The Open Sports Sciences Journal




ISSN: 1875-399X ― Volume 11, 2018
REVIEW ARTICLE

Physiological and Biomechanical Fatigue Responses in Karate: A Case Study



Keith S. Urbinati*, Agnelo D. Vieira, Caluê Papcke, Renata Pinheiro, Percy Nohama, Eduardo M. Scheeren
Graduate Program in Health Technology, Pontifical Catholic University of Parana, Prado Velho, Brazil

Abstract

Knowledge of the fatigue process in karate sport is essential to improve the performance of top athletes. The physiological and biomechanical behavior during the Karate Specific Aerobic Test (KSAT) fatigue protocol in karate was investigated. PCR, lactate, glucose and cortisol were collected before and after the fatigue protocol application in karate, besides that, and heart rate and technical speed were measured. The results indicated increase in C protein reactive (60%), creatine kinase (25%), cortisol (30%), lactate dehydrogenase (90.9%) and decrease in glucose (21.2%). The maximum speed was: in kizami zuki, 5.75 ± 0.31 m/s; in mawashi geri, 9.0 ± 0.24 m/s, in gyako zuki, 7.23 ± 0.54 m/s and in kizami mawashi geri, 6 ± 0.34 m/s. The mean time for each set was 2.99 ± 0.17 s. There was reduction in speed and duration of set for all techniques, especially in the final sets (p<0.05), indicating the presence of fatigue. Gyako zuki was the main blow affected by the phenomenon (p<0.05). Also, the high values observed in biochemical variables after the protocol application indicate metabolic fatigue with muscle damage. Therefore, the athlete adapted his motor behavior in order to hold his technical speed.

Keywords: Biochemistry of exercise, Cinemetry, Karate, Kicking, Martial arts, Physiological stress, Punching, Speed.


Article Information


Identifiers and Pagination:

Year: 2017
Volume: 10
Issue: Suppl-2, M10
First Page: 286
Last Page: 293
Publisher Id: TOSSJ-10-286
DOI: 10.2174/1875399X01710010286

Article History:

Received Date: 19/05/2016
Revision Received Date: 04/07/2017
Acceptance Date: 14/09/2017
Electronic publication date: 29/12/2017
Collection year: 2017

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© 2017 Urbinati et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


* Address correspondence to this author at the Graduate Program in Health Technology, Pontifical Catholic University of Parana, Imaculada Conceição, 1155, Prado Velho, CEP: 80215-901, Brazil; Tel: (5541) 3271-1561; E-mail: keith.msato@gmail.com




1. INTRODUCTION

Karate is a sport that requires high-speed demands [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
]. Indicate that the actions, during simulated combats, are of high-intensity with high-speed blows [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
-4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
]. Karate is an intermittent combat sport that requires both aerobic and anaerobic capabilities [4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
-12Billat VL, Hill DW, Pinoteau J, Petit B, Koralsztein JP. Effect of protocol on determination of velocity at VO2 max and on its time to exhaustion. Arch Physiol Biochem 1996; 104(3): 313-21.
[http://dx.doi.org/10.1076/apab.104.3.313.12908] [PMID: 8793023]
].

The force-velocity parameters during anaerobic tests indicate that both force and velocity were higher in world-class athletes than non-athletes, suggesting that karate performance depends on the maximal velocity and explosive strength [5Chaabène H, Hachana Y, Franchini E, Mkaouer B, Montassar M, Chamari K. Reliability and construct validity of the karate-specific aerobic test. J Strength Cond Res 2012; 26(12): 3454-60.
[http://dx.doi.org/10.1519/JSC.0b013e31824eddda] [PMID: 22344054]
]. In combat situation, the duration of high intensity actions per fight is approximately 1-3 seconds each [2Beneke R, Beyer T, Jachner C, Erasmus J, Hütler M. Energetics of karate kumite. Eur J Appl Physiol 2004; 92(4-5): 518-23.
[http://dx.doi.org/10.1007/s00421-004-1073-x] [PMID: 15138826]
]. High demands in production of force-velocity can cause physiological stress, affecting the technical and tactical response from the participants.

Muscle fatigue is classified as a motor deficit, a perception or a decline in mental function; it can describe the gradual decrease in the muscle strength capacity or the endpoint of a sustained activity with reduction in muscle strength [6Enoka RM, Duchateau J. Muscle fatigue: What, why and how it influences muscle function. J Physiol 2008; 586(1): 11-23.
[http://dx.doi.org/10.1113/jphysiol.2007.139477] [PMID: 17702815]
]. During the fatigue process the speed variable can suffer several changes and compromise the athletes performance [7Ravier G, Grappe F, Rouillon JD. Application of force-velocity cycle ergometer test and vertical jump tests in the functional assessment of karate competitor. J Sports Med Phys Fitness 2004; 44(4): 349-55.
[PMID: 15758845]
]. Therefore, it is very important to study the occurrence of biological and motor behavior during karate fatigue process.

It was not found in the literature studies that have analyzed muscle damage markers during a specific incremental load test for karate in association with performance changes in speed of punches and kicks. However, could biochemical changes occur concomitantly with a decrease in technical speed?

It is unclear how the biomechanical and physiological mechanisms limit human performance and how detailed measurements of an individual’s neuromusculoskeletal system can be used to make subject-specific recommendations for training for individual specific sport [8Neptune RR, McGowan CP, Fiandt JM. The influence of muscle physiology and advanced technology on sports performance. Annu Rev Biomed Eng 2009; 11: 81-107.
[http://dx.doi.org/10.1146/annurev-bioeng-061008-124941] [PMID: 19400707]
]. The aim of this study was to investigate the physiological and biomechanical behavior during the induced fatigue protocol in karate.

2. MATERIALS AND METHODS

One male karateka volunteer, athlete of karate (21 y.o., black belt, international level, practitioner for 6 years, 78 kg, 1,82 m, 14,4% fat, VO2 max = 55 kg.ml-1.min-1) stated his agreement to participate the research. All procedures received local ethics committee approval (number 38400/2012).

To evaluate pre-participation was applied the Physical Activity Readiness Questionnaire (PAR-Q) [9Thomas S, Reading J, Shephard RJ. Revision of the physical activity readiness questionnaire (PAR-Q) 1992.] as risk identification criteria. Anthropometric data were collected according to the International Society for the Advancement of Kinanthropometry [10Marfell-Jones M, Olds T, Stewart A, Carter L. International standards for anthropometric assessment 2006.]. The body composition was calculated as percentage of fat, bone mass and lean mass [9Thomas S, Reading J, Shephard RJ. Revision of the physical activity readiness questionnaire (PAR-Q) 1992.]. The anaerobic threshold was obtained using the progressive test [10Marfell-Jones M, Olds T, Stewart A, Carter L. International standards for anthropometric assessment 2006.], and calculating the heart rate inflexion method [13Vucetić V, Sentija D, Sporis G, Trajković N, Milanović Z. Comparison of ventilation threshold and heart rate deflection point in fast and standard treadmill test protocols. Acta Clin Croat 2014; 53(2): 190-203.
[PMID: 25163235]
] 96 hours before the Karate Specific Aerobic Test (KSAT) protocol (Fig. 1).

Fig. (1)
Description of Karate Specific Aerobic Test (KSAT). In (A), front arm punch; in (B), roundhouse back leg kick; in (C), back arm punch; and in (D), roundhouse front leg kick.


The athletes performed the KSAT until exhaustion [14Nunan D. Development of a sports specific aerobic capacity test for karate - A pilot study. J Sports Sci Med 2006; 5(CSSI): 47-53.
[PMID: 24357976]
], this test consists in sequential sets (Fig. 1). Each set is composed of: kizami zuki (front arm punch) (A), mawashi geri (roundhouse back leg kick) (B), gyako zuki (back arm punch) (C) and kizami mawashi geri (roundhouse front leg kick) (D).

Each set starts with a beep, the time among the beeps decreases along the test. When the subject does not succeed in finishing the complete set before the next beep, the test is ended [15Milanez V, Lima M, Perandini L, Golçaves C, Franchini E. Avaliação e comparação das respostas da percepção subjetiva de esforço e concentração de lactato em uma competição oficial de caratê. Rev Educ Fis UEM 2011; 1: 57-64.]. The heart rate (V800 Polar heart rate monitor) was measured all the time during the KSAT test. It was collected 5 ml of blood before and after the KSAT test. It was assessed to lactate dehydrogenase (ADVIA automation 1200/1800), creatine kinase, C reactive protein (Imunoturbidimetric method), cortisol (chemiluminescence essay) and glucose (hexokinase method). Ten minutes after the end of KSAT protocol, it was applied the effort perception test (Borg Scale) with a scale from 6 to 20 [16Tabben M, Coquart J, Chaabène H, Franchini E, Ghoul N, Tourny C. Time-motion, tactical and technical analysis in top-level karatekas according to gender, match outcome and weight categories. J Sports Sci 2015; 33(8): 841-9.
[http://dx.doi.org/10.1080/02640414.2014.965192] [PMID: 25358098]
].

The biomechanical model used a six-camera video-based motion analysis system (Vicon System) set to record at 200 Hz. Forty-three reflecting markers were placed on specific anatomical landmarks. The marker protocol was based on the Plug-in-gait marker set of the the full body model Vicon System. The model was reconstructed using the polynomial model, with a Butterworth 4th order filter (6 Hz).

It was developed a Matlab (The MathWorks, Inc.) routine to determining the speed and time landmarks: styloid process of the ulna (both arms) and lateral malleolus (both legs). It was calculated the maximum speed through the landmarks and the time of set in each cycle of the test.

The duration of the set was computed with the interval time between ‘kizami zuki – kizami mawashi geri’ peak speed.

The temporal data analysis was obtained in three moment sets: ten first (initial sets), ten middle (middle sets), and ten final (final sets).

Normality was confirmed via Shapiro-Wilk test. Linear regression models were computed to predict speed in landmarks. In order to compare the speed in the three moments sets it was applied ANOVA for repeated measurements, with post-hoc Bonferroni (p<0.05). Compound symmetry was tested through Mauchy test and Greenhouse-Gleisser correction. Effect size was calculated and linear regression (p<0.05) was computed to determine the behavior of speed blows.

3. RESULTS

The athlete completed 30 sets of the KSAT protocol. The heart rate peak was 190 beats per minute (BPM). During KSAT, the athlete was 80% above his anaerobic threshold. The period to exhaustion was 241.95 s. The efforts perception the athlete varied between ‘very tired’ (for lower limbs) and ‘almost tired’ (for upper limbs and trunk). There was an increase (Table 1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
) in C protein reactive 60% after the protocol application. The cortisol increased 30%, creatine kinase 25% and the lactate dehydrogenase 90.9% after the protocol. The glucose decreased 21.2%.

Table 1
Behavior of biochemical variables.


The average for the maximum speed (Table 2) was higher in the mawashi geri (roundhouse back leg kick) (F=7,84; p=0,002; η2 = 0,58).

Table 2
Maximum speed for technique.


The mean time for each set was 2.99 ± 0.17 s (CI=2.64 – 3.35 s). In the Table 3, there are decreased speed for all techniques, especially in the final sets (F=12.3; p=0.001; η2 = 0.32). The main blow affected by the fatigue was the gyako zuki (F=9.85; p=0.001; η2 = 0.75).

Table 3
Behavior of speed and set time in three different moments.


Fig. (2) shows the behavior of speed blows. By comparing the maximum speed blows, reduction in the angular coefficient was observed, especially in gyako zuki (β = -0,025), followed by mawashi geri (β = -0,016), kizami mawashi geri (β = -0,015) and kizami zuki (β = -0,011). The determination coefficient was higher in mawashi geri (R2 = 0,66) than gyako zuki (R2 = 0,33), kizami mawashi geri (R2 = 0,32) and kizami zuki (R2 = 0,21).

Fig. (2)
Speed blows response during the KSAT.


4. DISCUSSION

The present study aimed to evaluate the physiological and biomechanical behavior during the induced fatigue protocol in karate. The physiological response shows that the heart rate peak was greater than the found by Chaabéne et al. [4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
, 5Chaabène H, Hachana Y, Franchini E, Mkaouer B, Montassar M, Chamari K. Reliability and construct validity of the karate-specific aerobic test. J Strength Cond Res 2012; 26(12): 3454-60.
[http://dx.doi.org/10.1519/JSC.0b013e31824eddda] [PMID: 22344054]
]. Similar values to the anaerobic threshold were found in situation of simulated combat [4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
, 17Iide K, Imamura H, Yoshimura Y, et al. Physiological responses of simulated karate sparring matches in young men and boys. J Strength Cond Res 2008; 22(3): 839-44.
[http://dx.doi.org/10.1519/JSC.0b013e31816a5af6] [PMID: 18438232]
, 18Dopsaj V, Martinovic J, Dopsaj M, Kasum G, Kotur-Stevuljevic J, Koropanovski N. Hematological, oxidative stress, and immune status profiling in elite combat sport athletes. J Strength Cond Res 2013; 27(12): 3506-14.
[http://dx.doi.org/10.1519/JSC.0b013e31828ddeea] [PMID: 24270459]
]. The period to exhaustion was lower than reported by Chaabéne et al. [4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
] indicating the text leads the athlete to fatigue. The perception efforts were similar to intensities of effort in fight exercises [17Iide K, Imamura H, Yoshimura Y, et al. Physiological responses of simulated karate sparring matches in young men and boys. J Strength Cond Res 2008; 22(3): 839-44.
[http://dx.doi.org/10.1519/JSC.0b013e31816a5af6] [PMID: 18438232]
].

The protocol applied induced high level of physiological stress with significant changes in lactate dehydrogenase, creatine kinase, protein C, cortisol and glucose, suggesting that the physical effort during KSAT induced muscle damage. Acute high-intensity and prolonged exercise by itself causes production of stress hormones and alterations in the circulating quantity and function of various immune cells, including C-reactive protein (CRP) [19Nakajima T, Kurano M, Hasegawa T, et al. Pentraxin3 and high-sensitive C-reactive protein are independent inflammatory markers released during high-intensity exercise. Eur J Appl Physiol 2010; 110(5): 905-13.
[http://dx.doi.org/10.1007/s00421-010-1572-x] [PMID: 20640440]
-21Duffield R, Cannon J, King M. The effects of compression garments on recovery of muscle performance following high-intensity sprint and plyometric exercise. J Sci Med Sport 2010; 13(1): 136-40.
[http://dx.doi.org/10.1016/j.jsams.2008.10.006] [PMID: 19131276]
]. CRP is a biomarker that measures the acute inflammatory response to the exercise [19Nakajima T, Kurano M, Hasegawa T, et al. Pentraxin3 and high-sensitive C-reactive protein are independent inflammatory markers released during high-intensity exercise. Eur J Appl Physiol 2010; 110(5): 905-13.
[http://dx.doi.org/10.1007/s00421-010-1572-x] [PMID: 20640440]
, 20Benedini S, Longo S, Caumo A, Luzi L, Invernizzi PL. Metabolic and hormonal responses to a single session of kumite (free non-contact fight) and kata (highly ritualized fight) in karate athletes. Sport Sci Health 2012; 8(2-3): 81-5.
[http://dx.doi.org/10.1007/s11332-012-0132-7] [PMID: 23440907]
]. The release of acute phase of CRP helps contain amplification of the inflammatory process in different ways: by activativing the complement system, proteases action, removal of microorganisms and cell metabolites, cellular remodeling and control of gene expression, antithrombotic control, hemostasis, respiratory burst triggered by cells and inflammatory action of proteolytic enzymes, in addition to activation of local inflammation [19Nakajima T, Kurano M, Hasegawa T, et al. Pentraxin3 and high-sensitive C-reactive protein are independent inflammatory markers released during high-intensity exercise. Eur J Appl Physiol 2010; 110(5): 905-13.
[http://dx.doi.org/10.1007/s00421-010-1572-x] [PMID: 20640440]
]. Despite the increase in protein C, reactive showed a small increase in a present study. Dopsaj et al. [18Dopsaj V, Martinovic J, Dopsaj M, Kasum G, Kotur-Stevuljevic J, Koropanovski N. Hematological, oxidative stress, and immune status profiling in elite combat sport athletes. J Strength Cond Res 2013; 27(12): 3506-14.
[http://dx.doi.org/10.1519/JSC.0b013e31828ddeea] [PMID: 24270459]
] identified lower values in 18 professionals karatekas.

In present study, the creatine kinase (CK) increased 20% after the KSAT. The sarcolemma rupture allowed the release of enzymes such as CK and lactate dehydrogenase (LDH) to the serum [22Detanico D, Dal Pupo J, Franchini E, Dos Santos SG. Effects of successive judo matches on fatigue and muscle damage markers. J Strength Cond Res 2015; 29(4): 1010-6.
[http://dx.doi.org/10.1519/JSC.0000000000000746] [PMID: 25426512]
]. An increase of these enzyme levels in serum is considered evidence of muscle damage. To evaluated 24 full-contact karate practitioners, Graham et al. [23Graham MR, Pates J, Davies B, et al. Should an increase in cerebral neurochemicals following head kicks in full contact karate influence return to play? Int J Immunopathol Pharmacol 2015; 28(4): 539-46.
[http://dx.doi.org/10.1177/0394632015577045] [PMID: 25816397]
] found that after kicks to the head and body, the practioners showed significant increases in CK serum total

The increase of CK serum, LDH and PCR occurs when muscle fibers are metabolically exhausted due to effort, exhibiting a decrease in the membrane resistance, or even cytoskeletal and sarcolemma disruption, which permits the release of these enzymes to the serum [24Hassan ES. Muscle damage and immune responses to prolonged exercise in environmental extremes. J Sports Med Phys Fitness 2016; 56(10): 1206-13.
[PMID: 26329839]
].

We had as a limiting factor of our study, the lack of measures of CK, LDH and PCR in some moments after the KSAT. Some studies [22Detanico D, Dal Pupo J, Franchini E, Dos Santos SG. Effects of successive judo matches on fatigue and muscle damage markers. J Strength Cond Res 2015; 29(4): 1010-6.
[http://dx.doi.org/10.1519/JSC.0000000000000746] [PMID: 25426512]
, 24Hassan ES. Muscle damage and immune responses to prolonged exercise in environmental extremes. J Sports Med Phys Fitness 2016; 56(10): 1206-13.
[PMID: 26329839]
, 25Smith LL. Cytokine hypothesis of overtraining: A physiological adaptation to excessive stress? Med Sci Sports Exerc 2000; 32(2): 317-31.
[http://dx.doi.org/10.1097/00005768-200002000-00011] [PMID: 10694113]
] indicate that there were many clusters of these enzymes in the period of 24-96 hours post exercise. Thus, we believe that higher concentrations of enzymes measured in other moments can indicate higher muscle damage.

The muscle damage occurs because of the damage to the contraction tissue and cytoskeletal protein long with disorganization in myofibrillar structure, disruption, enlargement or extension of the line Z causing subsequent impairment of anchoring filaments and connection of adjacent fiber [25Smith LL. Cytokine hypothesis of overtraining: A physiological adaptation to excessive stress? Med Sci Sports Exerc 2000; 32(2): 317-31.
[http://dx.doi.org/10.1097/00005768-200002000-00011] [PMID: 10694113]
].

The increase of LDH shows the enriched H lactate dehydrogenase (H-LDH) isoenzyme content in slow twitch fibers (LDH). It suggest that the delivery, uptake and subsequent oxidation of lactate are facilitated when these fibers are active during low-intensity exercise, as well as the rate of blood flow which influences lactate efflux from skeletal muscle [26Ouergui I, Hammouda O, Chtourou H, Gmada N, Franchini E. Effects of recovery type after a kickboxing match on blood lactate and performance in anaerobic tests. Asian J Sports Med 2014; 5(2): 99-107.
[PMID: 25834703]
].

The cortisol and lactate increases were also higher than in combat simulation [3Iide K, Imamura H, Yoshimura Y, et al. Physiological responses of simulated karate sparring matches in young men and boys. J Strength Cond Res 2008; 22(3): 839-44.
[http://dx.doi.org/10.1519/JSC.0b013e31816a5af6] [PMID: 18438232]
, 5Chaabène H, Hachana Y, Franchini E, Mkaouer B, Montassar M, Chamari K. Reliability and construct validity of the karate-specific aerobic test. J Strength Cond Res 2012; 26(12): 3454-60.
[http://dx.doi.org/10.1519/JSC.0b013e31824eddda] [PMID: 22344054]
, 20Benedini S, Longo S, Caumo A, Luzi L, Invernizzi PL. Metabolic and hormonal responses to a single session of kumite (free non-contact fight) and kata (highly ritualized fight) in karate athletes. Sport Sci Health 2012; 8(2-3): 81-5.
[http://dx.doi.org/10.1007/s11332-012-0132-7] [PMID: 23440907]
], kumite karate training or in competition event [16Tabben M, Coquart J, Chaabène H, Franchini E, Ghoul N, Tourny C. Time-motion, tactical and technical analysis in top-level karatekas according to gender, match outcome and weight categories. J Sports Sci 2015; 33(8): 841-9.
[http://dx.doi.org/10.1080/02640414.2014.965192] [PMID: 25358098]
]. When evaluated 9 elite-level male karatekas in combat situation in Tunisia, Chaabene [27Chaabène H, Hellara I, Ben Ghali F, et al. Physiological stress and performance analysis to karate combat. Performance in Anaerobic Tests. Asian J Sports Med 2014; 5(2): 99-107.
[PMID: 25834703]
] identified double of cortisol values post combat, when compared to the pre-combat situation. It has been well established that Cortisol, as representative of circulating free cortisol, is an accurate index of training and/or competition stress [28Passelergue P, Lac G. Saliva cortisol, testosterone and T/C ratio variations during a wrestling competition and during the post-competitive recovery period. Int J Sports Med 1999; 20(2): 109-13.
[http://dx.doi.org/10.1055/s-2007-971102] [PMID: 10190771]
]. Results showed that despite the short duration of karate KSAT (241.95 seconds of test), there is a progressive and very important increase of cortisol.

However, the glucose decreased possibly occurred due to the higher energy demands of the KSAT. Benedini et al. [20Benedini S, Longo S, Caumo A, Luzi L, Invernizzi PL. Metabolic and hormonal responses to a single session of kumite (free non-contact fight) and kata (highly ritualized fight) in karate athletes. Sport Sci Health 2012; 8(2-3): 81-5.
[http://dx.doi.org/10.1007/s11332-012-0132-7] [PMID: 23440907]
] found glucose increase after the combat simulation, but not identified the effort intensity. Thus, high-intensity exercise elicits inflammatory responses similar to many clinical physical stressors including surgery, trauma and sepsis, indicating that the high intensity exercise may be a good model for the inflammatory response [19Nakajima T, Kurano M, Hasegawa T, et al. Pentraxin3 and high-sensitive C-reactive protein are independent inflammatory markers released during high-intensity exercise. Eur J Appl Physiol 2010; 110(5): 905-13.
[http://dx.doi.org/10.1007/s00421-010-1572-x] [PMID: 20640440]
].

The muscle damage can contribute to the decrease the blows speed. After the application of KSAT there was a decrease in the speed of gyako zuki, mawashi geri, kizami mawashi geri and kizami zuki technicals. During fatigue situation, the speed of the mawashi geri (roundhouse back leg kick) was higher than gyako zuki (back arm punch). Perhaps due to fatigue process used in this study offer high intensity effort, the gyako zuki speed was lower than gyako zuki speed reported by Urbinati et al. [29Urbinati KS, Scheeren E, Nohama P. A new virtual instrument for estimating punch velocity in combat sports. Conf Proc IEEE Eng Med Biol Soc 2013; 2013: 571-4.
[PMID: 24109751]
].

The protocol requires that the athlete perform the fastest possible the four blows, similar to competition situation. Actions of attack vary between 0.3 until 2.1 s [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
-3Iide K, Imamura H, Yoshimura Y, et al. Physiological responses of simulated karate sparring matches in young men and boys. J Strength Cond Res 2008; 22(3): 839-44.
[http://dx.doi.org/10.1519/JSC.0b013e31816a5af6] [PMID: 18438232]
, 16Tabben M, Coquart J, Chaabène H, Franchini E, Ghoul N, Tourny C. Time-motion, tactical and technical analysis in top-level karatekas according to gender, match outcome and weight categories. J Sports Sci 2015; 33(8): 841-9.
[http://dx.doi.org/10.1080/02640414.2014.965192] [PMID: 25358098]
].

Nevertheless, the protocol test induced the fatigue process, which increased the blows time. Other studies did not indicate the time set in KSAT. The decreased speed along the KSAT protocol indicates fatigue.

Changes in the speed of gyako zuki will ocassionate decrease in sport performance [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
, 4Chaabène H, Franchini E, Miarka B, Selmi MA, Mkaouer B, Chamari K. Time-motion analysis and physiological responses to karate official combat sessions: Is there a difference between winners and defeated karatekas? Int J Sports Physiol Perform 2014; 9(2): 302-8.
[http://dx.doi.org/10.1123/ijspp.2012-0353] [PMID: 23881174]
]. In a combat situation, karatekas used more upper-limb than lower-limb techniques [5Chaabène H, Hachana Y, Franchini E, Mkaouer B, Montassar M, Chamari K. Reliability and construct validity of the karate-specific aerobic test. J Strength Cond Res 2012; 26(12): 3454-60.
[http://dx.doi.org/10.1519/JSC.0b013e31824eddda] [PMID: 22344054]
, 16Tabben M, Coquart J, Chaabène H, Franchini E, Ghoul N, Tourny C. Time-motion, tactical and technical analysis in top-level karatekas according to gender, match outcome and weight categories. J Sports Sci 2015; 33(8): 841-9.
[http://dx.doi.org/10.1080/02640414.2014.965192] [PMID: 25358098]
]. The gyako zuki is the most used technique in competitive situation [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
, 30Gulledge JK, Dapena J. A comparison of the reverse and power punches in oriental martial arts. J Sports Sci 2008; 26(2): 189-96.
[http://dx.doi.org/10.1080/02640410701429816] [PMID: 17943591]
, 31Laird P, McLeod K. Notational analysis of scoring techniques in competitive men’s karate. Int J Perform Anal Sport 2009; 2(9): 171-87.]. Punching is a highly complex technique that requires the coordinated action of arm, trunk and leg muscle groups [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
].

Despite the blows speed suffer decrease along the protocol, the set time also decreased (Table 3). Contrary to expectations, the time in the final set and the blows speed were smaller. This fact indicates: (1) that the athlete did not perform the blows in the maximum limbs extension; (2) when the athlete is positioned closer to the target, it decreases the displacement for blows.

Different strategies for motor control and coordination have been developed aiming the maintenance of blows speed [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
, 30Gulledge JK, Dapena J. A comparison of the reverse and power punches in oriental martial arts. J Sports Sci 2008; 26(2): 189-96.
[http://dx.doi.org/10.1080/02640410701429816] [PMID: 17943591]
, 32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
]. Experienced athletes have longer arm flexion movement and forearm extension in a shorter period of time, which could allow longer segment acceleration [32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
].

Martinez and Benett [33Martinez de Quel O, Bennett SJ. Kinematics of self-initiated and reactive karate punches. Res Q Exerc Sport 2014; 85(1): 117-23.
[http://dx.doi.org/10.1080/02701367.2013.872222] [PMID: 24749243]
] compared karate athletes and non-athletes with kinematic analyses, finding that reactive movements had shorter time to reach the speed peak and shorter time to execute the movement.

Experienced athletes are faster than non-athletes because they have better motor control technical. Ferreira and Brito [32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
] examined the electromyographic (EMG) activity during punch execution of the anterior and posterior portions of deltoid, pectoralis major, latissimus dorsi, triceps brachii, and biceps brachii. The authors found that the athletes had significantly shorter delay in arm flexion of the agonist muscles and significantly higher delay in arm flexion of the antagonist muscles and in agonist forearm extension [32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
].

Brito et al. [34VencesBrito AM, Rodrigues Ferreira MA, Cortes N, Fernandes O, Pezarat-Correia P. Kinematic and electromyographic analyses of a karate punch. J Electromyogr Kinesiol 2011; 21(6): 1023-9.
[http://dx.doi.org/10.1016/j.jelekin.2011.09.007] [PMID: 22005009]
] when evaluating 19 karate athletes, found that the skill performance, the arm, flexion and internal rotation, and the forearm extension and pronation movements were executed with smaller amplitude than in untrained subjects.

In the fulfillment of gyako zuki blow, athletes performed multiple moving segments, containing both rigid (bone) and soft structures (muscle, tendon and ligaments) [32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
]. It is assumed that this ballistic mass flies at the target and strikes it with a measured incoming velocity [35Lenetsky S, Nates RJ, Brughelli M, Harris NK. Is effective mass in combat sports punching above its weight? Hum Mov Sci 2015; 40: 89-97.
[http://dx.doi.org/10.1016/j.humov.2014.11.016] [PMID: 25544341]
]. The ballistic movements cannot be changed voluntary during the course of the action [32Rodrigues Ferreira MA, Vences Brito A. Electromechanical delay in ballistic movement of superior limb: Comparison between karate athletes and nonathletes. Percept Mot Skills 2010; 111(3): 722-34.
[http://dx.doi.org/10.2466/05.25.PMS.111.6.722-734] [PMID: 21319612]
], however experienced athletes can perform faster voluntary decision before the blow [36Mori S, Ohtani Y, Imanaka K. Reaction times and anticipatory skills of karate athletes. Hum Mov Sci 2002; 21(2): 213-30.
[http://dx.doi.org/10.1016/S0167-9457(02)00103-3] [PMID: 12167300]
].

There are other differences between athletes muscles that can influence the adjustments during fatiguing contractions, such as the afferent feedback is activated by the metabolic products of the muscle contraction [6Enoka RM, Duchateau J. Muscle fatigue: What, why and how it influences muscle function. J Physiol 2008; 586(1): 11-23.
[http://dx.doi.org/10.1113/jphysiol.2007.139477] [PMID: 17702815]
].

Another important aspect is the contribution of the lower body in the maintenance of speed in punches. The lower-body is predictive of punching acceleration [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
], suggesting that karate athletes aiming at improving punch acceleration should improve the lower-body propulsive power.

There was short variability in maximum speed, especially in kicks. The roundhouse kicks involved the high muscle groups, but the punches involved the balistic movement. The gyako zuki is directly associated with the mechanical impulse generated in specific movement. It occurs due the sum of the forces the displacement in balistic movements [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
]. A higher speed value of technical movements in karate depends on motor learning strategies [35Lenetsky S, Nates RJ, Brughelli M, Harris NK. Is effective mass in combat sports punching above its weight? Hum Mov Sci 2015; 40: 89-97.
[http://dx.doi.org/10.1016/j.humov.2014.11.016] [PMID: 25544341]
, 36Mori S, Ohtani Y, Imanaka K. Reaction times and anticipatory skills of karate athletes. Hum Mov Sci 2002; 21(2): 213-30.
[http://dx.doi.org/10.1016/S0167-9457(02)00103-3] [PMID: 12167300]
]. Generally is the result in alterations in the internal processes that determine an individual capacity to produce a motor action after practice [34VencesBrito AM, Rodrigues Ferreira MA, Cortes N, Fernandes O, Pezarat-Correia P. Kinematic and electromyographic analyses of a karate punch. J Electromyogr Kinesiol 2011; 21(6): 1023-9.
[http://dx.doi.org/10.1016/j.jelekin.2011.09.007] [PMID: 22005009]
, 36Mori S, Ohtani Y, Imanaka K. Reaction times and anticipatory skills of karate athletes. Hum Mov Sci 2002; 21(2): 213-30.
[http://dx.doi.org/10.1016/S0167-9457(02)00103-3] [PMID: 12167300]
].

Muscle damage markers increased after the KSAT and happened a decrease in technical speed, the gyako zuki is the most affected blow at variable speed. Considering speed of blows as potential predictors of karate performance [1Loturco I, Artioli GG, Kobal R, Gil S, Franchini E. Predicting punching acceleration from selected strength and power variables in elite karate athletes: A multiple regression analysis. J Strength Cond Res 2014; 28(7): 1826-32.
[http://dx.doi.org/10.1519/JSC.0000000000000329] [PMID: 24276310]
], these findings may provide important information for coaches and physical trainers to delineate specific training to improve physical performance. It is recommended that the design of a training regime be directed to ballistic movement in the lower limbs for maintaining optimum levels of neuromuscular performance during punches performance.

Another important aspect is that the speed reduction observed in this study may suggest the possibility of using recovery strategies in competitive situations, which aim to delay the onset of fatigue and improve neuromuscular recovery.

CONCLUSION

Considering that karate is a sport whose variable speed predicts the sporting success, our results show the speed of behavior over an induced fatigue process. The results showed physiological fatigue after the KSAT fatigue protocol. During the protocol application there was a fall in the speed blow due to techniques in execution. There was a fall in the set too, indicating motor adaptations to fatigue process.

The process of fatigue generates motor adaptations to maintain speed blows. Soon, the athlete gets closer to the target, generating competitive disadvantage. Based on our findings, we will further develop studies involving a larger sample and comparing advanced athletes with beginners. We intend to identify at what time the fatigue process occurs more abruptly fall in scams speed.


CONSENT FOR PUBLICATION

Not applicable.

CONFLICT OF INTEREST

The authors declare no conflict of interest, financial or otherwise.

ACKNOWLEDGEMENTS

The authors are grateful to João Carlin Padilha (coach of the Brazilian national karate) for granting access to the athlete.

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[34] VencesBrito AM, Rodrigues Ferreira MA, Cortes N, Fernandes O, Pezarat-Correia P. Kinematic and electromyographic analyses of a karate punch. J Electromyogr Kinesiol 2011; 21(6): 1023-9.
[http://dx.doi.org/10.1016/j.jelekin.2011.09.007] [PMID: 22005009]
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