Comparing a Successful vs. Unsuccessful Snatch in High Level Competition

What makes the difference between making or missing a big lift in competition?

Well when we look at high-level lifters, the answer is usually not much. When a novice lifter misses a lift, there are usually one or more key technical faults that caused the miss and they aren’t hard to spot. However, elite lifters have highly developed and consistent mechanics. These lifters push so close to their strength maximum that the smallest margins make the difference between success or failure.

Below is a video from Hookgrip of Anthony Pomponio at the 2015 National Championships missing a 154 kg snatch (340 lbs) on his second attempt, then coming back to make the same weight on his third attempt. Like for the analysis of Jared Fleming, this video is in slo-motion from an almost perfect side view that allows a great analysis of the bar path for both lifts. Pomponio’s miss and his comeback make look almost identical at full speed, serving as a great case study to break down the differences between the attempts.

Video Credit: @hookgrip (Full video: https://www.youtube.com/watch?v=Iq4OpCYZ1yY)

Bar Path, Bar Velocity, and Bar Acceleration

The first thing that jumps out from Table 1 is that the max bar height and max bar velocity were almost identical between the two lifts. This may be surprising as these two values are often thought to be critical differentiators between successful and unsuccessful lifts. This is true for lifts that exceed an athlete’s strength when they just aren’t able to pull the bar high enough and fast enough to get underneath it. But when looking at lifts that are within a non-fatigued athlete’s strength abilities, these values do not seem to be a primary cause of a missed lift. This same conclusion has been found in published research studying both the snatch and clean [1,2]. In fact, when looking at successful vs unsuccessful power clean attempts, athletes often had higher bar velocities for missed lifts than those they made [2]. In fact, the maximum vertical bar acceleration was greater in the missed lift than the made lift in this comparison. This means that the Pomponio actually applied a greater maximum force to the bar during the unsuccessful lift.

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So what does make the difference then?

The two key differences seen in the data of the missed lift are the max horizontal acceleration and the minimum vertical acceleration. The greater horizontal acceleration means the force vector applied to the bar was pushing the bar more away from the body compared to the successful lift (Figure 1). The direction of the bar acceleration has been shown to be a critical aspect between successful and unsuccessful lifts for both the snatch and clean [1,2]. This is intuitive since the most efficient method to lift the bar is to maximize the vertical acceleration and minimize the horizontal. This slightly greater horizontal acceleration may be why the catch position for the missed lift was a little more forward compared to the made lift. Once again, the missed lift was very close to being successful with the bar being pulled plenty high. The small difference in bar position in the catch position may have put the bar in front of the Pomponio’s center of mass, causing it to drop in front when he tried to support the weight.

Pomponio bar path compare.jpg
Figure 1. Bar path comparison of the two attempts

 

The second key difference for the missed snatch is the greater magnitude of negative bar acceleration during the transition between the 1st and 2nd pull (Table 1). This negative acceleration reduces bar velocity and requires the athlete to transfer more energy back into the bar overcome these losses. Anthony does goes up on his toes a little more at the start of the second pull in the unsuccessful lift, simultaneously bringing his hips to the bar earlier instead of letting the bar travel back farther as it did in the the third attempt. This could be a compensation for the slowing bar velocity, in an attempt to re-accelerate the bar, leading to greater horizontal bar acceleration off the hip and the decreased second pull power.

 

Screen Shot 2017-05-22 at 8.14.11 PM
Picture 1. Comparison of the power position of each lift. Right picture: Successful 3rd Attempt. Left Picture: Unsuccessful 2nd Attempt

 

Barbell Energy

When looking at the energy transferred to the bar during each phase of the pull in tables 1 and 2, the energy transfer for the 1st pull and transition was greater for the missed lift. However, the successful lift had a much greater contribution during the 2nd pull, accounting for a greater proportion and total magnitude of energy compared to the unsuccessful lift, and may be another defining difference between the two attempts.

 

Comparing this data to the previous bar energy data calculated for Jared Fleming’s American record shows the differences in the styles between the two athletes. Pomponio produced a much greater proportion of his total bar energy in the 1st pull and transition (64%) compared to Fleming (51.8%). However, Fleming had much greater proportion of bar energy generated during the second pull (36.4%) compared to Pomponio (26.3%). This data quantifies the different techniques employed by each athlete to be successful with Pomponio relying on his strong pull from the floor and Fleming using a very explosive second pull.

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Technical Notes: The location of the barbell was digitized at a rate of 60 frames per second using a program written in Matlab. The position data was filtered with a low-pass Butterworth filter at 6 hz. This was chosen based on similar methods utilized in scientific literature [2].

References:

  1. Gourgoulis, Vassilios, et al. “Unsuccessful vs. successful performance in snatch lifts: a kinematic approach.”The Journal of Strength & Conditioning Research 2 (2009): 486-494.
  2. Kipp, Kristof, and Carolyn Meinerz. “A biomechanical comparison of successful and unsuccessful power clean attempts.” Sports Biomechanics 16.2 (2017): 272-282.

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