L.A. Khasin, associate professor, Ph.D., director of SRIIT, head of complex research group on track and field athletics
Scientific research institute of information technologies
Moscow state academy of physical culture, Malakhovka

Key words: elite athletes, athletic throws, high speed video recording, rational technique.

I assume it is advisable to consider two information groups of indices when assessing technical skills of elite athletes in athletic throws, weightlifting and other sports.

Considering technique as a system of movements for elite athletes, one can act in the following way: 1) register a sports movement with proper accuracy and keep searching for indices closely related to sports result. For example, in shot put the duration of certain phases and other values of space and time, kinematic and dynamic characteristics of movement can be such indices. Elite athletes can perform the above task in the following way: repeated registration of a movement executed by an athlete and determination of the phase structure and other parameters of this movement. The relations of some characteristics with result can be detected using the methods of mathematical statistics and other methods of data analysis and processing. In our case the movements were registered using high speed video recording. The relations with result were detected using the methods of mathematical statistics, including correlation analysis.

As an example, let us consider some characteristics of shot put performed by leading Russian and foreign athletes. These athletes used “in jump” technique of shot putting. Duration of the following phases was estimated: jump, rolling and final speed-up. Kinematical and dynamical parameters of athletes’ techniques, namely movements, speed and acceleration of the shot and athlete’s interaction with the shot were determined. The above factors were bound to video records. The correlation analysis was used to reveal the relations between movement characteristics and shot putting results.

The parameters of the second group were assigned for estimating the degree of movement “automatism”; the latter was estimated using standard deviations of the durations of phases. In my opinion, the automatism of movement is determined by the performance of athlete’s inter- and intramuscular coordination, and by the perfection of the system that controls this coordination, including control program, feedback, etc.

The parameters important for result and estimation of automatism by video records were determined using the correlation analysis; descriptive statistics were formed for Olympic Games champion 2008 and 2012, World and European championships prize winner T. Maevsky, 2003 World champion and 2010 European champion, Olympic Games and World championship prize winner A. Mikhnevich, and multiple champion of Russia and 2008 Olympic Games finalist P. Sof’in. The video recording was carried out in 2009 at Moscow Open and Brothers Znamensky Memorial, and in 2013 at the World championship in Moscow. High speed video recording up to 500 FPS was used, that allowed to reveal the microstructure of movements. This rate provided high accuracy of the measurements of movements and phase durations; for instance, the accuracy of measurements of the latter parameter was 4 ms. Kinematical and dynamical parameters were calculated by means of movement approximation by a fifth degree polynomial.

The following phases were studied:

Т₁ – jump duration (between lift-off and landing on right foot).

Т₂ – time between right foot and left foot landings (rolling phase)

Т₃ – time between left foot landing and left foot lift-off (support phase).

Т₄ – time between left foot lift-off and shot throwing (unsupported phase).

Т₅ – time between left foot landing and shot throwing (final speed-up).

Т₆ – total time between jump start and shot throwing.

The distance of shot put in a try was considered as a result.

Let us consider the video records of athletes’ movements, the results of correlation analysis, and the descriptive statistics.

Table 1. Descriptive statistics according to T. Maevsky’s phase structure and results

Table 2. Correlation analysis of T. Maevsky’s phase durations and results (n=4)

Table 3. Descriptive statistics on A. Mikhnevich’s phase structure and results

Table 4. Correlation analysis of A. Mikhnevich’s phase durations and results (n=5)

A high stability of phase durations was shown by T. Maevsky. It should be noted that the athlete has kept constant phase structure of movements: in 2009 and 2013 the phase durations were virtually identical, though the athlete’s weight had grown by more than 10 kg in this period of time.

Table 5. Descriptive statistics on P. Sof’in’s phase structure and results

Table 6. Correlation analysis of P. Sof’in’s phase durations and results (n=5)

The analysis of P. Sof’in’s phase structure showed weak correlations between the results and phase durations, and a lower level of the stability indices as compared to T. Maevsky and A. Mikhnevich, (Table 6). Significant differences in the kinematical and dynamical parameters of movements are also observed. Let us consider these differences by comparing T. Maevsky’s and P. Sof’in’s techniques using high speed video recording.

Figures 1–12 show the movement parameters, such as body inclination angle in the beginning of final speed-up, forces of interaction with the shot at various stages, points of maximum force application, and time and speed indices corresponding to them.

The postures of T. Maevsky and P. Sof’in are shown in figures 1 and 2. The former athlete’s vertical force curve at high angles of declination from the normal in the beginning of the final speed-up is shown in Figure 3. P. Sof’in opened early, and the angle with the normal in the beginning of final speed-up was smaller (Figure 4). The maximum vertical force was applied by P. Sof’in at earlier movement stages.

Fig. 1 – T. Maevsky in the beginning of final speed-up. The angle of the body declination is 49 degrees.

Fig. 2 – P. Sof’in in the beginning of final speed-up. The angle of body declination is 39 degrees.

Fig. 3 – Upright force vs. time (T. Maevsky, final speed-up).

Fig. 4 – Upright force vs. time (P. Sof’in, final speed-up).

The first force peak is caused by P. Sofin’s body extension. The curve in figure 4 evidences about an early body extension. The position corresponding to the second force peak is shown in Figure 5. The athlete’s right arm is already straightened at the elbow. The force is generated mainly by body rotation about the longitudinal axis. P. Sof’in applies higher maximum force and has worse results compared to T. Maevsky, whereas he generates a lower force impulse which determines the shot put distance. This can be explained by an early arm straightening at the elbow, causing a movement reduction and an ineffective activity.

The extension of the time gap between maximum forces along Oy and Ox axes is a positive factor that characterizes the shot put technique.

Fig. 5 – P. Sof’in: posture at the maximum force applying.

F = 634.9 N, t = 0.12 s, V = 9.66 m/s.

Fig. 6 – Athlete’s interaction with shot put vs. time.

The comparative analysis of the techniques of T. Maevsky and P. Sof’in, based on the high speed video records, showed that T. Maevsky used significantly higher angle of body declination (Figures 11–12). Maximum force was applied by T. Maevsky exactly at the start of arm straightening at the elbow, whereas P. Sof’in straightened his arm “in vain”. Besides, after the jump phase P. Sof’in’s knee joint noticeably flexed, causing a reduction in the speed of movement (Figure 11). T. Maevsky’s technique can be considered as more rational according to the general canons. P. Sof’in’s technical errors were caused largely by insufficient speed and force training. The high speed video recording and the mathematical methods of data processing allowed to elucidate these details and to calculate the above parameters.