Setting up the Skeleton Push-Start: Foot Placement PART I

This is going to be a short two part series.

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The start is a significant aspect of being successful in any short-distanced sporting event. Good coaches of sprinters understand what technique delivers the fastest start This article is mostly geared towards analyzing the start technique for the skeleton push-start, and because skeleton hasn’t been researched that heavily – 9 published articles – it could potentially be of benefit to look at other models in sports that have similar start characteristics of the skeleton push-start.

My Master’s researches all begin with the simple question of what’s the best foot placement for going fast in skeleton. However, whether it’s in track and field, swimming, or skeleton, the way you start influences how you finish. Fortunately, I follow some people who’ve studied the start in other sports more than I have, and they’re pretty smart people. One of those characters is Coach Dan Pffaf, and the setup of blocks in track and field are important to him!

Pffaff BlockSetup Twitter.png

However, I’m not one to just rely on what others say. The great coaches, like Coach Pfaff, did a lot of their own investigation and I think we’re going to have a big problem when they leave the next generation of us behind because all we do is read information and are not engraining the principles necessary for solving the unique problems that face elite sport, athletes, coaches, and national governing bodies.

As a track and skeleton push-start coach and an amateur investigator, I’m always trying to figure out cleaner ways to do something or more powerful ways to teach people.

So let’s dive into why foot placement at the start matters for any speed/power athlete.

SKELETON PUSH-START STYLES:

When I was first exposed to a skeleton push-start during my internship at the Olympic Training  Center, it became rapidly apparent that there were multiple ways of setting ones feet for the push-start. This confused me at first because, as a track coach, I only know of the staggering of the feet. I now realize why there are the two main start styles, and their respective variations.

The start styles are:

TRACK START –

VannRun21FBGSetup.png

Track Start Big Gap (TSBG)

Athlete places rear foot half on the starting block and half on the track/ice. Athlete kneels down with rear foot knee on the ground. Athlete lines up front foot’s toe or heel with the rear foot’s knee. Athlete lifts up into a set position and sprints. Similarities to Track & Field, Bobsled (Driver/Pushers), and Swimming (Track Start).

VannRun21FSGSetup.png

Track Start Small Gap (TSSG)

Athlete places rear foot half on the starting block and half on the track/ice. Athlete kneels down with rear foot knee on the ground. Athlete places front foot toes 10cm back from the knee. Athlete lifts up into a set position and sprints. Similarities to Track & Field, Bobsled, and Swimming (Track Start).

TWO-FOOTED –

VannRun22FSTSetup.png

Two-Footed Static (2FST)

Athlete places both feet on the starting block. Athlete lifts up into a set position and sprints. Similarities to Bobsled (Brakeman) and Swimming (Grab Start).

VannRun22FDYSetup.png

Two-Footed Dynamic (2FDY) Setup

VannRun22FDYLoad.png

Two-Footed Dynamic (2FDY)

Athlete sets up foot like Track Start Big Gap, however, before the athlete sprints, they pull the front foot back to the starting block, which at this point, looks like the two-footed static. The athlete then quickly sprints from this position.

NEWTON’S 3rd LAW:

In order to fully understand how foot placement influences acceleration, we need to understand some basic physics.

Newton’s 3rd law states,

For every action, there is an equal and opposite reaction. 

Given this, let’s look at two examples below.

Screen Shot 2016-01-02 at 3.04.20 PM.jpg

Newton’s 3rd Law Example. First can be viewed as Ground Reaction Force and the other can be seen as reaction off a track starting block.

Example I shows how force moving in the downward direction returns in the opposite direction and at the same magnitude  when it interacts with something (i.e. ground). Example II is the same as Example I but I orientated it in a way that looks similar to what happens when using starting blocks like we see in track and swimming.

FOOT PLACEMENT IN TRACK:

Track & Field coaches and athletes have made slight variations to the block start technique over the past century. However, there has been a consensus that the feet should be staggered, like the one-footed, or track start I referred to in my research with the Skeleton Push-Start. The current variation in the start positions in track involves figuring out the placement of the blocks that put the sprinter into the best posture in order to accelerate and reach a high velocity.

There are several variables for setting up your start. They are:

  • Distance from start line and front block
  • Block Spacing (distance between front and rear block)
  • Angle of blocks
  • Height of hips in “set” position
  • Lean of body (either forward, center, or backward (rarely seen)) in set position

Block spacing should influence takeoff angle, which is influenced by the athlete’s height, leg length, strength, speed, technique, and ankle mobility. Quite a few variables to play around with here but you get the point, that is, each variable influence the end product of the start – proper acceleration.

So, let’s look at how they do it in the pros (CAUTION: Elite athletes aren’t always the best model for amateurs, or other elites, nonetheless, it can be helpful looking at how the best do it.). I found a picture of the 2012 London Olympic Men’s 100m Final just after the gun.

london_2012_olympic_100m_final_start

2012 London Olympics Men’s 100m Final Block Start

Right away I notice similar takeoff angles; some lower and some higher, but overall small variations of similar technique. I do notice more variance in block spacing. The first thing I want to know is how far apart are they. I not too tech savy but I know that I could probably measuring the distance between blocks using the PowerPoint drawing a line function. We can draw a line and see how long the line is.  Now, the measurement given in the table below does not represent the actual measurement in inches, but the measurement in scale of the picture. Also, note that the picture is not taken exactly perpendicular to the reference point (the blocks or athletes) so there will be some parallax. But, and the big but, is that we can still get information from the picture that could help further our investigation of foot placement and the resultant performance. It may not be good enough for scientific research but as a coach, I’m not waiting till research is published…I’m going to try to figure it out myself!

Screen Shot 2016-01-02 at 2.32.49 PM.jpg

Block Spacing – 2012 London Olympic Men’s 100m Final (Red – Big Gap; Blue – Small Gap)

Lane Name Height(m) Block Spacing* Finish
Lane 2 Thompson 1.88 0.52″ 6th
Lane 3 Powell 1.90 0.65″ 7th
Lane 4 Gay 1.80 0.41″ DQ
Lane 5 Blake 1.80 0.31″ SILVER
Lane 6 Gatlin 1.85 0.47″ BRONZE
Lane 7 Bolt 1.95 0.49″ GOLD
Lane 8 Bailey 1.93 0.74″ 4th
Lane 9 Martina 1.78 0.42″ 5th

*Block Spacing measurement taken from above photo by measuring the length between the front of each block to the front of the next block with the draw line function in powerpoint. I measured from outside of right foot block (closest to camera) and inside of left foot (furthest from camera) so I can take most accurate measurement.

Since I’m a more visual learner, I like to look at the data, and see if there are any trends. If you look at block spacing and finish order there is no clear trend (See chart below). Ok so not a direct, 1-to-1 relationship. I didn’t think it’d be that clear cut. However, if we look at block spacing and the height of the athlete there seems to be a trend. And, in fact, I ran a linear regression in SPSS and the regression was significant. I’m also even more curious about where the top performances are within datasets (i.e. to see if the data can explain the why or how of the performance) so I marked up the data points with Bolt (Gold), Blake (Silver) and Gatlin (Bronze) on the data set. The interesting point to me is that Bolt (tallest) and Blake (tied for 2nd shortest) are under the trend, with Gatlin (5th tallest), Gay (tied for 2nd shortest, and DQ’d but had 4th fastest time) and Thompson (6th) are on the trend line.

 Screen Shot 2015-12-30 at 1.00.48 PM.png
Linear regression of relationship between Athlete Height and Block Spacing for the 2012 London Olympic Men’s 100m Final.

The two athletes with the largest block spacing (seen with red line in 100m start above) is the furthest off, and above the trend line, were Bailey (5th fastest time if you count Gay, and 2nd tallest) and Powell (8th fastest time if you count Gay, and 3rd tallest).

FOOT PLACEMENT IN SWIMMING:

As a reminder, there are two different start techniques (track start and two-footed) with two main variations that exist within each start technique (track start: big gap and small gap; two-footed: static and dynamic) swimming and track & field are two sports that have sprint starts and utilize similar techniques that may be comparable.

Swimming research has risen in popularity over the past decade with advances in technology and alterations to the rules (Vantorre, Chollet, and Seifert, 2014). Of particular interest to this study is the depth and quantity of research looking at the swim start. Researchers have compared the two most prevalent styles – the Grab start (GS) and the Track start (TS) (Issurin & Verbitsky, 2003; Jorgic, Puletic, Stankovic, Okicic, Bubanj, and Bubanj 2010; Murell & Dragunas, 2012; Vantorre, Seifert, Fernades, Vilas-Boas, and Chollet, 2010).

 Swim Start.png
A participant from research on assessing swim start technique by Murrell & Dragunas (2012). Researchers explored the differences between the grab start (two-footed) and track start (one-footed).

Researchers noted that takeoff angles were an important separator of performance level (Vantorre et al., 2014). Researchers found that swimmers who utilized a track start were quicker off the blocks and had a flatter or more horizontal trajectory (Jorgic et al., 2010; Vantorre et al, 2010), while also having a quicker reaction time (Issurin & Verbitsky, 2002) and shorter time duration to 2-meters (Murrell & Dragunas, 2012). Whereas, the grab start (two-footed) has a greater flight length (Jorgic et al., 2010) and vertical impulse (Vantorre et al., 2010).

 Screen Shot 2016-01-04 at 5.03.45 PM.jpg
Participants performing the two different swim starts, the track start and the grab start respectively by Jorgic et al., (2010). Colored arrows added by me.

Swimming is unique in that they’re landing in water so the takeoff angle will be slightly different when compared to a land-based sport. I actually saw the opposite effect in skeleton, where the track starts were a higher takeoff angle when compared to the two-footed starts. So, let’s get into how this relates to skeleton.

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In PART II we’ll look directly at the Skeleton Push-Start.

References:

Issurin, V. & Verbitsky, O. (2003). Track Start Vs. Grab Start: Evidence of the Sydney Olympic Games. In : Chatard JC, Ed. Swimming Science IX, 2002; Saint Etienne, France : University of Saint Etienne; 2003; 213-217.

Jorgic, B., Puletic, M., Stankovic, R., Okicic, T., Bubanj, S., & Bubanj, R. (2010) The Kinematic Analysis of the Grab and Track Start in Swimming. Facta Universitiatis series: Physical Education and Sport. 8(1): 31-36

Kivi, D., Smith, S., Duckham, R., & Holmgren, B. (2004). Kinematic Analysis of the Skeleton Start. Paper presented at XXII International Symposium on Biomechanics in Sports Ottawa, Canada 8-12 August, 2004. International Society of Biomechanics in Sports Conference

Murrell, D. & Dragunas, A. (2012). A Comparison of Two Swimming Start Techniques from Omega OSB11 Starting Block. Western Undergraduate Research Journal: Health and Natural Sciences. Vol 3 – Fall 2012

Vantorre, J., Seifert, L., Fernades, R.J., Vilas-Boas, J.P., Chollet, D. (2010). Biomechanical Influence of Start Technique Preference for Elite Track Starters in Front Crawl. The Open Sports Science Journal. 3: 137-139.

Vantorre, J., Chollet, D., Seifert, L. (2014) A Biomechanical Analysis of the Swim-Start: A Review. Journal of Sports Science and Medicine. 13: 223-231.

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