Mid Mark Chart

[souleman]

OK, I am now entering "shark" territory. I say that because those that are arguing the validity of the chart are some of the best vault minds in the world. I on the other hand am no where near as accomplished as you all. That in itself might make my comments even more appropriate. There was a saying back in the 60's that went "don't knock it if you haven't tried it". This really applies here. Anyone who has used DJ's chart and understood it fully has had success with it The vault doesn't start once the vaulter leaves the ground. It starts at the top of the runway. We'd all be millionaires if we would have gotten $10 for every time we have heard "my steps are off". My gosh people! Here is a tool that if applied correctly (shoot, even somewhat incorrectly as is the case in my case) that takes a ton of the guess work out of running down the runway. It works for 8 footers as well as 19 footers. We buy books and DVD's and watch hours of videos studying this event. We spend a lot of time and money trying to "figure this thing out". Here is a tool that was created after years of research, based on the principles of the physics of pole vaulting and............IT'S FREE! It also comes with a support system.....THE CREATOR OF IT HIMSELF! All of you that don't buy into it, please, stop debating it. Just use it. You'll see the benefits of it almost immediately. Not to lay out a challenge but, if you try it and it doesn't work.............you're doing it wrong. Later.......................Mike

[Carolina21]

Hello,
To settle one aspect of this argument I thought I might offer some actual scientific research. Stride length has been proven to be almost completely related to ground force, inputs such as leg length or height, actually has almost no impact on stride length and stride frequency as DJ has tried to explain. Please read attached article maybe it will be slightly more clear:

Stride Length and Frequency
The fastest sprinters tend to have stride lengths and stride frequencies as great as 2.6m and 5 steps per second respectively (Mann, 2005). Interestingly, the source of these outstanding characteristics is actually a single attribute. Previous research by Weyand and colleagues (2000) indicates that force applied at ground contact is the most important determinant of running speed. This same research indicated that the speed at which an athlete moves their legs through the air is of little importance. The benefit of greater force application is two-fold. First, greater force application will increase stride length. This benefit is fairly obvious. If all else is equal, greater force applied to the ground will cause a greater displacement of the athlete’s body. More simply, a greater distance will be covered with each stride. The second benefit of increased force application is not so obvious and is often overlooked. This benefit is that of increased stride frequency. How, you ask, can increased stride frequency come about as a result of increased force application to the ground? This is where things can get difficult. Stride frequency is comprised of two components: ground contact time and flight time. Research on elite sprinters indicates that the best sprinters spend less time on the ground (Mann, 1986; 2005; Mann & Herman, 1985). This is because the forces they produce are so great that they enter a period of flight more rapidly than their less efficient counterparts. As a result, despite not moving their limbs significantly faster through the air (Weyand et al., 2000), better sprinters tend to have greater stride frequency because they reduce the amount of time they spend on the ground. However, this presents a challenge to an athlete striving to move at increasingly greater speeds. That is, they must produce greater forces over increasingly shorter periods of time.

Takeaway,
Although it seems logical that a taller athletes will have longer stride and slower frequency, the scientfic evidence (25 years of research) does not support this.

[vtcoach]

I'm going to disagree on your conclusion of what the research shows Carolina21. On the contrary. The research shows two things which do NOT contradict each other. 1) more force = greater stride length = greater speed 2) taller athletes (ON AVERAGE - NO ANTIDOTAL EVIDENCE PLEASE) have longer strides

Here is the most recent study I could find. It also contains a good bibliography if you are interested in readying the literature on sprinting.

"Elite Male and Female Sprinters' Body Build, Stride Length, and Stride Frequency"
by Marzena Paruzel-Dyja, Anna Walaszczyk, and Janusz Iskra
University School of Phyiscal Education in Katowice, Poland
Studies in Phyiscal Culture and Tourism, Vol 13, No. 1, 2006

http://www.wbc.poznan.pl/Content/44721/ ... ja_REV.pdf

One of the findings, quoted directly:

"Body height has a significant influence on the running stride length as well as on the stride frequency in both groups - men and women - regardless of their sport level (Table 2)."

Code: Select all


Parial listing of Correlation factors from Table 2

                   ==========  Stride Length  ===========
                   ======================================
                   All Elite   Faster ELite  Slower Elite
Parameter          Sprinters    Sprinters      Sprinters
================   ==========  ============  ============
Height - Females      0.59         0.67          0.55
Height - Males        0.56         0.40          0.65

                   p <= 0.01



That is a pretty low p value to dispute.

Also see

Mero, A., Komi, P., & Gregor, R. (1992). Biomechanics of Sprint Running. Sport Medicine, 13 (6), 376-392.

Plisk, S.S. (2000) Speed, Agility and Speed-Endurance Development. In Essentials of Strength and Conditioning. T.R. Baechle, ed. Champaign, IL: Human Kinetics. pp. 471- 491.

Hoffman, K. (1971). "Stature, leg length and stride frequency". Track Technique 46: 1463-69.

Rompottie, K. (1972). "A study of stride length in running". International Track and Field: 249-56.

There is also a study by Atwater I am trying to find a full reference for that studied 23 elite sprinters and also found the same high correlation between height and stride length.

Again realize that this finding is NOT contrary to the idea that more force into the ground = longer stride length. The force you put into the ground absolutely determines stride length... for a given sprinter. Do two sprinters that exert the same force necessarily have the same stride length? No. Is ground force the only thing that determines stride length? No. Mass, Height, leg length, flexibility... these also play a factor.

As an extreme example consider the South African sprinter with prostetic legs that is lobbying to get into the Olympics. His stride length is huge and yet he has exceeded at least the B standard. Do the laws of physics not apply to him?

I'll go back and read the study that Carolina21 is quoting. My guess is that it simply does not examine height but rather with things an athlete can control.

I like the fact that this thread is turning toward looking at existing data and research!

Cheers

[vtcoach]

Chris,

Can you give us the full reference for the 2005 article by Mann?

[PVstudent]

Parial listing of Correlation factors from Table 2

========== Stride Length ===========
======================================
All Elite Faster ELite Slower Elite
Parameter Sprinters Sprinters Sprinters
================ ========== ============ ============
Height - Females 0.59 0.67 0.55
Height - Males 0.56 0.40 0.65

p <= 0.01

The data here are fair and actually support the Weyand finding, though indirectly. Just consider elite sprinters finding R^2 value for 0.55 = 0.30 and the R^2 value for 0.65 = 0.422. In females height accounted for 30% of the variance leaving 70% attributable to other factors. In males 42.2 % of the variance is accounted for by the height factor leaving 57.8% attributable to other factors. So height contributes about 30 - 42% of elite female and male sprint speed. Stated alternatively and in concordance with the Weyand findings body height is not as important a contributor to sprinting speed as other factors. Nevertheless it is a determinant factor (about 1/3). Note this is not saying Height causes step length. The relationship is proportionally and positively related ie taller people will tend to have long strides and short people short strides in sprinting at the elite male and female levels according to the study.

vt coach and others I repeat again I believe DJ's chart is a very useful and valuable tool that has been emprically put to the test by many whose anecdotal testimony I am happy to believe. It is the scientific basis and rationale that may be underlying the claimed success that I am trying to unravel. Thank you and Carolina21 for the contributions. They are very important to the process.

[agapit]

lewis and Mo greene had the same number of strides, i think 47, with Mo crossing the line on his 47th 23 inches ahead of Carl.

I have counted

Mo Green - 9.86s in 47.5 steps
Tyson Gay – 9.76s in 44 steps
Asafa Powell – 9.74s in 43.5 steps

Am I way off?

I think Bolt is 41 for his WR and is by far the tallest.

If MO Green is 47 steps and Bolt is 41 the 6 step difference is 6 feet. That is Mo Green 55 feet mid and Bolt is 61 feet mid (approximation) with roughly the same speed. The same could be observed in the vault. Russ Buller mid is about 55 with 10.1 m/sec fastest known in run up and Derek Miles, reportedly, 58 feet mid and under 10.0 m/sec speed.

[PVstudent]

Code: Select all

                               4th last  3rd last  2nd last   Last
Name      grip   height  mass  Sf   sl    sf  sl    sf  sl   sf   sl
          (m)    (cms)   (kg)  s/s   m   s/s   m   s/s   m   s/s   m
Bubka    5.17m    184     77   4.5 2.25  4.8 2.09  4.9 2.16  5.1 1.94
Vigneron 5.00m    181     73   ---  ---  4.6 2.12  4.3 2.19  4.9 2.00
Gataulin 5.10m    190     77   4.6 2.04  4.9 2.16  5.1 1.87  4.9 2.03
Bell     4.95m    193     82   4.3 2.10  4.3 2.06  4.5 2.13  5.3 2.03


The Table 1. above records the Step Frequency and Step Length at the Rome: IAAF World Championship 1987.

Code: Select all

                               4th last  3rd last  2nd last   Last
Name      grip   height  mass  Sf   sl    sf  sl    sf  sl   sf   sl
          (m)    (cms)   (kg)  s/s   m   s/s   m   s/s   m   s/s   m
Bubka                          4.3 2.26  5.4 2.07  4.8 2.11  5.1 1.95
Vigneron                       4.4 2.10  4.5 2.01  4.7 2.00  4.3 2.05
Gataulin                       4.4 2.02  5.0 2.03  5.4 1.80  5.3 1.94
Bell                           4.0 2.27  4.7 2.05  4.2 2.27  4.5 2.10
Collett           184     77   4.9 1.92  5.1 1.96  4.7 2.01  5.4 1.93


The Table 2. above records the Step Frequency and Step Length at the Seoul Olympic Games 1988.


The tables above show that there is an interplay between step frequency and length in the final phase of the approach run to the pole vault. There is a tendency for the step frequency to get higher and the steps somewhat shorter. To date I have never seen published data recording stride lengths as long as 2.6m for males. The data may exist I haven't seen it. There are very good reasons why pole vaulters increase their cadence and show variable trends in associated step lengths.

The fastest sprinters tend to have stride lengths and stride frequencies as great as 2.6m and 5 steps per second respectively (Mann, 2005).

I agree with Manns findings for sprinters in the short sprints (100 - 200m).
I think that pole vaulters have other problems to worry about other than pure speed horizontally.

This is because the forces they produce are so great that they enter a period of flight more rapidly than their less efficient counterparts. As a result, despite not moving their limbs significantly faster through the air (Weyand et al., 2000), better sprinters tend to have greater stride frequency because they reduce the amount of time they spend on the ground. However, this presents a challenge to an athlete striving to move at increasingly greater speeds. That is, they must produce greater forces over increasingly shorter periods of time.

Couldn't agree more. I have read a number of Weyand studies and I dont recall it being claimed that

Although it seems logical that a taller athletes will have longer stride and slower frequency, the scientfic evidence (25 years of research) does not support this.

. In fact this sentence

Previous research by Weyand and colleagues (2000) indicates that force applied at ground contact is the most important determinant of running speed. [quote] clearly implies that the forces applied at ground contact whilst they are the major determinants they are not the only ones. By the way how else other than by exerting forces whilst in contact with the ground could a sprinter or pole vaulter propel their body horizontally forwards? The finding is not news!

Far more interesting is Weyands final comment:
"As a result, despite not moving their limbs significantly faster through the air (Weyand et al., 2000), better sprinters tend to have greater stride frequency because they reduce the amount of time they spend on the ground. However, this presents a challenge to an athlete striving to move at increasingly greater speeds. That is, they must produce greater forces over increasingly shorter periods of time".

It is in the final six steps of the pole vault approach the vaulter must solve this problem. It is usually a lost cause and consequently the final acceleration is negative.

I hope the pole vault last 4 step data is of interest.

[PVstudent]

I would be very grateful to my computer guru if they could clean up the tables. I have spent ages trying to get the things to display properly and failed miserably. Heeeeeellllllppppp Please!

[Carolina21]

PVStudent,
You are correct the article to my knowledge does not examine height.

VT,

I am sorry I do not actually have access to the articles referenced. And for those who know me, I am certainly not a biomechanical expert.

I guess my next question would be is how or why do PV Student believe that taller athletes on average apply more ground force?

Also I agree the same ground force will not produce exact same stride length in certain situations, but I think what we are trying to determine is whether two people who both run technically "perfect" with equal ground force would achieve the same step length. Of course we can all cite different excpetions to a rule, but they are simple exceptions.

Dr. Ralph Mann (who I have had the privaledge to work with a few times), actually has computer simulations that can be adjusted to body stature to show perfect running form for any height athlete. It would be very very interesting to know whether his computer model of a 6'4 male vs. a 5'9 male both running 10 or 11 mps would have the same stride length? The models are based on well over 100 sprinters likely the largest data base available. I think, and this is only a guess from watching the model several times, that you find the model would predict extremely similar stride lengths, when perfect running form is taken into account.

Thats all for now, great discussion. PVStudent thanks for the articles you are correct a P of .01 is very compelling. I will have to read more on that study.

[SlickVT]

I am not going to get in on this discussion, because I am not nearly as qulified as the people discussing, but I am going to throw my numbers out there.

On my PR vault:

Bar height: 5.28m (17'4")
Hand Grip: 4.67m (15'4")
Takeoff: 4.97m (13'0")
Mid: ??.??m (50'0") <--- ~18" variance from the chart


Despite the differences of opinions and data, if nothing else, this thread has become one of the most interesting that I have read since I have been a PVP member.

I know some people are frustrated with where this has gone, but it has certainly caused for some great discussion.

Good thread. I hope it continues...

[agapit]

I am not going to get in on this discussion, because I am not nearly as qulified as the people discussing, but I am going to throw my numbers out there.

On my PR vault:

Bar height: 5.28m (17'4")
Hand Grip: 4.67m (15'4")
Takeoff: 4.97m (13'0")
Mid: ??.??m (50'0") <--- ~18" variance from the chart

That is Takeoff: 3.97m (13'0") I think.

All you have to do is to adjust your mid to what the chart says and you clear 18' I guess?

[Carolina21]

PVStudent,

As a quick follow up I read the article cited. One part I didn't like and I may have misread it was Table 3 of "fast" vs. "slower" males and 100 times.

The height ranges listed go from:

Taller = 175.67 to 184.67 (ie 5'9 to 6'0.5")
Shorter = 171.45 to 184.13 (5'7.5" to 6'0)
This P value of .05 is a little high for my liking.

The stride length of faster vs. slower

Faster = 212.48 to 226.14 (6'11" to 7'5")
Slower = 206.8 to 221.04 (6' 9" to 7'3")
P of .01 is good, longer stride = faster run.

Over the total population the tallest athlete was 6'2 and was 2 SD's outside the mean.

Furthermore, body mass had a higher correlation to stride length than height. What do we make of this?

None of these atheltes are truely "Tall" in my opinion. The heights have significant overlap.

My take aways:

1) Optimum height according to the article seems to be around 180 cm (average of faster athletes).

2) Therefore, calling people who are 5'9 to 6'0 "Tall" is not what people on this board and in the PV world think tall is, at least I don't. Obviously in the context of the article they are the taller athletes.

The significance level of height as a factor is a little questionable given the ranges and P value. There is no set cut-off, it is a judgement call and my judgement would be to take a p value of .05 from 100 observations with a grain of salt. There is obviously something there, but how much and how strong I am not sure.

You do make a good point also about the correlation. It is not causation. What also needs to be taken into account is some / many of the sprinters still have technical deficiencies in their running form, which probably causes much of the different combonations of stride length and frequency.