Associate Professor, PhD A.A. Jalilov
Dr.Hab. V.F. Balashova
Togliatti State University, Togliatti

Keywords: dynamics, speed, acceleration, body/ body segment angular/ linear spatial positioning indices, mawashi geri (lateral round) kick, ushira geri (rotation) kick.

Relevance of the study. Analysis of the available theoretical and practical studies and competitive sport practices shows that it is the right assessment of the spatial/ temporal/ dynamic movement profiling rates of the mawashi geri (lateral round leg kick to the head) and ushira geri (rotation leg kick to the body) kicking techniques that is central for the choice of the most appropriate kicks in a kickboxing fight. In some of the available theoretical and practical study reports on kickboxing, the authors mention the need in the kickboxing motor qualities and skills development/ improvement tools being prudently selected and implemented in parallel with the individual kicking techniques being mastered and excelled with an emphasis on the body segment movement profiles in the kicking sequences [1, 2, 3, 4, 5]. The theoretical studies, however, give no biomechanical structural analysis of the mawashi geri and ushira geri leg kicking techniques.

In view of the above, we have designed this study to analyze two most complicated techniques of the modern kickboxing sport – that are the mawashi geri and ushira geri leg kicking movement sequences – and profile them by the relevant spatial/ temporal/ dynamical movement characteristics.

Objective of the study was to obtain biomechanical specifications to make the spatial/ temporal/ dynamical movement structure profiles for the mawashi geri (lateral round leg kick to the head) and ushira geri (rotation leg kick to the body) leg striking techniques in kickboxing.

Methodology and design of the study

The kickboxing techniques were studied and rated using the following two methods: (1) direct individual performance monitoring; and (2) video- and audio- recording method. The obtained data were used to:

1) Record the individual striking movement sequences of the subject kickboxing techniques;

2) Accumulate video-databases giving the means to analyze the individual striking movement sequences on a dynamic basis; and

3) Apply snap-shooting and slow-replay toolkits to improve the accuracy and dependability of the movement profiling analysis.

Biomechanical performance measurements of the kicking movement sequences were designed to record the following data: dynamic rates; speed/ acceleration rates; spatial angular/ linear movement rates to profile the body/ body segments spatial positioning in the process; and the mawashi geri (lateral round leg kick to the head) and ushira geri (rotation leg kick to the body) movement sequence profiling data. 

Furthermore, we used the action sequence profiling diagrams (i.e. actigrams, cyclograms) to identify the general regularities of the kicking movement sequences and obtain significant efficiency rates for different versions of the kicking techniques. Subject to analysis under the study were the basic and most complicated spatial/ temporal/ dynamic movement structures of the mawashi geri (lateral round leg kick to the head) and ushira geri (rotation leg kick to the body) leg striking techniques in kickboxing. The study data were processed using a standard mathematical statistics toolkit.

Subject to the study were 30 athletes including 15 highly-skilled and 15 lower-skilled (Class II) kickboxers of 19-24 years of age having the 5-12 years-long formal sport career records. The study was performed in the period of November 2013 through June 2015 at facilities of the Togliatti-based “Boyevye Perchatky” [“Fighting Gloves”] Club and included a field study and a laboratory study component.

Study results and discussion

The video-capturing data obtained under the study were found representative of the subject movement sequence kinematics and agreeable with the study data reported by many authors [6, 7, 8]. The mawashi geri kicking movement sequence was classified into the following three phases: preparatory phase (skip (nearing jump), move, swing-up); main phase (strike, leg extension); and final phase (leg bending, follow through).

The highly-skilled kickboxers performing the offensive mawashi geri kick were tested with the higher striking leg mass-centre/ body mass centre (BMC) acceleration rates than the lower-skilled ones. Our analysis of the experimental data profiles of the highly-skilled kickboxers versus the lower-skilled ones showed the vertical acceleration constituent of the most efficient striking techniques varying in a wide range (V = 17.9-37.1%).

The offensive mawashi geri kicking sequence starts from a swinging move of the striking leg with the support leg being actively extended. The BMC in the legs extension process moves up and forward keeping over the support area. Supported kicking sequence efficiency may be stepped up conditional on the segmental accelerations being increased in the striking action. The associating movements will help notably increase the BMC height in the sequence.

It is the swinging leg move in kickboxing that is viewed as a preparatory phase for the mawashi geri kick may be described as a move directed opposite to the coming kick. The striking leg extension and swinging sets necessary conditions for getting the motor system and every structure involved in the kicking sequence prepared for the strike to accumulate and release powerful tension and contraction and keep the optimal spatial/ temporal position in the mawashi geri kicking sequence at the same time. Variations of the striking foot mass centre were found statistically significant (p < 0.001). It is important to emphasize that the highly-skilled kickboxers were tested with the wider variation range of body segment accelerations in the main phase of the mawashi geri kicking sequence. Furthermore, the analysis found that the highly-skilled kickboxing sequences are notably better in the movement control aspects as the “acceleration wave” in the striking leg, for instance, was found to be reasonably and distinctly phased, the phased structure being indicative of the high harmony of the receptor/ effector control processes in the neuromuscular system that exercises active search and correction of the movement sequence in the process.

The video-captures demonstrate that the mawashi geri kicking sequence ends up by the BMC of the kickboxer going down closer to the support spot. The athlete ends up the strike by landing on springy legs with the knee ankles bent at 150-165⁰ and the whole body slightly leaning forward at 15-27⁰ to the vertical axis.

It may be pertinent to mention that the athlete’s body position in space varies in a relatively narrow range in the kicking process, and this is the reason why the efficiency of the mawashi geri kicking sequence largely depends on the athlete’s body position. The joint angle variation indices for the lower support leg and upper striking leg were found to vary in a wide range in case of the highly-skilled kickboxers.

The process of the leg being actively extended in every joint is finalized by an elastic tension of the muscles and explosive release of the viscoelastic muscular energy. And again it is the skill level of the kickboxer that the joint angle variations were found to clearly depend on. The striking leg unbending angles of the highly-skilled athletes executing mawashi geri kicks were found to be 22° higher in the knee joint, 13° higher in the hip joint and 9° higher in the ankle joint than that of the lower-skilled athletes.

In the preparatory swinging movement, the knee joint angle of the highly-skilled kickboxers was measured to average 174 ± 1.62° as compared to 153 ±1.03° of the lower-skilled athletes; the ankle joint angle (to the vertical axis) was measured at 43± 1.04° and 36 ± 1.01^о, respectively; and the hip joint angle (to the vertical axis) averaged 24 ± 3.13° and 12 ± 4.16°, respectively.

In the mawashi geri kick execution process, the striking leg is straightened in the hip joint and ankle joint with the leg muscles being elastically strained; with the highly-skilled athletes showing the knee/ ankle/ hip joint angles being 23°/17°/ 10° higher than those of their lower-skilled peers, respectively. Therefore, a key element of the mawashi geri kicking technique is the active extension of the striking leg in the ankle joint to the almost fully straightened position of the ankle, with the leg movements being variable in a wide range. It should be also noted that the highly-skilled kickboxers are notably faster than the lower-skilled ones in this phase execution process that may be due to the higher movement control in the distal (feet) body segments by the highly-skilled kickboxers.

 The study found that the upper and lower limb bio-kinematic chains in the mawashi geri kicking sequence are in complicated interactions with the support and target. Striking power of the dynamic supported kick in the point of the left foot toe contact with the target in the mawashi geri kicking sequence executed by the highly-skilled kickboxers was measured to be 28.7 kg higher than that of the lower-ranking fighters; and the heel-area striking power was 29.4 kg higher, respectively. The right-foot-toe/ heel striking power of the Master of Sport ranked kickboxers was found to be 47.5/ 23.3 kg higher than that of the lower-ranking kickboxers, respectively. The target contact time of the highly-skilled kickboxers was found to vary around the minimal level (p < 0.05) to generate a higher reactive force in the striking movement (as compared to that achieved by the lower-skilled athletes) with extra power and speed being released (with the energy recuperation effect) in the striking action by the elastically acting muscles. It is the support leg repulsion action that is very important in the mawashi geri kicking sequence for the BMC rising, and the repulsion is largely due to the degree of harmonic interaction in the power impulse being transmitted through and multiplied by the body segments, i.e. by the amount of transmitted energy. And the total power is reflected in the BMC height achieved in the execution, albeit the generated power depends to a degree on the body weight and leverage (moment of force) of the body segments involved. The study found this aspect to be in good agreement with the data reported by a few other studies [9, 10, 11, 12].

The differences in the the mawashi geri kick execution by the athletes, in opinions of the experts, were found more expressed in the highly-skilled athletes’ group versus the lower-skilled ones. There are good reasons to believe that the differences may be also due to the inequalities in the neuromuscular system functionalities of both of the skill groups. Efficient mawashi geri kick execution was found to be always lightning-fast (with high reactive force generated) and taking shortest time due to the prior sequential strain of the muscular system to reduce to minimum the muscle extension/ flexion time and thereby increase the reactive force of the striking leg in contact with the target. Visual expert analysis of the video-capturing data gave the reasons to conclude that it is the ballistic work mode of the muscles (i.e. lashing phase of the movement sequence) that makes the kick action of the highly-skilled kickboxer so efficient.

In addition, the study rated the target hitting accuracy of the mawashi geri kick execution by the subjects; and the highly-skilled kickboxers were found better in these ratings with the score of 27.1 ± 2.81% versus 12.0 ± 0.14% scored by the lower-skilled fighters.

Furthermore, the above methods and analysis were used to obtain biomechanical sequence profiles of the ushira geri kicks executed by the right/ left legs.

Visual data profiles gave the material for designing the movement sequence kinematics to generally classify the sequence into the following three phases: preparatory (swinging movement) phase; main (strike) phase and final (follow-through) phase. In the preparatory phase, the kickboxer straightens the striking right leg simultaneously rotating the knee-bent support leg and turns his back to the target. The striking right leg unbends in the knee and the athlete pushes his body forward moving the body mass centre (BMC) onto the left support leg to maintain balance of the musculoskeletal system. At the same time the right leg rotates with acceleration and the foot makes the ushira geri strike to the target. Comparative analysis of the ushira geri kick execution by the kickboxers of different skill levels shows that the highest acceleration rates in the movement sequence are achieved in its lateral (horizontal) component. Therefore, driving in the leg swinging phase is the accelerated move of the foot till it strikes/ contacts the target. The highly-skilled athletes were tested with notably higher striking foot/ body segment acceleration rates than the lower-skilled ones.

In the main phase of the kick, the striking foot moves towards the target at a high acceleration rate with the BMC of the striker going forward. The acceleration rates in the ushira geri kick execution sequence may be very high, particularly in the lateral component of the movement that comes to as much as 12.1±0.37 m/s².

The video-capturing data showed that the highly-skilled kickboxers' knee joint bending (around the frontal axis) angle in the swinging phase of the sequence was on average 8° lower than that of the lower-skilled fighters, with the difference of the average values being statistically significant (p < 0.01). The foot joint extension angle was also found higher in case of the highly skilled kickboxers. The same applies to the hip joint extension angle that was 29° higher on average for the kicks executed by the highly skilled kickboxers. In the ushira geri kick execution with the right striking leg by the highly skilled kickboxers, the leg straightens in the knee joint around the frontal axis up to 169° with the foot joint being extended up to 143° and the hip joint being unbent up to 27° (to the vertical axis). The lower-skilled kickboxers were tested with notably lower rates in these measurements.

In the ushira geri kick execution sequence, the kickboxer moves the body forward pushing the body weight onto the relevant leg. The study found that the reactive force generated by the left leg toe/ heel of the highly skilled kickboxers in contact with the target was 39.8/ 26.8 kg higher than that by the lower skilled kickboxers, respectively. Furthermore, the reactive force generated by the right leg toe/ heel of the highly-skilled kickboxers in contact with the target was 63.7/ 49.9 kg higher than that by the lower-skilled kickboxers, respectively.

It may be pertinent to note that the study found the reactive force in the toe being always higher than in the heel. This finding may be explained by the fact that the front part of a foot is rigid enough to produce extra elastic force (associated with the stretch-reflex of the foot) in contact with the target. The more unbent is the foot the higher is the reactive force of the strike and the higher is the energy transfer due to the longer bio-kinetic chain (or lever).

It should be mentioned that the increased elastic tension of the motor system of the highly-skilled kickboxers was particularly expressed in the striking leg chain acceleration phase when the movement speeds came to 7-9 m/s and the reactive force generated in contact with the target amounted to as much as 374 kg. In the next moment, however, the body segments were found to be driven mostly by the forces of inertia with the electric activity rates in relevant muscle groups falling down to the point of the forced inhibition of the segment speed.

Furthermore, the study produced the following efficiency rates of the ushira geri kick execution by the highly-skilled kickboxers versus the lower-skilled ones: 37.1 ± 2.54% for the left-leg kicks to the body; 46.6 ± 1.14% for the right-leg kicks to the body; 16.6 ± 0.11% for the left-leg kicks to the head; and 21.0 ± 2.78% for the right-leg kicks to the head. The same tests of the lower-skilled kickboxers produced the following kick efficiency rates: 13.3 ± 1.14% for the left-leg kicks to the body; 16.0 ± 2.17%, for the right-leg kicks to the body; 9.3 ± 1.18% for the left-leg kicks to the head; and 11.3 ± 2.71% for the right-leg kicks to the head.

Therefore, it may be stated that the study generated the kinematic/ dynamic movement profiling data for the offensive ushira geri kick execution sequence that are indicative of the kicking technique efficiency being rather dependent on the skill level and the applied training system efficiency, with due priority being given to the movement sequence biomechanics in the training process.

Conclusions and practical recommendations. The theoretical and practical experimental findings of the study gave the means to develop and offer an educational process management system applicable in the competitive offensive ushira geri kicking technique mastering and excelling process. The practical results of the study including the temporal/ dynamic data profiles of the mawashi geri and ushira geri leg kicking techniques gave us good grounds to put together special practical recommendations (supported by the scientifically justified biomechanical sequence profiling data) to improve the practical kickboxing training systems.

1. We would recommend the following to improve the efficiency of the competitive technical skills mastering process in kickboxing:

• Apply sets of special physical practices designed for different skill levels of trainees in kickboxing;
• Make a due emphasis on the distal (both the upper and lower limbs) segments control process in the mawashi geri and ushira geri kicking technique mastering/ excelling process; and
• Apply the relevant portable real-time data collection unit with a feedback capacity to intensify and control the kicking technique excelling process.

2. In the mawashi geri and ushira geri kicking technique excelling process, the coaches are recommended to:

• Focus the training tools and capacities so as to develop reasonably stable mawashi geri and ushira geri kicking technique structures with an emphasis on the offensive strike accuracy;
• A few versions of the offensive techniques need to be rotated, tried and varied in the training process (on-site kicks; short/ mid/ long distance kicks; variable fight tactics etc.) for better adaptation of the trainees to the real fight conditions and progress in offensive kicks, with due consideration for the kinematic/ dynamic kicking sequence profiles tailored to the variable fighting situations;
• Different versions of the kicking techniques and tactics need to be combined on an interactive basis to optimize the body segments spatial/ temporal positioning in the kicking sequence to attain the optimal dynamic force application profiles in the kicking techniques; and
• Apply special striking (for leg kicks with knee bending angles variable in a wide range) appliances and practices with extra weights (varying within 5-15% of the athlete’s body weight) fixed on the pelvis segment and distal body segments to achieve the maximum possible rates of the supported responses and reactive forces generated by the kicks.

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