Relationship Between Ankle Mobility, Elastic Strength, and Rate of Force Development in the Two Karate Disciplines: Kata and Kumite

Abstract

Karate is divided into two disciplines, Kata (forms) and Kumite (sparring), both of which are strongly influenced by the function of the tibiotarsal joint. However, the performance model differences between the two have not yet been thoroughly explored. The aim of this study is to evaluate the differences in ankle range of motion between Kata and Kumite, investigating the correlations between joint mobility, elastic strength, and Rate of Force Development (RFD). The sample consisted of 36 athletes, of male sex, evenly split between the two disciplines, who underwent a specific training protocol for three months. Three tests were administered: Weight Bearing Lunge, Counter Movement Jump, and Squat Jump. Data were analysed using Pearson’s correlation. In the Kata group, a moderate negative correlation emerged between ankle ROM and elastic strength (R = −0.521), and between ankle ROM and RFD (R = −0.570). In the Kumite group, the correlations were weakly negative: R = −0.261 for elastic strength and R = −0.257 for RFD. Greater ankle mobility, typical of Kata, appears to be associated with lower explosive capabilities, whereas more limited mobility in Kumite correlates with higher reactive strength and a faster rate of force development.

1. Introduction

The practice of Karate, both at amateur and competitive levels, requires a high degree of neuromuscular control, movement coordination, explosive strength, and reactivity [1]. These characteristics manifest differently in the two main disciplines of the sport: Kata and Kumite [2]. Kata consists of codified sequences of movements that simulate combat against imaginary opponents [3]. This discipline emphasises technical precision, aesthetic quality of movement, executional fluidity, and postural control [4]. In this context, the tibiotarsal joint plays an important role, providing stability, mobility, and dynamic control during transitions between different stances [5]. Maintaining balance and the ability to perform fluid transitions between postures are crucial for the effectiveness and quality of the specific movement [6]. In Kumite (fighting), on the other hand, there is direct confrontation with the opponent, and performance is based on speed of action, anticipation ability, and explosive power [7]. In this context, the tibiotarsal joint plays a decisive role in generating rapid acceleration, sudden changes in direction, and balance management during offensive and defensive phases. In practice, during high-speed movements or changes in direction, the articular configuration of the ankle (especially in dorsiflexion/plantarflexion) promotes the efficient transmission of forces and dynamic stability. For example, one study showed that as acceleration increases during walking, the relationship between torque and angle at the ankle changes: this indicates that the ankle is an active part in the modulation of impulse for rapid accelerations [8]. A key element in both disciplines is elastic strength, which is closely related to the efficiency of the Stretch-Shortening Cycle (SSC) [9]. This conditional capacity allows the neuromuscular system to accumulate energy during the eccentric phase of movement and release it effectively in the subsequent concentric phase [10], thereby enhancing the power of technical action and reducing energy expenditure [11]. In Kumite, this translates into quick movements and powerful attacks; in Kata, it contributes to dynamism and incisiveness in transitions, such as in jumps, direction changes, and strikes performed with controlled explosiveness [12]. Another fundamental parameter in performance within the discipline is the Rate of Force Development (RFD), which consists of the rate at which force is developed. This indicator reflects the neuromuscular system’s ability to produce force in the shortest possible time, making it essential in disciplines that require explosiveness and reactivity [13]. A high RFD is closely linked to the ability to perform fast and powerful actions, in Kumite, for lightning attacks and reactive defensive movements; in Kata, for expressing force in simulated strikes and dynamic transitions [14]. Ankle joint mobility, in addition to directly affecting performance, also plays a preventive role in injury occurrence [15].

Combat sports show a high incidence of trauma involving the tibiotarsal joint, often caused by explosive movements, poorly controlled landings, or sudden changes in direction [16]. Optimal ankle mobility, differentiated by discipline, could reduce the risk of injury and contribute to the sporting longevity of practitioners [17]. Currently, athletic preparation programmes for karateka tend to overlook the interaction of these elements, despite their potential impact in redefining and optimising training protocols [18].

Some studies have highlighted the importance of ankle mobility and stability in combat sports [19,20,21,22], stressing that an optimal range of motion is crucial for performance quality [23]. In continuity with this evidence, other studies have directly examined the differences between Kata and Kumite, highlighting anthropometric, physiological, and performance specificities. Koropanovski et al. (2011) [24] showed that elite karatekas specialised in Kumite present physical characteristics different from those of Kata practitioners, suggesting that specialisation directs the development of distinct neuromuscular qualities. In a subsequent work, the same authors [25] identified the main factors of competitive success, emphasising the decisive role of speed and explosiveness in Kumite, while in Kata technical precision, postural stability, and motor control emerge. Analyses based on wearable sensors confirmed that the two specialities involve different physical demands and movement patterns [26]. More recently, Gaweł and Zwierzchowska (2024) [27] documented how Olympic training programmes specific to Kata can induce structural and functional changes in posture in national-level athletes. Taken together, this evidence confirms that Kata and Kumite represent non-overlapping performance models, characterised by peculiar biomechanical and neuromuscular demands. In the present study, the reference to variables such as balance, dynamic stability, acceleration capacity, and changes in direction aimed to contextualise the functional role of the ankle in sports performance. These aspects, however, were not directly assessed. The present study aims to analyse and comparatively evaluate the role of the tibiotarsal joint in the two main Karate disciplines: Kata and Kumite. The primary objective is to assess the differences in terms of range of motion (ROM) between the two specialities, exploring possible correlations between joint mobility and the ability to generate elastic strength. Specifically, the research also aims to investigate the relationship between RFD and ankle joint range of motion, in order to understand how these variables influence specific performance in the different types of competition.

2. Materials and Methods

2.1. Study Participants

The study sample consisted of 36 male athletes, evenly divided into two groups of 18 participants each, based on their discipline: forms (Kata) and sparring (Kumite). All participants practised the Shotokan style, which in Kata is characterised by wide and deep stances, with particular attention to stability, postural control, and execution precision, while in Kumite it prioritises rapid movements, functional to supporting action speed, explosiveness, and anticipation ability. All subjects were competitive athletes with at least five years of continuous practice in the discipline and with a minimum grade of 1st Dan black belt: in the Kata group, 12 athletes had experience in national competitions and 6 at regional level; in the Kumite group, there were 10 athletes with national experience and 8 at regional level. The choice to include athletes belonging to the same style and with a comparable competitive level made it possible to ensure greater homogeneity of the sample in relation to the objectives of the study. The anthropometric data were differentiated for the two groups. Kata athletes (n = 18) had a mean age of 21.4 ± 2.1 years, a height of 174.5 ± 5.8 cm, and a body mass of 66.8 ± 4.7 kg. In this discipline, anthropometric characteristics may play a relevant role, since the execution of techniques, especially in this specific style, requires wide and deep stances: greater height or longer limbs may affect the amplitude of movements, postural stability, and the fluidity of transitions. Kumite athletes (n = 18), on the other hand, had a mean age of 21.1 ± 2.3 years, a height of 171.6 ± 6.1 cm, and a body mass of 69.2 ± 5.1 kg. In this speciality, morphological differences are particularly relevant in relation to weight categories, with potential repercussions on speed, power, and the effectiveness of strikes. Additionally, participants were required to have had no significant injuries in the six months prior to the start of the study and no chronic illnesses or medical conditions that could interfere with the parameters under investigation.

Athletes who had recently sustained trauma, who had a history of musculoskeletal disorders (either current or past), or who had taken part in training programmes specifically aimed at improving joint flexibility within the previous six months were excluded. All participants were fully informed about the objectives, procedures, and duration of the study, and provided their written informed consent before commencing any of the scheduled activities.

2.2. Study Design

Both groups followed a standardised training protocol specifically tailored to their respective disciplines over a period of three months. The Kata group athletes undertook five weekly training sessions: three focused on technique and two on general physical conditioning. From the fifth week onwards, the emphasis shifted to execution intensity, explosiveness, and full technical integration of the Kata. The training load increased to six sessions per week, including three technical sessions, two physical sessions, and one session dedicated to mental and cognitive aspects. Technically, athletes practised full execution of the Katas selected for competition. During the final four weeks, a refinement phase took place, where the objective was to maintain the physical capacities developed, optimise technical expression, and simulate real competition conditions. The athletic training load was reduced, but some sessions were maintained to focus on reactivity, mobility, and movement precision. Each technical session included full simulations: the athlete would present themselves, bow, perform the complete Kata, receive immediate feedback, and then work on any identified weaknesses. The athletic workload prioritised cardiovascular endurance, functional bodyweight strength, and joint mobility, with particular focus on core strength, postural stability, and lower limb conditioning, which are constantly engaged in the Kata for propulsion, control, and transitions. Sessions included mixed circuits with exercises such as squats, dynamic planks, lunges, light plyometric drills, and active stretching. In parallel, the technical work focused on advanced Kihon, that is, sequences of techniques in motion (tsuki, uke, geri), aiming to refine posture, balance, and continuity. Analytical work on Kata was also introduced, breaking down the main Katas into sections of three to five movements to facilitate detailed learning. All this is summarised in

Table 1. Three-month training protocol for Kata athletes.

Period (Weeks)	Specific Physical Exercises	Technical/Tactical Content Trained
Phase 1 (Weeks 1–4) Base construction	General mobility Central stability reinforcement (core: plank, dead bug, medical ball) Lower limb strengthening (squats, lunges, monopodal exercises) Postural and proprioceptive control (BOSU, instability)	Fundamental techniques: stances (zenkutsu, kiba, kokutsu), moves and transitions. Work on hikite, torso rotation and kime First Kata segments analysed in sections (simplified technical bunkai) Study of breathing and timing
Phase 2 (Weeks 5–8) Specific development and coordination	Controlled plyometrics: vertical and horizontal jumps, split squat jumps Explosive power exercises with elastic bands (punch band, squat jump with resistance) Isometric work on positions (kiba dachi, zenkutsu dachi) for postural endurance Technique combinations in balance (on unstable cushion, trampoline) Segmental quickness training (fist and kicks in quickness with minimal resistance)	Complete Kata at low/medium intensity, focusing on rhythm and form Analysis of the critical points of the chosen Kata (shitei or tokui) Study of smooth transitions and emphasis on kime Work on lines, timing and quality of movement
Phase 3 (Weeks 9–12) Refinement and simulation race	Short pre-race activation sessions: leaps, dynamic mobility exercises, light core Explosive strength recall (2×/week, with controlled load) Relaxation and breathing routines (box breathing, myofascial release) Simulations with actual race times and specific recovery times Posture and centring optimisation	Performance of complete Kata at competition intensity Bunkai work and interpretation of technical gestures Correction of postural and temporal micro-errors Simulations with judges or external evaluators (including video) Study of pre-execution rituality (entrance, greeting, breathing)

.

During the first four weeks, the Kumite group athletes focused on general physical preparation, consolidation of basic technique, and neuromuscular activation. The intensity was moderate, while the training volume was relatively high. From the fifth week onwards, the athletes transformed the foundation built in the previous phase into specific abilities, through high-intensity drills and simulated tactical situations. In the final weeks, up to the twelfth, the aim was to bring the athletes to an optimal fitness condition, through a progressive reduction in the overall technical and athletic load and an increase in the specificity of the training, tailored to the type of performance required in the competition. Priority was given to the quality of execution, mental sharpness, and speed in performing punching and kicking techniques. All of this is represented in

Table 2. Three-month training protocol for Kumite athletes.

Period (Weeks)	Specific Physical Exercises	Technical/Tactical Content Trained
Phase 1 (Weeks 1–4) Construction	Free-body circuit training (squats, lunges, push-ups, planks, jumping jacks) Core stability (dynamic plank, Russian twist, empty body grip) Continuous running (30–40′) and mild interval training (3 × 6′) General active mobility Dynamic functional stretching (leg swings, hip openers)	Fundamental techniques in movement: kizami tsuki, gyaku tsuki, uraken, mae geri, mawashi geri Guarding transitions, maintaining balance when attacking Study of maai (distance) and rhythm control Reactivity exercises on visual/sound stimulus
Phase 2 (Weeks 5–8) Specialisation	Plyometrics: box jumps, monopodalic jumps, reactive sprints 10–15 m Technical HIIT (20′/10′ with specific techniques) Work with elastic bands for acceleration/deceleration Changes in direction (agility ladder, cone drill) Speed training with partner (variable resistance)	Attack combinations: kizami-gyaku, mae geri-gyaku, kizami-mawashi Techniques on change in direction (tai sabaki + attack) Advance and counter-attack strategies Themed training: attack after feint, point and exit, countering the opponent’s attack
Phase 3 (Weeks 9–12) Refining and competition simulation	Pre-competition neuromuscular activation: mini-jumps, reactivity, light work with elastic bands Dynamic stretching and fluid mobility Booster circuits (medium-low intensity, short duration) Volume reduction to maintain freshness Training with race times (1:30–2:00)	Simulated fights Tactical management: advantage, disadvantage, draw Personal strategy training (offensive/defensive) Pre-fight routines: breathing, visualisation

.

It should be emphasised that the three-month preparation period was not introduced with the aim of detecting pre–post variations in the variables analysed, but rather to ensure that all athletes undertook the tests after a uniform training phase specific to their discipline. The central objective of the study was in fact to investigate the relationships between ankle mobility (ROM), elastic strength, and RFD in a sample of karatekas who were already adequately prepared, rather than to monitor the longitudinal effects of a training programme. Following the three-month preparation period, each athlete underwent an assessment of ankle joint mobility with the Weight Bearing Lunge Test using the Leg Motion System, a validated tool for measuring the range of motion of the tibiotarsal joint in dorsiflexion while controlling for knee valgus compensation. The test was administered bilaterally and in a single leg standing position, and the values were recorded in centimetres. The athlete, barefoot and in an upright position, performed a forward lunge trying to touch the wall with the knee while keeping the heel in contact with the ground. The maximum distance between the big toe and the wall was measured with a rigid ruler. Three attempts were carried out for each limb, and the mean value was used for the analysis. Subsequently, to assess the explosive components of the SSC, two vertical jump tests were administered: the Counter Movement Jump (CMJ), and the Squat Jump (SJ). The CMJ was performed starting from an upright position, with a rapid bending of the lower limbs (eccentric phase) followed by an explosive upward push (concentric phase). During the jump, the hands were kept on the hips to eliminate the influence of the upper limbs. The SJ was performed starting from a squat position (knee angle approximately 90°) maintained statically for 2–3 s, in order to cancel the contribution of the stretch–shortening cycle. From this position, the athletes executed an explosive upward push, again with their hands on the hips. Both tests were performed on force and balance platforms (Deltas, Italy), connected via Bluetooth to the proprietary software, which allowed the recording of kinematic and dynamic parameters. From the difference between the jump heights in the two tests, the eccentric utilisation ratio (EUR) was calculated, expressed as the ratio between the height reached in the CMJ and that in the SJ. This indicator provides an estimate of SSC efficiency and, consequently, of the ability to store and release elastic energy during explosive movements. The RFD was calculated during the execution of vertical jumps on the force platforms (sampling rate 1000 Hz). In particular, for each attempt the force–time curve was recorded, identifying the onset of the concentric contraction (increase in force compared to baseline) and the maximum force peak. The RFD was expressed as the ratio between the change in force (ΔF, in Newtons) and the time interval (Δt, in seconds) required to reach it. The RFD values were then related to ankle joint mobility (ROM) and to the elastic strength index (EUR), in order to explore the existence of specific correlations within the Kata and Kumite groups.

2.3. Statistical Analysis

In order to verify the existence of possible linear relationships between physical variables and specific performance in Karate (Kumite and Kata), Pearson’s linear correlation was used. The Pearson correlation coefficient was chosen as an appropriate tool to measure the degree and direction of the linear association between two continuous quantitative variables, under the assumption of normal distribution. The analysis was conducted using the Statistical Package for Social Science (IBM SPSS Statistics for Windows, version 25.0, IBM, SPSS Inc., Armonk, NY, USA).

The interpretation of the values of the coefficient r considered the reference parameters established for Pearson’s correlation:

• 0.1–0.3: low correlation, −0.1/−0.3 Weak negative correlation
• 0.4–0.6: moderate correlation, −0.4/−0.6 Moderate negative correlation
• 0.7–0.9: high correlation, −0.7/−0.9 Strong negative correlation
• >0.9: very strong correlation. −1.0 Perfect negative correlation

3. Results

In the group of athletes specialised in Kata, the results obtained from the tests carried out are presented in

Table 3. Test Results Kata Group.

Ankle ROM DX (cm)	Ankle ROM SX (cm)	Elastic Force Contribution (cm)	Propulsive RFD (kg/s)
19.5	16	5.38	222.77
17	17	2.39	418.88
20	20	2.27	246.66
18	17.5	2.89	498.50
17	16.5	4.79	330.10
17,5	17	3.38	440.54
18	16	4.28	435.25
19	18	3.49	470.86
16	16	6.52	420.15
19	19	2.98	290.35
20	18	3.24	295.97
19	17	3.75	265.25
20	20	2.70	410.86
18	18	3.42	460.14
17.5	17.5	3.77	435.48
19	19	2.9	300.10
20	20	3.19	298.99
20	19	2.28	315.8

.

The analysis using Pearson’s correlation coefficient in this group revealed a moderate negative correlation between ankle ROM and elastic strength, with a value of R = −0.521. Furthermore, the correlation between ankle ROM and RFD was also found to be moderately negative, with R = −0.570. All results are shown in Figure 1.

In the group of athletes specialised in Kumite, the results obtained from the tests carried out are presented in

Table 4. Test Results of the Kumite Group.

Ankle ROM Dx (cm)	Ankle ROM Sx (cm)	Elastic Force Contribution (cm)	Propulsive RFD (kg/s)
14	14	1.99	668.47
14 5	14	1.95	468.79
14	13.5	1.99	361.56
14	14	1.18	322.67
10.5	10.5	4.85	419.68
10	10	3.22	1119.17
14	14	1.19	488.33
14	14	1.22	460.06
11	11	5.7	318.25
13	11	−0.72	292.44
14	14	1.22	667.15
13	13	6.09	456.76
14	14	1.09	555.93
14	12	1.42	647.36
13	13	6.40	555.14
12.5	12.5	7.65	518.11
13	13	−0.72	519.22
14	14	11.58	636.35

.

In this group, the correlation between ankle ROM and elastic strength was weak and negative, with a coefficient of R = −0.261. Similarly, the relationship between ankle ROM and RFD showed a weak negative correlation, with a value of R = −0.257. All of this is shown in Figure 2.

4. Discussion

The analysis conducted using the Pearson correlation coefficient highlighted, in both groups of Karate athletes examined, the existence of an inverse relationship between ankle joint mobility (Ankle ROM) and neuromuscular explosive capacities, expressed through elastic strength and RFD. However, while maintaining the same direction of the relationship (negative correlation), the intensity of this association varies between the two groups analysed, suggesting a direct influence of the performance model and the specific demands of the discipline practised. In the Kata group, the correlations found are moderately negative (r = −0.521 between Ankle ROM and elastic strength; r = −0.570 between Ankle ROM and RFD). These results can be interpreted in light of the typical motor demands of the speciality: Kata requires joint amplitude, precision, and postural control, often maintained under isometric work conditions or controlled dynamics [28]. This leads to motor adaptation being more oriented towards mobility and active stability, which may functionally reduce the ability to produce high levels of explosive force in the short time required by tests such as the CMJ and SJ [29]. Although greater joint range of motion is advantageous in terms of execution within the context of Kata, it may be less efficient in terms of elastic force transfer, slowing the transition between the eccentric and concentric phases of movement [30]. Conversely, in the Kumite group, the correlations are weak but still negative (r = −0.261 and r = −0.257). This finding seems to indicate that, in this context, a certain degree of muscle-tendon stiffness at the ankle level is functional to performance. Considering that Kumite is based on rapid, unpredictable, and highly explosive actions such as sprints, feints, counterattacks, and sudden changes in direction, excessively high joint mobility could represent a limiting factor, as it would compromise the ability to transmit force quickly and efficiently through the kinetic chain [31]. On the other hand, a stiffer ankle, within physiological ranges, may facilitate vertical and horizontal force transmission, enhancing the effectiveness of the SSC typical of combat sports movements [32]. Further experimental evidence has shown that the ability to modulate ankle tendon stiffness represents a decisive factor for the efficiency of the stretch–shortening cycle (SSC) in open skill sports [33]. This supports the view that the differences observed between Kata and Kumite may reflect not only technical specificities, but also broader neuromuscular adaptations, which affect the way elastic energy is stored and released [34]. Moreover, recent studies on combat sport athletes have highlighted that an adequate balance between joint mobility and dynamic stability contributes not only to performance but also to injury prevention, reducing the risk of recurrent ankle sprains during explosive and multidirectional movements [35,36]. This aspect is of particular relevance in training protocols, as it allows performance and protective objectives to be integrated within a single training pathway. Looking ahead, the systematic inclusion of functional tests aimed at assessing ROM, SSC, and RFD could represent a key step for monitoring the adaptations induced by the practice of the two specialities, promoting truly individualised programming. Such an approach, already adopted in other high-intensity disciplines, could also represent an innovative element in training methodology within Karate.

4.1. Practical Applications

These results show a functional consistency between the type of performance required and the neuromuscular characteristics adapted over time through training [37].

The data distribution and the difference in the intensity of correlations between the two groups support the evidence that technical-motor specialisation influences the development of conditional abilities, leading to different responses in athletes. In other words, the practice of Kata would appear to promote greater joint mobility at the expense of immediate muscular reactivity, whereas Kumite favours the preservation (or development) of functional stiffness, which allows for a more efficient explosive response, even with a reduced range of motion. In the context of Kata, it may be useful to combine joint mobility work with a programme aimed at developing SSC efficiency and functional stiffness. In Kumite, on the other hand, the maintenance of controlled ankle mobility, alongside plyometric and neuromuscular training focused on explosiveness, could optimise the motor response during competition.

4.2. Limitations

Among the main limitations of the study, the absence of participant stratification by age, technical level, or sporting experience should be noted, as well as the sample size, which, although adequate for an initial analysis, does not allow for broad generalisations. Furthermore, the analysed sample consists exclusively of male athletes; this choice, although justified by the need to homogenise the group in terms of anthropometric characteristics, excludes potential gender differences that could influence neuromuscular and joint responses. Future studies should therefore include participants of both genders, in order to verify the presence of any functional differences or specific adaptations in the female group as well. Although the absence of an initial test (pre-test) may be perceived as a limitation, it is consistent with the aim of the study, which did not involve a pre–post evaluation but described the performance differences in the parameters considered in the two specialities, namely ankle joint mobility, elastic strength, and the Rate of Force Development. From this perspective, the preparation period served to standardise the condition level of the participants in the two groups, improving the comparability of the data. The study also did not include a control group subjected to a regular protocol. This methodological choice derives from the exploratory and descriptive nature that characterises it, although we acknowledge that the inclusion of a comparison group could have strengthened the interpretation of the data.

5. Conclusions

The results of this study highlighted the existence of a functional relationship between ankle joint mobility and the ability to express explosive strength, both in elastic form and through RFD, within athletes specialised in two types of Karate: Kata and Kumite. These relationships indicate that neuromuscular and joint adaptations are closely linked to the specific performance model of the discipline practised and manifest in different forms depending on motor and technical demands. In the Kata group, the greater joint mobility observed is associated with lower explosive efficiency, likely because of a specialisation oriented towards postural control, stability, and motor precision. In this context, the anthropometric characteristics of the athletes, together with the peculiarities of the Shotokan style (deep and wide stances), may also have an influence on movement dynamics and on the management of stability. Conversely, in the Kumite group, although a similar inverse relationship is present, the correlation was weaker, suggesting that a certain functional ankle stiffness, within physiological limits, may represent an advantage for the rapid and effective production of force in the explosive and reactive movements required in combat. In this case, morphological differences, which are relevant in the weight categories, may also contribute to modulating performance capacities. These findings prompt critical reflection on the use of standardised training protocols, which are often adopted indistinctly in both contexts. Such protocols, frequently oriented towards general or transversal physical preparation, do not consider the structural and functional differences between the two Karate specialities and of the competitive level of the athletes involved Considering the findings, it appears necessary to reconsider the organisation of workload, mobility, and explosive development specifically for the discipline practised, integrating tools for functional assessment and individualised strategies. In conclusion, the data collected supports the need to adopt differentiated and evidence-based training protocols, moving beyond the generalist approach that has so far dominated Karate training methodology. The integration of specific functional tests and the adaptation of training loads to the neuromuscular characteristics, anthropometric and technical of the two specialities represent a direction to pursue for improving performance and preventing injuries.