Physiological responses to karate specific activities

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SCISPO-2924; No. of Pages 9 Science & Sports (2015) xxx, xxx—xxx

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Physiological responses to karate specific activities Les réponses physiologiques aux activités spécifiques de karaté H. Chaabène a,d,∗, E. Franchini e, S. Sterkowicz c, M. Tabben b,f, Y. Hachana a,d, K. Chamari d,g a

Research unit ‘‘sport performance and health’’, higher institute of sport and physical education of Ksar Said, Tunis, Tunisia b Tunisian research laboratory ‘‘sport performance optimisation’’, National centre of medicine and science in sport, Tunis, Tunisia c Department of Theory of Sports and Kinesiology, University School of Physical Education, Al. Jana Pawla II 78, 31-571 Cracow, Poland d Higher institute of sports and physical education, Manouba university, Tunis, Tunisia e Martial arts and combat sports research group, school of physical education and sport, university of Sao Paulo, Sao Paulo, Brazil f CETAPS, university of Rouen, Mont-Saint-Aignan, France g Athlete health and performance research centre, ASPETAR, Qatar orthopaedic and sports medicine hospital, Doha, Qatar Received 11 February 2015; accepted 19 March 2015

KEYWORDS Karate kata; Karate kumite; Physiological responses; Time-motion analysis

Summary Objectives. — The aim of this critical review was to discuss performance analysis characteristics and particular physiological demands related to karate kata and kumite. News. — The intermittent nature of karate has been revealed via kumite’s time-motion analysis, with a 1:1.5 effort-pause ratio during official competition. Karate combat is mainly dependent on the aerobic metabolism. However, decisive actions’ energy is provided by the anaerobic system. Concerning kata, it seems that the fraction of the energy supply is mainly a function of kata’s duration. The high-energy phosphate seems to be the major contributors while the aerobic energy system’ participation rises with the increased kata’s duration.

∗ Corresponding author. Research unit ‘‘sport performance and health’’, higher institute of sport and physical education of Ksar Said, Tunis, Tunisia. E-mail address: [email protected] (H. Chaabène).

http://dx.doi.org/10.1016/j.scispo.2015.03.002 0765-1597/© 2015 Elsevier Masson SAS. All rights reserved.

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H. Chaabène et al. Prospects and projects. — Future investigations in an ecologically valid environment are needed to support the findings presented in the current review. Conclusion. — Irrespective of karate’s discipline, the aerobic system represents the main energy system, especially in longer kata. Kumite appears to demand much higher metabolic power than kata, regardless of gender, while kata appears to require more ATP-PCr energy system contribution than kumite. © 2015 Elsevier Masson SAS. All rights reserved.

MOTS CLÉS Karaté kata ; Karaté kumité ; Réponses physiologiques ; Analyse du mouvement du temps

Résumé Objectif. — Cette étude est une synthèse critique de la littérature concernant l’analyse de la performance en karaté et les réponses physiologiques suite au karaté kata et kumité. Actualités. — Les travaux traitant l’analyse des combats officiels ont montré que le karaté est un sport à caractère intermittent avec un rapport effort/récupération de 1:1.5. Le système oxydatif domine la synthèse énergétique durant le combat avec intervention de la filière anaérobie au cours des actions décisives. En ce qui concerne le kata, la fraction d’intervention des filières énergétiques est tributaire de la durée du kata. En effet, la part d’intervention du système des phosphagènes (ATP-PCr) prédomine avec une intervention de plus en plus importante de la filière aérobie qui va de paire avec l’augmentation de la durée du kata. Perspectives et projets. — Des études futures dans des conditions officielles de compétition (kata et/ou kumité) semblent être nécessaires pour confirmer les résultats actuels de la présente revue. Conclusion. — Indépendamment de la spécialité (kata ou kumité), la filière aérobie semble être le premier responsable de la synthèse énergétique, particulièrement durant les kata de longue durée. La puissance métabolique durant le kumité semble être plus prononcée par rapport au kata indépendamment du sexe tandis que l’intervention du système ATP-PCr paraît être plus importante durant le kata par comparaison au kumité. © 2015 Elsevier Masson SAS. Tous droits réservés.

1. Introduction Karate contains two main practices (i.e., kata and kumite) [1]. Kata represents a pre-arranged form of demonstrating methods of attack, defense, and counter attack [2]. It is defined as a performance of set sequences of basic techniques (i.e., stances, hand punches and leg kicks and strikes) in a fight with an imaginary opponent [3]. Currently, kata competition takes either the form of team (three person per-team exclusively males, or exclusively females), and individual competition [1]. Karatekas have a time-range from 60-s to 80-s to finish the kata [1]. Kumite represents the process of sparring utilizing karate skills (i.e., punching and kicking techniques) performed by two opponents [4]. Kumite requires, from the karateka, a rapid programming of the adequate action responses to the process of defense and/or attack [5]. During kumite, punching (tsuki) and kicking (geri) techniques are allowed at the head (jodan) and abdomen (chudan). Kumite competition is divided into team matches and individual matches. Individual match is divided into age and weight categories [1]. Nowadays, kumite lasts three minutes for senior male (both teams and individuals) during eliminatory matches and four minutes in the individual bouts for medals. In regards to senior female, bouts are two minutes during eliminatory matches and three minutes in the individual bouts for medals [1]. Previously, athletes took part in both kata and kumite competitions. Currently, specialization of elite karate

competitors for kata and kumite has become more prominent. Kumite scoring system involves: 3 points (Ippon) are awarded for leg kicks to the head and the techniques of cleaning and throwing, which result in a final fall of the opponent or a final punch, 2 points (Waza-Ari) are adjudicated for kicks to the trunk and punches to the back, including the back of the head and neck. Finally, 1 point (Yuko) is awarded for single arm punches to the head and body [1]. It should be noted that the new rules are stricter about prohibited behaviors, including excessive contact when attacking permitted areas and particularly the head [1]. Otherwise, punches and kicks must be controlled (without injury to the opponent) or stopped before contact with the opponent’s body. All these changes had made the kumite competitions more attractive, explosive, spectacular, and dynamic [4]. Unlike the kumite, the kata competition has not been evolved and modified so much since the basic requirements remained virtually unchanged. All the above cited reasons show the quite big difference between these two karate’s disciplines. According to Arriaza [6], each modality (i.e., kata or kumite) requires specific extensive and intensive training stimulus, then karate practitioners tend to focus early on their training to one of these. Performance analysis is one of the basic elements for developing sport-specific training and/or proper conditioning programs. Additionally, the identification of the physiological demand is one of the most important factors in improving performance and achieving the best results in all kind of sport (including karate). Thus, recognizing

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Karate physiology performance analysis elements, in conjunction with physiological variables and their mechanisms related to either kata or kumite, would help coach and professionals concerned with the planning of karate’s training program to lead them to the best way to monitor training load and improving performance. It has been well established that karate practice requires both aerobic and anaerobic capabilities, and is defined by explosive, intermittent, and quick movements performed either by the upper or lower part of the athlete’s body [7]. Therefore, within the present article, we review and discuss performance analysis characteristics and particular physiological demands related to karate kata and kumite from the available scientific studies in this area. The US National Library of Medicine (Pub Med), MEDLINE, ProQuest, SportDiscus, CINAHL, and Google Scholar databases were used to find original scientific studies related to karate physiological responses. The specific terms used included: karate, karate performance analysis, karate kumite, and karate kata. The retrieved studies were further selected based on their purpose, methodology, and number of karate athletes investigated as well as their characteristics. The literature search period adopted was from January 1980 to November 2014. Only styles related to the World Karate Federation competition rules were considered in our review. In some cases, articles cited in these previous investigations retrieved during the original search were also included when the authors considered that they could contribute in specific topics.

2. Karate kumite: time-motion analysis and energy system contributions 2.1. Time-motion analysis Studies dealing with the time-motion pattern during karate competition are relevant. This type of investigations is extremely useful for coaches to improve both the technicaltactical and the physical and conditioning training sessions. During simulated karate contest, Beneke et al. [8] reported an effort-pause ratio of 2:1 (combat phases total duration last 18 ± 6 s and the mean duration of pause was 9 ± 6 s). During the combat phase, high-intensity actions from 1 to 3-s are performed 16.3 ± 5.1 times per combat, i.e., 3.4 ± 2.0 high-intensity actions per minute. When analyzing simulated 2 and 3-min duration fights, Iide et al. [9] observed that short high-intensity actions lasted 0.3 ± 0.1-s in both combat durations, while long high-intensity actions lasted 2.1 ± 1.0 s in 2 min matches and 1.8 ± 0.4-s in the 3-min matches. The total time duration of high-intensity actions was 13.3 ± 3.3-s in the 2 min match and 19.4 ± 5.5-s in the 3 min match, i.e., near 6.5-s of high-intensity actions per min. In a study conducted by Chaabène et al. [10], it has been revealed that the effort-pause ratio during an official karate combat was 1:1.5 and the high-intensity action to rest ratio was 1:10. Karatekas executed 17 ± 7 highintensity actions per fight ranging from < 1 to 5-s each with 83.8 ± 12.0% of the actions lasting less than 2-s [10]. In another study by Chaabène et al. [11], compared parameters of performance analysis difference between official and simulated karate contest and revealed that elite level karatekas

3 performed more high-intensity actions, lasting from < 1 to 5-s each, during simulated karate combat (18 ± 5) when compared to official one (14 ± 6). As a natural consequence of the former results, total duration of fighting activity was lower during official when compared to simulated kumite (21.0 ± 8.2-s vs. 30.4 ± 9.9-s, respectively). During simulated combat, effort (10.0 ± 2.8-s) to rest (11.9 ± 2.7-s) ratio (E:R) was 1:1 and high-intensity actions (1.6 ± 0.3s) to rest (11.9 ± 2.7-s) ratio was higher than 1:7. During official karate match, the activity and rest duration were 10.0 ± 3.4-s and 16.2 ± 4.1-s, respectively (E:R ratio 1:1.5), while high-intensity actions were 1.5 ± 0.3-s, resulting in an E:R ratio of 1:11. Recently, very interesting investigation [12] that aimed to define the activity profile of the 2012 World Karate Championship in relation to gender, match outcome and weight division categories reported that the referee’s decisions caused an overall activity-to-break ratio of ∼1:1.5 with a significant difference between karateka’s weight categories (light weight = 1:1.5; middle weight = 1:2 and heavy weight = 1:1), and this ratio achieved ∼1:8 in the case of considering high-intensity actions-to-break ratio. Male athletes had higher mean fighting activity, breaking activity and preparatory activity compared to females ones. Authors explained this difference by the karate combat’s duration difference between gender (i.e., 4-min for male and 3-min for female) [12]. As with the study of Chaabène et al. [10], there was no significant difference in all the temporal analysis variables between winners and defeated athletes. From all these findings, authors concluded that training programs might need to be specific to the particular requirements of the gender and weight categories. All these results have to be reinforced by further investigations. Altogether, these data seem to suggest that during kumite karateka performs short high-intensity actions separated by long periods of low-to-moderate-intensity actions. This pattern also has important relevance to the physiological response during the match, as the high-intensity actions are probably mainly maintained by the ATP-PCr energy system, while the other longer periods are probably maintained by the aerobic metabolism. The speed of the movements is very important since there is a great changeability of the situations. According to the studies of Ruchlewicz et al. [13] and Cavanagh and Landa. [14] describing the duration of techniques, it is normally in ranging from 0.101 to 0.293-s. The hand techniques are characterized by the shorter duration time: uraken shita uchi (0.101-s), chudan seiken tsuki (0.123-s) [13] and shuto uchi (0.150-s) [14] than kicks: mawashi geri (0.177-s), mae geri (0.243-s), ushiro geri (0.263-s), ushiro mawashi geri (0.272-s), and yoko geri (0.293-s) [13]. The fastest kick was the roundhouse kick (mawashi geri) (0.177-s) [13]. Although in laboratory studies, it was found out that the time to perform the punches (from 0.101to 0.150-s) [13,14] was in many cases shorter than the time to respond to them (simple reaction time [RT] = 0.165-s) [15]. Accordingly, anticipation skills are considered very important in karate [16]. Overall, results of time-motion analysis presented above should be considered as an important rationale for the construction of the specific tests used in karate as well as in proper training methods selection [17].

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2.2. Karate kumite: energy systems contribution Karate kumite performance is well established to be mainly a function of explosive power [7,10]. Previous scientific research considered the anaerobic metabolism to be the predominant energy source [18,19] during kumite, since sparring has been ranked as a high-intensity event [20]. Moreover, Sterkowicz [21] and Lehmann [18] considered the glycolytic system as the main energy source, hence and according to these authors, it should be particularly developed. The latter results were based on the observation of karate combat [18]. They considered that the activity pattern within karate sparring is comparable to intervaltraining. Additionally, this assumption was based on the attempts to simulate karate kumite activity by periods of 60 legs or arm attack technique per minute without interruption during two minutes duration against a striking pad [20]. However, during their study, Baker and Bell [20] revealed that the mean value of the energy expenditure during the two minutes periods of continuous leg and hand attack was 16.35 ± 2.33 kcal/min. Authors considered this value as very heavy compared to other kind of sports (e.g. cycling, tennis, swimming) and concluded that karate requires high-level of energy expenditure. Heart rate (HR) at the end of the two minutes attained a value of 187 ± 4 bpm showing the high physiological demand of performing continuous offensive leg and hand karate skills [20]. It should be noted that the gender of the athletes who participated in the study of Baker and Bell [5] had not been described. Recently, it has been reported that the karatekas spent 65% of the time exercising at HR > 90% of the individual HRpeak with a mean heart rate value of 177 ± 14 bpm (91 ± 5% of HRpeak ) during official karate combat [10]. Currently, studies dealing with the energy cost of karate have been established using kumite. These investigations revealed that both aerobic metabolism and ATP-PCr pathways represented the main energetic systems involved during kumite performance [8,9,22]. In a study conducted with high-level male karateka during kumite simulation, Beneke et al. [8] reported that blood lactate concentration (BLC) post-fight was 7.7 ± 1.9 mmol/l, with the difference between of pre- and post-fight equaling 4.2 ± 1.9 mmol/l (Table 1). BLC in pre-combat conditions was negatively correlated to the break’s duration between fights. Since BLC is often used as an indicator of energy production from anaerobic glycolysis [23—25], the low values recorded in the study of Beneke et al. [8] suggested a relatively low participation estimative (6.2 ± 2.4%) of the glycolytic system in the energy production during kumite. In the same way, they reported that the fraction of aerobic and anaerobic alactic metabolism were 77.8 ± 5.8% and 16 ± 4.6%, respectively. According to the same researchers, the acyclic profile (high-intensity actions interspersed by short-break periods) during kumite activity make the aerobic system the dominant energy source with the intervention of ATP-PCr during the short periods of attack and/or defense, which are considered the decisive actions during the match. These findings highlight the importance of these two energy systems and the need for their development in order to reach high-level performance during kumite instead of developing the lactic energy system as reported previously [18,21,26]. It should be noted that the study of Beneke et al. [8] represents the first

successful approach to analyze the metabolic cost of kumite based on the assessment of BLC and oxygen consumption pre-, during and post-kumite simulation. Authors concluded that karate kumite is based on activities that require a high metabolic rate. Another study performed by Iide et al. [9] with male black belt karatekas revealed that the corresponding percentage of VO2max values calculated from VO2 measured during 2 and 3-min bouts of sparring were 42.3 ± 10.0% and 47.8 ± 8.0%, respectively. Authors reported that BLC post-simulated kumite were 3.1 ± 1.0 mmol/l and 3.4 ± 1.0 mmol/l, respectively, for 2 and 3-min bout of fighting (Table 1). In another study conducted with top-level athletes, Doria et al. [22] reported that the net-BLC (highest post-competition BLC minus resting) were 7.5 ± 2.4 mmol/l and 10.6 ± 4.8 mmol/l for male and female athletes, respectively. The values recorded in male athletes were relatively higher than those reported by Beneke et al. [8] and Iide et al. [9] in male karateka during combat simulation. This can be due to the difference in duration between the combat simulation adopted between the studies, i.e., it was 180-s in the study of Beneke et al. [8], 120 and 180-s in the study of Iide et al. [9], and 240-s in the study of Doria et al. [22], which corresponded to the longest durations of actual kumite World Championship competitions. Recently, a mean BLC of 7.80 ± 2.66 mmol/l has been established during kumite simulation [11] confirming the results previously discussed. Arriaza [6] reported that BLC recorded after karate kumite organized within the World Karate Championships was 11.1 mmol/l (range: 8.7 to 12.7 mmol/l). These results are in accordance with those established by Chaabène et al. [10] and Chaabène et al. [11] during official kumite (11.18 ± 2.21 mmol/l and 11.14 ± 1.82 mmol/l, respectively). Similarly, Tabben et al. [27] reported a BLC of 8.8 ± 2.0 mmol/l and 8.8 ± 0.9 mmol/l for male and female elite level athletes, respectively during official kumite. These values reflect the high demands of official kumite compared to the simulated one presented above [8,9,22]. Regarding BLC in relation to the match outcome, Roschel et al. [28] reported that there was no significant difference between winners and defeated athletes after kumite simulation (5.1 ± 1.2 mmol/l vs. 5.2 ± 2.2 mmol/l, respectively). Thus, it could be concluded that the glycolytic pathway is not the primary source of energy during karate nor is a discriminative factor with respect to performance. It has been established that the aerobic energy source was predominant and represent ∼70% of the total, the lactic source represents the lowest percentages (∼10%) of the total, and the ATP-PCr source represents ∼20% of the total, irrespective of gender [22]. These findings, although slightly different, agree with those previously reported by Beneke et al. [8] and highlight again the importance of the aerobic and the ATP-PCr energy system during kumite. All these findings contradict the hypothesis presented by Lehmann [29], Lehmann and Jedliczka [18], Schmidt and Perry [19], and Sterkowicz [21] who considered that the lactic anaerobic metabolism was the main energy source during kumite. Regarding differences between genders, oxygen consumed above resting and then the aerobic energy corresponding to this oxygen consumed during the simulated competition was significantly higher in males

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Karate physiology Table 1

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Blood lactate concentration after karate kumite.

Study Simulated kumite Beneke et al. [8] Doria et al. [22]

Iide et al. [9]

Roschel et al. [28]

Tabben et al. [30]

Chaabène et al. [11] Official kumite Arriaza. [6] Tabben et al. [27]

Chaabène et al. [11] Chaabène et al. [10]

Sample characteristics

Kumite’s time duration (s)

[La] mmol/l

Male athletes Elite level (n = 10) Italian male Elite level (n = 3) Italian female Elite level (n = 3) Japanese male Black belt karatekas with more than 2 years’ experience (n = 13) Brazilian male Elite level (n = 14) Winners Losers Tunisian elite level karatekas Male (n = 10) Female (n = 8) Tunisian elite level karatekas Male (n = 10)

267 ± 61a 240b

7.7 ± 1.9 La = 4.2 ± 1.9 7.5 ± 2.4

180b

10.6 ± 4.8

120b 180b

3.1 ± 1 3.4 ± 1

180b

[La]pre = 2.3 ± 0.4 [La]post = 5.1 ± 1.2 [La]pre = 1.8 ± 0.6 [La]post = 5.2 ± 2.2

180b 120b 180b

[La]post = 13.0 ± 1.8 [La]post = 13.5 ± 1.6 [La]post = 7.80 ± 2.66

Elite level karate athletes (n = 20) during World kumite championships Tunisian elite level karatekas Male (n = 4)

NR

11.1 [range: 8.7 to 12.7 mmol/l]

180b

Female (n = 3)

120b

Tunisian elite level karatekas Male (n = 10) Tunisian elite level karatekas Male (n = 14)

180b

Combat 1: [La]post = 8.8 ± 0.9 Combat 2: [La]post = 9.1 ± 3.0 Combat 3: [La]post = 8.4 ± 2.1 Combat 1: [La]post = 8.9 ± 3.1 Combat 2: [La]post = 8.9 ± 2.4 Combat 3: [La]post = 10.0 ± 2.0 [La]post = 11.14 ± 1.82

180b

[La]pre = 1.73 ± 0.54 [La]post = 11.18 ± 2.21

[La]: blood lactate concentration; [La]pre : blood lactate concentration pre-combat; [La]post : blood lactate concentration post-combat. a Taking into account the referee’s break. b Without taking into account the referee’s break.

(139.8 ± 12.0 mlO2 /kg, 225.5 ± 20.4 kJ) than in females (95.8 ± 18.5 mlO2 /kg, 113.4 ± 26.2 kJ). Similar results have been found concerning the total energy cost and the total metabolic work, as well as metabolic power, being higher in males than in females (225.5 ± 20.4 kJ vs. 113.4 ± 26.2 kJ; 304.8 ± 25.5 kJ vs. 184.6 ± 52.0 kJ and 1.27 ± 0.11 kW vs. 1.03 ± 0.29 kW, respectively; P < 0.05). Authors concluded that the aerobic and ATP-PCr sources, in percentage of the total, were significantly different between genders, while the lactic source was similar. There was no significant difference between gender in peak heart rate (HRpeak ) (175.0 ± 5.0 bpm vs. 187.0 ± 12.0 bpm for male and female, respectively). Compared to their maximal heart rate (HRmax ) measured during the cycle ergometer test, the HRpeak recorded during combat simulation represented 92 ± 2 and 97 ± 6% for male and female, respectively, which indicate the high-intensity of kumite activity. It should be noted that the above cited results should be considered

cautiously because of the very small sample size in the study of Doria et al. [22] (only 3 males and 3 females), although constituted by World Championship medal winners. Then, further investigations should be conducted to support these findings. Finally, it appears that the aerobic energy system represents the metabolic system that provides the major energy contribution during kumite. Additionally, the ATP-PCr system is also determinant, since it provides energy during decisive actions (i.e., attack and/or defense). When considering anaerobic glycolysis, it should be noted that its contribution cannot be totally neglected, but it seems that it still being lower than aerobic and ATP-PCr energy systems. This assumption need to be verified in future studies within official karate matches. Consequently, the development of both aerobic and ATP-PCr systems appears to be of great importance to achieve high-level performance during karate sparring.

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3. Karate kata: energy systems contribution Show and Deutsch [31] submitted ten karateka (9 males and 1 female) to the performance of the heian shodan kata (Shotokan style), constituted by 24 upper-body-movements, following four different conditions: • continuous condition, using a pace to complete each repetition in 30-s, i.e. 15 executions without rest; • continuous condition, using a pace to complete each repetition in 45-s, i.e. 15 executions without rest; • interval condition, using a pace to complete each repetition in 30-s, i.e. 15 executions with 60-s interval between each performance; • interval condition, using a pace to complete each repetition in 45-s, i.e. 15 executions with 60-s interval between each performance.

VO2 was measured during the third, ninth, and fifteenth kata of each of the four kata’s condition and the collection of expired gas was initiated at the beginning of the first kata movement and terminated at its end (i.e. at 30 or 45-s). Results from this study indicated that HR (bpm) and VO2 (ml/kg/min) were significantly higher during continuous kata conditions. More precisely, HR was higher during continuous 30-s protocol (168 ± 3.5 bpm) compared to the intermittent 45-s protocol (138 ± 3.8 bpm). The same was observed when VO2 was considered, i.e., higher values during the 30-s continuous protocol (31.1 ± 1.5 ml/kg/min; 54.9 ± 2.3% VO2max ) compared to the 45-s intermittent protocol (17.3 ± 0.9 ml/kg/min; 30.9 ± 1.4% VO2max ). They concluded that the heian shodan kata performed continuously at 30-s pace represents the best suitable condition to elicit HR responses to the accepted threshold level for enhancing cardiovascular fitness. In this context, VO2 was above the 50% VO2max (measured through the treadmill laboratory run test) during the continuous 30-s pace and below this limits during all other protocols conditions. Heian Shodan kata performed within the intermittent condition either in 30-s or 45-s paces elicited HR responses below the accepted threshold adopted by the authors, which was 60% of maximum heart rate reserve. However, these results have to be interpreted with caution due to the high heterogeneity of the subjects involved in the investigation regarding their karate experience, i.e. range between 4 months and 10 years. Four male black belt highly skilled karateka performed the Seisan kata (Shito-Ryu style), composed by 67 movements (6 kicks, 19 blocks, 18 punches, 4 strikes, and 20 sliding/stepping movements), repeatedly during 8 to 10 min [32]. Subjects were asked to execute the kata at two different intensities: • following normal pace that would be used during their training routine and/or actual tournament (subjects here were asked to complete the kata in approximately 1 min) (normal); • athletes were asked to complete each kata in 30-s (i.e. twice as fast than the last condition) (fast).

By continuously measuring VO2 and HR during the whole period (i.e. 8 to 10-min), Zehr and Sale [32] revealed that relative VO2 responses to performing Seisan kata following normal condition (33.3 ± 2.6 ml/kg/min, 73.2 ± 3% VO2peak from the leg cycling VO2max measurement protocol) and fast condition (43.6 ± 5.7 ml/kg/min, 93.7 ± 1.6% VO2peak ), were significantly different. Even in the normal condition, the VO2 achieved was higher than that previously reported by Shaw and Deutsch [31], suggesting that some more complex kata may result in high cardiovascular demand, especially when performed twice as fast as the usual condition. However, the difference in the athletes’ characteristics may be another aspect affecting the physiological response. Zehr and Sale [32] concluded that the practice of karate kata may increase the aerobic power since the VO2 consumption revealed were within the intensity zone of aerobic development which is 50—85% VO2max [33]. HR responses to Seisan kata in normal and fast conditions were 158.3 ± 14.2 bpm (92.7% HRmax ) and 172 ± 10.4 bpm (100.9% HRmax ), respectively. Regarding the BLC, it was considered as moderate during the two conditions (Table 2). Based on the findings established during this study, authors recommended the use of karate kata as an effective sport-specific training method for developing and maintaining aerobic power. Authors also concluded that it is of importance for coaches to know that there is dissociation between heart rate responses and oxygen uptake when performing kata exercise, then caution must be taken when trying to identifying optimal training intensity. This is probably due to the intense and isometric actions performed using the upper-body. Thus, the use of heart rate to monitor the kata intensity must be considered with caution. One major limitation that could be extracted from the two cited studies above is that, athletes actually do not perform kata continuously for a relatively long period of time during competition or training sessions as it has been presented, then these conditions can be considered far from the reality of performing kata’s exercise. In this context, performing kata exercises in a regular manner as was performed in these studies is considered as an abnormal condition [34]. In a study by Francescato et al. [35] conducted with eight recreational male karateka performing the Pinan ni dan kata (wado ryu style), the energy demands and the energy systems contributions were estimated. The Pinan ni dan kata has a duration of approximately 20 s and it is composed by 21 body displacements, including 21 karate techniques (10 blocks, 7 punches, 4 open hand movements). Within kata, every technique must be performed with as highest power as possible. The athletes performed the kata in six different conditions: • • • • • •

the first or the second half of the kata (∼10-s); the whole kata (∼20-s); one and half kata (∼30-s); twice kata (∼40-s); whole kata three times (∼60-s); whole kata four times (∼80-s).

Authors revealed that heart rate rose during the execution of the kata exercise from 133.6 ± 22.3 bpm for the shortest condition (10-s) to 163.3 ± 12.1 bpm for the longest condition (80-s). The metabolic power (in VO2 equivalent) was very high for the shortest duration (∼10-s) (9.5 L/min or

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Karate physiology Table 2

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Blood lactate concentration during karate kata exercise.

Study

Sample characteristics (n)

Kata (style)

Bussweiler and Hartmann [36]

German male athletes of various levels (n = 6; 2 advanced level, 2 expert level, and 2 elite level)

Heian Nidan (Shotokan style)

Doria et al. [22]

Arriaza [6] Imamura et al. [34]

Italian male Elite level (n = 3) Italian female Elite level (n = 3) Elite level athletes (n = 9) during the world kata championships Japanese male black belt level (n = 7)

Imamura et al. [38]

Japanese female black belt level (n = 6)

Zehr and Sale [32]

Four black belt practitioners (one 1st dan, two 2nd dan, one 5th dan)

One time (t = 31.9 ± 2.9 s)

Two times (t = 63.3 ± 6.9 s) Unsu kata (Shotokan style) (t = 138 ± 4 s) Hanan kata (Shito-ryu style) (t = 158 ± 14 s) NR Various kata levels (elementary to advanced level) performed during 20 min Various kata levels (elementary to advanced level) performed during 20 min Seisan kata (Shito-Ryu style) Normal pace: kata executed following the normal pace for 8 to 10 min repeatedly Fast pace: kata executed twice as fast as the normal pace for 8 to 10 min repeatedly

[La] (mmol/l)

4.6 ± 1.1 (first single session) 4.5 ± 0.2 (second single session) 6.9 ± 1.1 La = 6.5 ± 1.3 La = 3.9 ± 1.7 8.79 [range: 6.8 to 10.6] 1.4 ± 0.4

1.2 ± 0.3

0.75 ± 0.3

1.43 ± 0.29

NR: not reported; La: net blood lactate concentration (highest post-exercise blood lactate concentration minus resting/pre-exercise); [La]: blood lactate concentration; t: time duration in seconds.

130 ml/kg/min). These values decreased to about 4.9 L/min (68 ml/kg/ min) for the longest kata exercise duration (∼80s). This means that the metabolic power represents from 3.5 to 1.8 times the average VO2max of the subjects, which was low and of 36.83 ± 5.35 ml/kg/min. These values were higher than previously reported by Show and Deutsch [31] and Zehr and Sale [32], which reported values ranging from approximately 55% to 94% of the subject’s VO2max Technical content and the difference between kata’s styles may explain the difference between results [35]. Francescato et al. [35] reported that the fraction of the glycolytic system was negligible during the shortest kata duration (equal or less than 20-s), increasing to 13% during the longest kata duration (∼80-s). Concerning the aerobic contribution, it raised with the duration of the kata exercise from 11% for 10-s kata’s duration to 41% for 80-s duration. Finally, the major energy system contribution was provided via ATPPCr system from 90% to 46% for the shortest to the longest kata’s duration, respectively. In another study, Doria et al. [22] analyzed the energetics of kata in six (three males and three females) top-level Italian athletes performing the Unsu kata (Shotokan style) (for male athletes) and Hanan kata (Shito-ryu style) (for female athletes) during simulated competition. By continuously measuring the oxygen consumption using a portable breath-by-breath telemetric system and BLC as well as heart rate responses, authors revealed that the net-BLC (highest post-competition BLC

minus resting, mmol/l) were 6.5 ± 1.3 for male and 3.9 ± 1.7 for female (Table 2). Heart rate during the simulated competition represented 94 ± 7 and 90 ± 3% of maximal heart rate (HRmax ) in males and females, respectively, which is indicative of the high-intensity of kata exercise. It should be noted that the durations of the simulated Unsu and Hanan kata competition were 138 ± 4-s and 158 ± 14-s in males and females, respectively. Moreover, authors reported that the metabolic power during the simulated competition was lower than VO2max . Additionally, they revealed that the aerobic and anaerobic (ATP-PCr and lactic) energy sources were almost equally divided. The aerobic contribution in male athletes was 50 ± 6%. Doria et al. [22] indicated that they established similar results to those of Francescato et al. [35] concerning the contribution of the aerobic system, while the increased glycolytic participation, in their study was mainly due to the longer duration of the simulated kata performed (∼140-s). Regarding gender differences, the ATP-PCr contribution was similar in both male and female (28 ± 6% and 29 ± 5%, respectively). Results concerning gender differences must be considered cautiously because of the difference in kata style performed by males and females as well as the very small sample size. More recently, a scientific study dealing with the metabolic cost and the fractional energy supply of basic karate kata (Heian Nidan: Shotokan style), performed over ∼30-s has been established [36]. The Heian Nidan

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kata comprised 26 movements (5 single arm movements, 18 combined upper and lower-body movements, and 3 kicks). Oxygen uptake was recorded continuously by means of breath-by-breath respiratory gas system and BLC was measured before and post-kata execution. For one Heian Nidan repetition (∼30-s), authors revealed a percentage of 52% from the ATP-PCr source, 25% from the glycolytic system, and 23% from the oxidative system. These results are lower than previously reported by Doria et al. [22] particularly the fraction of the aerobic contribution. This can be due to the difference regarding the kata’s duration, i.e., it was approximately ∼30-s in the study of Bussweiler and Hartmann [36] and 138 ± 4-s in the study of Doria et al. [22], as well as due to differences between the kata style. Considering two successive repetition of the kata (∼60-s), Bussweiler and Hartmann [36] reported percentages of 33, 25, and 42 for ATP-PCr, lactic, and aerobic energy systems, respectively. For this duration, results were similar to those of Doria et al. [22]. They concluded that the highly energy requirement of two consecutive kata was provided essentially by the aerobic system. BLC at the end of the kata was about 4 mmol/l for one kata and 6.9 mmol/l for two consecutive kata (Table 2). This low concentration highlights the relatively low contribution of the glycolyic system. Authors concluded that the ATP-PCr seems to play the major role for karate specific fast movement and kata. These results agree with those reported by Francescato et al. [35] who revealed that the major energy contribution was provided via ATP-PCr system. Authors also concluded that the energy requirement is essentially regulated through the aerobic metabolism in responses to longer duration and then higher number of karate techniques. These results agree again with those established by Francescato et al. [35] who found that the aerobic contribution rose with the duration of the kata exercises. In a study conducted with nine high-level karateka, Arriaza [6] revealed that the mean BLC during official competition was 8.79 mmol/l (range: 6.8 to 10.6 mmol/l) after kata with no additional information about its type as well as its duration. These results clearly exceed the previously results cited within the present review study. This difference can be due to the fact that simulated and official kata competition condition may induce different metabolic demands. Moreover, BLC responses to performing 20-min kata exercises in male and female karateka were presented in Table 2. Imamura et al. [34] established with males karateka that the mean %HRmax was slightly above the threshold level for enhancing endurance capacity (60% HRmax , [4]) and that %VO2max was slightly below the lactate threshold (50% VO2max ) [37]. In another study with females karateka, Imamura et al. [38] revealed that the mean percentage of maximal heart rate (%HRmax ) as well as the mean percentage of heart rate reserve (%HRR) were well above the minimal threshold for enhancing cardiovascular fitness following kata, supporting the results obtained with males karateka and confirming the assumption that the practice of kata may increase aerobic fitness irrespective of gender. Overall, the fraction of the energy supply is a function of kata’s duration. It seems that the major energy production during kata is provided through the ATP-PCr system. The aerobic energy system’s participation rises with the increased kata’s duration, thus it can be considered as the main energy source responsible for energy regulation. A

weak participation has been reported by the glycolytic system by most of the studies. Important information must be stressed, which is the contribution of the karate kata in the cardiovascular fitness development [39,40], as such the kata can be used as a relevant and effective means for cardiovascular training of karatekas and others [31,32,34,38]. It seem also very interesting to note that kata varies a great deal in term of style (every karate style has their specific kata with their proper characteristics), technical content (i.e. number of techniques and total duration required by each kata), and level of kata (beginners or advanced). Then results should be interpreted cautiously taking into account all these above cited factors. Future studies in an ecologically valid environment (real kata competition) with a bigger sample size are needed. Additionally, further studies dealing with the difference between kata style as well as gender are required.

4. Conclusion The effort-pause ratio during official kumite was 1:1.5. The aerobic energy system can be considered as the metabolic system with higher contribution during kumite, although the decisive actions are mainly performed by the participation of the ATP-PCr system. Regarding kata, the aerobic contribution is a function of kata’s duration, but it seems that the ATP-PCr system plays the major role in providing the energy during kata. Nevertheless, these results should be confirmed in further studies including larger sample size of both genders. Overall, future investigations in an ecologically valid environment are needed to support the findings presented herein and to optimize karate’s training modalities. This review may represent the first relevant support for athletes’ specific training regarding karate’s discipline.

Disclosure of interest The authors declare that they have no conflicts of interest concerning this article.

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