The Study of Physiological Factors and Performance in Welterweight Taekwondo Athletes

Abstract

The purpose of this research was to investigate the variation in heart
rate, oxygen consumption and blood lactic acid for taekwondo athletes during
training and competition. Ten taekwondo athletes from a Division I university
volunteered for the research. The average age of the subjects was 19.5±0.5
.4 yr, the height was 174.6±2.8 cm, the weight was 63.6±1.4 kg, the black
belt rank was 2.5±0.5, and the average training period was 6.4±1.0 years.
The competition was of university class. During the experiment, each subject
rode the bicycle ergometer until complete exhaustion at a speed of 60 RPM
and power of 120W that increased by 30W every two minutes. The investigation
focused mainly on the variations during the rest period and the three recovery
periods after exercise (5th, 30th and 60th minute). Wireless heart recorder
(POLAR), Vmax29 gas analyzer, YSI2300 lactic acid analyzer and DAIICHI analyzer
were used to analyze heart rate, oxygen consumption, blood lactic acid and
urobilinogen. According to the statistical analysis on one-way ANOVA with
Repeated Measures and a Scheffe Post Hoc test, the results showed that:
1.There was no difference at the cardiac respiratory functioning between
training and competition period. The players can’t recovery quickly
for sixty minutes.2. There was a significant difference at the BLA on the
competition period higher than training period (7.0±1.3 vs. 6.3±1.2 mmol/l,
p<.05). 3.There was no difference at the URO between training and competition
period in the post-exercise 60 minute and rest.4. There was a difference
on the output power at training period higher than competition period (232.7±14.5
vs. 226.5±14.7 watt, p< .05). To recover the rest state more time and
improve intensive training in the blood lactic acid system and power output.
It’s a benefit and helpful for the players and coaches to investigate
the reference during the contest and sport science training.

I. Introduction

Fast development of world-class high strength training and science has
had a significant impact on scientific training. Examples include weight
control, not only covering the grading of various levels of athlete’s
body weight but also balancing physical ability and health. Sport training
is important even for excellent athletes. Only when their cardio respiratory
function, energy expenditure and blood lactate system are well-controlled
can they show their potential and maintain high performance. This is very
important to both coaches and athletes (Hiroyuki et al., 1999). Peaking,
or the ability of an athlete to perform at peak performance during the
main competition or games of the year, is also related to strength training.

According to the theory of Periodization of Strength, gains in muscular
strength (M*S) during the M*S phase should be transformed into either
muscular endurance (M-E) or P during the conversion phase so athletes
acquire the best possible sport-specific strength and are equipped with
the physiological capabilities necessary for good performance during the
competitive phase. To maintain good performance throughout the competitive
phase, this physiological base must be maintained (Bompa, 1999). The determination
of physiological variables such as the anaerobic threshold (AT) and maximal
oxygen uptake (VO2max) through incremental exercise testing, and relevance
of these variables to endurance performance, is a major requirement for
coaches and athletes (Bentley, Mcnaughton, Thompson, & Batterhan,
2001). Heller, et al. (1998) pointed out that Taekwondo could not only
improve human cardio respiratory endurance but also enhance practitioners’
martial arts spirit, and form good exercise and self-defense exercise.
It also is classified as a high-strength anaerobic capacity exercise.
Shin (1993) reported that excellent international Taekwondo athletes must
have high speed and power for them to win the international games. The
energy system of anaerobic power and anaerobic capacity mainly comes from
ATP and Glycolsis system. Taekwondo practice had a positive impact on
the improvement of human cardio respiratory and physical ability (Pieter
et al., 1990). Heller et al (1998) found that the maximum oxygen consumption
volume was 57.0 ml/kg/min in Spanish international Taekwondo athletes
and 53.8 ml/kg/min in Czech international athletes. The maximum oxygen
uptake in Taekwondo black-belt athletes is 44.0 ml/kg/min (Drobni et al.,
1995). Bompa (1999) investigated boxing and martial arts, and found that
a quick and powerful start of an offensive skill prevents an opponent
from using an effective action. The elastic, reactive component of muscle
is of vital important for delivering quick action and powerful starts.

The purpose of this study is to investigate the change of heart rate, oxygen
consumption, blood lactate, and urine urobilinogen in resting phase, and
in post exercise recovering phase at 5 min, 30 min and 60 min after a total
10-week period including training and competition phases.

II. Study Methods and Procedures

Selection of the Subjects

Ten male TaekwonDo athletes were recruited as volunteer subjects in this
study. The mean age, body height, weight, rank, and training experience
of these subjects were 19.3±0.5 years, 174.6±2.8 cm, 63.6±1.4 kg, 2.5±0.5,
and 6.4±1.0 years, respectively.

Time and Venue

The study was completed in the Sports Physiology Lab of Chinese Culture
University, Taiwan. The research of training phase was done from May 11
to 12, 2002. The research of peak phase was done from May 25 to 26, 2002.

Study Methods and Procedures

According to the training content completely controlled by the coach,
the training duration is 10 weeks, once every morning for 1.5 hours and
every afternoon for 2 hours. The research method was to arrange the subjects
to pedal on a bicycle to exhaustion at cycling rate 60 RPM and initial workload
120 W with 30 W increase every 2 minutes. The post-exercise physical changes
(heart rate, oxygen consumption, blood lactate, and urine urobilinogen value)
were measured in baseline phase, training phase and competition phase, collecting
3 samples in each phase.

(1) Informed consent forms were obtained after the study procedures and
potential effects were explained to the subjects, and were understood by
the subjects. The status of subjects’ general health was also recorded.

(2) Subjects who were in a bad mood and not in good physical condition
were not allowed to perform the test, and were scheduled to return at
another time.

(3) 30 minutes before the experiment, the experimental
equipment started to warm up, and experimental material was prepared. The
subjects were arranged on a bicycle to start pedaling to exhaustion at cycling
rate 60 RPM and initial workload 120 W with 30 W increase every 2 minutes.
The physical changes (heart rate, oxygen uptake, blood lactate, urine urobilinogen
value)were measured at 1. Resting phase 2. First minute of post exercise
recovering phase 3. 5th minute of post exercise recovering phase 4. 30th
minute of post exercise recovering phase 5. 60th minute of post exercise
recovering phase.

(4) During the experiment, the research staff recorded the information
obtained from the instruments. When the first experiment ended, the subject
would be informed of the time of next experiment.

(5) Study Equipment and Instruments: The following items were utilized
in this research:

  1. SENSOR MEDICS Vmax29 Gas Meter
  2. YSI2300 PLUS Lactate Analyzer
  3. DAIICHI 701 Analyzer
  4. 586 PIII computer and Laser printer
  5. (POLAR) Mobile heart rate recorder
  6. Stopwatch
  7. Hygrometer

Data Management

(1) All data collected from the study were analyzed using 3 statistical
software programs: Microsoft Excel 8.0, SPSS/PC 10.0, and SPSS for Windows.

(2) Multiple variants were analyzed by ONE-WAY ANOVA and subsequent Scheffe’
way for post-hoc analysis.

(3) Significant difference was set at α=. 05.

III. Results and Discussion

1.Assessment of Cardio respiratory function

(1)The result of heart rate measurements. There were no statistically
significant differences for heart rate between training and competition
period(188.7±2.8 vs. 189..6±1.6 bpm , p>.05) (Table 3-1)(Figure3-1).
The results showed no overstraining of the heart rate between training
and competition period. Arja & Uustitalo(2001) reported overstraining
syndrome as a serious problem marked by decreased performance, increased
fatigue, persistent muscle soreness, mood disturbances, and feeling ‘burn
out ‘ or stale.

Lin & Kuo (2000) found Tae-kwon-Do competition with 3 runs (3 min
per run), and 1-min break in every game, the score decides who is the
winner. During a game, their heart rates would increase to 165 time/min.
Some may reach 192 time/min. It shows that Tae-kwon-Do is a high-intensity
exercise, which has greater impact on circulation and respiratory systems.
Related to this study, the athletes in different grades of technique and
body weight have different fitness physical conditions. Guidetti, Musulin,
& Baldari (2002) reported eight elite amateur boxers’ HRmax
at 195±7 bpm. The measurement of maximum heart rate is important because
it is often used to determine the intensity of cardiovascular training
zone. In reality, a larger size athlete would tend to have a lower HRmax
value than the predicted value (McArdle et al., 2001). Melhim (2001) et
al. found that Tae-kwon-Do exercise could improve children’s cardio respiratory
function, improve practitioners’ attack and defense skills and enhance
self-health adjusting ability. The result shows that the resting heart
rate did not have significant difference after aerobic power training;
Anaerobic power and anaerobic capacity had a significant difference, 28%
and 61.5% increase respectively; Before and after the training, there
was no significant difference in resting heart rate (80.0±6.0 vs. 77.0±9.0
time/min, p>. 05) and in maximum oxygen uptake (VO2 max ) (36.3±9.2
vs. 38.2±7.8 ml/kg/min, p>.05). In 80-second Tae-kwon-Do competition,
VO2max is 68/ml/kg/min. There was no difference at the heart rate in the
training period between post-exercise 60 minute and rest (73.6±3.7 vs.
67.6±3.2 bpm , p>.05). There was no difference at the heart rate in
the competition period between post-exercise 60 minute and rest (72.9±3.7
vs. 67.0±2 .0 bpm , p>.05).

Table 3-1 Heart rate comparisons between training and competition n=10
(unit: bpm)

Rest Hrmax post-5 p-30 p-60
Training 67.6±3.2 188.7±2.8 121.3±7.0 84.2±3.2 73.6±3.7
Competition 67.0±2.0 189.6±1.6 115.7±13.2 80.4±5.8 72.9±3.7

* means significant different between training and competition

The elite athlete can recover quickly to a rest state and have low a
heart rate. Heart rates of general athletes at rest, before and after
exercise, were 71, 59, 36 time/min, and their maximum heart rates were
185, 183, 174 time/min, respectively(Jack & David, 1999). The results
showed the athletes didn’t recover to the rest period for sixty
minutes in the post-exercise between training and competition period.
Maybe the players need more time to improve the recovery state. It’s
important for the coach and players to improve the recovery system on
time because the players have to keep peak performance to success. Prevention
is still the best treatment, and certain subjective and objective parameters
can be taken by athletes and coaches to prevent over training between
practice and competition periods.

Figure 3-1 Heart rate comparisons between training
and competition

(2)The result of VO2max There was no difference at the VO2max
between training and competition period (49.6±3.3 vs. 50.3±3.0 ml/kg/min,
p>.05)(Table3-2)(Figure3-2). Drobnic(1995)discussed recreational Tae-kwon-do
athletes had a mean VO2max about 44.0 ml/kg/min; however, the
VO2max values for elite athletes would be significantly higher
than the athletes of recreational level. The National Taekwando Team of
China had an average of VO2max of 57.57 ml/kg/min. The mean
VO2max value of the Korean National Team, the perennial dominant
power of this event, was about 59.56 ml/kg/min (Hong, 1997).Heller et
al(1998) reported the average VO2max of the black-belt athletes
on the Spanish national squad was 57.0 ml/kg/min, and as for the Czech
Republic Team, the value was 53.8 ml/kg/min. Based on the results of previous
research, it was suggested that male and female contestants with VO2max
of 65 ml/kg/min and 55 ml/kg/min respectively, had a better chance to
win Olympic medals. Intensive aerobic training could improve the physiological
functions of highly trained sport contestants (Cooke et al., 1997).

Macdougall, Wenger & Green(1990)found ranges of VO2max reported
for international athletes in male wrestling, soccer, basketball, and untrained.
Their result were 50-70 ml/kg/min, 50-70 ml/kg/min, 40-60 ml/kg/min, 38-52
ml/kg/min. Guidetti, Musulin, & Baldari (2002) examined the physiological
characteristics of the middleweight class boxers. Their VO2max
at the individual anaerobic threshold was about 46.0±4.2ml/kg/min and their
VO2max was 57.5±4.7 ml/kg/min. In addition, their hand-grip strengths
and wrist girths were measured and compared to other combat-sports athletes.

In a competitive Olympic (non-professional) boxing match, boxers must fight
for a total of 11 minutes. The fight is structured for three 3-minute rounds
with a 1-min rest interval between each round. An athlete must have a high
anaerobic threshold level and aerobic power level to meet the demand of
this sport (Guidetti et al., 2002). Zabukovec & Tiidus(1995) investigated
the physiological characteristics of kickboxers .Professional male middleweight
(73-77 kg) and welterweight (63-67 kg) kickboxers were determined to have
relatively higher aerobic capacities (VO2max, 54-69 ml/kg/min)
than previously reported for many other power or combat athletes.

Table 3-2 Oxygen consumption comparisons between training and competition
n=10 (unit: ml/kg/min)

Rest VO2max post-5 p-30 p-60
Training 3.9±0.3 49.6±3.3 20.8±1.1 5.9±0.3 4.3±0.1
Competition 3.8±0.4 50.3±3.0 20.7±0.9 5.9±0.3 4.2±0.1

*means significant different between training and competition

The results showed lower VO2max than elite players. Therefore,
to monitor the phenomena of physiological characteristics to improve the
efficiency in the sport science, there was no difference at the VO2max
in the training period between post-exercise 60 minute and rest (4.3±0.1
vs. 3.9±0.3 bpm, p>.05). There was no difference at the VO2max
in the competition period between post-exercise 60 minute and rest (4.2±0.1
vs. 3.8±0.4 ml/kg/min, p>.05). The result showed similarly between
post-exercise 60 minute and rest in the training and competition period
, but need more time to recovery in the rest period.

Figure 3-2 Oxygen consumption comparisons between
training and competition

2. The result of blood lactic acid measurement. There was difference
at the BLA on the competition period higher than training period (7.0±1.3
vs. 6.3±1.2 mmol/l, p<.05)(Table 3-3)(Figure 3-3). Heller et al (1998)
reported that in male and female international TKD competitions, peak
blood lactate after 143 seconds could reach the highest, 11.4 mmol/l.
The change in the blood lactate has a close relationship with the TKD
competition intensity and competition performance (Hultman & Sahlin,
1980). The result showed lowered blood lactic acid than others to improve
the intensive training to the player between training and competition
period. Hetzler et al (1989) pointed out that excellent martial players
should have the characteristics of very good physical ability, high speed
and great strength, blood lactate ranging from 1.51-3.23 mol/100 ml, and
blood pH value decreasing from 7.39 to 7.34 mg/dl. TKD players not only
must have anaerobic metabolism with greater explosive power, but also
have very good aerobic endurance; therefore, TKD athletes must have very
good anaerobic ability and demand for higher aerobic metabolism capacity
(Ho, 1997).

Table 3-3 Blood lactic Acid comparisons between training and competition
n=10 (unit: mmol/l)

Rest post-5 p-30 p-60
Training 0.8±0.0 6.3±1.2 3.6±1.1 1.2±0.2
Competition 0.8±0.0 7.0±1.3 * 3.3±0.7 0.9±0.1

* means significant different between training and competition

Jack & David (1999) found that the resting blood lactate are 1.0 mmo/l、1.0
mmol/l、1.0mmol/l respectively for ordinary athletes, and international
athletes before and after exercise; maximum blood lactate are 7.5、8.5、9.0
mmo/l respectively.

Ho., Chiang & Tsai(1998) found that in 1998 Asia Games, having 4 TKD
athletes participate in the winning competition in the training team, the
results showed that their maximum blood lactate was 6.74 mmol/l, and BUN
tended to increase gradually after competition. From these results, we know
although the time of TKD games is short, it may cause the damage in muscle
fiber. To excellent athletes, if the quality and quantity of training intensity,
cardio respiratory function, energy consumption, and blood lactate system
during training can be well controlled, furthermore to well control their
body weight and physical ability, the athletes can elaborate their potential
and maintain peak performance. It is very important to coaches and athletes
(Hiroyuki et al., 1999).

Figure 3-3. Blood lactic Acid comparisons between
training and competition

3. The result of URO There was no difference at the URO between training
and competition period (92.0±91.1 vs. 195.0±158.4 mg/dl ,p>.05).(Table3-4)(Figure3-4).
Urine biochemistry tests can be the evaluation index of nutrition assessment
and test exercise intensity (Robert & David, 1993). There was no difference
at the URO in the training period between post-exercise 60 minute and rest
(36.5±37.2 vs. 15.8±10.4 mg/dl, p>.05).There was no difference at the
URO in the training period between post-exercise 60 minute and rest (43.5±35.5
vs. 25.0±12.6 mg/dl , p>.05). The greater the fatigue, the greater the
negative training aftereffects such as low rate of recovery, decreased coordination,
and diminished power output (Bampa,1999). Related to this study, probably
10-week peak phase of training over-exhausts the physical function and elevates
urine protein level that will take longer to recover. Lin(1996)discussed
that the factors affecting exercise urine protein included: 1.urine protein
and physical function.2.quantity and intensity of training.3.age and environments.4.the
effect of emotion on urine protein.

Table 3-4 URO comparisons between training and competition n=10(unit:mg/dl)

Rest post-5 p-30 p-60\
Training 15.8±10.4 92.0±91.1 105.0±126.1 36.5±37.2
Competition 25.0±12.6 195.0±158.4 120.0±73.3 43.5±35.5

* means significant different between training and competition

This finding can be an objective reference factor for contestants in
the training and competition. It is possible that nine weeks of training
may increase the urine protein level. Urine protein and exercise intensity
have strong relationship. Competitive games and high intensity training
make urine protein increase. The stronger the exercise intensity, the
more the urine protein.

Figure 3-3 URO comparisons between training and competition

4.The difference of PO(power output) There was difference at the power
out at competition period greater than training period (232.7±14.5 vs.
226.5±14.7 watt ,p<.05) (Table3-4) (Figure3-4). It could be training
for 10th week to promotion the muscle of power output. Zabukovec
& Tiidus (1995) investigated professional male middleweight (73-77
kg) and welterweight (63-67 kg) kickboxers. The results showed relatively
anaerobic capacities (8.2-11.2 Watt/Kg) than previously reported for many
other power or combat athletes. The results showed lower than Kickboxers’
anaerobic capacities. Hoffman & Kang (2002) investigated a major concern
of many of these studies focused on the applicability of a cycle ergo
meter test for anaerobic power in athletes that perform primarily sprinting
activities. To find the peak power of the football, basketball, wrestlers,
male physical education students were 16.8±5.2 w/kg, 21.8±5.0, 18.5±2.7,
18.8±5.6 W/kg. Female group of the soccer and physical education students
in peak power is 15.7±4.2 and 12.9±3.0 W/kg. However, the results showed
lowered power output than others to improve the athlete’s muscle
power to promote the physical state.

Bompa (1999) investigated strength training has become widely accepted
as a determinant element in athletic performance. Thus, the main objective
of the conversion phase is to synthesize those physiological foundations
for advancements in athletic performance during the competitive phase.
The determining factors in success of the conversion phase are its duration
and the specific methods used to transform M*S gain into sport-specific
strength.The power value measured by the simple product of the applied
force and the speed developed remains inferior to the real power performed
by the subjects since the forces of friction and inertia are not taken
into account (Arsac et al.,1996).Thus other factors, such as metabolic
and structural properties of taekwon-do players’ muscles, should
be considered. Therefore, martial arts and boxers must be able to react
quickly and powerfully to an opponent’s attack. Both aerobic and
anaerobic energy is used during a bout. Reactive strength and agility
are necessary to respond to an opponent’s strategy. Limiting factors:
Power endurance P-E), reactive power, M-E (muscle endurance)medium or
long(professional boxer (Bompa,1999). Taekwon-do exercises the need for
stronger power including speed and velocity. Power is the ability of the
neuromuscular system to produce the greatest possible force in the shortest
amount of time. Power is simply the product of muscle force (F) multiplied
by the velocity (v) of movement: P=F*V for athletic purpose, any increase
in power must be the result of improvements in either strength, speed,
or a combination of the two (Bompa, 1999).

Table 3-4 Power Output comparisons between training and competition n=10 (unit: watt) ; average power: AP

Power Output
Training 226.5±14.7 *
Competition 232.7±14.5

*means significant different between training and competition

The advantage of explosive, high-velocity power training is that it “trains”
the nervous system. Increase in performance can be based on neural changes
the help the individual muscles achieve greater performance capability
(Scale,1986). This is accomplished by shorting the time of motor unit
recruitment, especially FT fibers, and increasing the tolerance of the
motor neurons to increased innervations frequencies (Hakkinen, 1986; Hakkinen
& Komi,1983). The other way, it’s important technology for the
coach and player to improve the starting power because it is an essential
and often determinant ability in sports where the initial speed of action
dictates the final outcome (boxing, karate, fencing, the start in sprinting,
or the beginning of an aggressive acceleration from standing in team sports).
The athlete’s ability to recruit the highest possible number of
FT fibers to start the motion explosively is the fundamental physiological
characteristic necessary for successful performance (Bompa,1999).

Figure 3-4 Power Output comparisons between training and competition

IV. Conclusion

  1. There was no difference of the cardiac respiratory functioning between
    training and competition period. The players can’t recovery quickly
    for sixty minutes.
  2. There was a difference at the BLA at the competition period higher
    than training period. To improve the intensive training to the player
    between training and competition period.
  3. There was no difference at the URO between the training and competition
    period in the post-exercise 60 minute and rest.

The competition period was greater than training at
the power out, but less than elite athletes in the professional period.
Athletes are constantly exposed to various types of training loads, some
of which exceed their tolerance threshold. When athletes drive themselves
beyond their physiological limits, they risk fatigue (Bompa,1999). Thus,
to monitor the physiological characteristics between training and competition
period. It’s benefit for the player and coach to manage the peak
performance and avoid the over training. To recover quickly and keep a
steady state is important for the coach and player.

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