Secondary Logo

Journal Logo

Original Research

Proposal of a New Specific Cardiopulmonary Exercise Test for Taekwondo Athletes

Araujo, Marcus P.1,2; Nóbrega, Antônio C.L.1; Espinosa, Gabriel1,2; Hausen, Matheus R.1,2; Castro, Renata R.T.3; Soares, Pedro P.1; Gurgel, Jonas L.1,2

Author Information
Journal of Strength and Conditioning Research: June 2017 - Volume 31 - Issue 6 - p 1525-1535
doi: 10.1519/JSC.0000000000001312
  • Free

Abstract

Introduction

Taekwondo is a martial art originated in Korea more than 120 years ago (21). A combination of punching and kicking techniques characterize the art, different types of kicking are the most common techniques in training and competitions (26). Its popularity had increased over time, mainly in the last 2 decades, when it became an Olympic sport (20). Since then, many scientists have studied the physiological demands of Taekwondo, what is determinant for athlete's better performance (5,6,23).

The duration of the contest shall be 3 rounds of 2 minutes each, with a 1-minute rest period between then. In the case of a tie, there is an extra fourth round. Along the round, there are some breaks due to interruptions conducted by the referee (42). The official match structure leads to a complex intermittent metabolic demand, characterized by anaerobic and aerobic metabolic pathways' contributions (5,7). It is well known that Taekwondo training improves anaerobic capacity (5). However, recent studies reported that Taekwondo athletes also have an improved aerobic fitness (10,16,40).

Campos et al. (10) showed the contribution of the 3 metabolic pathways during a Taekwondo combat simulation, showing the main contribution of the aerobic metabolism during combat (66 ± 6%). The aerobic power is usually represented as maximum oxygen uptake (V̇o2max), being the most relevant variable to determine sportive performance, more precisely to prescribe Taekwondo training (8,15). Bridge et al. (8) pointed that high levels of aerobic fitness are important to support the complex metabolic demand of international taekwondo competition and have influence in recovery between the matches (5,10,16).

The literature also indicates that Taekwondo recreational practitioners, intermediate-level and elite athletes, are more resistant from anaerobic metabolism consequences such as acidosis (38,40). Regarding aerobic power, high-level athletes present V̇o2max values between 44 and 58 ml·kg−1·min−1 (5,15,26). The development of aerobic fitness contributes to the maintenance of intensity during the matches and increases the anaerobic threshold by improving blood lactate removal, phosphocreatine regeneration, and exercise tolerance (8,16,38,40).

Considering the importance of aerobic fitness for the performance of these athletes, it becomes essential to have feasible methods to assess V̇o2max during the execution of Taekwondo-specific techniques. The instruments and protocols commonly used do not impose the combat structure or techniques performed in this sport, that is, movements are not specific. Sports such as cycling, rowing, swimming, and running have specific ergometers and tests based on their key features (17–19,22,43,44). In other combat sports such as karate (11,29,37) and Muay Thai (13), cardiorespiratory exercise testing was developed based on specific motor tasks. In other words, unspecific tests may hinder the use of physiological responses in training prescription. There is a lack of studies dedicated to the development of specific testing techniques for evaluating Taekwondo and other combat sports athletes (31).

Although several studies have attempted to investigate V̇o2max, heart rate (HR) and blood lactate concentration in an attempt to define the role of aerobic and anaerobic pathways and their contribution to performance during Taekwondo competition (4,5,10), they have used nonspecific tests as the ones performed on a cycle ergometer or treadmill (23,24,26). In fact, few studies have investigated elite training and competition situation because of the low feasibility of this kind of essay. It is important to note that the measurement of V̇o2 and determination of anaerobic thresholds after nonspecific protocols usually shows results that cannot be extrapolated to a contest situation.

The high cost of gas analyzers may be a limiting factor for the use of cardiorespiratory exercise test. It is important to study more feasible variables such as HR and reserve heart rate (HRR), and the relationship between those and V̇o2 and V̇o2R. The reserve variables seem to have a linear behavior, with proximity to the identity line (14). This relationship was investigated using different protocols and ergometers, but still unknown for Taekwondo (33–35).

The development of a specific test that enables evaluation of the cardiorespiratory response during Taekwondo practice is crucial to individualize aerobic training, focusing on athletes' performance improvement (8,31). Because of the importance of sports specificity, we hypothesized that a Taekwondo-specific protocol would be an appropriate method for cardiorespiratory assessment of Taekwondo athletes. Therefore, the objective of this study was to propose a specific cardiopulmonary exercise test protocol for Taekwondo athletes and compare its results with the traditional exercise treadmill test.

Methods

Experimental Approach to the Problem

The study evaluated the behavior of the cardiorespiratory variables during a specific Taekwondo exercise test (TKDtest). The proposed test used a ramp protocol, followed the premise that this approach is a more appropriate method to assess the V̇o2peak and HRpeak, and the ventilatory thresholds (VTs). The obtained measurements during TKDtest were compared using an individualized ramp protocol (treadmill exercise test [TREADtest]) (28). The tests were realized in separate days to avoid the learning effect.

The subjects answered a questionnaire about the level of physical activity and cardiovascular risk and passed by a familiarization of the instruments and methods used in this research. A portable gas analyzer V̇o2000 (Medical Graphics, St. Louis, MN, USA) assessed the V̇o2 and a cardiotachometer (Polar RS800Cx; Polar Electro, Kempele, Finland) measured the HR. The instruments were used during the rest pretest for the obtention of reserve and rest variables and during the cardiorespiratory exercise test and rest period postexercise. Afterward, the results of both protocols (TKDtest and TREADtest) were compared to identify any possible differences.

The V̇o2 and HR are variables usually used to prescribe exercise. Otherwise, the VTs utilization is also indicated to help in the evaluation of aerobic fitness, performance, and training efficiency. The identification of these variables and a better understanding of their relationship could provide essential information to coaches and physical trainers to have a greater training control, training sessions design, and achieve an improved athletic performance during the competitive period.

Subjects

Fourteen male Taekwondo athletes (mean ± SD: 22 ± 4 years—max: 28 y·min−1: 18 years; body weight 69.2 ± 12.2 kg; height 176.5 ± 9.6 cm; and body mass index 22.1 ± 2.7 kg·m−2) participated in this study. This sample size considered a minimal statistical power of 0.8 and a significance level of 0.05 for all variables, mainly V̇o2peak. The inclusion criteria were (a) age between 18 and 35 years; (b) male athletes; (c) black belt level—World Taekwondo Federation style; (d) participation in a competitive training program and national official competitions (Brazilian Taekwondo Confederation or State affiliates events) in the last 2 years. Pursuing the most homogenous sample as possible, only black belt subjects participated in this study mainly because of the necessity of mastering technical and tactical aspects of this sport, thus contributing to minimize the variance of mechanical efficiency and metabolic behavior during the execution of techniques. All subjects were evaluated during the same competitive phase, after the main national competitions. Individuals taking any medication, with chronic comorbidities, or unable to perform the tests were excluded. All participants were properly informed about the purpose and procedures of the study and signed an informed consent to participate. The study had the approval of the university ethical committee (report number 276/996 on May 20, 2013), according to the resolution 466/12 of Brazilian National Health Council.

The study design included 3 visits to the laboratory. On the first day, the subjects participated in anthropometric assessment and familiarization to the treadmill (Super ATL; Inbrasport, Porto Alegre, Brazil). On the second and third days, subjects were randomly submitted to the maximum incremental exercise test on the treadmill (TREADtest) and specific incremental exercise test (TKDtest). Each exercise test was performed in a counterbalanced order and separated by 2–7 day's interval to avoid adaptation effects. Because of possible circadian variation in athletic performance, all tests were performed at the same time of the day.

Procedures

The participants received a series of recommendations: (a) to rest on the night before the exercise protocols performance; (b) to not consume foods or beverage that contains caffeine or any other ergogenic substance; (c) to repeat the same diet pattern recorded in all visits, to ensure similar energetic balance; (d) to avoid intense or severe exercises for 24 hours before the tests.

At the first visit, the volunteers once signed the informed consent. Subjects completed the Physical Activity Readiness Questionnaire to rule out individuals with cardiovascular disease or orthopedic problems and completed a questionnaire for the classification of cardiorespiratory fitness without exercise to predict V̇o2max (25). Moreover, height and weight were measured. Then, the subjects performed an adaptation trial. At this opportunity, they could be presented to protocols and equipment devices, such as face mask, perceived exertion scale, the kicking targets, and the sound signals for the Taekwondo-specific protocol. Before exercise, each athlete rested for 14 minutes in a supine position while V̇o2 and HR were monitored (Figure 1A). These values were used for analysis of their reserve variables.

Figure 1.
Figure 1.:
Representative figure of TREADtest and TKDtest. A) Resting period. B) TREADtest. C) Gas analyzer instrumentation for TKDtest. D) TKDtest (roundhouse kick). TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test.

The incremental exercise test on the treadmill Super ATL (Inbrasport) consisted of an individualized ramp protocol. The athletes should achieve a maximum effort in 10 minutes of exercise, with a regular increment of speed and a fixed grade (1%) (9) (Figure 1B). The V̇o2max estimated by the Matthews model was converted to maximum velocity (vV̇o2max), using the American College of Sports Medicine running equation to individualize the work-rate (1). The work-rate was determined by the difference between vV̇o2max and 50% of vV̇o2max divided by target time (10 minutes), according to Myers et al. (28). All participants performed a warm-up light running exercise for 3 minutes at a constant speed of 4.5 km·h−1 before the treadmill test.

Tests were considered maximal when at least 3 of the 4 previously established criteria were achieved (14,27): (a) maximum perception of effort as reflecting assigned 10 in adapted Borg's scale; (b) HR ≥90% of predicted HRmax (220-age) or presence of a HR plateau (ΔHR in 2 consecutive work rates <4 b·min−1); (c) presence of a plateau of V̇o2 (ΔV̇o2 in 2 consecutive work rates <2.1 ml·kg−1·min−1); (d) a gas exchange ratio (Rmax) > 1.1.

A previous pilot study defined the TKDtest, inspired on the commonly used ramp protocol, where the load increases progressively until the maximum effort. During the test, each athlete performed Roundhouse kick (Dolio-Tchagi) repeatedly, according to sound signals, with 2 evaluators checking if the subject was performing the correct frequency of kicks. The high rate of Roundhouse kick during competition and training was the main reason to choose this technique. Roundhouse kick is the most used technique in Taekwondo competitions (10,38). The load increment was based on increasing kick frequency. Two experimenters have controlled the kick impact by visual inspection. Before the test, participants were asked to perform kicks with a typical scoring impact, establishing a reference kicking impact for subsequent visual inspection. In addition, experimenters were responsible to check the proper kicking frequency. Subjects started at 10 kicks per minute and increased 3 kicks each minute through the end. Before the protocol begins, the subjects participated in a warm-up period of 5 minutes. This warm-up consisted of free Taekwondo displacements and kicks, wearing the full test equipment, with an intensity zone ranging between 100 and 120 b·min−1 (Figure 1C–D). After that, subjects were instructed to remain in the fight position waiting for the sound signal to perform the roundhouse kicks alternating the legs. The criteria to consider the test as maximal were the same criteria as mentioned earlier for the TREADtest with the addition of 1 specific criterion: 3 consecutive missed kicks. In other words, when the subject could not respect the sonorous stimulus for 3 consecutive kicks, the test was interrupted.

Oxygen consumption was measured by a portable gas analyzer V̇o2000 (Medical Graphics) based on the open chamber system, and data were recorded every 10 seconds. A low-flow pneumotachograph was used to measure respiratory variables at the initial resting, and a medium-flow pneumotachograph was used for exercise measurement, following the manufacturer instructions. Heart rate was monitored with a cardiotachometer (Polar RS800Cx; Polar Electro). All tests were performed in a controlled setting, and the temperature was kept approximately at 20° C. The equipment was calibrated and fixed, according to the manufacturer specifications.

Oxygen uptake and HR were directly measured from de warm-up to the posttest resting. Other variables were derived from these data: the highest value of V̇o2 and HR during the test (V̇o2peak and HRpeak); ventilatory thresholds 1 and 2 (VT1 and VT2); VT1 and VT2 normalized by V̇o2peak (%V̇o2peak) and HRpeak (%HRpeak). Ventilatory threshold 1 was considered as the lowest point of the ventilatory equivalent (V̇E/V̇o2) and fraction of expired oxygen (FE/O2) before its progressive increase. Ventilatory threshold 2 was obtained at the lowest point of the fraction of expired carbon dioxide (FE/Co2) and the lowest point of the carbon dioxide ventilatory equivalent (V̇E/V̇Co2) before its progressive increase. Two experienced and independent evaluators analyzed the data. If both evaluators disagreed by more than 10% when identifying thresholds, a third evaluator would be included. However, a third evaluator was not necessary for any tests. Finally, reserve oxygen consumption (V̇o2R) and HRR were obtained by the difference between the instant and resting variables: (V̇o2R = V̇o2−V̇o2rest) and (HRR = HR−HRrest).

Statistics Analyses

For the statistical analysis, first the Shapiro-Wilk test was used to confirm data normal distribution, thereby allowing the use of mean and SD values. Paired student's T-test was used to compare data between tests. To investigate possible differences in the behavior of the variables V̇o2, V̇o2R, HR, and HRR during the 2 tests, data were divided into quartiles considering test duration. A 2-way analysis of variance followed by Bonferroni post hoc test (in case of significative F ratios) was used for comparison of quartiles, assuming the p value after significance verification of the Mauchly's sphericity test. Being used the value of sphericity assumed or the Greenhouse-Geisser adjustment was used when sphericity was rejected by Mauchly test. To analyze the V̇o2-time and HR-time relationship and its proximity to the identity line, Passing-Bablok regression was used and paired samples Student's T-test was used to compare intercepts and slopes obtained between tests.

The intraclass correlation coefficient (ICC) was calculated to express the reliability of the specific protocol. To analyze the magnitude of the differences, effect size (ES; Cohen's d) was calculated (12). Effect size values were considered in accordance with Rhea (30) as trivial (<0.25), small (0.25–0.50), moderate (0.50–1.00), and large (>1.00). Bland-Altman analysis was used to test the concordance between methods, quantifying the 95% limits of agreement (95% LOAs) (the mean difference ± 1.96 times the SD of the differences). The level of significance adopted for all tests was p ≤ 0.05. The statistical package SPSS (SPSS 17.0 for Windows; SPSS Inc., Chicago, IL, USA) was used for almost all tests except Passing-Bablok regressions, which used MedCalc 12.7.5 (MedCalc Software, Ostend, Belgium), and ES (d), which used GPower 3.0.10 software (Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany).

Results

Table 1 shows cardiorespiratory variables during both tests: TREADtest and TKDtest. A significant difference was found only in V̇o2R (p = 0.03/ES = 0.422), no differences were found for the other variables and ES was considered small.

Table 1.
Table 1.:
Comparison between cardiopulmonary exercise test on treadmill and Taekwondo-specific exercise test*.

Heart rate and oxygen uptake were divided into quartiles, in function of time, to verify the kinetics of variables along the tests. Figure 2 presents the oxygen uptake during the tests. There was no significant difference between the tests. The same behavior can be observed in V̇o2R, and therefore no differences were found between tests in quartiles; however, the specific test values tend to be higher in first and second quartiles and similar in third and fourth quartiles (Figure 3).

Figure 2.
Figure 2.:
o 2 in the 2 tests on quartiles. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; V̇o 2—oxygen consumption; Q = quartile.
Figure 3.
Figure 3.:
o 2R in the 2 tests on quartiles. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; V̇o 2R = reserve oxygen consumption; Q = quartile.

Figure 4 shows that HR increased faster in the TREADtest than in the TKDtest, although peak HR was the same in both tests. Significant differences were found in the first (p = 0.030/ES = 0.982) and second (p = 0.017/ES = 1.048) quartiles, ES for both were considered large. However, no significant differences were found in third and fourth quartiles. For HRR, no significant differences were found between tests in quartiles (Figure 5). In this case, the values of the first and second quartiles are higher in TKDtest, although the values of the third and fourth quartiles were similar.

Figure 4.
Figure 4.:
HR in the 2 tests on quartiles. *Differences between TREADtest and TKDtest, p ≤ 0.05. TREADtest = Treadmill Test; TKDtest = Taekwondo-specific Exercise Test; HR = Heart rate; Q = quartile.
Figure 5.
Figure 5.:
HRR in the 2 tests on quartiles. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; HRR = reserve heart rate; Q = quartile.

Table 2 shows the values of intercept and slope obtained in the Passing-Bablok regressions. In the regressions, linearity was not found for any variables in the 2 tests (p < 0.01). Comparing the values of the intercept and slope between TREADtest and TKDtest, significant differences were found for HR, in the values of the intercept (p = 0.01/ES = 1.132) and slope (p = 0.05/ES = 0.970), and the slope (p = 0.02/ES = 1.081) of HRR only; ES were considered moderate for HR slope and large for HR intercept and HRR slope. The results show that the slope values were higher in TREADtest and intercept values were higher in TKDtest.

Table 2.
Table 2.:
Values of intercept and slope to V̇o 2, V̇o 2R, HR, and HRR on tests*.

Finally, to verify the reliability and consistency of the measures (assessment) in the 2 tests, ICC was calculated for the variables V̇o2peak (ICC = 0.855, p = 0.003), V̇o2 VT1 (ICC = 0.709/p = 0.030) and V̇o2 VT2 (ICC = 0.848/p = 0.003), HRpeak (ICC = 0.594/p = 0.086); HR VT1 (ICC = 0.388/p = 0.194) and HR VT2 (ICC = 0.364/p = 0.213). Significant reliability was found for the variables V̇o2peak and V̇o2 VT1 and VT2. The 95% LOAs of the same variables, including time at peak (TAP), are presented on the Bland-Altman plots (Figures 6–12).

Figure 6.
Figure 6.:
Bland-Altman plot for V̇o 2peak in TREADtest and TKDtest. Mean = 2.2, 95% CI = −0.2 to 4.6, SD = 4.2; lower limit = −6.0, 95% CI = −10.3 to −1.7; upper limit = 10.5, 95% CI = 6.2 to 14.8; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; V̇o 2peak = maximum oxygen consumption.
Figure 7.
Figure 7.:
Bland-Altman plot for V̇o 2 VT1 in TREADtest and TKDtest. Mean = 2.7, 95% CI = 1.3 to 6.7, SD = 7.0; lower limit = −11.1, 95% CI = −18.2 to −3.9; upper limit = 16.5, 95% CI = 9.4 to 23.6; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; V̇o 2 VT1 = oxygen consumption in ventilatory threshold 1.
Figure 8.
Figure 8.:
Bland-Altman plot for V̇o 2 VT2 in TREADtest and TKDtest. Mean = 0.4, 95% CI = −2.6 to 3.5, SD = 5.4; lower limit = −10.1, 95% CI = −15.6 to −4.7; upper limit = 11.0, 95% CI = 5.5 to 16.5; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; V̇o 2 VT2 = oxygen consumption in ventilatory threshold 2.
Figure 9.
Figure 9.:
Bland-Altman plot for HRpeak in TREADtest and TKDtest. Mean = 2.2, 95% CI = −2.2 to 6.7, SD = 7.7; lower limit = −12.9, 95% CI = −20.8 to −5.0; upper limit = 17.5, 95% CI = 9.6 to 25.4; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; HRpeak = heart rate peak.
Figure 10.
Figure 10.:
Bland-Altman plot for HR VT1 in TREADtest and TKDtest. Mean = −2.4, 95% CI = −8.6 to 3.8, SD = 10.8; lower limit = −23.7, 95% CI = −34.6 to −12.7; upper limit = 18.8, 95% CI = 7.8 to 29.8; n = 14). TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; HR VT1 = heart rate in ventilatory threshold 1.
Figure 11.
Figure 11.:
Bland-Altman plot for HR VT2 in TREADtest and TKDtest. Mean = 4.5, 95% CI = −2.3 to 11.3, SD = 11.9; lower limit = −18.8, 95% CI = −30.9 to −6.8; upper limit = 27.8, 95% CI = 15.8 to 39.9; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; HR VT2 = heart rate in ventilatory threshold 2.
Figure 12.
Figure 12.:
Bland-Altman plot for TAP in TREADtest and TKDtest. Mean = 16.6, 95% CI = −99.3 to 132.5, SD = 200.8; lower limit = −376.9, 95% CI = −580.0 to −173.9; upper limit = 410.1, 95% CI = 207.0 to 613.2; n = 14. TREADtest = treadmill test; TKDtest = taekwondo-specific exercise test; TAP = time at peak.

Discussion

This study has proposed a new method for cardiorespiratory assessment of Taekwondo athletes, based on the ramp protocol, commonly used in a conventional cardiopulmonary exercise test. Previous studies proposed specific methods; however, these have limitations on the assessment of respiratory variables (7,28). The results of this study showed that the kinetics of V̇o2, V̇o2R, HR, and HRR, viewed by comparison between quartiles and Passing-Bablok regressions, were partially different, suggesting a possible influence of specificity of motor tasks involved. That may be due to a specificity of the motor task, but this finding needs further investigation.

Commonly, the competitive Taekwondo training emphasizes the anaerobic capacity (21,31), although studies show that elite athletes have a significant development of aerobic fitness (32,39). Campos et al. (10) assessed Taekwondo athletes during a simulated combat situation, aiming to investigate the following physiological responses: HR, oxygen uptake, and blood lactate concentration. V̇o2peak values (49.9 ± 7.1 ml·kg−1·min−1) and peak HR (181 ± 9 b·min−1) were similar to the findings in this study (table 1). The V̇o2peak values were slightly higher and HR slightly lower at the second (52.1 ± 5.9 ml·kg−1·min−1/169 ± 9 b·min−1) and third rounds (53.4 ± 5.9 ml·kg−1·min−1/175 ± 10 b·min−1). These results may be related to the experimental study design, characterized by intervals between rounds, which is in agreement with the official fight structure.

Comparing with this study, it can be observed that the values of V̇o2peak and HRpeak approached those found in a simulated combat situation and Taekwondo-specific exercises. The values obtained by TKDtest are similar to the studies that evaluated Taekwondo and other intermittent exercises as shown (6,11,38,44). Thus, these values are close to those found in TREADtest. This suggests a significant contribution to cardiorespiratory fitness and, consequently, aerobic fitness, in agreement with the study by Campos et al. (10) and Markovic et al. (23).

These considerations related to simulated combat or specific motor task assessment are also valid for others combat sports. Nunan (29) proposed a karate-specific aerobic test (KSAT) to evaluate the aerobic fitness of karate practitioners. The V̇o2peak and HRpeak values were similar to those found in this study. Chaabene et al. (11) studied the reliability of KSAT and found similar results, reinforcing this evidence. Tabben et al. (37) proposed a new karate specific-test (KST) to assess aerobic capacity and verify the validity and reproducibility of measures. No significant differences were found in V̇o2peak, HRpeak and time to exhaustion (TE) between KST and progressive maximal exercise test on a cycle ergometer, same as in the present study (Table 1). However, the V̇o2peak, HRpeak, and TE values are higher compared with those in TKDtest.

Even considering the technical and tactical differences between karate and taekwondo, they seem to have a similar metabolic demand. However, they showed an important participation of aerobic metabolism during the combat, similar to taekwondo (7,8).

Regarding the comparisons between cardiorespiratory variables in the tests, no significant difference was found in most of the analyzed variables, except to V̇O2R. At the same time, the similarity between HRpeak during TREADtest and TKDtest can corroborate the considerations about the V̇o2peak. The results found in this study are consistent when compared with the values of V̇o2peak and HRpeak found in other taekwondo-specific training protocol or combat simulation trials (7,10,25,31). Regarding the V̇o2 and HR in VT 1 and 2, the results were similar between tests. Thus, the TKDtest structure allows easy detection of these thresholds, which are directly related to the training prescription (1,28,41). For the TAP, there was no difference between the TREADtest and TKDtest. In contrast, the TKDtest, less prolonged and based on a traditional protocol established in the literature for assessment of cardiopulmonary function, may be useful to evaluate athletes in a shorter period (Table 1).

Studies such as Whipp et al. (41) and Myers et al. (28) indicate that the ramp protocol enables a better linear relationship between the work rate and V̇o2. Making more reliable to assess the variables kinetics, considering that the treadmill cardiopulmonary exercise test is the gold standard for cardiorespiratory assessment (1,2). The similarity between the peak values in the tests suggests that the Taekwondo-specific test assessment is valid. In terms of applicability on sports teams and training centers, TKDtest requires less time, allowing the evaluation of several athletes in 1 session. In terms of material resources, the test allows coaches and trainers to conduct the assessments in own training centers.

However, the assessment of cardiorespiratory variables still needs the use of a gas analyzer, because variables such V̇o2 or V̇o2R did not present a linear relationship with HR or HRR. Added to that, remains the fact that is still necessary to build a predictive model for V̇o2max estimation. The findings of this study may allow a better aerobic training prescription for Taekwondo practitioners, showing the importance of cardiorespiratory variables' measurements and the study of their interrelationships.

Therefore, evaluations would not be more conditioned to the availability of an ergometer, being available, faster and cheaper. Besides, the specific test compared with treadmill running can be more comfortable for athletes, because motor tasks are more specific to Taekwondo training and combat situations.

Similarities can also be observed in the comparisons between the V̇o2, V̇o2R, HR, and HRR kinetics in both tests (Figures 2–5). Significant differences were found in HR in the first and second quartiles, which possibly can be attributed to the difference in the motor task and muscle mass volume involved (36). Several studies have proposed specific methods for other sports, indicating significant differences in the mean values and their kinetics when compared with traditional exercise tests (11,37,43,44). The difference between the ergometer and protocols used in conventional cardiopulmonary testing is also evidenced (28,41).

Regarding the variables V̇o2, V̇o2R, HR, and HRR, no studies were found that compared or described the kinetics of these variables in Taekwondo performance. Although the relationship between these variables in diverse populations is not clear, the literature has shown that these variables are important for exercise prescription, providing more precision and effectiveness (14). For the determination of these variables, there is no further standardization in the type of protocol used for exercise testing, it is possible to find studies with different ergometers and protocols (14,34,35).

The Passing-Bablok regressions showed no linearity in the kinetics of these variables in the 2 tests (p < 0.01). At the same time, significant differences were found for HR and HRR, indicating a different cardiovascular demand between the tests. These results corroborate other findings showing that the kinetics of cardiorespiratory variables between the tests are different, and the motor task performed on the treadmill and the specific motor task are different. Finally, this study shows that Taekwondo-specific test is reliable for the evaluation of cardiorespiratory variables.

Bland-Altman plots reported variations in the agreement values for V̇o2peak and V̇o2 during VTs (Figures 6–8), but still within the agreement limits. V̇o2peak presented a mean difference (bias) ± 95% LOA of 2.2 ± 8.4 ml·kg−1·min−1 between TREADtest and TKDtest. V̇o2 in VT2 (V̇o2 VT2) exhibited fewer differences between tests with limits of 0.4 ± 0.7 ml·kg−1·min−1 when compared with V̇o2 in VT1 (2.7 ± 13.8 ml·kg−1·min−1). Similar behavior occurred for HRpeak and HR during VT1 (HR VT1) (Figures 9–11). However, HRpeak (2.3 ± 15.2 b·min−1) and HR VT1 (2.4 ± 16.4 b·min−1) presented less variation than HR VT2 (4.5 ± 23.4 b·min−1). Time at peak also presented variations, but most of the values are still within the agreement limits (16.6 ± 393.5 seconds) (Figure 12). Tabben et al. (37) reported a mean difference of 1.9 ± 7.35 ml·kg−1·min−1 for a specific karate test. Although these results are similar to those of this study, the mean difference is higher in TKDtest for the V̇o2peak. The V̇o2 VT1 and V̇o2 VT2 exhibited less variation than V̇o2peak, suggesting that these variables may be used to prescribe the aerobic training for taekwondo athletes.

The specific motor task is a factor that must be considered in the cardiorespiratory fitness assessment and exercise prescription for this population. Additionally, specific training zones can be established based on cardiorespiratory responses during the execution of Taekwondo-specific activities. Probably, this would result in a more efficient and accurate exercise prescription, because of the mastering of cardiorespiratory responses during Taekwondo-specific exercise. Although both exercise tests are dynamic and involve the effective participation of lower limbs, the motor tasks (running and kicking) are biomechanically different. Therefore, the neuromuscular response is also different, which results in a singular metabolic demand (36). It is suggested that possible mechanisms could be involved such as the amount of muscle mass involved and the optimal recruitment of specifically trained muscle fibers (36). However, further studies are needed to clarify those mechanisms for different modalities tests.

In practical terms, the results of this study are important to aerobic training prescription for Taekwondo practitioners. The various VT zones, cardiorespiratory reserve variables, and peak values should be essential to exercise prescription during different phases of training. Other studies corroborate the importance of aerobic fitness to Taekwondo performance (7,8,15,21). This is indispensable to the maintenance of intensity during combat and recovery between rounds and fights. These aspects can be determinant of athletic performance.

Future studies may suggest an individualized ramp protocol for the specific Taekwondo test, considering this has been the most used strategy in conventional cardiopulmonary exercise tests. It is possible that this strategy could improve the linearity behavior of the relationship between the cardiorespiratory variables and power, making the gas analyzer dispensable. It is necessary to point out that the difficulty in instrumentation is a complicating factor, but the findings of this study and the previous ones are important for the development of the scientific corpus of knowledge.

However, the differences between cardiorespiratory variables between the tests were not significant. The TKDtest presents a viable method for evaluation of Taekwondo athletes, enabling coaches or exercise physiologists to conduct evaluations in training facilities, thereby eliminating the need of an ergometer. The specific test does not involve all techniques of Taekwondo or mental stress of an official combat (7,8,23). However, it presents satisfactory specificity, feasibility, and accuracy to assess the cardiorespiratory fitness of this population.

Practical Applications

Based on the cardiorespiratory approach, this study has some limitations such as not measuring the impacts of kicking, neuromuscular behavior, and blood lactate. Before the widespread use of the TKDtest, as opposed to more traditional tests, reliability needs to be confirmed. Repeatability and sensibility are important aspects of a reliable testing method. The findings of this study may be useful for aerobic training prescription, providing sport-specificity for the aerobic assessment. Furthermore, oxygen uptake and HR may respond differently to Taekwondo stimuli, modifying the test outcome. The proper aerobic evaluation and training prescription may improve several capacities such as between-bouts recovery and enhanced tolerance to training sessions. Finally, the presented method fits the technique repertoire of Taekwondo athletes and presents a compelling alternative to training centers.

Acknowledgments

The authors thank those who helped too much this study: the athletes who voluntarily participated in this study. The authors also thank the organs that supported the study: Carlos Chagas Filho Foundation for the Research Support in the State of Rio de Janeiro (FAPERJ) by a funding program, the Brazilian Council for the Technological and Scientific Development (CNPq), and the Coordination for the Improvement of Higher Level Personnel (CAPES) for the researchers' grants. This study was supported by funds from the Carlos Chagas Filho Foundation for the Research Support in the State of Rio de Janeiro (FAPERJ) and else grants from the Brazilian Council for the Technological and Scientific Development (CNPq), and the Coordination for the Improvement of Higher Level Personnel (CAPES).

References

1. American College of Sports Medicine (ACSM). Guidelines for Exercise Tests and Prescription (8th ed.). Philadelphia, PA: Lippincott Williams & Wilkins, 2010. pp. 250.
2. Bellar D, Tomescu V, Judge LW. Relationship of an equivalence point for change in VCO2 and VO2 to endurance performance. J Strength Cond Res 27: 1394–1399, 2013.
3. Bogdanis GC, Nevill ME, Boobis LH, Lakomy HK. Contribution of phosphocreatine and aerobic metabolism to energy supply during repeated sprint exercise. J Appl Physiol (1985) 80: 876–884, 1996.
4. Bouhlel E, Jouini A, Gmada N, Nefzi A, Abdallah BK, Tabka Z. Heart rate and blood lactate responses during taekwondo training and competition. Sci Sports 21: 285–290, 2006.
5. Bridge CA, Jones MA, Drust B. Physiological responses and perceived exertion during international taekwondo competition. Int J Sports Physiol Perform 4: 485–493, 2009.
6. Bridge CA, Jones MA, Hitchen P, Sanchez X. Heart rate responses to taekwondo training in experienced practitioners. J Strength Cond Res 21: 718–723, 2007.
7. Bridge CA, McNaughton LR, Close GL, Drust B. Taekwondo exercise protocols do not recreate the physiological responses of championship combat. Int J Sports Med 34: 573–581, 2013.
8. Bridge CA, Santos JF, Chaabene H, Pieter W, Franchini E. Physical and physiological profiles of taekwondo athletes. Sports Med 44: 713–733, 2014.
9. Buchfuhrer MJ, Hansen JE, Robinson TE, Sue DY, Wasserman KA, Whipp BJ. Optimizing the exercise protocol for cardiopulmonary assessment. J Appl Physiol Respir Environ Exerc Physiol 55: 1558–1564, 1983.
10. Campos FA, Bertuzzi R, Dourado AC, Santos VG, Franchini ED. Energy demands in taekwondo athletes during combat simulation. Eur J Appl Physiol 112: 1221–1228, 2012.
11. Chaabene H, Hahcna Y, Franchini E, Mkaouer B, Montassar M, Chamari K. Reliability and construct validity of the karate-specific aerobic test. J Strenght Cond Res 26: 3454–3460, 2012.
12. Cohen J. Statistical Power Analysis for the Behavioral Sciences. Hillsdale, HJ: Eribaum, 1988.
13. Crisafulli A, Vitelli S, Cappai I, Milia R, Tocco F, Melis F, Concu A. Physiological responses and energy cost during a simulation of a muay thai boxing match. Appl Physiol Nutr Metab 34: 143–150, 2009.
14. Cunha FA, Midgley AW, Monteiro WD, Farinatti PT. Influence of cardiopulmonary exercise testing protocol and resting VO(2) assessment on %HR(max), %HRR, %VO(2max) and %VO(2)R relationships. Int J Sports Med 31: 319–326, 2010.
15. Fong SS, Ng GY. Does taekwondo training improve physical fitness? Phy Ther Sport 12: 100–106, 2011.
16. Heller JP, Peric T, Dlouha R, Kohlikova E, Melichna J, Novakova H. Physiological profiles of male and female taekwon-do (ITF) black belts. J Sports Sci Med 16: 243–249, 1998.
17. Holmér I, Lundin A, Eriksson BO. Maximum oxygen uptake during swimming and running by elite swimmers. J Appl Physiol 36: 711–714, 1974.
18. Huntsman HD, DiPietro L, Drury DG, Miller TA. Developmente of a rowing-specific VO2max field test. J Strenght Cond Res 25: 1774–1779, 2011.
19. Ingham SA, Pringle JS, Hardman SL, Fudge BW, Richmond VL. Comparison of step-wise and ramp-wise incremental rowing exercise testes and 2000-m rowing ergometer performance. Int J Sports Physiol Perform 8: 123–129, 2013.
20. International Olympic Committe. Taekwondo: Participation During the History of the Olympic Games. Research and Reference Service Olympic Studies, 2011. Available at: http://www.olympic.org/Assets/OSCSection/pdf/QR_sports_summer/Sports_Olympiques_taekwondo_eng.pdf. Accessed January 26, 2017.
21. Kazemi M, Perri G, Soave D. A profile of 2008 Olympic taekwondo competitors. J Can Chiropr Assoc 54: 243–249, 2010.
22. Lawton TW, Cronin JB, McGuigan MR. Strength, power, and muscular endurance exercise and elite rowing ergometer performance. J Strength Cond Res 27: 1928–1935, 2013.
23. Markovic G, Mišigoj-Duraković M, Trninić S. Fitness profile of elite croatian female taekwondo athletes. Coll Antropol 29: 93–99, 2005.
24. Matsushige KA, Hartamnn K, Franchini E. Taekowndo: Physiological responses and match analysis. J Strength Cond Res 23: 1112–1117, 2009.
25. Matthews CE, Heil DP, Freedson PS, Pastides H. Classification of cardiorespiratory fitness without exercise testing. Med Sci Sports Exerc 31: 486–493, 1999.
26. Melhim AF. Aerobic and anaerobic power responses to the practice of taekwon-do. Br J Sports Med 35: 231–235, 2001.
27. Midgley AW, Carroll S, Marchant D, McNaughton LR, Siegler J. Evaluation of true maximal oxygen consumption based on a novel set of standardized criteria. Appl Physiol Nutr Metab 34: 1–9, 2009.
28. Myers J, Buchanan N, Smith D, Neutel J, Bowes E, Walsh D, Froelicher VF. Individualized ramp treadmill. Observations on a new protocol. Chest 101: 236–241, 1992.
29. Nunan D. Development of a sports specific aerobic capacity test for karate—A pilot study. J Sports Sci Med 5: 47–53, 2006.
30. Rhea M. Determining the magnitude of treatment effects in strength training research through the use of the effect size. J Strength Cond Res 18: 918–920, 2004.
31. Sant'Ana J, Silva JF, Guglielmo LG. Physiological variables identified during a specific progressive test for Taekwondo. Motriz 15: 611–620, 2009.
32. Santos VG, Franchini E, Lima-Silva AE. Relationship between attack and skipping in taekwondo contests. J Strength Cond Res 25: 1743–1751, 2011.
33. Swain DP. Energy cost calculations for exercise prescription: An update. Sports Med 30: 17–22, 2000.
34. Swain DP, Leutholtz BC. Heart rate reserve is equivalent to %VO2 reserve, not to %VO2max. Med Sci Sports Exerc 29: 410–414, 1997.
35. Swain DP, Leutholtz BC, Branch JD. Relationship between % heart rate reserve and %VO2reserve in treadmil exercise. Med Sci Sports Exerc 30: 318–321, 1998.
36. Stromme SB, Ingjer F, Meen HD. Assessment of maximal aerobic power in specifically trained athletes. J Appl Physiol Respir Environ Exerc Physiol 42: 833–837, 1977.
37. Tabben M, Coquart J, Chaabène H, Franchini E, Chamari K, Tourny C. Validity and reliability of a new karate-specific aerobic field test for karatekas. Int J Sports Physiol Perform 9: 953–958, 2014.
38. Thompson WR, Vinueza C. Physiologic profile of Tae Kwon Do black belts. Sports Med Train Rehab 3: 49–53, 1991.
39. Tomlin DL, Wenger HA. The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Med 31: 1–11, 2001.
40. Toskovic NN, Blessing D, Williford HN. Physiologic profile of recreational male and female novice and experienced Tae Kwon Do practitioners. J Sports Med Phys Fitness 44: 164–172, 2004.
41. Whipp BJ, Davis JA, Torres F, Wasserman K. A test to determine parameters of aerobic function during exercise. J Appl Physiol Respir Environ Exerc Physiol 50: 217–221, 1981.
42. World Taekwondo Federation. Competition Rules & Interpretation, 2010. pp. 194. Available at: http://www.worldtaekwondofederation.net/wp-content/uploads/2010/2/WTF_Competition_Rules__Interpretation_May_11_2010.pdf. Accessed January 26, 2017.
43. Yoshiga CC, Higuchi M. Rowing performance of female and male rowers. Scand J Med Sci Sports 13: 317–321, 2003.
44. Zamparo P, Swaine IL. Mechanical and propelling efficiency in swimming derived from exercise using a laboratory-based whole-body swimming ergometer. J Appl Physiol (1985) 113: 584–594, 2012.
Keywords:

aerobic fitness; oxygen uptake; heart rate; martial arts

© 2015 National Strength and Conditioning Association