Denard "Shoelaces" Robinson

The other day I was watching an ESPN College Football show on TV and the sportscaster was reporting on the University of Michigan’s sophomore quarterback sensation, Denard “Shoelace” Robinson. The ESPN reporter was marveling on Shoelaces’ “unique” ability to combine quick feet (stride rate) and stride length. According to the sportscaster, Robinson was able to get through the defensive line with his incredibly quick feet and then pull away from pursuit by increasing his stride length once he got to the second level of defenders.  ESPN went on to demonstrate via slow motion video how Robinson covered nearly 3 yards with each stride leaving defensive players reaching for air as he flew past them.

Although some might say, and I definitely wouldn’t disagree, athletes like Robinson and Michael Vick before him, are simply blessed with amazing God given talent.  However what was so obvious to me, as I watched Robinson leave defenders in his wake in the ESPN report, was his sprint mechanics. Along with his cannon for an arm and 4.32 40 yard dash, Robinson ran a 10.44 100m in high school and was the Big Ten 60m dash Champion as a freshman this past season.

The ESPN crew only confirmed what track coaches have known for years. Running fast, like in the case of Denard Robinson, is the direct result of the athletes stride rate and stride length.   The million dollar question is how we maximize both of these to achieve top-level performance?

What makes one athlete faster than another? Although most discussion today involves the different training methods used to achieve faster speeds, the one area that we need to thoroughly understand before talking about training routines in practice is mechanics. What does the sprinter need to be doing during the stride to make them more efficient and faster?

The reality of sprinting is that we cannot have a maximum stride length and stride rate and be our fastest. What is needed is a maximum stride rate with an optimal stride length. Maximal stride rate is how fast we can produce one stride. For example, in the case of the 100m dash that would be about 50 strides over the duration of the race. Stride rate is dependent upon a number of factors including, strength and mechanics. In order to produce greater stride rates one must be able to execute the correct stride cycle as fast as possible and with optimal length. Optimal stride length is one that allows the athlete to execute the correct stride pattern in as short a time frame as possible.

In order to better understand how all of this works let’s take a closer look at some of the factors involved.

First starting with stride length. There are a number of key factors in determining optimal stride length. First is the distance the foot contacts the ground in front of the center of mass at touchdown. If the foot is placed too far in front of the athlete’s center of mass it creates a breaking action with each stride. This breaking action allows for more force application to the ground but will also slow the athlete down because it will take the athlete more time to  move his/her body past the foot and then get off the ground again. What would be considered a good distance for an athlete to make ground contact? According to a 1990 study published by former Olympian and Ph.D.in Biomechanics Ralph Mann, good elite (9.8-10.0) sprinters made contact with the ground at an average distance of about seven inches in front of the center of mass.  Athletes in the 10.3-10.5(poor elite) range land about eleven inches on average from the center of mass. This shortened distance from the center of mass also translates into greater horizontal velocity at touchdown. This means that the athlete is traveling faster as the body passes over the touchdown foot.  Good elite sprinters are moving at 27.8 feet/second, while poor elite sprinters are moving at 22.0 feet/second.

The other action that takes place in the preparation to touchdown is the extension of the lower leg. As the takeoff leg moves forward to a position in front of the center of mass, the upper leg should be near 90 degrees, in relationship to the ground. As the upper leg begins to move in a downward back motion, the lower leg will begin to open.  All of this should happen naturally. If an athlete forces the extension of the lower leg, they will cause it to be overextended. This over extension causes the touchdown foot to plant further in front of the center of mass than desired. By allowing the lower leg to open as the upper leg is being pulled back into the track a better angle will be achieved at touchdown allowing the foot to be placed closer to the center of mass.

The second important part of the stride occurs at takeoff. It has long been held that sprinters need to drive off the ground with the takeoff leg at full extension. Again, although this might allow for maximum force application against the ground, it delays the athlete’s ability to get into the next stride. There are three key areas that need to be looked at to determine the quality of the stride at takeoff. These are lower leg takeoff angle, flexion and ankle cross. Each of these angles is discussed here in relationship to the upper leg.

According to an article published by Jeff L. Hoskisson, Assistant Track Coach Western Michigan University, takeoff in elite sprinters was found to be at 139 degrees, while in poor elite sprinters it was at 169 degrees. What this means is that the top sprinters are leaving the ground before the takeoff leg reaches full extension. The slower sprinters are coming off the ground closer to full extension, but even they are not reaching full extension.  Again according to Hoskisson, “By getting off the ground sooner the sprinter is able to execute a more efficient recovery in preparation for touchdown of the next stride.”  As the leg is being recovered forward, the angle between the upper and lower leg should be as small as possible, this is the position of full flexion. In good elite sprinters this angle is around 34 degrees. In poor elite it is 46 degrees.”  What is the reason for this huge variation? The longer the foot stays on the ground at takeoff, the less time it has to reach full extension before it must be cycled through to prepare for touchdown.  The final area in examining stride length is ankle cross. Where does the ankle cross over the opposite foot as it moves forward in preparation for touchdown? According to Coach Hoskisson, in the good elite sprinters the ankle crosses the opposite knee at a 34° angle. The poor elite sprinter crosses with a greater angle of 46°. This means that the lower leg is already opening, as it is moving forward in the poor elites. This puts the poor elite sprinter at a bigger disadvantage to the good elite sprinter. The good elite sprinter is in a better position to be able to prepare for touchdown. By crossing over the opposite knee at a tighter angle the foot can be cycled through to a better position on the front side to allow the sprinter to keep their touchdown distance closer to the center of mass.

Stride rate is not rocket science. It is however a direct result of a sprinter being able to correctly perform the sprint cycle described above.  When performed correctly, the sprinter moves through the stride cycle faster while spending less time on the ground.  Ground time is the largest contributor to stride rate. It’s common knowledge that almost all athletes spend approximately the same amount of time in the air during the sprint stride. The big difference comes in the amount of time spent on the ground. The goal of all sprinters should be to spend as little time on the ground as possible. In order to achieve this, the sprinter needs the necessary strength to get them through the correct cycle.

Again, getting back to Shoelace, the reason he is able to cover so much ground per stride so quickly is because of the efficiency of his sprint stride and sprint mechanics.  Bottom line, no matter what your sport, in order to run faster, proper training is critical. One of the main components to proper training is understanding just what you need to do in order to correctly execute the sprint stride and run more efficiently. Finally, by understanding the sprint stride it becomes easier to plan training activities to improve your sprint mechanics and ultimately improve your overall athletic performance.

References

Mann, Ralph. The Mechanics of Sprinting, 1990. CompuSport. Orlando, FL.

Hoskisson, Jeff.  Sprint Mechanics Revisited, Assistant Track Coach Western Michigan University

From the Flight Deck, Coach Jay Murdock

jmurdock@flight101ssd.com

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Comments
  1. […] and stride frequency.   We have discussed stride length and and frequency in other articles  (Understanding Stride Length and Stride Frequency) so we won’t spend a lot of time discussing here.  Suffice it to say, there is a relationship […]

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