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We aimed to compare the change in exercise response to taekwondo-specific circuit workouts before and after competition rule amendments. A total of 240 workouts in 15 elite athletes were analyzed over two years. Physiological and kinematic data were gathered with the wireless Bioharness system along with capillary blood samples for lactate concentration. Progressive exercise tests until exhaustion were periodically performed to obtain reference data. The rule changes resulted in significant increases (mainly medium or large effects) in the physiological (2.9-14.4%) and kinematic (4.8-10.1%) response to taekwondo-specific workouts. The largest increases were for peak breathing rate (12.0%), energy expenditure (6.6%), blood lactate immediately after exercise (10.2%) and at the 30th min of recovery (14.4%), and peak kinematic activity (10.1%). Significant differences between taekwondo-specific workouts and tournament combats persisted after the shift from old to new rules, ranging from 2.4 to 38.5% for physiological and from 2.9 to 15.5% for kinematic variables. The largest workout-combat differences were revealed for post-exercise (15.9%) and recovery (38.5%) blood lactate, peak (-15.8%) and relative (-15.0%) breathing rate, and mechanical (13.5%) and physiological (14.2%) intensity. Our study suggests that the rule amendments significantly modify the exercise response to discipline-specific workouts and that taekwondo-specific training sessions do not fully recreate the tournament demands in terms of physiological and kinematic load.
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International Journal of
Environmental Research
and Public Health
Article
The Eect of Sports Rules Amendments on Exercise
Intensity during Taekwondo-Specific Workouts
Michał Janowski 1, Jacek Zieli ´nski 1, Monika Ciekot-Sołtysiak 1, Agata Schneider 2and
Krzysztof Kusy 1, *
1
Department of Athletics, Strength and Conditioning, Poznan University of Physical Education, ul. Kr
ó
lowej
Jadwigi 27/39, 61-871 Pozna´n, Poland; mjanowski@awf.poznan.pl (M.J.); jacekzielinski@wp.pl (J.Z.);
ciekot@awf.poznan.pl (M.C.-S.)
2Department of Cardiology Intensive Care Therapy and Internal Medicine, Poznan University of
Medical Sciences, ul. Przybyszewskiego 49, 60-355 Pozna´n, Poland; aamille@wp.pl
*Correspondence: kusy@awf.poznan.pl
Received: 25 July 2020; Accepted: 16 September 2020; Published: 17 September 2020


Abstract:
We aimed to compare the change in exercise response to taekwondo-specific circuit
workouts before and after competition rule amendments. A total of 240 workouts in 15 elite athletes
were analyzed over two years. Physiological and kinematic data were gathered with the wireless
Bioharness system along with capillary blood samples for lactate concentration. Progressive exercise
tests until exhaustion were periodically performed to obtain reference data. The rule changes resulted
in significant increases (mainly medium or large eects) in the physiological (2.9–14.4%) and kinematic
(4.8–10.1%) response to taekwondo-specific workouts. The largest increases were for peak breathing
rate (12.0%), energy expenditure (6.6%), blood lactate immediately after exercise (10.2%) and at the
30th min of recovery (14.4%), and peak kinematic activity (10.1%). Significant dierences between
taekwondo-specific workouts and tournament combats persisted after the shift from old to new rules,
ranging from 2.4 to 38.5% for physiological and from 2.9 to 15.5% for kinematic variables. The largest
workout–combat dierences were revealed for post-exercise (15.9%) and recovery (38.5%) blood
lactate, peak (
15.8%) and relative (
15.0%) breathing rate, and mechanical (13.5%) and physiological
(14.2%) intensity. Our study suggests that the rule amendments significantly modify the exercise
response to discipline-specific workouts and that taekwondo-specific training sessions do not fully
recreate the tournament demands in terms of physiological and kinematic load.
Keywords: acceleration; blood lactate; breathing rate; energy expenditure; heart rate
1. Introduction
Sports rules are amended to strengthen the ethos of a sport discipline, adapt it to capabilities and
needs of specific groups, attract spectators, respond to media pressure and interest, recruit athletes,
or improve sports performance [
1
,
2
]. To achieve these goals, structural (space, time, equipment),
functional (athletes’ behavior, obligations, rights, prohibitions, penalties), and other rules are being
modified [
1
]. As shown in various sport disciplines, rule changes aect exercise response to competition
tasks. In particular, the modifications impact exercise intensity or overall physical load, usually by
increasing [39] or, less often, by decreasing it [10,11].
In recent years, World Taekwondo incorporated modern technology into the discipline, i.e.,
the Protector Scoring System (PSS), the instant Video Replay System (VRS), and relevant competition
rule changes [
12
16
]. The latest revisions in Olympic taekwondo rules penalize non-fighting actions,
the presence of “phantom striking”, and unnecessary leg elevation; limit possible fouls; and modify the
scoring system. Each penalty, regardless of reason, results in a point gain for the opponent. Our previous
Int. J. Environ. Res. Public Health 2020,17, 6779; doi:10.3390/ijerph17186779 www.mdpi.com/journal/ijerph
Int. J. Environ. Res. Public Health 2020,17, 6779 2 of 18
research showed that these amendments of competition rules were linked to a noticeable shift in
taekwondo combat profile toward greater body movement dynamics, higher intensity, and greater
post-exercise fatigue than observed previously. Significant increments in kinematic variables (3–8%),
heart rate (1.5–1.8%), energy expenditure (3–5%), overall physiological load (2–4%), and lactate
concentration (15% immediately after combat and 25% in recovery) suggest that new rules are more
demanding [
5
]. Apart from modifying the exercise response to taekwondo combat by increasing its
intensity, the recent rule amendments have forced the coaches and athletes to modify their workout
regime. Even if training sessions have not been changed in terms of exercise volume, repetitions,
or exercise/rest ratio, the exercise intensity could have been altered due to subtle but crucial modifications
in kicking mode.
According to earlier studies, taekwondo-specific workouts, and even simulated combats, although
relatively intense, did not fully recreate the physiological response to tournament combats [
17
,
18
].
However, certain types of high-intensity interval training seem to be optimal for adapting to taekwondo
competition [
19
22
]. Moreover, taekwondo-specific circuit training forms (i.e., incorporating the
fighting techniques) are suggested to be preferred instead of non-specific exercise (e.g., running or
cycling) to combine physical conditioning with fighting specificity [
5
]. Simulating tournament combat
conditions during training sessions is still a very topical issue. The question arises as to how the rule
changes have aected the exercise profile during taekwondo-specific workouts and how adequately
the taekwondo-specific workouts reflect the demands of the tournament combat in this new situation.
To the best of our knowledge, no scientific investigation has focused on the direct impact of sports rule
amendments on the exercise response to any discipline-specific workouts.
This study aimed to compare the physiological and kinematic exercise response to
taekwondo-specific circuit training sessions in highly trained taekwondo athletes before and after
rule changes. We analyzed a large number of training sessions throughout a longer period (2 years)
as opposed to previous studies [
17
,
18
,
20
,
23
35
]. We hypothesized that the rule amendments and
related modifications in kicking modality would increase the exercise intensity of taekwondo-specific
workouts and reduce the gap between real combat situation and workout in terms of physiological
and kinematic response.
2. Materials and Methods
2.1. Participants
We monitored 15 highly trained taekwondo athletes aged 16–25 (19.9
±
2.7) years, both male
(n=10) and female (n=5), in a period of two years. They were black belt holders, members of the Polish
national team, national champions, or medal winners in international tournaments. One athlete took
part in the Olympic games, seven took part in continental championships (four medals), four took part
in world championships (two medals), and nine took part in the Universiade (six medals). The study
was performed according to the ethical standards laid down in the Declaration of Helsinki. The local
bioethics committee at the Poznan University of Medical Sciences approved the study design (decision
nos. 418/13 and 143/15). We informed the participants of the benefits and risks of the research
procedures. All athletes or their parents (for participants aged <18 years) provided signed, written
consent before the commencement of the research project.
2.2. Experimental Design
Our main idea was to compare the exercise intensity during equivalent taekwondo-specific
workouts conducted before and after taekwondo rule changes. The revisions of taekwondo rules
were the result of an alteration planned beforehand by World Taekwondo (www.worldtaekwondo.
org) (discussed among coaches and members worldwide). We performed the measurements in
old rules from February 2016 until May 2017 and in new rules from June 2017 until March 2018.
We monitored taekwondo-specific training sessions and tournaments using wearable bio-monitors to
Int. J. Environ. Res. Public Health 2020,17, 6779 3 of 18
record physiological and kinematic parameters. Athletes underwent blood sampling directly before
and after each training session or combat and after 30 min of recovery. Basic reference physiological
indices were obtained on the basis of progressive cardiorespiratory treadmill tests until exhaustion
performed between training subphases of the annual cycle. Identical procedures were used during
both old and new rule periods. Importantly, the head coach and the members of the coaching sta
remained the same during the whole study period. The coaches organized the taekwondo-specific
training sessions in the same manner in old and new rules, i.e., they used the same kicking techniques,
number of series/repetitions, and exercise-to-rest ratios. The only dierence was kicking modality
imposed by new rules. Therefore, potential confounding factors resulting from changing training
approach/strategy, goals, methods, organizational solutions, etc. were minimized or avoided. Before
the rule changes, athletes were allowed to keep the leg elevated to facilitate consecutive strikes or to
deceive opponents. New rules prohibited such behavior. Consequently, coaches forbade athletes to
execute “phantom striking” or continuous leg elevation during training sessions. Instead, athletes
were ordered to set foot on the ground between strikes. Therefore, the strikes investigated in this study,
that is, front kicks, turning kicks, and double roundhouse kicks, were first executed following the old
(February 2016–May 2017) and then following the new (June 2017–March 2018) taekwondo rules.
The number of monitored training person sessions equaled 362 (195 under old rules and 167
under new rules), 122 of which were excluded. Finally, 240-person sessions (127 under old and 113
under new rules) were included in the analysis. We monitored each athlete for 8.4
±
1.6 (range 6–11)
sessions under old rules and 7.5
±
1.0 (range 6–9) sessions under new rules. This dierence was not
significant (p=0.075). Real combat monitoring included 16 tournaments, covering a total of 298
combats (142 under old and 156 under new rules). We excluded 51 combats and analyzed the remaining
247 (126 old vs. 121 new). Each athlete was monitored for 8.4
±
3.2 (range 4–15) combats under old
rules vs.
8.0 ±3.4
(range 3–15) combats under new rules. This dierence was also not significant
(p=0.783). Exclusion criteria for data recordings from training sessions and tournament combats were
(i) insucient exertion time (i.e., incomplete circuit, knock out, disqualification, injury, or any pause
regardless of source longer than 5 min)—49 and 13 exclusions, respectively; (ii) prolonged time (above
5 min) of VRS challenge during tournament combat—0 and 18 exclusions; (iii) uncommon interferences
(coach interventions, round shortening)—15 and 3 exclusions; (iv) technical issues (signal breaking, lag
spikes, PSS or VRS malfunctions)—4 and 6 exclusions; and (v) insucient time for blood sampling—54
and 11 exclusions. Laboratory measurements, aimed at obtaining reference cardiorespiratory responses
to a standard progressive exercise, were performed six times under the old rules and three times under
the new rules at intervals of approximately 3 months.
2.3. Laboratory Data Collection
Height and weight were measured using a digital stadiometer (Seca 285, Seca GmbH and Co.,
KG, Hamburg, Germany). Body fat and total lean body mass were measured with dual-energy
X-ray absorptiometry (Lunar Prodigy device, Encore Software 16 Sp.1, GE Healthcare, Chicago, IL,
USA). The same operator scanned the participants according to the standardized protocol described
elsewhere [
26
]. Then, athletes performed an exercise treadmill tests until exhaustion. Briefly, after 3
min of standing on a treadmill (pulsar 3p, h/p/cosmos sports and medical GmbH, Nussdorf-Traunstein,
Germany), the athletes started the exertion at 4 km/h, with an increase to 8 km
·
h
1
after 3 min.
Afterward, the speed increased by 2 km
·
h
1
every 3 min. Athletes ran until volitional exhaustion
was reached. Cardiorespiratory characteristics were measured breath-by-breath by an ergospirometer
(MetaMax 3B-R2, Metasoft Studio Software 5.2.0, Cortex Biophysik, Leipzig, Germany), calibrated
according to the manufacturer’s guidelines. We used the values of following cardiorespiratory
variables as reference data for a training session and combat analysis: heart rate (HR; Polar Electro
Oy, Kempele, Finland), breathing rate (BR), energy expenditure (EE), and maximum oxygen uptake
(
.
V
O
2max
). Maximal oxygen uptake was considered achieved if at least three of the following criteria
were met: (i) a plateau in
.
V
O
2
despite an increase in minute ventilation, (ii) blood lactate concentration
Int. J. Environ. Res. Public Health 2020,17, 6779 4 of 18
9 mmol
·
L
1
in males and
7 mmol
·
L
1
in females, (iii) respiratory exchange ratio
1.10, (iv) heart
rate
95% of the maximal value recorded in the previous tests, and (v) the Borg Scale rating
17.
Athletes were verbally encouraged by coaches and the researchers conducting the test to achieve the
highest possible running speed. Additionally, we determined exercise parameters at the ventilatory
threshold (VT) and respiratory compensation point (RCP) on the basis of the ventilatory equivalents for
oxygen (
.
VE
/
.
V
O
2
) and carbon dioxide (
.
VE
/
.
V
CO
2
), partial pressures of O
2
(PETO
2
), and CO
2
(PETCO
2
).
Capillary blood samples were obtained from the fingertip before exercise, at exhaustion, and after
30 min of recovery to assay lactate concentration (LA) using the blood analyzer Biosen C-Line (EKF
Diagnostics, Cardi, United Kingdom).
2.4. Data Collection during Taekwondo-Specific Workouts and Tournaments
Athletes wore bio-monitors (described below) through the whole training session or tournament
day up to 30 min recovery period after the last workout exercise or combat, as described elsewhere [
5
].
The devices did not hamper their activity. The taekwondo-specific training sessions were organized
in the form of a circuit containing nine exercise sets, each lasting 2 min (Figure 1). Typical combat
consisted of three 2-min rounds with a 1-min rest period between each round.
Each taekwondo-specific circuit session was preceded by a standard ~40-min warm-up involving
stretching (~15–20 min) and jogging (~15 min), followed by preliminary light to moderate kick exercises
(~25 min). All circuits had the same structure and were divided into three series of exercise sets (“mini
circuits”) separated by two 8-min active pauses. Each series, lasting 6 min net, was divided into
three 2-min exercise sets separated by 1-min pauses to reflect the time structure of typical tournament
combat. Each single exercise set contained taekwondo-specific kick techniques normally used during
real combat—a minimum of 16 kicks per one leg, 32 kicks in total [
27
,
28
]. The names of the techniques
are given in Figure 1. The circuit exercise was performed in pairs, where one athlete was an “attacker”
(main exercise) and the second a “defender” (during the active 8-min pause). After each set, athletes
changed their roles and exercise partners. The kicks were delivered on the chest protector or target
pad held by the defending partner, depending on a particular technique. The athletes moved forward
and backward during each exercise set to simulate real combat behavior. The total duration of each
taekwondo-specific circuit was 40 min, including intervals between series and exercise sets, whereas
net exercise time was 18 min.
Int. J. Environ. Res. Public Health 2020,17, 6779 5 of 18
Int. J. Environ. Res. Public Health 2020, 17, x FOR PEER REVIEW 6 of 19
Figure 1. The structure of the analyzed taekwondo-specific circuits. Vertical downward arrows denote blood sampling.
Recovery
30 min
Front Kicks on Tar get Pad
Turning Kicks on Protector
Double Roundhouse Kicks
on Protector
Set 7
2
min
Rest
1
min
Set 8
2
min
Rest
1
min
Set 9
2
min
Active
Recovery
8 min
Set 4
2
min
Rest
1
min
Set 5
2
min
Rest
1
min
Set 6
2
min
Series 3
32 Kicks
Leg switch every 2 kicks
Series 1
Set 3
2
min
Rest
1
min
Series 2
32 Kicks
Leg switch every 8 kicks
Set 1
2
min
Rest
1
min
Set 2
2
min
Leg switch every 8 kicks
32 Kicks
Figure 1. The structure of the analyzed taekwondo-specific circuits. Vertical downward arrows denote blood sampling.
Int. J. Environ. Res. Public Health 2020,17, 6779 6 of 18
Athletes used identical measuring equipment during training sessions and real combats to ensure
the credibility of comparisons [
17
]. During tournaments and training sessions, we verified the ambient
temperature with the K204 digital thermometer (Voltcraft, Wollerau, Switzerland). The temperatures
ranged from 20.7 to 22.3
C and from 19.9 to 22.6
C, respectively. Capillary blood samples (fingertip)
for lactate concentration were drawn five times during one training session: before the first exercise
set, after each exercise set, and after the 30-min recovery period (Figure 1). During tournaments, blood
was drawn before and immediately after each fight, and after the 30-min recovery period after the last
combat. The physiological and kinematic indices were measured with a portable wireless piezoelectric
recording system (Bioharness 3, Omnisense 3.9.7, Zephyr Technology Corp., Annapolis, MD, USA).
According to the manufacturer’s definitions, the analyzed variables were as follows:
1.
Peak activity (ACT
peak
)—squared root of (x
2
+y
2
+z
2
); x, y, and z are peak values of the three axial
accelerations, where ~0.2 represents walking, ~0.5 jogging, ~0.8 running, and ~1.0+sprinting.
2.
Average activity (ACT
avg
)—squared root of (x
2
+y
2
+z
2
); x, y, and z are the averages of the three
axial accelerations over the previous 1-s epoch, where ~0.2 represents walking, ~0.5 jogging, ~0.8
running, and ~1.0+sprinting.
3.
Physiological intensity (PHYS
int
)—range 0–10 (incremental step of 5%), where 0 is below 50%
and 10 equals or exceeds 100% of maximum HR on the basis of the HR range of each athlete.
4.
Physiological load (PHYS
load
)—the accumulation of the PHYS
int
over time (average value
multiplied by the total exertion time).
5.
Mechanical intensity (MECH
int
)—displayed in the range of 0–10 (incremental step of 5%), where
0 denotes motionless, whereas 10 is equal to an acceleration of 3.0 g or greater.
6.
Mechanical load (MECH
load
)—the accumulation of the MECH
int
over time (average value
multiplied by the total exertion time).
7. Training intensity (TRAINint)—arithmetic average of PHYSint and MECHint.
8. Training load (TRAINload)—arithmetic average of PHYSload and MECHload.
9.
Energy expenditure—estimated according to the formula: EE (kcal) =Gender
×
(
55.0969 +0.6309
HR +0.1988 Weight +0.2017 Age) +(1
Gender)
×
(
20.4022 +0.4472 HR
0.1263 Weight
+0.074 Age). Gender—1 for male, 0 for female.
Other research teams [
29
31
] evaluated the reliability and validity of the Bioharness bio-monitor
and recommended it as a high-precision tool in comparison with gold standards (r=0.91, p<0.01,
CV (coecient of variation) <7.6% for heart rate and r=0.94, p<0.01 for acceleration).
2.5. Statistical Analysis
We compared the basic somatic and aerobic capacity profiles between dierent rule settings using
the t-test for dependent samples. We cleaned raw training and combat data of any technical errors.
The basic unit for analysis was one exercise set (average duration 120
±
5 s) during training sessions
or one combat round during tournaments (~120 s), as well as the last 10 min of the 30-min recovery
following the last circuit or combat exertion. All values were presented as either mean
±
standard
deviation (general characteristics) or adjusted mean
±
standard deviation of the mean (workout and
combat data). We applied the analysis of covariance (ANCOVA) for repeated measures to identify the
dierences in circuit training and combat profiles between old and new competition rules. We adjusted
the dependent variables for the following covariates that could potentially aect the magnitude of
exercise response: (i) the order of exercise series or combat rounds (first, second, third), (ii) age category
(junior, senior), and (iii) sex (male, female). Partial
η2
was used as a measure of eect size and the
following scale was adopted: small (0.01), medium (0.06), or large (0.14). An a priori calculation of
required sample size revealed that at least 63 cases (workouts or combats) were needed to perform
ANCOVA, assuming large eect size, p-level =0.05, statistical power =0.8, and three covariates, or 155
cases if medium eect size was assumed (G*Power 3.1.9.6, Franz Faul, Universität Kiel, Germany).
Int. J. Environ. Res. Public Health 2020,17, 6779 7 of 18
The significance level was established at p<0.05. We analyzed the data using Statistica 13.3 (TIBCO
Software Inc., Palo Alto, CA, USA).
3. Results
Basic somatic and aerobic capacity profiles are displayed in Table 1. A vast majority of dierences
between old and new rule periods were nonsignificant. Exceptions were a decrease in oxygen uptake
at the ventilatory threshold in males and increases in weight and absolute (but not percentage) lean
body mass in the combined group.
Table 1.
Somatic and aerobic capacity profiles of the studied taekwondo athletes at the start of circuit
training under old and new rules.
Male Female Combined Group
Old
Rules
New
Rules
Old
Rules
New
Rules
Old
Rules
New
Rules
Age (years) 19.5 ±3.3 20.5 ±3.3 20.8 ±1.5 21.8 ±1.5 19.9 ±2.8 20.9 ±2,8
Experience (years) 8.6 ±2.7 9.6 ±2.7 9.2 ±2.2 10.2 ±2.2 8.8 ±2.5 9.8 ±2.5
Height (cm) 182.0 ±5.9 182.0 ±5.9 176.6 ±8.1 176.6 ±8.1 180.2 ±6.9 180.1 ±6.0
Weight (kg) 66.7 ±11.1 70.1 ±9.2 67.5 ±12.5 68.9 ±11.8 67.0 ±11.1 70.1 ±9.7 *
Lean body mass (kg) 53.8 ±9.0 57.0 ±7.6 44.6 ±9.2 46.6 ±7.4 50.7 ±9.8 53.5 ±8.9 **
Lean body mass (%) 80.7 ±2.6 80.9 ±2.2 66.4 ±1.8 68.2 ±2.0 76.0 ±7.4 76.7 ±6.5
Fat mass (kg) 9.8 ±2.4 10.3 ±2.3 19.5 ±4.3 19.0 ±4.2 13.0 ±5.6 13.2 ±5.2
Fat mass (%) 14.7 ±2.6 14.5 ±2.1 28.9 ±2.7 27.7 ±2.2 19.4 ±7.4 18.9 ±6.7
.
VO2VT (mL·min1·kg1)41.0 ±4.9 35.2 ±3.7 ** 30.0 ±1.9 32.6 ±5.7 37.3 ±6.7 34.3 ±4.4
.
VO2RCP (mL·min1·kg1)47.9 ±5.2 50.7 ±3.3 39.0 ±1.7 41.0 ±3.2 44.9 ±6.1 47.5 ±5.7
.
VO2max (mL·min1·kg1)54.1 ±4.2 56.6 ±4.1 44.6 ±5.3 45.6 ±4.8 50.9 ±6.4 52.9 ±6.8
LAmax (mmol·L1)8.4 ±1.8 9.2 ±1.7 8.0 ±1.5 8.2 ±1.3 8.3 ±1.7 8.9 ±1.7
Abbreviations: LA
max
—maximum blood lactate concentration after exercise test until exhaustion,
.
VO2max—maximum oxygen uptake, .
VO2RCP—oxygen uptake at respiratory compensation point, .
VO2VT—oxygen
uptake at ventilatory threshold; t-test: * p<0.01, ** p<0.001—significantly dierent from old rules.
Peak, average, and recovery HR during circuit training were significantly higher under new rules
compared with under old rules (Table 2), and the dierences ranged between 2.4% and 6.8% (Figure 2).
Under both old and new rules, peak, average, and recovery HR were significantly higher during
tournament combat (~100% or >100% of maximum HR in the laboratory test until exhaustion) than
taekwondo-specific training. The eect sizes, in general, were large, except for recovery HR (small).
The same pattern of dierences was revealed for physiological intensity (medium to large eect size)
and load (small to medium eect size), with a ~4% dierence between old and new training sessions
(Figure 2) and ~4–16% dierence between training sessions and real combats (Figure 3).
Int. J. Environ. Res. Public Health 2020,17, 6779 8 of 18
Int. J. Environ. Res. Public Health 2020, 17, x 8 of 19
(medium effect size). In both old and new rule settings, the energy expenditure rate was in general
higher during real combats than training circuits by ~0‒6%, however, the effect size was small or even
negligible (Table 4 and Figure 3).
Figure 2. Percentage differences in exercise response to taekwondo-specific circuit workouts between
new and old rule settings. Black bars denote statistically significant and white bars insignificant
changes, as indicated in Tables 2‒6. Positive numbers indicate higher values obtained in new vs. old
rules. See table legends for the explanation of variable abbreviations.
6.2
6.8
5.3
2.4
3.9
4.0
12.0
9.7
4.3
5.0
6.6
6.0
2.9
-0.3
6.3
0.3
-2.1
10.2
4.6
14.4
10.1
9.1
6.5
5.6
5.1
4.8
-5 0 5 10 15
HR peak
%HR max
HR avg
HR rec
PHYS int
PHYS load
BR peak
%BR max
BR avg
BR rec
EE
%EE vt
%EE rcp
%EE max
EE rec
%EE
LA pre
LA post
%LA max
LA rec
ACT peak
ACT avg
MECH int
MECH load
TRAIN int
TRAIN load
Circuit in New vs Old Rules (%)
Figure 2.
Percentage dierences in exercise response to taekwondo-specific circuit workouts between
new and old rule settings. Black bars denote statistically significant and white bars insignificant changes,
as indicated in Tables 26. Positive numbers indicate higher values obtained in new vs. old rules.
See table legends for the explanation of variable abbreviations.
Int. J. Environ. Res. Public Health 2020,17, 6779 9 of 18
Table 2. Heart rate and relative physiological intensity/load during taekwondo-specific circuit training and combat—comparison between old and new rules.
Circuit Old
Rules
Circuit New
Rules
Combat Old
Rules
Combat
New Rules
Circuit
Old vs. New Rules
Circuit vs. Combat
Old Rules
Circuit vs. Combat
New Rules
p-Value Eect Size p-Value Eect Size p-Value Eect Size
HRpeak (beats·min1)174.9 ±7.1 185.7 ±6.8 187.2 ±11.5 193.3 ±11.3 <0.001 0.37 (large) <0.001 0.29 (large) <0.001 0.14 (large)
%HRmax 92.6 ±4.3 98.9 ±4.8 99.4 ±5.8 102.6 ±6.9 <0.001 0.32 (large) <0.001 0.31 (large) <0.001 0.09 (medium)
HRavg (beats·min1)165.8 ±6.7 174.6 ±6.7 179.1 ±12.3 184.0 ±13.2 <0.001 0.30 (large) <0.001 0.31 (large) <0.001 0.17 (large)
HRrec (beats·min1)102.8 ±8.4 105.3 ±8.1 107.6 ±11.2 109.3 ±10.7 0.022 0.02 (small) 0.002 0.05 (small) <0.001 0.04 (small)
PHYSint (au) 7.5 ±0.5 7.8 ±0.6 8.7 ±0.6 8.9 ±0.6 <0.001 0.06 (medium) <0.001 0.51 (large) <0.001 0.49 (large)
PHYSload (au) 18.4 ±2.0 19.2 ±2.1 19.4 ±2.1 20.1 ±2.0 <0.001 0.03 (small) <0.001 0.06 (medium) <0.001 0.05 (small)
Abbreviations: HR
peak
—peak heart rate, %HR
max
—HR
peak
as percentage of maximum heart rate obtained in progressive treadmill test, HR
avg
—average heart rate during training session
or combat, HRrec—heart rate at the end of a 30 min recovery, PHYSint—physiological intensity, PHYSload—physiological load.
Table 3. Breathing rate during taekwondo-specific circuit training and combat—comparison between old and new rules.
Circuit Old Rules Circuit New
Rules
Combat Old
Rules
Combat New
Rules
Circuit
Old vs. New Rules
Circuit vs. Combat
Old Rules
Circuit vs. Combat
New Rules
p-Value Eect Size p-Value Eect Size p-Value Eect Size
BRpeak (breaths·min1)43.7 ±3.1 48.9 ±2.9 40.2 ±4.6 41.2 ±4.6 <0.001 0.42 (large) <0.001 0.16 (large) <0.001 0.50 (large)
%BRmax 69.7 ±8.8 76.4 ±10.0 64.3 ±10.0 65.0 ±9.8 <0.001 0.11 (medium) <0.001 0.08 (medium) <0.001 0.25 (large)
BRavg (breaths·min1)36.5 ±2.7 38.1 ±2.6 35.9 ±5.0 37.3 ±4.8 <0.001 0.08 (medium) 0.040 0.01 (small) 0.004 0.02 (small)
BRrec (breaths·min1)16.5 ±2.2 17.3 ±2.2 17.1 ±3.1 17.8 ±2.6 0.003 0.03 (small) 0.130 <0.01 (negligible) 0.266 <0.01 (negligible)
Abbreviations: BR
peak
—peak breathing rate, %BR
max
—BR
peak
as percentage of maximum breathing rate obtained in progressive treadmill test, BR
avg
—average breathing rate during
training session or combat, BRrec—breathing rate at the end of a 30 min recovery.
Table 4. Energy expenditure during taekwondo-specific circuit training and combat—comparison between old and new rules.
Circuit Old Rules Circuit New
Rules
Combat Old
Rules
Combat New
Rules
Circuit
Old vs. New Rules
Circuit vs. Combat
Old Rules
Circuit vs. Combat
New Rules
p-Value Eect Size p-Value Eect Size p-Value Eect Size
EEavg (kcal·kg1·h1)14.1 ±1.2 15.0 ±1.1 13.2 ±2.5 15.9 ±2.9 <0.001 0.14 (large) <0.001 0.03 (small) <0.001 0.04 (small)
%EEvt 132.4 ±22.6 140.5 ±18.0 135.8 ±26.5 147.4 ±23.0 <0.001 0.04 (medium) 0.06 <0.01 (negligible) <0.001 0.03 (small)
%EERCP 104.2 ±11.9 107.2 ±9.6 106.8 ±20.4 112.1 ±15.5 0.010 0.02 (small) 0.04 0.01 (small) <0.001 0.03 (small)
%EEmax 91.8 ±11.7 91.5 ±7.6 94.1 ±17.6 94.9 ±13.2 0.720 <0.01 (negligible) 0.03 0.01 (small) <0.001 0.02 (small)
eErec (kcal·kg1·h1)5.3 ±0.6 5.6 ±0.6 5.8 ±1.4 5.8 ±1.2 <0.001 0.08 (medium) <0.001 0.06 (medium) 0.094 <0.01 (negligible)
%eerec 37.2 ±4.4 37.2 ±4.3 37.3 ±10.7 36. 9 ±9.7 0.984 <0.01 (negligible) 0.944 <0.01 (negligible) 0.795 <0.01 (negligible)
Abbreviations: EE
avg
—average energy expenditure rate, %EE
VT
—percentage of energy expenditure rate measured at the ventilatory threshold, %EE
RCP
—percentage of energy expenditure
rate measured at respiratory compensation point, %EE
max
—percentage of energy expenditure rate measured at exhaustion in the progressive treadmill test, EE
rec
—absolute energy
expenditure rate at the end of a 30 min recovery after the last series of the circuit or tournament combat, %EErec—EErec as percentage of EEavg.
Int. J. Environ. Res. Public Health 2020,17, 6779 10 of 18
Table 5. Lactate concentration during taekwondo-specific circuit training and combat—comparison between old and new rules.
Circuit Old Rules Circuit New
Rules
Combat Old
Rules
Combat New
Rules
Circuit
Old vs. New Rules
Circuit vs. Combat
Old Rules
Circuit vs. Combat
New Rules
p-Value Eect Size p-Value Eect Size p-Value Eect Size
LApre (mmol·l1)2.0 ±0.5 2.0 ±0.4 2.2 ±0.9 2.1 ±1.0 0.451 <0.01 (negligible) 0.01 0.03 (small) 0.261 0.01 (small)
LApost (mmol·l1)10.0 ±2.8 11.1 ±2.9 11.2 ±2.4 12.8 ±2.3 <0.001 0.03 (small) <0.001 0.03 (small) <0.001 0.07 (medium)
%LAmax 120.8 ±36.8 126.3 ±34.5 131.1 ±29.1 142.4 ±27.6 0.039 0.01 (small) 0.004 0.02 (small) <0.001 0.06 (medium)
larec (mmol·l1)2.2 ±0.5 2.5 ±0.44 2.7 ±0.8 3.5 ±1.0 <0.001 0.11 (medium) <0.001 0.15 (large) <0.001 0.32 (large)
Abbreviations: LA
pre
—resting blood lactate concentration, LA
post
—post-exercise blood lactate concentration, %LA
max
—post-exercise lactate concentration as a percentage of maximum
concentration at exhaustion in progressive treadmill test, LArec—blood lactate concentration at the end of a 30 min recovery.
Table 6. Kinematic response to taekwondo training and combat—comparison between old and new rules.
Circuit Old Rules Circuit New
Rules
Combat Old
Rules
CombatNew
Rules
Circuit
Old vs. New Rules
Circuit vs. Combat
Old Rules
Circuit vs. Combat
New Rules
p-Value Eect Size p-Value Eect Size p-Value Eect Size
ACTpeak (m·s2)12.3 ±1.5 13.6 ±1.7 13.2 ±2.5 13.6 ±2.4 <0.001 0.14 (large) <0.001 0.04 (small) 0.944 <0.01 (negligible)
ACTavg (m·s2)7.1 ±0.5 7.7 ±0.5 7.5 ±0.8 8.0 ±0.6 <0.001 0.28 (large) <0.001 0.11 (medium) <0.001 0.04 (small)
MECHint (au) 7.1 ±0.5 7.5 ±0.6 8.1 ±0.7 8.5 ±0.6 <0.001 0.17 (large) <0.001 0.43 (large) <0.001 0.46 (large)
MECHload (au) 16.8 ±1.8 17.8 ±1.8 17.6 ±2.2 19.0 ±1.9 <0.001 0.07 (medium) <0.001 0.04 (small) <0.001 0.10 (medium)
TRAINint (Pau) 7.3 ±0.5 7.6 ±0.5 8.4 ±0.6 8.7 ±0.5 <0.001 0.13 (medium) <0.001 0.53 (large) <0.001 0.52 (large)
TRAINload (Pau) 17.6 ±1.7 18.5 ±1.8 18.5 ±2.0 19.6 ±1.8 <0.001 0.06 (medium) <0.001 0.06 (medium) <0.001 0.09 (medium)
Abbreviations: ACT
peak
—peak mechanical activity, ACT
avg
—average mechanical activity, MECH
int
—mechanical intensity, MECH
load
—overall mechanical load, TRAIN
int
—average
summary of exertion intensity, TRAINload—average summary of exertion loads, au – arbitrary units.
Int. J. Environ. Res. Public Health 2020,17, 6779 11 of 18
Int. J. Environ. Res. Public Health 2020, 17, x 9 of 19
Figure 3. Percentage differences in exercise response between taekwondo-specific circuit sessions and
real combat. Old rules are displayed as gray bars and new rules as black bars. Positive numbers
indicate higher values obtained during combat vs. training sessions. See table legends for the
explanation of variable abbreviations.
7.0
7.4
8.0
4.7
15.9
5.1
-8.0
-7.8
-1.6
3.9
5.8
2.6
2.4
2.5
9.7
0.2
11.6
11.6
8.5
24.8
6.6
6.6
15.0
4.9
15.5
5.0
4.1
3.8
5.4
3.8
14.2
5.0
-15.8
-15.0
-2.2
2.8
5.9
5.1
4.5
3.7
4.5
-0.8
5.6
15.9
12.7
38.5
0.1
2.9
13.5
6.9
13.9
6.0
-30 -10 10 30
HR peak
%HR max
HR avg
HR rec
PHYS int
PHYS load
BR peak
%BR max
BR avg
BR rec
EE
%EE vt
%EE rcp
%EE max
EE rec
%EE
LA pre
LA post
%LA max
LA rec
ACT peak
ACT avg
MECH int
MECH load
TRAIN int
TRAIN load
Old Rules
New Rules
Figure 3.
Percentage dierences in exercise response between taekwondo-specific circuit sessions and
real combat. Old rules are displayed as gray bars and new rules as black bars. Positive numbers indicate
higher values obtained during combat vs. training sessions. See table legends for the explanation of
variable abbreviations.
Peak and average breathing rate during circuit training were significantly higher (medium or large
eect size) under new rules compared with under old rules (Table 3). The dierences ranged between
4.3% and 12.0% (Figure 2). Peak and average breathing rate were significantly higher during circuit
training when compared with real combat (medium or large eect size), with a smaller dierence
Int. J. Environ. Res. Public Health 2020,17, 6779 12 of 18
under old (~8%) compared with new (~15%) rules (Figure 3). The dierences in breathing rate during
post-exercise recovery were not significant or the eect size was small.
The estimated energy expenditure rate during the taekwondo-specific circuit (expressed as the
percentage of expenditure at the ventilatory threshold and respiratory compensation point as well
as absolute values) was significantly higher under new rules compared with under old rules overall
(small to large eect size, 2.9–6.6% dierence; Table 4and Figure 2). The energy expenditure rate
expressed as the percentage of expenditure at exhaustion during the progressive laboratory test was
not dierent between rule settings. The average energy expenditure rate during the workouts was
slightly above that for the respiratory compensation point ~104–107%). Absolute, but not percentage,
energy expenditure during post-workout recovery was also significantly higher under new rules
(medium eect size). In both old and new rule settings, the energy expenditure rate was in general
higher during real combats than training circuits by ~0–6%, however, the eect size was small or even
negligible (Table 4and Figure 3).
Pre-exercise blood lactate concentration was not dierent between old and new rules (Table 5).
Post-exercise values were significantly higher after training sessions administered under new rules
compared with under old rules for both absolute and percentage values (4.6–10.4% dierence; Figure 2),
however, the eect size was small. Lactate levels during post-workout recovery were significantly
higher under new rules compared with under old rule settings (14.4%, medium eect size). In both
rule settings, lactate concentration was higher during tournaments than training sessions, with a small
to medium eect for measurements directly after exercise and a large eect for recovery. The dierence
in post-exercise and recovery lactate concentration between training and combat increased from ~12%
to 16% and from ~25% to ~39%, respectively, after rule amendments (Figure 3).
After the change from old to new rules, a significant increase by 4.8–10.1% was revealed in the
levels of kinematic variables measured during taekwondo-specific circuits (Table 6and Figure 2),
especially in peak activity (medium to large eect size). Moreover, in old rules, the kinematic response
to circuit training sessions was significantly weaker than the response to combat (small to large eect
size). The dierences (up to ~15%) persisted into new rules—circuit training was still less intensive
than combat (medium and large eect size), except for peak activity (negligible dierence).
4. Discussion
In this study, we found that the rule changes brought about visible increases in the physiological
and kinematic exercise response to taekwondo-specific circuit training sessions. Moreover, significant
dierences in physiological and kinematic response to taekwondo-specific circuit sessions vs. real
tournament combat persisted after the shift from old to new rules. Importantly, there was no change in
the circuit protocol between both rule periods. However, one single but crucial qualitative modification,
imposed by new rules, was introduced by coaches. Athletes were instructed to set foot on the ground
between strikes, whereas under old rules athletes were allowed or even encouraged to remain in a fixed
body position with an elevated leg before striking. The current taekwondo technique has become more
dynamic and contains less isometric muscular activity such as keeping the leg elevated or holding the
opponent. While the coaches in our study did not plan training sessions to become more intensive,
they were forced to indirectly increase the circuit intensity after implementing new rule restrictions.
In principle, this should be seen as a positive phenomenon because the taekwondo-specific circuit is
a tool designed to prepare for exertion in real combat, which has become more intense since the rules
were changed. However, there is also a negative side. Because the intensity has risen, the coaches
should avoid a snowballing eect of cumulative training load, which has become substantially greater
than in previous rule settings. It would be beneficial to take this into account when planning workouts
and loads in a longer perspective. For example, coaches could schedule taekwondo-specific workouts
closer to o-training days to prevent excessive fatigue and resulting overload, overtraining, or injuries.
In the past, multiple research teams investigated exercise response to taekwondo-specific training
sessions [
17
,
22
25
,
27
,
32
38
] and high-intensity interval training [
19
22
] in male, female, cadet, junior,
Int. J. Environ. Res. Public Health 2020,17, 6779 13 of 18
and elite adult taekwondo athletes. The training sessions required high-intensity exertion, resulting
in blood lactate concentrations of 8.0–11.4 mmol
·
L
1
, heart rate equal to 82–94% of the maximum,
and a very high kinematic activity. Our results, including a large number of training sessions, are in
general consistent with those studies that were only based on single or a few workouts. However,
we obtained even higher lactate and heart rate values (Table 2), especially after the rule changes.
Moreover, we characterized the exercise response with a much wider range of variables.
Our male athletes had a significantly lower oxygen uptake at the ventilatory threshold (
.
V
O
2VT
) at
the start of the new rules period. From the individual perspective of a particular athlete, the temporarily
lower
.
V
O
2VT
means that with increasing exercise intensity, anaerobic metabolic processes (glycolysis)
start to intensify earlier, including a raise in, for example, lactate levels, ventilatory equivalent for
oxygen, and fatigue. Consequently, post-exercise recovery can be somewhat prolonged. However,
during specific workouts and tournament combats, taekwondo athletes exclusively operate in the
exercise intensity range between
.
V
O
2RCP
and
.
V
O
2max
[
5
]. These indicators of ability to high-intensity
exercise were not dierent between both rules settings. We assume that the
.
V
O
2VT
was of much lesser
significance for exercise response to taekwondo-specific tasks. It also seems that it was an incidental
decline in
.
V
O
2VT
, related to individual athletes, rather than a regular trend across multiple tests
during the study period. In our previous report comparing combats in old and new rule settings [
5
],
we did not reveal significant dierences in
.
V
O
2VT
, neither in male nor in female athletes. Moreover,
in the combined group (Table 1), the dierences in aerobic capacity between old and new rules
were insignificant for all three
.
V
O
2
indicators. As we used data from the combined group in our
analysis, only those characteristics were relevant as the background for workout or tournament exercise.
Importantly, across the study period, we used each time reference dataset from the laboratory test
closest to a particular training session or tournament; therefore, the workout parameters were adjusted
to the current threshold or maximum aerobic parameters and any particular laboratory test was not
decisive for the obtained results.
Some studies showed that exercise mode itself (technique or type of muscle contraction) aects
physiological indices without modification of the external load. For example, in elite cross-country
skiers, running, double poling on roller skis, and skating on roller skis resulted in significantly dierent
heart rates and lactate concentrations, despite the same test protocol [
39
]. Moreover, equivalent
dynamic and isometric muscular contractions in healthy males elicited dierent responses, i.e., rating
of exertion, blood pressure, and rate pressure product were higher during isometric contraction,
whereas breathing frequency, minute ventilation, oxygen uptake, and carbon dioxide output were
higher during dynamic contraction [
40
]. In crawl swimming, it was revealed that the energy cost of
swimming increased linearly along with changes in underwater torque (one of the biomechanical
technique parameters) despite constant speed [
41
]. This supports the view that it is the change in
kicking mode in taekwondo athletes that modified the exercise response to circuit training sessions in
new competition rules, despite unchanged training session protocol.
There is very scarce research on the eect of rule changes on sport technique. Adam et al.
pointed out that the rule changes in judo imposed important alterations in the eciency of hand
techniques, importance of leg techniques, as well as decline of all throwing techniques [
42
]. However,
their study was focused on the combat strategy (choice/frequency of techniques during tournament
combats), not on biomechanical analysis. Studies on the eect of fatigue or exercise intensity on sport
technique are also interesting. Rule changes in taekwondo brought about increases in exercise intensity,
and thus we assume that fatigue also increased. Aragones et al. found that among karate practitioners,
noticeable kinematic changes emerged with fatigue development when repeating a complex action
such as a karate front kick many times, despite the participants’ intention of performing identical
repetitions [
43
]. Rusidiana et al. [
44
] revealed that fatigue aected the quality of a header’s motor
performance in soccer. Some water sports-related studies [
45
47
] demonstrated that increased fatigue
was related to technique including stroke characteristics and fingertip patterns. Prieske et al. concluded
that fatigue was responsible for sex-specific knee motion strategies during jumping in elite volleyball
Int. J. Environ. Res. Public Health 2020,17, 6779 14 of 18
players [
48
]. Grasaas et al. showed that high-intensity exhausting exercise resulted in less ecient
technique in country skiers [
49
]. Kellis at al. revealed that fatigue induced significant impairment of
soccer kick performance [
50
]. The above studies strongly indicate that an increase in intensity and
resulting fatigue have a significant impact on movement technique including kinematic properties and
the quality of motion. We suppose that such an eect also occurred in our taekwondo athletes.
With regards to the similarity between taekwondo-specific workout and tournament, the circuit
training we analyzed did not fully recreate the combat situation in either rules version. An acceptable
level of similarity between workout tasks and competition may be debatable. It may be also questioned
as to whether a full identity of any training exercise with real combat is possible at all. Two studies
are available on dierences between real combat and taekwondo-specific training sessions, however,
the authors reached opposed conclusions. Bridge et al. [
17
] demonstrated that taekwondo-specific
exercise did not recreate the physiological responses of real combat (heart rate was higher by ~8% and
post-exercise LA concentration higher by ~70% compared with during specific training). In contrast,
Herrera-Valenzuela et al. [
20
] concluded that the training can successfully replicate the physiological
demands of the tournament. They showed similar divergences in average heart rate (~2–8%) but
much smaller dierences in LA concentration (3–13%). In our study, we obtained divergences equal
to ~5% in average heart rate and ~15% in lactate, thus closer to the latter research. The problem
seems to be more complex than it appears and is not solely a matter of one or two physiological
or kinematic variables. Similarity or discrepancy between training sessions and combat depends
on a particular exercise protocol used, which may be focused either on technical/tactical skills or
athletes’ specific conditioning [
17
20
]. Striking the balance between the two crucial components to
find a “golden rule” is dicult. Shifting the burden to technical/tactical skills will result in lower
workout intensity (inadequate to combat conditions), whereas focusing primarily on conditioning can
result in technique deterioration. Additionally, other factors also play a role. For example, during
training sessions, our athletes were forced to hit a moving opponent instead of a training kick-bag. We
believe that the lack of a real opponent is the main constraint on combat imitation. During training
sessions, athletes are usually not exposed to the risk of being hit upon by an opponent and, thus,
are less emotionally involved. Bridge et al. [
17
]. observed a much higher increase in post-exercise
blood adrenaline and noradrenaline levels during real combat than training sessions in international
taekwondo athletes (4.5–4.8-fold dierence), which suggests that the high-stress response present
during ocial competition is hard, if not impossible, to fully recreate during simulated exercise. This
may explain the dierences in kinematic and physiological indices between combat and training
sessions in our study, persisting despite the increase in circuit intensity after the rules change.
The discrepancies between training and combat may be unavoidable, however, they can
be diminished by appropriate modification of quantitative and qualitative exercise parameters.
Quantitative parameters, such as volume (exercise time, number of series/sets or repetitions), intensity
(kicking frequency), and intervals between series/sets (short, long), are relatively easy to recreate
during training. Qualitative parameters such as kicking techniques and their variations, non-fighting
activities, opponent’s presence, and emotional involvement seem to be more challenging to imitate,
but they could be crucial. In sports practice, it is important to design such a training protocol that,
on the one hand, mimics the technical and tactical characteristics of real combat and, on the other hand,
can replicate the kinematic and physiological response to combat. The appropriate balance between
kinematic, physiological, technical, and tactical requirements ensures that taekwondo-specific exercise
will be eective. An excessive emphasis on any of the above aspects may result in the loss of exercise
specificity (similarity to real combat).
In our study, the breathing rate during training sessions significantly increased in new rules
and was the only variable for which the discrepancy between training and combat deepened. In our
previous study [
5
], athletes faced problems with low breathing frequency during combat. Unrestricted
breathing is not possible during tournaments due to body dynamic movements, frequent explosive
kicks, hand strikes, and blocks—all based on the Valsalva maneuver, i.e., the forceful attempt to exhale
Int. J. Environ. Res. Public Health 2020,17, 6779 15 of 18
against a closed airway (holding the breath) to stabilize the trunk. Hence, breathing frequency is
limited in combat as opposed to training where athletes can breathe relatively free. The breathing
rate during circuit workouts increased after the rules change, whereas breathing during combat was
limited. As a consequence, the “breathing gap” between the taekwondo-specific circuit and real combat
widened. In new rules, we also observed a significant increase in workout variables measured after
recovery, especially lactate levels, accompanied by a decrease in the discrepancies between training
and combat. It seems that post-session fatigue persisted longer in the new than old rules period.
The results of our study can be seen from a broader perspective. In any sports discipline, the rule
changes directly or indirectly aect specific training exercise load, not only the exertion during
competition. Because the rule changes are an inevitable part of the development of virtually all sports,
it would be beneficial to conduct similar research in other sports to reveal the discipline-specific
direction and magnitude of eects. Coaches should be aware of rule changes and prepare their athletes
for training intensity of a dierent magnitude than before. As revealed in this study, rule amendments
have a direct impact on exercise response to discipline-specific workouts. Thorough recreation of real
combat situations seems to be necessary to prepare athletes for the modified exercise load imposed by
new rules. Recreating quantitative parameters (intensity, repetitions, etc.) is less cumbersome than
qualitative factors (e.g., opponent, emotional stress). Coaches should be aware that dierences in
exercise response between competition and training sessions can be mitigated but will persist. Any
changes in movement technique induced by rule amendments should be seriously taken into account
when designing discipline-specific workouts.
Finally, the uniform nationality and club aliation of the examined athletes may be seen as
a limitation because one cannot be sure how other groups of taekwondo athletes have physiologically
responded to the rule changes. Undoubtedly, local (national, club) factors could be moderators of the
change in exercise response between the old and new rules. However, there are some arguments that
our results can be generalized to a large extent. Having a homogenous group, we avoided the eect of
some confounding factors. In a mixed group (various countries or sports clubs), it would be dicult to
separate the “local” eects (specific coaching sta, dierent training methods/programs/schedules,
social and physical environment, etc.) from the real eect of the rule changes. In our study, rule changes
were “isolated”, and three potentially confounding factors were controlled statistically. Importantly,
after the rule changes, the same structure of the taekwondo-specific circuit training was maintained,
as well as the same coaching sta. This may be considered as a strength in the context of the study
goal. Moreover, we examined individuals on a certain sports level who can be representative of the
cohort of highly trained internationally experienced taekwondo athletes. The rule changes apply to
taekwondo athletes worldwide, and thus they all have to adjust their technique and, most likely, they
experience the same associated intensification of exertion in physiological and biomechanical terms.
5. Conclusions
After the competition rules change, the intensity of the taekwondo-specific circuit training sessions
significantly increased due to modifications in the kicking technique itself without any change in
exercise volume, repetitions, and exercise or rest duration. Moreover, the significant dierences in
exercise response between taekwondo-specific circuit training and real combat persisted or even
deepened. Our study suggests that the amendments in sports regulations significantly modify the
exercise response to specific training loads and that training sessions do not fully recreate the real
combat situation.
Author Contributions:
Conceptualization, M.J. and K.K.; methodology, M.J. and K.K.; software; M.J.; validation,
M.J.; formal analysis, M.J.; investigation, M.J., J.Z., M.C.-S., A.S., and K.K; resources, M.J., J.Z., M.C.-S., A.S.,
and K.K.; data curation, M.J.; writing—original draft preparation, M.J.; writing—review and editing, J.Z., M.C.-S.,
A.S., and K.K.; visualization, M.J. and K.K.; supervision, K.K.; project administration, K.K. and J.Z.; funding
acquisition, J.Z. and K.K. All authors have read and agreed to the published version of the manuscript.
Int. J. Environ. Res. Public Health 2020,17, 6779 16 of 18
Funding:
This work was supported by funding from the Polish Ministry of Science and Higher Education under
grants RSA2 041 52 and N RSA3 03653.
Acknowledgments:
The authors express their sincere thanks to the ocials of World Taekwondo, World
Taekwondo Europe, Polish Taekwondo Union, and other national taekwondo associations that made this research
possible. Special thanks to the coaches and their outstanding athletes for participating in this study.
Conflicts of Interest: The authors declare no conflict of interest.
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... This sport has undergone many regulatory changes over the preceding decades, and, as a consequence of this dynamism, the inclusion of new electronic scoring systems (electronic body protector and headgear) is now ubiquitous. During taekwondo matches, over an area of 16 m 2 , fighters use quick displacement chained by various types of dodges with change-of-direction (COD), powerful movements for attacking and counterattacking the opponent's his/her torso and head, including punching, complex unipedal standing and jumping kicks, and defensive actions with hands and feet (cuts, blocks) (Singh et al., 2017;Menescardi et al., 2019;da Silva Santos et al., 2020;Janowski et al., 2020). ...
... It is generally accepted that taekwondo became, and is, famous for the great variety in striking techniques (Kwok and Cheung, 2021). Although the use of wearable protection devices for the head, body, hands and feet, which reliably measure the power of striking by means of sensors and electronic chips, has changed the paradigm of taekwondo from a game to an objective, qualitative, and scientific sport (Sevinç, 2017;Sevinç and Çolak, 2019;Cho et al., 2020;Janowski et al., 2020;Park et al., 2021), Chaabene et al. (2018a) did not use this electronic scoring system to reliably count kicks scored during Taekwondo-specific agility test performance. During the Taekwondo-specific agility test, the roundhouse kicks were only projected on kick-targets held by partners, at the torso height of the tested athlete. ...
... The results of the above study suggest that~52% of attacks are performed by the front leg and 47% by the rear leg. As shown in various sport disciplines, rule changes affect exercise response to competition tasks, and, consequently, the discipline-specific tests (Janowski et al., 2020). Thereby, the choice of an appropriate field-based test for a sport or other physical activity must be centered on the specificity principle and the requirements of the sport or activity to be assessed (Pauole et al., 2000;Chaabene et al., 2018b). ...
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The purpose of this study was to examine the test-retest reliability, and convergent and discriminative validity of a new taekwondo-specific change-of-direction (COD) speed test with striking techniques (TST) in elite taekwondo athletes. Twenty (10 males and 10 females) elite (athletes who compete at national level) and top-elite (athletes who compete at national and international level) taekwondo athletes with an average training background of 8.9 ± 1.3 years of systematic taekwondo training participated in this study. During the two-week test-retest period, various generic performance tests measuring COD speed, balance, speed, and jump performance were carried out during the first week and as a retest during the second week. Three TST trials were conducted with each athlete and the best trial was used for further analyses. The relevant performance measure derived from the TST was the time with striking penalty (TST-TSP). TST-TSP performances amounted to 10.57 ± 1.08 s for males and 11.74 ± 1.34 s for females. The reliability analysis of the TST performance was conducted after logarithmic transformation, in order to address the problem of heteroscedasticity. In both groups, the TST demonstrated a high relative test-retest reliability (intraclass correlation coefficients and 90% compatibility limits were 0.80 and 0.47 to 0.93, respectively). For absolute reliability, the TST’s typical error of measurement (TEM), 90% compatibility limits, and magnitudes were 4.6%, 3.4 to 7.7, for males, and 5.4%, 3.9 to 9.0, for females. The homogeneous sample of taekwondo athletes meant that the TST’s TEM exceeded the usual smallest important change (SIC) with 0.2 effect size in the two groups. The new test showed mostly very large correlations with linear sprint speed (r = 0.71 to 0.85) and dynamic balance (r = −0.71 and −0.74), large correlations with COD speed (r = 0.57 to 0.60) and vertical jump performance (r = −0.50 to −0.65), and moderate correlations with horizontal jump performance (r = −0.34 to −0.45) and static balance (r = −0.39 to −0.44). Top-elite athletes showed better TST performances than elite counterparts. Receiver operating characteristic analysis indicated that the TST effectively discriminated between top-elite and elite taekwondo athletes. In conclusion, the TST is a valid, and sensitive test to evaluate the COD speed with taekwondo specific skills, and reliable when considering ICC and TEM. Although the usefulness of the TST is questioned to detect small performance changes in the present population, the TST can detect moderate changes in taekwondo-specific COD speed.
... However, following the changes in competition rules, Taekwondo competition tactics now have offensive tactics as the main approach and counter-attack tactics as the secondary approach [9]. As foundation of athletes' competitive ability, physical fitness has also become increasingly prominent with the rule changes [10,11]. In terms of physiological characteristics, it has been found that elite taekwondo athletes tend to possess low levels of body fat [12,13], moderate to high levels of cardio-respiratory fitness [14] and high levels of both aerobic and anaerobic physical fitness [15], while muscle strength is often not a key role [16]. ...
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The competition and physical fitness test results of the 2020 National Taekwondo Championship Series were analyzed using curve fitting, linear regression, and other statistical methods. As far as we know, it is the first Taekwondo competition that uses physical fitness test (PFT) scores as the 8-in-4 selection criteria. The results show that the probability of the final total score of the series of championships entering the top 8 or top 3 is exponentially related to PFT results. It finds that athletes with better PFT scores are more likely to enter the quarterfinals. Among athletes entering the semifinals, the athlete with the best physical fitness has the greatest probability of winning the championship. The difference in physical fitness between athletes is mainly reflected in the 30-meter sprint. Overall, the competitive performance of professional Taekwondo athletes is significantly positively correlated with their physical fitness, especially for female Taekwondo athletes. Through the results obtained, it is concluded that Taekwondo athletes need to strengthen physical training, specifically enhancing the explosive power.
... Secondly, taekwondo contested its first official Olympic Games in 2000 at the Sydney Olympics [4]. The reconfirmations over the past 20 years as an Olympic sport are the result of the WC's efforts to make significant changes to the rules that have made taekwondo more dynamic [5,6], and the transition from using a manual to an electronic scoring system that has made it a more equal sport [7]. The differences between the WC and the OG of taekwondo are not limited to the different time paths. ...
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The aims of this study were to investigate the relative and chronological age among taekwondo world medal winners (by gender, Olympic 4-year period, Olympic weight category; N = 740), and to study the behaviour of multiple medallists (N = 156) to monitor changes in weight categories and wins over time. The observed birth quartile distribution for the heavyweight category was significantly skewed (p = 0.01). Female athletes (22.2 ± 3.5 years) achieve success at a significantly younger age (p = 0.01) than their male counterparts (23.6 ± 3.3 years). In the weight categories, female flyweights were significantly younger than those welterweights (p = 0.03) and heavyweight (p = 0.01); female featherweights were significantly younger than those heavyweights (p = 0.03). Male flyweights and featherweights were significantly younger than those welterweights and heavyweights (p = 0.01). When a taekwondo athlete won a medal several times, he/she did so within the same Olympic weight category group and won two medals in his/her career (p = 0.01). Multiple medallists of the lighter and heavier groups did not differ in the number of medals won but in the time span in which they won medals (p = 0.02). The resources deployed by stakeholders to achieve success in these competitions highlight an extremely competitive environment. In this sense, the information provided by this study can be relevant and translated into key elements.
... Kao takva više nije imala potrebu da kod sportista značajnije razvija izometrične mišićne aktivnosti, kao što je držanje podignute noge prema protivniku. Promenom pravila borbe, su postale intenzivnije što treba imati na umu prilikom dizajniranja programa treninga (Janowski et al., 2020). Pri planiranju kondicionog treninga, neophodno je konsultovati osnove biomehaničke analize tekvondoa, fizičkog i fiziološkog profila takmičara i pravila takmičenja. ...
Conference Paper
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CONDITIONING TRAINING IN TAEKWONDO Abstract: Taekwondo (TKD) is a Korean martial art and since the year 2000, it has become an Olympic sport. TKD requires a high level of motor skills, which can no longer be trained with methods on the level of martial art. In monitoring conditioning of athletes, it is necessary to apply modern technical equipment. The ability to explosively and quickly generate and maintain the output force of the muscles of the lower extremities by means of concentric and eccentric concentric contractions is important for fulfilling technical and tactical tasks in the combat. The explosive power (SSC) of a competitor can be considered fundamental in creating force in taekwondo combat. To achieve a high level of skill, it is necessary to continually and over a longer period of time introduce more demanding plyometric exercises and systematic monitoring of the progress. Recently, this monitoring could be achieved with available measurement methods (a contact plate or a smartphone and atablet app – My Jump). The development of force, in a great way, depends on the strength and the speed of the kick. By profiling the relation between the force and the speed (FvP), we get the information how an athlete generates the power from the spectrum of force and velocity. Whether we will pay more attention to strength or speed training depends on the position of an individual competitor on Force velocity Profile. Taekwondo athletes show a high level of anaerobic strength of the lower extremities and this seems to be the main attribute for achieving success on international competitions. The speed and the explosive nature of taekwondo indicate the dominance of the phosphogenic system. While in the final stages of preparation, specific methods of repeating the blows on the bags or focusers are used, in the other phases, running in short intervals is used. Even though the abilities of strength and conditioning are considered dominant in TKD athletes, they have to be integrated with other skills (balance, coordination and other). Conditioning training is an integral part of the training plan of every TKD competitor and is realized partially as an integration into technical and tactical elements of TKD training or as an independent training. Keywords: Taekwondo, Condition, Strength, Plyometric, Endurance, F-V profile
... 10,11 combat sports, such as taekwondo, involve an oppositional relationship between two athletes striving to win the match; 12 consequently, many aspects are considered important to achieve successful competitive performance in taekwondo, including a high degree of technical-tactical competence supported by physiological, psychological [13][14][15][16] and sport context-specific components such as periodization strategies 17,18 and nutritional preparation. 19,20 The various rule changes that have taken place over the last decade, [21][22][23] impacting on the kinematic and physiological profile of the fight, 24,25 have made taekwondo an even more dynamic sport. ...
Article
BACKGROUND: The aim of this study was to quantify the age at which taekwondo athletes competed in the Olympic Games and to provide initial insights into weight category changes over time. METHODS: For the first analysis, the study included all 611 taekwondo athletes who competed in the Olympics between 2000 and 2016; for each sex, a three-way ANOVA (edition of Olympic Games, competitive achievement, weight category) was performed to detect differences in the age of athletes. For the second analysis, we considered all 109 taekwondo athletes who took part in more than one edition of the Olympics between 2000 and 2016; chi-squared goodness of fit tests were performed to study the number of participations and changes in weight category of these athletes. RESULTS: Female athletes, with a mean age of 23.8 ± 4.1 years, are significantly younger (p=0.001) than their male counterparts, with a mean age of 25.1 ± 3.9 years. In weight category, lighter athletes being younger than heavier ones in both females (22.7 ± 3.7 vs 24.5 ± 4.2 yrs., p=0.04) and males (23.6 ± 3.8 vs 26.7 ± 3.8 yrs., p=0.001; 24.2 ± 3.5 vs 26.7 ± 3.8 yrs., p=0.001). When an athlete reaches Olympic competition several times, he/she generally competes in the same weight category (p=0.001) and takes part in two consecutive editions (p=0.001). Heavier athletes have greater longevity at Olympic level than lighter athletes (p=0.002). CONCLUSIONS: The current data provides important information for national federations engaged in the selection of athletes for Olympic competitions.
... Yapılan kural değişiklikleri antrenörleri, sporcuları ve spor bilimcileri antrenman programlarında revizeler yapmaya zorlamıştır. 5 Bu sebeple, performansı artırmak için teknik çalışmaların yanı sıra farklı fiziksel çalışmaların da antrenman programına dâhil edilmesi faydalı olacaktır. ...
Article
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174 Tekvando çıplak el ve ayakla yapılan, atak-kontra atak ve kombine tekniklerin bir arada kulla-nıldığı Kore kökenli bir mücadele sporudur. 1 Birçok beceri, yüksek enerji talebi ve sofistike teknikler ge-rektiren bir spor branşıdır. Bu branşta tüm dünya ül-keleri yarışmaktadır. Uluslararası birim olan Dünya Tekvando Federasyonu 5 kıtayı kapsamaktadır. 2 Branşın bu kadar yaygın ve popüler olması spor bi-limcileri sporcuların fiziksel ve fizyolojik tepkilerini incelemeye yöneltmiştir. 3
... Olympic taekwondo is described as a modern and constantly evolving combat sport whose performance requires athletes to develop and maintain a high level of physical fitness as part of their preparation [1]. Therefore, it is important to understand the characteristics of the components involved in physical performance in this sport in order to apply appropriate training stimuli in the preparation of athletes. ...
Article
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The aim of this research was to compare the effects of a technique-specific high-intensity interval training (HIIT) protocol vs. traditional taekwondo training on physical fitness and body composition in taekwondo athletes, as well as to analyse the inter-individual response. Utilising a parallel controlled design, sixteen male and female athletes (five females and 11 males) were randomly divided into an experimental group (EG) that participated in the technique-specific HIIT and a control group (CG) that participated in traditional taekwondo training. Both groups trained three days/week for four weeks. Squat jump (SJ), countermovement jump (CMJ), 5-metre sprint (5M), 20-metre shuttle run (20MSR), taekwondo specific agility test (TSAT), multiple frequency speed of kick test (FSKTMULT), total kicks, and kick decrement index (KDI), as well as body composition were evaluated. Results indicate that there are no significant differences (p > 0.05) in the factors group and time factor and group by time interaction (p > 0.05). Although percentage and effect size increases were documented for post-intervention fitness components in TSAT, total kicks, KDI, and 20MSR, responders and non-responders were also documented. In conclusion, a HIIT protocol based on taekwondo-specific technical movements does not report significant differences in fitness and body composition compared to traditional taekwondo training, nor inter-individual differences between athletes.
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Çoğu branşta olduğu gibi taekwondo branşında da süratli, güçlü ve kuvvetli olunması iyi bir performans için ön koşuldur. Yine çocuklarda kuvvet performansının geliştirilmesi için çok farklı görüşler öne sürülmektedir. Bu bağlamda bu çalışmada son dönemlerde hem yetişkinlerde hem de çocuklarda aerobik, anaerobik ve kuvvet performansı üzerinde olumlu etkileri olduğu sıklıkla bildirilen, yüksek şiddetli interval antrenman metotlarından biri olan tabata egzersizin çocuklarda kuvvet üzerine etkisi araştırılmıştır. Çalışmaya taekwondo eğitimi alan 30 çocuk (yaş 14.3±0,21 yıl, boy159.1±2.04 cm, vücut ağırlığı 50.9±2.11 kg) gönüllü olarak katılmıştır. Daha sonra katılımcılar rastgele Tabata grubu (n:15) ve Kontrol grubu (n:15) olmak üzere iki gruba ayrılmışlardır. Tabata grubuna, kendi rutin branş antrenmanlarına ek olarak, 8 hafta boyunca haftada 3 gün belirlenen egzersiz setleri ile tabata antrenmanı yaptırılmıştır. Kontrol grubu ise 8 hafta boyunca haftada 3 gün kendi rutin taekwondo antrenmanlarına katılmışlardır. Çalışmanın başında, 4. haftasında ve sonunda tüm katılımcılara dikey sıçrama, durarak uzun atlama, sağlık topu fırlatma, mekik ve şınav testleri yaptırılmıştır. Verilerin analizinde SPSS 23 paket programı kullanılmıştır. Araştırma grubunun 1., 4. ve 8. hafta test sonuçları Repeated Measures ANOVA Testi ile, farklılığın hangi gruptan kaynaklandığını tespit etmek içinde Bonferroni testi kullanılmıştır. İstatiksel olarak anlamlılık düzeyi p<0.05 olarak kabul edilmiştir. Çalışmada grup içi değerlendirme yapıldığında tabata grubunda dikey sıçrama, sağlık topu fırlatma ve mekik testlerinde anlamlı fark tespit edilmiştir. Kontrol grubunda ise sadece mekik testinde anlamlı fark tespit edilmiştir. Gruplar arası karşılaştırma yapıldığında ise iki grup arasında tüm parametrelerde anlamlı fark tespit edilememiştir. 13-14 yaş grubu taekwondo eğitimi alan çocuklarda tabata egzersizin kuvvet performansı üzerinde olumlu etkisi olduğu söylenebilir.
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Background. The introduction of the Protector and Scoring System (PSS) laid to rest, accusations of game manipulation in WTF sport taekwondo and ended disputes regarding scoring decisions; but, at a significant cost. Problem: The current WTF taekwondo competition system, with the PSS as its core feature, has given rise to a variety of strikingly negative trends, such as the overreliance on weak, stationary kicking techniques with the front leg, a preference for relatively tall and lean but less athletic competitors, and the appearance of a variety of unconventional, and sometimes bizarre scoring techniques. This article will argue that these characteristics are interrelated and largely the result of the hurried, unmanaged introduction of the PSS, which turned taekwondo competition from a full-contact combat sport into a partly light-contact, points game. Aim. This article aims to encourage a discussion about the fundamental soundness of and necessity for the PSS. Methods. Since the topic of this article lacks broad scientific research and empirical data, the methodology of this article relies largely on an analysis of deductions, and is based on a literature review, personal experience, conversations, and observations. Results and conclusion. On a positive note, today's taekwondo leadership has finally acknowledged how the quality of taekwondo sparring and competitions has worsened, although it remains to be seen whether or not the WTF can fix the problem.
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Objectives: To determine the effects of rule modification on player movement during matchplay in junior Australian football (AF). Design: Quasi-experimental study design. Methods: Time-motion analysis was used to record variables pertaining to player movement including total distance covered, high-speed running (HSR) distance (>14.4km/h) and HSR efforts. GPS data obtained from 145 players (7-12 years) were analysed across four junior AF leagues and three age group combinations (U8/U9, U9/U10 and U11/U12). The four leagues were collapsed into two separate conditions (compliant and non-compliant) based on their adherence to a modified junior sport policy. To control for the influence of age and physical maturity, a secondary analysis was performed on an adequately matched U8 subset of data (n=48). Results: Significant differences (p<0.05) were found between compliant and non-compliant leagues for age and all player movement variables, with participants in the compliant leagues achieving less player movement. Significant differences were also evident between conditions in the U8 subset in total and relative distance and HSR efforts, with moderate to very large differences (29-60%) observed for all player movement variables. Conclusions: Rule modifications limits the extent and intensity of player movement in junior AF compared to standard playing conditions. The unintended effect of reduced physical activity with rule modifications should be compensated for with additional activities wherever possible. League administrators and policy makers should consider the objectives of rule modifications and weigh up both positive and negative outcomes.