripetal forces did not increase maximum velocities on the curve to expected values and revealed the importance of the underlying asymmetry between inside and outside legs; and (3) the power fit exponent of our empirical velocity data was significantly different from Greene’s theoretical predictions.”

Cody

Cody,

If I show race research that the curve has shorter strides will you admit that you are wrong and move on? The larger the track radius (outdoor) will be a factor but remember the speed of the athlete in a race will be faster than the research. Also indoor tracks is a factor that you should look at as they did research on 200m tracks.

The outdoor 200m has a quarter of the stride length changes of an indoor 200m and we are talking about an indoor track not outdoor like you keep bringing up. Your math is wrong.

The splits at the 4 x 100 are clear and the strides are shorter statically. Obviously people are not running in a circle but in a oval and the oval radius is far larger. Still the speed into the curve is different than acceleration from the top of the curve.

With stride lengths needing to be near 2m for hurdles yet are likely to be 2.4 meters or so for open sprints running a tight curve makes a lot of sense. We are looking at strides near 210-220 cm. Nobody will going 1.4 unless one is running on a toddler or peewee indoor soccer field.

I think a drum helps as ground contacts are longer with curve runs.

Yes, why didn’t you lead off with this research? It would have saved much time. If you show me research that uses a curve nearly equivalent to an outdoor track and that research shows a significant decrease in stride length (say, from 2.4m to 2m like you say above), what else can I say? (we don’t have access to an indoor facility where I’m at, so I’m limited to outdoor tracks)

That being said, if you were talking about an indoor track and doing strides there a few posts ago, then I can agree that it would be a beneficial training tool because the radius in indoor is low. But the post does not make that clear and if an outdoor hurdle coach ran across the post and thought, “Man, I should be doing edit: sorry, flying sprints because it significantly decreases stride length and will get the athlete used to the shorter stride required” that coach may not have the correct idea. It is clear that the stride length will be decreased, but is it a significant decrease? If it is a foot or more, then that is significant...6 inches, maybe; less than that, probably not. That’s what I’m after.

Cody

He didn’t say curve accels--he said flying sprints on the curve.

Anybody who has ran 3rd leg on the 4x100 knows this happens.