PoleVaultPower.com

agapit wrote:

KirkB wrote:... RUNUP_SPEED + JUMPING_SPEED = TAKEOFF_SPEED

I think the rest holds true. And yes, JUMPING_SPEED is most often a negative value - but on a short-run vault, maybe not.

The shorter the run, the more likelihood that you'll be accelerating off the takeoff foot (because of lack of speed from the runup). No?

Kirk Bryde

I am sorry to tell you, but unless you are jumpping without run up the jump is always a negative value for the total speed. ...

KirkB wrote:I need some clarification here. Are you saying that it's physically impossible to accelerate on takeoff even on a short run vault, or are you just saying that it's unlikely, given certain assumptions about the number of steps in the run and the serious intent of the vaulter to run at a speed something close to his max?

Kirk Bryde

KirkB wrote:Maybe I'm just hung up on your superlative word "always". Do you really mean always, or just in all liklihood?

Kirk Bryde

vault3rb0y wrote:Nice post. Well organized, straight to the good stuff. One question... to what importance would you place run up acceleration compared to top speed into the box? Is it more important to accelerate into your last steps, or is being the same speed into box, but still fast, more important? I ask in relation to the optimimum run length for certain vaulters.

Myself, being a high 16, low 17 vaulter, come from 7 right steps. I accelerate pretty well into the box, but i feel like if i went to 8 steps, i would carry more speed but i wouldnt accelerate as much into the box. Which do you place more importance on? Is there a certain hieght you feel a vaulter should clear or a top speed they should be able to reach before they move their run back farther?

TOM TELLEZ PART II

Common Errors

Stressing stride length or stride frequency?

Debate on the best way of improving sprint speed focuses on two issues:

increasing stride length versus increasing frequency. We are limited physiologically to the amount of strides than can be performed in a second. It is true that most good sprint athletes have just about the same frequency. So, an athlete with adequate conditioning who takes the longest strides usually wins.
Stressing stride frequency alone results in inefficient sprint technique.

Common knowledge portrays stride frequency as a speed advantage. However, stride frequency differs from stride speed. Stride speed is angular velocity of a stride, while frequency is the number of strides, or impulses, per second. Even if a sprinter has the fastest turnover, without proper force application, stride length will be small. This is because frequency alone does cause linear motion; applying force to the ground does. Proper force application results in stride length and frequency increases.

Stride speed is involuntarily increased by the conservation of angular momentum. Shortening the radius, thus reducing the moment of inertia, results in an increase of angular velocity. The shorting of the lever occurs after the foot breaks contact with the ground. This movement is the response of the forces being applied correctly to the ground and is non-volitional.

Illusion of Speed

There is an illusion of speed when then lever does not go through the full range of motion; each movement looks and feels faster. For example if stride frequency is stressed, an athlete may not allow the hip extend through full range of motion to reap whatever benefits he created from applying force to the ground. Lack of hip extension detracts from momentum and ultimately decreases speed because of inefficiency. But the objective is not to move the lever fast but rather transport the mass down the track in the least time possible. Avoiding full range of motion also sacrifices proper force application.

Leg preactivation: pawing action

Pawing action is actually an illusion resulting from rapid hip extension. Too much voluntary action at the knees and ankles causes a reduction in angular velocity of the hip, which is the prime generator of force. Force causes motion while speed is a measurement of motion.
Cyclic force is applied from the hip (radial force) which results in tangential motion of the foot. At foot placement, the shin should be approximately 90 degrees to the ground (Fig. 5). As the center of mass passes over the point of support, the heel briefly touches the ground and the ankle angle closes. This motion puts the Achilles tendon and calf in a stretch position while the knee is bent, allowing a greater push off force from the ball of the foot. Hips extend in one continuous motion from the knee lift position through the end of the push off with no pauses in hip extension at foot contact.

High knee lift

Please see “Knee action” in Part 1.

Reach and Pull

Running action such as reaching and pulling with the hamstrings has been scientifically proven not to produce the most efficient movement (Weyand et. al. 1998). This running style is inefficient because it does not utilize the stretch reflex, but instead requires more muscle forces and volumes per unit of force applied to the ground (Weyand et al. 1998).

Summary

Scientific research across the world has yet to penetrate the track and field world. Athletes can be better sprinters with scientifically proven sprint technique. Better sprinters require coaches who are willing to learn scientific principles as well as a method of communicating their knowledge to the athlete.

Pretov.. said this about acceleration

Acceleration

Acceleration is the ability to reach the maximum of controllable speed within a certain distance.

An important feature of the acceleration is its increment value and the ability to keep a certain speed on a certain running distance.

Acceleration as an element of the pole vault has its own components which are interrelated and which determine the vaulter’s activity during acceleration. Any changes or disturbances in any of the components will retard the speed and efficiency of the acceleration. The length of the top vaulters’ run-up is on the average about 42-46 m, with 18-20 strides. This length of the run-up provides for the implementation of an athlete’s running abilities and allows for a smooth acceleration.

The 1st part of the approach takes place on a distance usually covered in 4 to 6 strides; it is here that the athlete lays the foundation of the approach:
1. set up of a single system: vaulter/ pole
2. evolving pattern of the first strides
3. run-up rhythm (acceleration), length and rate of the strides.

Maximum speed, its rationality towards the end of the run-up are established and depend on the correctly performed first strides.
It is necessary to stress here that the position of the pole and the vaulter/pole system influence the length and pace in the beginning of the acceleration.

Petrov.......An important feature of the acceleration is its increment value and the ability to keep a certain speed on a certain running distance.