Dummy rotation rate to assess hip throw and back throw execution quality in wrestling

PhD A.I. Laptev1
A.A. Shipilov2                                                              
1Russian State University of Physical Education, Sports, Youth and Tourism (SCOLIPE), Moscow
2CSTST of Moscow City Department for Physical Culture and Sport, Moscow

Keywords: competitive wrestling, throw techniques, dummy, throw biomechanics, technical fitness, kinematics analysis, throw execution speed.

Background. Training systems applied in the modern wrestling sport give a high priority to the throw techniques in every technical/ special physical training component, and this is the reason why the wrestling sports need modern computerized instruments to rate the throw execution quality in every element and exercise [1-6]. Any movement biomechanics test system in any sport discipline operates with a set of informative test rates to analyze the action execution quality, with these test data commonly referred to as the ‘performance rates’. It should be mentioned that the test equipment related problems seem to being resolved nowadays since the relevant test technologies, equipment and electronics are abundant on the market. We believe that the dummy angular speed (rotation rate) may be ranked among the most informative performance test rates applicable to throw techniques in modern wrestling sport.

Objective of the study was to analyze benefits of the modern biomechanical test equipment to rate the hip/ back throw execution quality in the modern competitive wrestling sport by the rotation rates versus the key movement timing and positioning indices.

Methods and structure of the study. Sampled for the study were the 17.3±1.13 years old Candidate Masters of Sport and Masters of Sport (n=14), weighing 66.7±6.82 kg and 170±4.47 cm tall on average. The study was performed at Sport Center of the Moscow Sport Committee. The wrestlers were required to make two 32.6kg dummy throws: one hip throw with the hand and neck hold; and one back throw with the body hold. The throws were performed as close as possible to the best competitive performance standard, with the high amplitudes and speeds. Every wrestler was given three test attempts for each of the two throws after a warm-up practice.

The dummy movement kinematics was rated by a 3D optical Qualisis Test System equipped with ten high-frequency (250Hz) video cameras. The dummy takeoff and landing moments were registered by AMTI dynamometric platform synchronized with the 3D optical test system. The test data were processed by the Qualisys Track Manager, Visual 3D, Math Lab and Microsoft Excel software tools.

The dummy movement (dummy body mass center [BMC] trajectory) was traced using a set of reflective markers on its surface. The virtual BMC was assumed to coincide with the dot in the middle between markers R2 and L2. In case when some marker was lost in the throw process, the BMC position was found in between markers R1-L1 and R3-L3: : see Figures 1 and 2. In addition, we used an inertial 200Hz metering YostLabs unit fixed on the dummy close to the BMC to read the dummy rotation (around the X axis of horoscope) rate. We obtained the following test rates in every throw attempt:

● Primary position of the dummy i.e. the distance between the surface and BMC at the takeoff moment: see Figure 3A;

● Dummy travel peak meaning the vertical distance between the surface and the topmost point of the dummy travel trajectory: see Figure 3B;

● Throw amplitude meaning the difference between the dummy travel peak and the takeoff point;

● Throw time i.e. the time difference between the takeoff and landing moments: see Figure 3A-C;

● Maximal dummy lift speed meaning the top speed of the dummy BMC in the lift phase (takeoff to peak time points): see Figure 2, A-B).

● Mean rotation rate that means the average angular movement speed of the dummy in the lift phase.

Figure 1. Dummy cross-section with markers R1, R2, R3 on the right side; and L1, L2, L3 on the left side

Figure 2. Dummy front view with markers

Figure 3. Hip throw phases: A- takeoff (primary position) moment; B- travel peak moment; C- dummy landing moment Lift phase Landing phase

Study findings and discussion. Having analyzed the test data using the Spearman range correlation method we found the dummy rotation rate being in a direct correlation with the back throw amplitude and lift speed and in an inverse correlation with the throw time: see Tables 1 and 2. The same correlations hold true for the hip throw, with the only exclusion for the throw time as verified by the statistically meaningful (p˂0.05) correlation of the mean rotation rate with the amplitude, maximal dummy lift speed and throw time: see Table 2. Thus it may be stated with confidence that the test data show the mean rotation rate being a highly informative indicator of the throw execution quality.

Table 1. Mean values of the movement test rates (n=14)

Test rate

Back throw

Hip throw

σ

σ

Dummy lift peak, m

1,241

0,067

1,157

0,059

Throw amplitude, m

0,441

0,068

0,359

0,058

Maximal dummy lift speed, m/s

2,51

0,26

2,20

0,32

Mean rotation rate, radian/ s

4,85

0,40

3,56

0,58

Throw time, s

0,809

0,030

0,860

0,066

Table 2: Correlation analysis
 

Test rate

Mean rotation speed, radian/s

Back throw

Hip throw

Throw amplitude, m

0,60

0,55

Maximal dummy lift speed, m/s

0,79

0,68

Throw time, s

-0,64

-0,33

 

* statistically meaningful values (p˂0.05)

Conclusion. The test method with a set of objectively measurable criteria make it possible to improve the accuracy of the technical/ special physical fitness tests in the wrestlers’ training process and, hence, step up the process controllability and efficiency. The growing accessibility and affordability of the relevant angular speed rating equipment (inertial metering units) makes it possible to design a reliable biomechanical process rating method compliant with the modern standards and requirements.

References

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Corresponding author: laptaleksej@yandex.ru

Abstract

The study analyzes benefits of the modern biomechanical test equipment to rate the throw quality in the modern competitive wrestling sport, and offers a set of elementary move scoring criteria for the sport. The study data and analyses made it possible to find the statistically significant correlations (p<0.05) of the mean angular rate with amplitude (r = 0.60); maximal dummy rotation rate (r = 0.79) with the execution time (r = - 0.64) for the back throw. The same correlations are true for the hip throw albeit to a lesser degree, with r = 0.55, r = 0.68 and r = - 0.33, respectively, whilst no meaningful correlation was found for the mean angular rate versus the hip throw execution time. On the whole, the study data and analyses showed benefits of the mean angular rate being applied to assess the execution quality of at least these two throws. The objectively measurable criteria make it possible to improve the accuracy of the technical and special physical fitness tests in the wrestlers’ training process and, hence, step up the process controllability and efficiency.