Bosco From Illinois Got Injured in Elite Academy Martial Arts

Sensors (Basel). 2020 Jun; 20(11): 3186.

Assessing the Furnishings of Kata and Kumite Techniques on Physical Performance in Elite Karatekas

Luca Molinaro

¹Department of Economics, Engineering, Society and Business Organization (DEIM), University of Tuscia, 01100 Viterbo, Italian republic; ti.sutinu@oranilom.acul (L.Chiliad.); ti.sutinu@issor.onafets (Due south.R.)

²Motustech – Sport & Health Applied science c/o Marilab, 00121 Ostia Lido, Rome, Italy

Massimo Montecchiani

ⁱⁱⁱFIAMME ORO – Polizia di Stato, 00148 Rome, Italy; moc.liamg@inaihccetnom.g

^fourFIJLKAM – Italian Federation of Judo, Wrestling, Karate and Martial Arts, 00100 Rome, Italy

Received 2020 May 12; Accustomed 2020 Jun 2.

Abstruse

This study aimed at assessing physical operation of elite karatekas and not-karatekas. More specifically, effects of kumite and kata technique on joint mobility, body stability, and jumping power were assessed past enrolling twenty-four karatekas and by comparing the results with eighteen non-karatekas healthy subjects. Sensor system was composed by a single inertial sensor and optical confined. Karatekas are more often than not characterized by better motor performance with respect non-karatekas, because all the examined factors, i.due east., mobility, stability, and jumping. In addition, the two techniques lead to a differentiation in joint mobility; in particular, kumite athletes are characterized by a greater shoulder extension and, in general, by a greater value of preferred velocity to perform joint movements. Conversely, kata athletes are characterized past a greater mobility of the ankle joint. By focusing on jumping skills, kata technique leads to an increase of the concentric stage when performing squat jump. Finally, kata athletes showed amend stability in closed optics condition. The outcomes reported here can be useful for optimizing coaching programs for both beginners and karatekas based on the specific selected technique.

Keywords: karate, sport biomechanics, inertial sensors, trunk stability, joint mobility, jumping

one. Introduction

Karate is a popular Japanese martial fine art with over 10 million athletes and 100 million practitioners in the world [1]. The popularity and scientific interest of karate grew up in the terminal decades, when the Globe Karate Federation has been recognized by the International Olympic Committee, and it volition make its first advent equally an Olympic Sport at the 2020 Summer Games in Tokyo. Karate contest consists in a sequence of attacks and defenses by using punches and kicks with loftier speed and power [two]. Karate is basically divided into two master techniques that stand for the ii disciplines in the globe tournaments: kumite and kata [3]. The word kumite means sparring; thus, karatekas use the basic techniques in interfering conditions during the competition confronting an adversary. Kumite matches final 3 min, and a high intensity activeness, concerning kicks, punches, and quick horizontal displacements, is required [4]. It is easily understandable that the main aspects that should exist trained in kumite karatekas are perceptual and anticipatory skills [v]. Conversely, kata contest consists in a standardized sequence of offensive and defensive gestures without the presence of the opponent; thus, it tin be considered equally a virtual fighting [6]. Both competitions are characterized by periods of lower intensity and periods of maximum work [7]; thus, maximal speed and explosive power are crucial elements of karate performance [8]. In the past, the coaching programs were similar for both techniques, and most of the athletes successfully participated in both kumite and kata during official competitions. However, the revised rules of the competitions made kumite more dynamic than kata; consequently, a proper specialization should be required in elite karatekas based on the specific technique [ix].

The technological innovations of the last years allowed using wearable sensor systems for motor operation evaluation [10,11], likewise in combat sports [12,13,fourteen]. In lodge to select the all-time discipline between kata and kumite for each karateka, data regarding physical and physiological characteristics of the athletes have to be taken into account [fifteen]. More specifically, physiological aspects include cardiorespiratory endurance, muscular strength, and body composition; instead, physical characteristics include speed, stability, power, mobility, coordination, and agility [16].

In literature, several studies take been already conducted on the physiological and physical differences between kata and kumite. Those studies were mainly focused on the evaluation of metabolic consumption [17], stability [1,18], agility [4,19,twenty], mobility, and ability [20].

Every bit regards metabolic consumption, Doria et al. found a greater request of metabolic power in kumite players rather than kata ones (in average 155.8 mL/kg vs. 87.eight mL/kg), with a predominance of the aerobic contribution [17]. By focusing on the stability skills, Gauchard and colleagues evaluated the postural functioning in aristocracy kumite and kata comparing them with sedentary subjects when performing static balance control in different visual and tactile conditions, i.e., open up and airtight optics and on different tactile supports. Every bit expected, sedentary subjects showed a greater torso sway than the athletes when performing bipodalic tasks; in addition, focusing on the 2 disciplines, kata players were characterized past a reduction of the trunk and area sway in both visual and tactile conditions [1]. Specifically, kata showed a reduction from 40 to 100 mm² considering all the tested conditions. Authors suggested that such findings can be related to the different postural strategies needed for the specialization of the karatekas. Mirmoezzi et al. plant that kumite athletes showed a amend dynamic balance, even though this comeback decreased with fatigue acquired by intense preparation [18]. Based on these findings, authors suggested to implement training programs to delay fatigue effects peculiarly in kumite karatekas. Moving to the agility evaluation, Syaquro et al. did not find any differences associated with the reaction time between the two disciplines during whole-body rotation; conversely, they constitute a deviation in the reaction speed (in average kumite = 0.32 s and kata = 0.23 s). In particular, kumite showed best results ascribable to the necessity of kumite to apace react to the opponent movements during the contest [19]. In the aforementioned context, Nedeljkovic et al. evaluated the reaction time in both offensive and defensive actions performed by kumite, kata, and beginners. Authors found differences merely between beginners and others, while a promising only not meaning difference was observed between kumite and kata, with the first i characterized by lower values of the reaction fourth dimension [iv]. In improver, the written report performed by Zemkova revealed that the agility alphabetize was significantly ameliorate in kumite players than kata ones (on boilerplate 270 ms vs. 330 ms); the contrary upshot was obtained for the movement velocity [21]. As regards the mobility and power, only Koropanovski et al. aimed at identifying the differences due to the kumite and kata disciplines on anthropometric characteristics and concrete performance [20]. Authors implemented a protocol involving dissimilar tasks to evaluate mobility of lower limbs, agility, power, and endurance, finding that an explosive power could exist fundamental in kumite technique, whereas a smaller stature and a higher mobility of the lower extremity could be relevant for kata competitors. Authors suggested as the reported findings could exist useful for an early on selection of karate competitors.

To the best of authors' knowledges, no studies have been carried out to investigate the differences due to the karate techniques on the upper limb mobility, jumping skills, and monopodalic stability in elite karatekas. Nevertheless, the mobility of upper limbs is ane of the bones fitness components in karate for the execution of full-range movements at loftier speeds [15]. In add-on, jumps and monopodalic stability represent motion tasks often required during competitions [22]. From this perspective, the study aims were twofold. We wanted, firstly, to assess the differences in motor performance between elite karatekas and non-karatekas, aiming at creating reference values of physical performance in elite karatekas useful to address beginners towards the most advisable training programs. Secondly, we aimed at measuring the influence of karate specializations on physical performance in elite athletes; in particular, we wanted to assess the differences between kata and kumite players in the terms of whole-body joint mobility, body stability, and skills in jumping. The outcomes of the 2d aim could be useful to provide guidelines for the optimization of the coaching programs based on the specific karate technique.

2. Materials and Methods

2.ane. Participants

Twenty-iv international level karatekas (xi men and xiii women) with at least xv years of exercise and belonging the Italian national karate squad were involved in the study. More than specifically, 16 of them were kumite athletes (KU—seven males and nine females, historic period = 24 ± six years, acme = 169.iv ± 7.six cm, trunk mass = 64.8 ± 9.4 kg) and the remaining 8 kata athletes (KA—4 males and four females, age = 26 ± 5 years, acme = 165.4 ± v.6 cm, body mass = 66.viii ± iv.4 kg). Amongst them, at that place were winners of the Italian championship, European champions, and World champions in dissimilar weight categories. All of them were involved in karate half dozen days per week and twice for each day. In add-on, 18 age-matched subjects (13 men and five women, age = 25 ± 6 years, height = 171.2 ± eight.6 cm, torso mass = 69.8 ± x.4 kg) were involved in the study as non-karatekas (NK). Subjects were included in the NK group if they did never exercise karate and they practice concrete activities at maximum twice per week at a noncompetitive level. Participants, both karatekas and not-karatekas, had not any recent injuries for at least 2 years. All participants were informed on the rationale of the report, and a written informed consent was obtained co-ordinate to the ethical standards outlined in the 1964 Declaration of Helsinki.

2.2. Experimental Setup

2 sensor systems were used in the experimental protocol: the OPTOGait and the GyKo.

The OPTOGait system (OPTOGait, Microgate S.r.I, Italy, 2010) consists in a fix of transmitting-receiving 1 yard long bars positioned above the ground. Each bar is equipped with ninety-six LED diodes. Information were recorded using OPTOGait Version 1.12.1.0 software (Microgate S.r.I, Italia). Through this device, it is possible to record flight and contact times of each human foot with an accurateness of one ms. The sampling frequency was set at one kHz. The OPTOGait organization is normally used in the analysis of human movements, peculiarly for gait [23,24] and jump gesture analyses [25].

The GyKo (Microgate S.r.I, Italy) contains the MPU9250 that is a single Inertial Measurement Unit (IMU) (dimensions: 50 × 70 × 20 mm, mass: 35 thousand) consisting in a triaxial accelerometer (full calibration ranged from ±2 g to ±16 g), a triaxial gyroscope (full scale ±2000 °/s) and a triaxial magnetometer (full scale ±4800 µT). The device can exist fixed on a body segment using a dedicated semi-elastic chugalug equipped with a device-specific magnetic support to avert relative movements during the execution of the tasks. Elastic belt guarantees besides the subject area comfort. Data gathered from the sensor is transferred via Bluetooth to a personal computer and stored using the GyKoRepower software version ane.ane.2.0 (Microgate South.r.I, Italy). The sampling frequency was prepare at 500 Hz. The MPU9250 is characterized by an accuracy of ±0.i° in the angle ciphering [26]. The GyKo inertial sensor is mainly used to evaluate motor activities in jump tests [27], muscle forcefulness test [28], and stability tests [29]; and its measures take been demonstrated to be reliable in both angle [xxx] and postural parameters ciphering [31].

Finally, 2 Webcams (Logitech C920 HD) were gear up at three thousand from the subject and were aligned with her/his frontal and lateral planes. Video were synchronized with data acquisition in order to record movements of the subject during the unabridged protocol. Videos were successively analyzed to verify the definiteness of the task execution in order to evaluate tasks to discard from the analyses.

two.3. Experimental Protocol

The experimental protocol consisted of iii tasks for the evaluation of whole-body joint mobility, monopodalic stability, and jumping ability. All the concrete exercises were adult co-ordinate to the requirements of the technicians of the Italian national karate team. All tests were carried out straight on the mat in barefoot status. Before each chore, a static conquering with the sensorized body segment in rest position was performed. The rest position coincided with the starting position specific for each individual examination, as described in the following paragraphs. All participants were able to complete the unabridged protocol, which lasted approximatively 45 min per subject.

2.3.1. Joint Mobility

As regards articulation mobility tasks, participants were asked to perform selected movements of shoulder, hip, and talocrural joint joints with the greatest possible excursion at the preferred velocity without making compensations with other parts of the trunk. In addition, merely for the shoulder movements and hip flexion motion, participants were asked to move body segments also at the maximum velocity (MV). Each required move was repeated once. Participants were instrumented with the GyKo placed on the torso segment proximal to the examined articulation in order to mensurate the linear dispatch and angular velocity of the segment, which the sensor was attached on. The full scale of the accelerometer embedded into the GyKo was set at ±2 one thousand in mobility tasks. The OPTOGait sensor was not used in the mobility task.

Shoulder

For the assay of shoulder mobility, iv movements were performed: flexion, extension, abduction, and actress rotation. Every bit regards the showtime iii movements, participants were asked to stand up on the mat and to perform the requested rotations starting with the arms along the body (Figure 1); for the extra rotation, instead, subjects started with an abduction of shoulder equal to ninety° resting the forearm and the hand on a flat support, as it is shown in Figure 2. During flexion and extension movements, subjects were requested to avert intra and extra rotations; instead, natural physiological movements were allowed during the abduction rotation. The device was placed on the bailiwick's arm at 15 cm from the centre of rotation of the shoulder during the flexion, extension, and abduction movements (Figure anea,b). For the extra-rotation movement, the sensor was placed on the forearm at fifteen cm from the elbow (Figure onec) All the movements were performed with both sides and at both preferred and maximum velocity. Each movement was repeated one time.

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Mobility of shoulder: sensor positioning and move direction for the flexion (a), abduction (b), and extension (c) task.

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Mobility of shoulder: sensor positioning and movement direction for the extra-rotation job.

Hip

For the analysis of the hip mobility, three movements were performed. The first move was a hip flexion starting from the supine position with the legs resting on the basis (Effigy 3a); subjects were asked to avert knee angle. The second movement, denominated carve up movement, consisted in a hip abduction performed with the two limbs simultaneously, starting with legs resting on the wall and the trunk extended on the ground; the hip flexion was maintained at 90° during the rotation (Figure iiib). Finally, the third movement, denominated sit down and reach, consisted in a further hip flexion performed with the trunk and starting from the sitting position with the legs directly on the floor (Figure 3c); the rotations faux a reaching motion [32]. The sensor was placed on the thigh at 15 cm from the human knee center of rotation during the flexion and split movements (Effigy threea,b). For the sit and attain move, the sensor was placed on the back at level L4 (Figure 3c). The flexion movement was performed with both sides; the split movement was repeated two times in club to measure one movement per each leg. Only the flexion movement was performed at both preferred and maximum velocity.

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Mobility of hip: positioning of the sensor and motion direction for flexion (a), split (b), and sit and reach (c) task.

Ankle

For the analysis of the ankle mobility, two movements were performed. The starting time movement was an talocrural joint flexion acquired by the foot rotation starting from a fully extended position of pes with the subject lying prone on the couch and the feet outside of it (Figure iva). The second motility was an ankle flexion caused by the leg rotation during an overhead squat (Figure ivb). The sensor was positioned on the plantar fascia of the foot (Effigy foura) during the flexion task and on the shank at a distance of 10 cm beneath the knee during the squat motion (Figure 4b). The flexion move was performed with both sides; the squat movement was repeated two times in order to measure movement 1 time per each leg. Ankle movements were performed simply at the preferred velocity.

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Mobility of talocrural joint: positioning of the sensor and movement management for flexion (a) and squat (b) chore.

2.three.2. Trunk Stability

Every bit concerns torso stability task, a novel monopodalic test was developed starting from the I-Leg Standing Balance [33,34] and modifying the position of the arms and the raised leg in accord with the indications provided by the karate technicians. More specifically, participants were asked to stand on one foot with hip, knee joint, and talocrural joint of the other leg flexed at xc° for 15 s, maintaining the easily crossed behind the head.

Participants were instrumented with the GyKo placed on the back at level L4 in society to measure the linear dispatch and angular velocity of the pelvis, which the sensor was attached on (Figure 5). For each subject, the altitude between the sensors and the ground was measured. The full scale of the accelerometer embedded into the GyKo was ready at ±2 g in stability tasks. The OPTOGait sensor was not used in the balance task. Test was performed with the dominant leg and with both open and closed eyes (EO and EC). During the EO condition, subjects were asked to prepare a point on the wall at 5 m. The exam was considered completed if the subject did not touch the ground with the raised limb or if he/she opened the eyes in EC condition within 15 s. Each status was recorded one time after an initial period needed to familiarize with the task.

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Residuum examination: positioning of the subject and sensor.

two.iii.3. Jumping Power

Every bit regards the analysis of jumping motor functioning, bound tests included Squat Jumps (SJ), Countermovement Jumps (CMJ), and Repeated Countermovement Jumps for 15 south (RCMJ) [20,35]. In both jumps, the subjects were asked to offset from a standing position with their anxiety shoulder-width autonomously and their hands on the iliac crests. In SJ, the athletes descended into a semi-squat position and held this position as long as they wanted before initiating the successive upwards/concentric phase to jump. Conversely, in the CMJ the subjects performed a downward motion, which is immediately followed by the concentric phase without the maintaining of the semi-squat position [36]. All the jumps were carried out on the mat, without the help of the upper limbs, i.eastward., field of study were instructed to maintain the hands attached to the torso for the whole task. Participants took a 2-min residual period between each test to avoid fatigue furnishings [37,38]. Participants were asked to jump equally loftier every bit possible without any restrictions of the knee joint bending during the squat stage. SJ and CMJ were repeated two times, instead the RCMJ was performed but ane time since it allowed to evaluate the fatigue effects. Participants were instrumented with the GyKo placed on the back at L4 level to collect the linear acceleration and athwart velocity of the pelvis. The full scale of the accelerometer embedded into the GyKo was gear up to ±xvi g in jumping tasks. The OPTOGait system was positioned on the tatami with bars at 2.5 chiliad (Figure 6).

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Jump exam: subject and sensor position and sequence of movements.

2.4. Data Analysis

Information gathered during static trial was used for the re-alignment of the sensor axes with the accented reference organization; successively linear accelerations and athwart velocities gathered from the GyKo were processed using a sensor fusion algorithm and the Mahony filter to compute the orientation of the sensor [39]. This post-processing performance was conducted for all the performed tests. Videos recorded during the task execution were advisedly checked to discard trials in the following cases: (i) incorrect movements during the mobility tests; (two) disability to perform the monopodalic tests, i.eastward., touch the ground with contralateral leg or open the eyes during the EC condition; and, (iii) incorrect position and execution during jumping task. Only the second state of affairs occurred, as reported in the Section 3.ii.

two.4.ane. Joint Mobility

As regard mobility tests performed at the preferred velocity, we defined every bit $θ$ the highest difference between the bending computed during the execution of the movement and the 1 gathered at the showtime of the job with the body segment in the rest position, along the examined axis. Successively, $\dot{θ}$ was defined as the average velocity of the performed movement.

By moving to the tests performed too at the maximum possible velocity (MV), i.e., all shoulder movements and the hip flexion, the same values were computed, and they were addressed as $θ_{Grand Five}$ and ${\dot{θ}}_{M V}$ .

2.four.ii. Torso Stability

Torso stability was analyzed considering the projection of the vertical centrality of sensor on the horizontal plane corresponded to the floor. The indicate represented by this project was evaluated knowing the distance between the position of GyKo sensor and the flooring that was initially assessed past a measuring record. The evaluated point can be assumed as the middle of pressure level (COP); then, the antero-posterior (AP) and the medio-lateral components (ML) of the COP were computed. Finally, as stability indices nosotros computed parameters that are typical considered in posturographic analysis [forty,41,42]. Specifically, the path length (PL), the ellipse area (EA) and the hateful frequency (FREQ) were evaluated by following the equations reported in Reference [41].

The path length (PL) was defined as the total length of the COP path computed by the sum of the distances betwixt two sequent points of the COP path (Equation (ane)).

$PL = \sum_{n = one}^{N - ane} {[{(AP [n + 1] - AP [n])}^{2} + {(ML [northward + one] - ML [northward])}^{2}]}^{1 / 2},$

(1)

where North represents the number of points of the COP. The PL was also evaluated considering the antero-posterior (PL_AP) and medio-lateral (PL_ML) components one at a fourth dimension.

The 95% confidence ellipse area (EA) was computed representing the surface area of the 95% bivariate confidence ellipse, which was expected to enclose approximately 95% of the COP (Equation (2)).

$EA = 2 {π F}_{0.05 [two, N - 2]} {[s_{AP}^{two} {south}_{ML}^{two} - s_{APML}^{two}]}^{1 / 2},$

(2)

where $F_{0.05 [2, Northward - two]}$ is the F statistic at a 95% confidence level for a bivariate distribution with North points. ${southward}_{AP}^{ii}$ and $s_{ML}^{2}$ are the variance of the AP and ML, and $s_{APML}^{2}$ is the covariance.

The hateful frequency (FREQ) was defined every bit the angular frequency of the COP if it had traveled the full excursions around a circle with a radius equal to the hateful distance (MD), and it was evaluated as (Equation (three)):

where VEL was the boilerplate velocity of the COP, and Physician was the boilerplate distance of each COP point from the origin defined equally the projection of the gravity vector on the floor (Equation (4)):

$MD = \frac{1}{North} \sum_{due north = 1}^{N - i} \sum {[AP {[due north]}^{2} + ML {[n]}^{2}]}^{\frac{i}{ii}} n = i, \dots, N,$

(4)

and VEL was the boilerplate velocity of the COP. The FREQ parameter was also evaluated considering the antero-posterior (FREQ_AP) and medio-lateral (FREQ_ML) components individually.

The stability indices were calculated past eliminating the get-go 3 southward of the examination to discard the transition stage where the subject area moved from the relaxed position, on 2 feet, to the monopodalic position.

For all the above-mentioned parameters, the Romberg Index (RI) was also computed equally the ratio between the stability parameters obtained during the EC and EO conditions [40]. Values of RI shut to ane indicate a improve adaptation to the closed eyes status.

ii.4.three. Jumping Ability

As concerning the jump tests, the time instants in which the subject hit and detached himself from the footing were estimated by using the OPTOGait arrangement. The linear acceleration gathered from the GyKo was integrated to obtain the linear velocity in society to identify the eccentric and concentric phases of the jumps. Specifically, the eccentric stage is identified as the time interval between the start of downwardly motion and the instant of time in which the bailiwick reverses the motion, i.due east., the zero of the velocity, and starts pushing upwards. The concentric phase, instead, is defined as the fourth dimension interval between the terminate of the eccentric phase and the instant in which the subject detaches himself from the ground. In the SJ, the Flight Time (T_F) and the Concentric Phase Time (T_CP) were evaluated. In the CMJ, we besides computed the Eccentric Phase Fourth dimension (T_EP). For both SJ and CMJ, all indices were averaged across the two repetitions for each participant. All previous parameters were computed also during RCMJ, and, in improver, we evaluated the Contact Fourth dimension (T_C).

2.v. Statistical Analysis

Data computed for all the examined tasks was firstly tested for normality with the Shapiro-Wilk test. As regard, the index computed for the mobility test, a 1-mode ANOVA test was performed because the three examine groups equally independent variables and by because one index per time. Thus, a total of 28 ANOVA tests were performed because each mobility alphabetize independently. Similar steps of statistical analysis were performed for each index related to the jumping exam for a total of nine ANOVA tests. Every bit regards the trunk stability task, i-mode ANOVA test was performed considering the three examined groups as between-subject effect. It is worth highlighting that the results obtained for the two visual atmospheric condition were tested independently. Thus, a total of 21 ANOVA tests were performed considering each stability index independently. For all the ANOVA tests, a Bonferroni Post-Hoc multiple comparison examination was used to make up one's mind differences among ways when ANOVA test was significant. Statistical significance was set at p < 0.05 for all the performed tests. The statistical power analysis was performed through the M*Power software [43]. Ability values ranged from 82% to 91% were plant, because a medium effect size (0.5).

3. Results

3.1. Joint Mobility

Mean values and standard errors of the angles computed during the joint mobility tasks performed at the preferred velocity, and the relative statistical results are reported in Table 1. Right and left values were considered together due to similar results between the two sides obtained in a preliminary assay within each group.

Tabular array 1

Mean values (standard errors) for $θ$ and $\dot{θ}$ obtained during the joint mobility examination performed at the preferred velocity for all the examined groups. KU, KA, and NK stand for kumite, kata, and not-karatekas group, respectively. Superscripts represent statistical differences, with * indicating difference among all groups.

	Movement	θ (°)			$\dot{θ}$ (°/s)
	Movement	KU	KA	NK	KU	KA	NK
Shoulder	Flexion	179.ii (2.1) ^NK	172.0 (two.i) ^NK	160.ane (1.8) ^KA,KU	278.4 (24.6) ^NK,KA	143.4 (23.2) ^KU	199.i (8.iv) ^KU
	Extension	82.1 (2.3) ^NK,KA	68.one (2.8) ^KU	66.iii (1.eight) ^KU	178.8 (xx.3) ^NK,KA	ninety.five (19.1) ^KU	105.0 (6.5) ^KU
	Abduction	172.vi (1.7) ^NK	171.4 (ii.3) ^NK	155.0 (2.ii) ^KA,KU	306.1 (26.8) ^NK,KA	148.vii (30.nine) ^KU	215.vii (10.3) ^KU
	Actress-Rotation	108.1 (i.9) ^NK	105.six (2.4) ^NK	89.four (1.7) ^KA,KU	229.six (22.7) ^NK,KA	115.7 (xx.1) ^KU	166.8 (ix.9) ^KU
Hip	Flexion	122.4 (ii.ii) *	112.6 (3.3) *	82.one (one.eight) *	213.four (15.0) ^NK,KA	119.5 (xx.i) ^KU	100.7 (4.9) ^KU
	Split	78.0 (1.5) ^NK	76.5 (ii.2) ^NK	49.5 (1.vii) ^KA,KU	155.9 (viii.6) *	105.0 (13.three) *	37.seven (2.8) *
	Sit and Accomplish	37.iii (2.5) ^NK	36.7 (2.6) ^NK	19.four (two.1) ^KA,KU	59.eight (6.9) ^NK	51.0 (half dozen.half dozen) ^NK	xvi.five (2.4) ^KA,KU
Talocrural joint	Flexion	71.5 (1.one) *	fourscore.5 (1.five) *	57.9 (2.0) *	96.5 (11.2)	80.i (x.4)	121.3 (11.0)
Talocrural joint	Overhead squat	29.2 (1.3) ^KA	37.eight (1.three) ^KU,NK	28.8 (1.0) ^KA	32.half dozen (iv.1)	34.0 (iv.7)	24.5 (2.1)

Regarding the $θ$ value for shoulder mobility, differences in all movements were found between the KU and NK groups (p always lower than 0.01), with the KU grouping showing the highest values for all movements. The only difference between KU and KA was found for the extension motility (p = 0.03), where the KU group showed a greater value. In the same motion no difference was observed between KA and NK (p = 0.45). Considering movement velocity, KU grouping was always associated with a statistically greater value of $\dot{θ}$ than the other groups (p always lower than 0.01). In addition, KA showed the lowest value for all the movements likewise with respect to the NK. It can exist observed that the values of the standard error of $\dot{θ}$ were always greater when focusing on karatekas with respect to NK.

By moving to the hip mobility, all the values of $θ$ were statistically different between the NK and the karatekas (p always lower than 0.01); in these cases, the just significant deviation betwixt KU and KA was observed in the flexion move (p = 0.02), where KU showed greater values. The $\dot{θ}$ parameter was always statistically unlike betwixt KU and NK (p always lower than 0.01), whereas, between KU and KA, the differences were found for all movement (p ranged from 0.01 to 0.04) with the exception of the Sit down and Achieve (p = 0.lxx). KA and NK showed no different behavior only for the flexion movement (p = 0.12).

As regards the movements related to the ankle, values of $θ$ obtained during the flexion motion showed significant differences amongst all groups (p ranged from <0.01 to 0.04); instead, no divergence between KU and NK was plant for the overhead squat (p = 0.59). By and large, the KA grouping showed greater values for both movements. By moving to the velocity of the movements, no differences were found (p ranged from 0.07 to 0.53).

Mean values and standard errors of the angles computed during the articulation mobility task performed at the maximum speed, and the relative statistical results are reported in Table 2. Right and left values were considered together due to similar results between the 2 sides obtained in a preliminary analysis within each grouping.

Table 2

Mean values (standard errors) for $θ$ _MV and $\dot{θ}$ _MV obtained during the joint mobility test performed at the maximum possible velocity for all the examined groups. KU, KA, and NK correspond kumite, kata, and not-karatekas grouping, respectively. Superscripts represent statistical differences, with * indicating difference among all groups.

	Motion	$θ_{M V}$ (°)			${\dot{θ}}_{M V}$ (°/s)
	Motion	KU	KA	NK	KU	KA	NK
Shoulder	Flexion	192.0 (1.7) ^NK	190.2 (2.2) ^NK	171.0 (1.8) ^KA,KU	550.4 (18.9) ^NK	491.ane (21.6) ^NK	407.4 (12.9) ^KA,KU
	Extension	100.9 (two.ix) ^NK	94.7 (2.4) ^NK	eighty.eight (1.7) ^KA,KU	378.8 (14.5) ^NK	346.1 (21.half dozen) ^NK	234.2 (10.7) ^KA,KU
	Abduction	179.2 (1.7) ^NK	180.four (1.8) ^NK	162.0 (2.0) ^KA,KU	522.3 (14.iv) ^NK	474.1 (23.nine) ^NK	392.9 (9.three) ^KA,KU
	Actress-Rotation	117.half-dozen (1.7) ^NK	120.six (two.7) ^NK	96.2 (two.3) ^KA,KU	529.4 (15.9) *	448.2 (17.8) *	354.7 (16.0) *
Hip	Flexion	139.5 (1.9) ^NK	137.0 (3.two) ^NK	94.7 (two.seven) ^KA,KU	331.5 (10.8) ^NK	295.four (14.1) ^NK	190.3 (6.8) ^KA,KU

Regarding the shoulder motility, karatekas showed $θ_{G V}$ values always greater values than NK (p always lower than 0.01), simply no deviation was shown between KU and KA (p ranged from 0.43 to 0.88). In addition, the $\dot{θ}$ _MV parameter in all movements was statistically dissimilar betwixt NK and the 2 groups KU and KA (p always lower than 0.01), while the only difference between KU and KA was observed in the extra-rotation movement (p = 0.01), with KU associated to the highest boilerplate values.

By moving to the hip, statistical lower value of $θ_{M V}$ was constitute related to the NK (p < 0.01); instead, no difference was plant betwixt the two karatekas groups (p = 0.66). Similar outcomes were obtained for the $\dot{θ}$ _MV related to the aforementioned movement.

3.2. Body Stability

Results related to the body stability tests were reported in Table 3. All participants were able to perform the exam in EO condition. Conversely, as concerns the test performed with airtight eyes, it is worth emphasizing that NK group was not considered in statistical tests since only three subjects of NK succeeded in completing test, while xv subjects had to rest the contralateral limb during the execution of the test. For this reason, the comparisons amid KU, KA, and NK were performed only in the EO, whereas t-tests betwixt KU and KA were conducted on the parameters related to EC test and on the RI.

Table 3

Mean values (standard errors) for the torso stability tests for all the examined groups. KU, KA, and NK stand up for kumite, kata, and non-karatekas group, respectively. Superscripts stand for statistical differences. EO and EC indicate test performed with open and closed eyes, respectively. * Romberg Index (RI) is adimensional for each parameter.

	EO			EC		Romberg Alphabetize *
	KU	KA	NK	KU	KA	KU	KA
Path Length (cm)	48.nine (3.4) ^NK	65.8 (8.7)	68.8 (4.7) ^KU	119.0 (12.3)	120.9 (xv.0)	2.four (0.iii)	1.8 (0.two)
Path Length AP (cm)	33.viii (two.7) ^NK	43.8 (five.four)	46.0 (3.i) ^KU	76.6 (nine.1)	72.half-dozen (viii.1)	2.3 (0.iii)	one.7 (0.ii)
Path Length ML (cm)	28.3 (1.9)	39.iv (6.3)	42.six (iii.4)	74.six (6.7)	79.vii (11.9)	2.vii (0.3)	2.ane (0.iii)
Ellipse Area (cm²)	36.four (7.4) ^NK	55.four (xiv.7)	92.7 (13.ii) ^KU	179.0 (38.3)	204.9 (47.0)	nine.ane (ii.four) ^KA	3.ix (0.7) ^KU
Frequency (Hz)	0.19 (0.01)	0.19 (0.02)	0.13 (0.05)	0.xx (0.01)	0.xviii (0.02)	1.20 (0.x)	1.06 (0.08)
Frequency AP (Hz)	0.22 (0.02)	0.26 (0.03) ^NK	0.16 (0.01) ^KA	0.22 (0.01)	0.22 (0.03)	1.23 (0.12)	1.12 (0.sixteen)
Frequency ML (Hz)	0.23 (0.02)	0.24 (0.05)	0.16 (0.01)	0.26 (0.xviii)	0.22 (0.04)	ane.32 (0.15)	i.17 (0.12)

As regards EO status, statistical differences were found between KU and NK for the EA (p < 0.01), PL (p = 0.01) and PL_AP (p = 0.01), while the only deviation between NK and KA was observed for the FREQ_AP (p < 0.01). No meaning differences were institute between KU and KA (p ranged from 0.10 to 0.91).

By moving to the tests performed with closed eyes, no statistical differences were establish between KU and KA (p ranged from 0.20 to 0.56). Finally, the Romberg Alphabetize (RI) computed for EA of KA was significantly lower in KA than the one computed for KU (p = 0.02).

3.3. Jumping Power

Mean values and standard errors of the indices related to the SJ, CMJ, and RCMJ tests are reported in Figure 7 with related statistical differences.

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Mean values and standard errors of the parameters related to the jumping tests. From left to right: Squat Jumps (SJ), Countermovement Jumps (CMJ), and Repeated Countermovement Jumps (RCMJ) tests. Parameters: Flying Time (T_F), Concentric Stage Time (T_CP), Eccentric Phase Time (T_EP), and Contact Fourth dimension (T_C). KU, KA, and NK stand for kumite, kata, and control group, respectively. * indicates statistical differences.

Every bit regards SJ, T_F showed pregnant differences between the NK and karate athletes (p always lower than 0.01), with the NK having the lowest boilerplate value. Relative to the T_CP, statistical differences were institute among all the examined groups (p always lower than 0.01), with the KA showing the highest average value.

Past analyzing CMJ, T_F and T_EP parameters showed statistical differences between the NK and the karatekas (p always lower than 0.01); specifically, NK showed the lowest values for T_F and the highest for T_EP. No pregnant differences were constitute between the two groups of karatekas. No difference among groups was constitute for T_CP (p = 0.32).

By moving to the RCMJ exam, statistical differences were establish between NK and the karatekas for all the examined parameters (p always lower than 0.01). In item, NK showed lowest average values for T_F and the highest ones for T_C, T_CP, and T_EP. No statistical difference was shown between karatekas (p ranged from 0.15 to 0.72).

4. Discussion

Joint mobility, body stability, and jumping ability were assessed on sixteen kumite karatekas, eight kata karatekas, and eighteen non-karatekas to: (i) assess the differences between karatekas and non-karatekas to provide guidelines for training programs in beginners; and, (2) evaluate the differences induced by the karate technique on these kinematic parameters to provide suggestions for coaching programs addressed to aristocracy athletes based on the specific karate technique.

Which are the kinematic characteristics that differ karatekas and not-karatekas? Is information technology possible to provide guidelines for training programs addressed to beginners?

Past discussing the mobility results, the presence of statistical differences between non-karatekas and both karatekas' groups, with the only exception of the shoulder extension at the preferred velocity, allows affirming that joint mobility and agility is fundamental for the physical preparation of a karateka, every bit also reported in previous studies [15,44]. More specifically, the greatest differences between karatekas and non-karatekas found for the shoulder and hip joints confirmed the results reported by Podrigalo et al., who assessed as the two mentioned joints are the about involving in karatekas due to the punching and kick specialization in martial arts [44]. Monopodalic equilibrium examination revealed itself as a complex task, and only karatekas were able to perform it in both open up and closed eye conditions. This finding suggests that karate training considerably increases body stability [1]. As regards the jumping tests, the differences plant betwixt karatekas and non-karatekas for all the examined parameters confirmed as motor ability in jump execution represents one of the concrete aspects to railroad train in karatekas. In improver, the differences institute for the RCMJ tests can be ascribed to an early on occurrence of the fatigue furnishings in non-karatekas [45]. These findings are in line with the ones reported in Reference [15]. We tin speculate that jumping skills and resistance to fatigue are more than developed in karatekas due to the specific training program addressed to the leap kicks [46].

Taking into business relationship the higher up discussed outcomes, we tin can identify the physical characteristics to be trained in beginners in order to improve their motor performance in karate. Specifically, the differences institute for all the examined motor abilities between karatekas and non-karatekas group lead to the conclusion that coaching programs addressed for karate beginners should stress the post-obit aspects: upper and lower limb mobility, movement velocity, body stability, and jumping power. More than specifically, it is clear that the shoulder and the hip represent the most important joints to train since they are the main actors in punching and kick gestures, which are the principal movements performed past a karateka during a contest [46]. This speculation is in line with the outcomes reported by Reference [47], in which authors assessed the training of both the shoulder through throwing tasks and the hip past means of sit and reach tasks, and found that they allow increasing joint mobility in primary school children. Concerning the movement velocity, beginners should pay attention on 2 aspects: the explosion of the movement just besides the command of the gesture; in fact, we accept demonstrated that the motility velocity differs for the two techniques. From this perspective, training programs based on sound feedback have revealed themselves to be useful for the beginners [48].

In addition, information technology appears evident every bit the trunk stability in monopodalic task represents the weak spot of non-karatekas; thus, interventions focused on the improvement of stability too in single support condition should have explicit attending in beginners training sessions. In fact, it is demonstrated every bit monopodalic stability strategies are fundamental for providing upper and lower limb gestures with loftier intensity [49]. Finally, the right trade-off between eccentric and concentric phase, likewise equally flight and contact fourth dimension, during jumping has to exist advisedly trained in order to improve the movement explosion during jump kicks [46]. As a decision, nosotros tin can also advise to constantly monitor these parameters to evaluate if the planned grooming programs are causing the desired improvements in the motor abilities. The acquisition of these knowledges can lead to overcome errors in teaching, especially in the initial menses of training.

Which are the furnishings of karate techniques on joint mobility, body stability and jumping ability? Is information technology possible to provide guidelines for training programs addressed to elite athletes based on karate specialization?

The articulation angles related to the shoulder extension, hip flexion, and talocrural joint flexion related to the movements performed at the preferred velocity reveal themselves equally the mobility indices that are more than influenced by the karate technique. As regards the shoulder, the finding can be associated to the gesture required during kumite and kata competition. In fact, unlike the KU, the recall of the upper limb is not foreseen later on a punch in the KA. Conversely, the think of the upper limb, which requires a shoulder extension, represents a typical gesture of the KU after attacking the opponent; in fact, a punishment is assigned during official competition if the kumite athlete hits the opponent without calling the arm back [22]. The outcomes related to the hip flexion confirmed the i reported in Reference [15]. In fact, kumite athletes demand a greater hip mobility since they must execute high kicks with an adequate velocity to defeat the opponent; instead, kata athletes can perform more than controlled movements. The lower values of mobility that KU showed, with respect to the KA in the ankle articulation, can exist justified by the different ankle movements required by the two discipline and confirmed the results reported by Reference [20]. During their competitive activities, kumite athletes are often on the forefoot by making small-scale hops in society to optimize the reaction time in example of set on or defense [4]. Such behavior causes an almost constant eccentric-concentric stress on the muscles of the leg, particularly on the triceps surae, leading to an increase of ankle rigidity and, consequently, to a reduction of the range of motion [50,51].

As regard the movement velocity at the preferred speed, the lower value of velocity reported for the kata, with the exception of the ankle joint, is direct continued to the specialization required past the technique. In fact, KA athletes perform fine and controlled gestures during their exhibition. This difference was not confirmed in tasks performed with maximum velocity, suggesting that the lower velocity in mobility tasks performed at the preferred velocity for the kata athletes with respect to the kumite ones is effectively due to the technique rather than to less agility of the kata athletes. Still, the employ of the velocity as a useful index should be deeply examined due to the high intra-grouping variability, which suggests a high heterogeneity also among athletes specialized in the aforementioned technique.

By moving to the body stability, the loftier values of standard error associated with all the parameters suggest that each karateka adopted a different strategy to complete the task regardless the specific technique. The absence of statistical differences betwixt the 2 techniques is in dissimilarity with the results reported in Reference [one], in which kata showed greater stability than kumite athletes. Nonetheless, it should be underlined that the observed better remainder skills are related to bipodalic tests. A monopodalic exam should be considered more appropriate to appraise stability skills of a karateka since athlete is often in a unmarried support position when boot during the competition. Thus, the absence of statistical difference suggests that both techniques require a loftier level of body stability. The only parameter useful to differentiate the two karateka groups is the Romberg Alphabetize (RI) related to the ellipse area. The lowest value associated with the KA athletes described a better accommodation of KA grouping in performing rest tests without the assist of the visual apparatus. Thus, it is possible to assess that kata athletes develop stability skills, mainly involving the proprioceptive inputs rather than the visual ones; instead, kumite athletes are adept in reacting to visual stimuli due to opponent movements both during grooming and competition. Thus, we can speculate that the KA athletes suffer less from the lack of visual input in balance direction [52].

The outcomes obtained from the bound test analyses allow affirming that the two techniques practise not lead to different motor performance in jumping due to the general absenteeism of statistical differences between kata and kumite athletes. The only useful parameter seems to exist the duration of the concentric phase during squat jump, which KA group showed a longer elapsing than KU. This result tin can be ascribed to the starting position of KA athletes characterized by a greater value of the knee angles, leading to deeper squat than the KU athletes. The unlike starting position can be justified because 2 factors. Firstly, it can be linked to the unlike ankle mobility previously discussed, allowing to reach a lower starting position for the spring for the kata. Secondly, information technology can be attributed to the different specialization due to the discipline as KA athletes oftentimes assume squat positions, like to SJ, when a push button phase is needed from an isometric situation [53].

Because the above discussed outcomes, we tin speculate that a single wearable sensor and the employ of optoelectronic confined can allow to provide synthetic indices useful to monitor karate specialization and to focus coaching programs for emphasizing the motor abilities required past the specific karate technique. Focusing on articulation mobility, kumite athletes should focus their attending mainly on the shoulder mobility, especially related to the extension movement; instead, kata should stress the training of the talocrural joint mobility. Even though the talocrural joint mobility is shown as one predictive factor, we can speculate that too kumite athletes should have into account the training focused on the ankle mobility; in fact a poor mobility, i.e., joint rigidity, tin can lead to a worsening of the operation during jumping, as plant in the examined jumping tests and likewise reported in Reference [54]. Furthermore, it has already been demonstrated as an excessive of talocrural joint rigidity can lead to an increase of injuries [55]. From the aforementioned perspective, it would exist useful the introduction of specific preparation sessions addressed to increase the ankle mobility during the training programs of kumite athletes, for case, through BHC (Banded Heel String) and BCS (Barbell Dogie Smash) programs that allow improving ankle mobility with respect to traditional dogie stretch technique [56]. In addition, kata training should have specific attending to the control of the move by avoiding uncontrolled gesture during competition [22].

v. Conclusions

Through the aim of quantifying the effects of unlike karate techniques on motor performance, joint mobility, trunk stability, and jumping ability were assessed by analyzing xx-four karateka and eighteen non-karateka healthy subjects. A unmarried inertial sensor and optoelectronic bars data were used to acquired data during the execution of specific tasks. Karatekas showed meliorate motor performance in terms of articulation mobility, body stability, and jumping power than non-karatekas. Mobility outcomes reveal themselves as the most influenced by the specific karate techniques, especially when looking at shoulder and talocrural joint joints. The greater ankle mobility of kata than kumite also leads to a better performance in jumping. Kata athletes are, finally, performing better than kumite athletes when monopodalic stability tests are executed with airtight optics. The findings of this written report tin exist useful for coaching program implementation addressing both beginners and karatekas who want to attain aristocracy level in a specific technique.

Writer Contributions

Conceptualization, 50.M., J.T., Grand.M., and Due south.R.; Data curation, 50.One thousand. and J.T.; Formal analysis L.One thousand. and M.M.; Methodology, L.M., J.T. and S.R.; Projection administration, L.M., J.T. and S.R.; Supervision, J.T. and Due south.R.; Writing—original draft, L.M. and J.T. Writing—review & editing, J.T. and S.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Conflicts of Interest

The authors declare no disharmonize of involvement.

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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7309074/