| Combat
Sports Special Issue Research article |
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DEVELOPMENT OF A SPORTS SPECIFIC AEROBIC CAPACITY TEST FOR KARATE
- A PILOT STUDY
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School of Life Sciences, Kingston University, Kingston-upon-Thames, UK.
©
Journal of Sports Science and Medicine (2006) 5 (CSSI), 47
- 53
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| ABSTRACT |
| The
purpose of the study was to develop an aerobic fitness assessment
test for competitive Karate practitioners and describe the preliminary
findings. Five well-trained, competitive Karate practitioners participated
in this study. A protocol simulating common attack strikes used in
competition Karate sparring was developed from video analysis. In
addition, pilot testing established a specific sequence of strikes
and timings to be used in the test. The time to perform the strike
sequence remained the same, whilst the time between strike sequence
performances was progressively reduced. The aim of the test was to
increase intensity of exercise through a decrease in recovery. On
two separate occasions, absolute and relative peak oxygen uptake (VO2peak),
peak ventilation (VEpeak), maximum heart rate (HRM), and
time to exhaustion (TE) obtained during the test were recorded. Subjective
feedback provided by the participants was positive in that participants
felt the test accurately simulated actions of a competitive sparring
situation, and as a result athletes felt more motivated to perform
well on this test. There was no significant between test difference
in absolute VO2peak, relative VO2peak, HRM and
TE (p > 0.05), indicating a potentially high reproducibility with
the new test for these variables (test 1-test 2 difference of 0.04
L·min-1, 1 ml·kg-1·min-1, -3 beats·min-1,
and 28 s; respectively). However, VEpeak displayed potentially
less reproducibility due to a significant difference observed between
tests (test 1- test 2 difference of -2.8 L·min-1, p <
0.05). There was a significant relationship between TE and relative
VO2peak (R2 = 0.77, p < 0.001). Further developments
to the test will need to address issues with work rate/force output
assessment/monitoring. The new test accurately simulates the actions
of competitive Karate sparring.
KEY
WORDS: Maximal test, oxygen consumption, Karate, motivation.
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| INTRODUCTION |
In recent years, training and physiological testing have become
progressively tailored to the specific demands of the sport. For example,
in cycling, the KingcycleTM ergometer allows the cyclist
to use his or her own bicycle as the ergometer, making for a more
sports specific and therefore, arguably, valid test (Palmer et al.
, 1996).
There are numerous direct (i.e. laboratory) maximal oxygen uptake
(VO2max) tests developed for the treadmill and cycle ergometers
(Ĺstrand and Rodhal, 1986;
McArdel et al., 1973).
Several methods of predicting VO2max have also been developed
in an effort again to be more sports specific and allow measurements
to take place whilst accurately simulating the activity in which the
athlete participates (Cooper, 1968;
Shephard, 1979).
An example of such a test is the 20m multistage fitness test developed
by Léger et al., 1988
used for predicting VO2max in multidirectional, stop -
start type activities (e.g. soccer, rugby).
For participants of high-intensity intermittent activity, direct VO2max
assessment tests are limited to exhaustive continuous or discontinuous
protocols with the use of a treadmill or cycle ergometer (McArdel
et al., 1973).
For participants of activity that does not involve running or cycling,
these tests are not specific to the nature of their activity. Competitive
Karate is one of these high-intensity intermittent activities (Lewis,
1996).
Sparring in the competitive Karate environment involves the use of
systematic attack and defence techniques against an opponent. Competition
matches last 3 continuous mins for senior men, with intermittent pauses
when fighters commit an offence (e.g. illegal strike), step out of
a marked fighting area, or when an injury is sustained. Competitive
sparring is very intermittent in nature, divided into periods of very
high intensity activity (when attacking or blocking/parrying an attack)
and low intensity activity when the fighter is preparing for an attack
or just moving around ('dancing on their toes'). Much of the research
available on Karate has focused on the nature of the activity in stressing
the cardiovascular system and the potential health benefits this may
elicit to the practitioner (Francescato et al., 1995;
Shaw et al. 1982;
Zher et al. 1993).
This theme is continued in what little literature exists in competition
Karate and Karate type sparring (Imamura et al., 1996;
Schmidt et al., 1985).
These studies have collectively shown Karate and Karate type sparring
to be of intensity to stress the cardiovascular system and improve
cardiovascular fitness.
It is well established that short and intense bouts of exercise, similar
to that seen in competition Karate, rely predominately on the immediate
(ATP-PCr) and short-term (anaerobic glycolysis) systems for the resynthesis
of ATP. However, there is evidence to suggest aerobic processes are
also involved in ATP resynthesis during all-out, high-intensity exercise
(MedbŘ et al. 1989;
Serresse et al., 1988).
MedbŘ et al. (1989)
have shown the contribution of energy from aerobic pathways to be
as high as 40% during 30 s maximal work, and 50% during 1 min of maximal
work. These findings indicate that even for activities considered
to be 'anaerobic' in nature, there is significant involvement of the
aerobic system to energy production. For activities that are highly
intermittent in nature, such as competitive Karate, the relative contribution
of oxidative pathways to the resynthesis of ATP could be even higher.
Indeed, a recent study highlights the importance of aerobic pathways
during Karate type sparring. Heller et al., 1998
assessed the physical characteristics of male and female Taekwondo
(Korean equivalent of Karate) black belts performing in competition
sparring. The study observed the actual fighting time (periods of
attack/defence) compared to non-fighting time (pauses between scores,
'ring-outs' and injuries) in competition. The authors reported that
the maximal (fighting time) to low intensity (pauses) activity ratio
was 1:3 to 1:4. They concluded that competitive Taekwondo practitioners
demonstrated high anaerobic and aerobic abilities. Furthermore, the
authors also state 'it would be useful to detail more sport-specific
tests to evaluate Taekwondo black belts during the training season'.
Evidence exists to suggest that competitive sparring, of which Karate
is included, stresses the aerobic energy pathways to produce energy
for the resynthesis of ATP (Francescato et al. , 1995;
Imamura et al., 1996;
Shaw et al., 1982).
As with any sport, the assessment of the physiological processes important
to success in that sport is, especially at the elite level, compulsory.
A number of sports specific protocols to assess aerobic capacity exist
for sports highly dependent on the aerobic system (Léger et al., 1988;
Palmer et al., 1996).
To date, no protocol exists to assess the aerobic capacity of competitive
Karate practitioners whilst simulating the nature of the activity.
The aim of the present study was to develop such a test protocol. |
| METHODS |
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Participants
Five male competitive Karate practitioners participated in this
study. All participants were highly competent in Karate kumite (sparring)
to at least England National Squad level; Age (M = 31, SD = 9 years),
height (M = 1.80, SD = 0.05 m), body mass (M = 78.9, SD = 13.2 kg)
and experience (M = 15. 4, SD = 8.6 years). All participants were
informed of the procedures of the investigation and completed a
pre-test health-screening questionnaire and provided written consent,
according to ACSM guidelines (ACSM, 1995)
prior to participation. The University Research Ethics Committee
approved all experimental procedures.
Sport
specific protocol development
Pilot testing took place over a 1-month period. Figure
1 (a-d) illustrates the techniques performed in the test with
gas analysis equipment attached. These techniques were selected
from video analysis of competition Karate and the most common techniques
observed were selected. These included the straight punch and the
roundhouse kick.
The test protocol itself involved a sequential set of straight punch
and roundhouse kick combinations on a heavy punch/kick bag suspended
from a wall mounted bracket. The combination consisted of a leading
straight punch (Figure 1a),
followed by a rear leg roundhouse kick (Figure
1b), a rear straight punch (Figure 1c), and a leading roundhouse kick (Figure 1d), repeated twice. The time to complete this set
of movements accurately and without haste was set at 7 seconds.
This allowed sufficient time to execute and prepare each strike
in a controlled manner.
The
progression in intensity of the exercise during the test was based
on a similar sequence of emitted audio beeps as the multistage fitness
test (Léger et al., 1988).
The test was designed with 2 auditory signals, the first to let
the participant know when to begin the bout of exercise and a second
sound to indicate when they should rest (7 seconds later).
The time to complete the exercise bout remained the same, 7 seconds,
whilst the recovery time between bouts would be progressively decreased.
Participants had to perform each strike and kick with as maximum
force as possible. The aim here was to maintain maximal exercise
intensity whilst progressively making the test more demanding by
reducing the recovery between exercise bouts. One additional participant
performed 3 experimental trials to obtain sets of recovery periods
and subsequent decrements in time allotted for each particular set
of recovery periods. This participant was not included in the actual
experimental trials due to the imbalance in familiarity with the
test. Once the data from these trials was analysed, a final test
protocol was developed.
The protocol was again similar to that of Léger et al., 1988,
in that stages and levels were adopted to correspond to certain
periods of the recovery time. The outcome of pilot testing and the
final test protocol is presented in Table 1. The final test protocol was placed onto a laptop
PC.
Procedures
30 minutes before the onset of the experiment, participants were
allowed to warm- up and stretched for 15 minutes. 10 minutes prior
to test commencement participants were allowed a trial, with the
portable gas analysis system and heart rate monitor attached, to
practice the techniques used on the heavy bag and familiarise themselves
with the test procedure. 5 minutes before the test all systems were
checked again and the computer programme was put to ready. The test
began after a pre-recorded 5 second auditory countdown. Expired
air was analysed continuously throughout the test (Cosmed K4b2,
CosmedTM S.r.l, Italy). Often peak oxygen uptake (VO2peak)
is used to express the highest oxygen uptake obtained when the criteria
for achieving a VO2max are not strictly met (BASES, 1997).
Both relative (ml·kg-1·min- 1) and absolute (L·min-1)
peak oxygen uptake (VO2peak) were defined as the highest
30 second average VO2. The K4b2 is an upgraded version
of the K2 gas analyser (Vacumetrics Inc., Ventura, CA), which has
been shown to be both a valid (Lothian et al., 1993)
and reliable (Bigard et al. 1995; Crandall et al., 1994)
system for analysing VO2 uptake. The heart rate (HR)
was recorded every 5 seconds during the test via short wave telemetry
(Polar Vantage, Polar Electro OY, Kempele, Finland). During the
test, one of the researchers held the heavy bag in place to avoid
unwanted movement. The test ended when the participant achieved
volitional exhaustion at which point time to exhaustion (TE), exercise
level and the cycle number obtained on the test were recorded. A
second performance of the test was carried out 1 week after the
initial test. Following both trials subjective feedback was noted,
however this was not formally standardised.
Data
handling and statistics
All results are presented as mean ± S.D. Due to the small sample size,
a non- parametric differences test (Wilcoxin signed-rank) was carried
out on all dependant variables. In addition, relative and absolute
VO2peak values obtained from the two tests were individually
plotted against TE to examine possible relationships via linear
regression. Where a significant correlation was observed, the coefficient
of determination (variance) was determined. A significance level
of p < 0.05 was established prior to analysis. Statistical tests
were run using SPSS version 12.1 for windows.
|
| RESULTS |
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There was
no significant difference in VO2peak, HRM and TE between
test 1 and test 2 (p > 0.05). However, a significant difference
in VEpeak between test 1 and test 2 was observed (p <
0.05). Figure 2 illustrates a significant relationship
(R2 = 0. 77, p < 0.001) between time to exhaustion
and relative VO2peak. The calculated coefficient of determination
was 0.593 (0.77 x 0.77). Therefore, 59.3% (0.593 x 100) of the variance
in TE is accounted for by relative VO2peak. There was
no relationship between TE and absolute VO2peak, (R2
= 0.28, p > 0.05). Table 2
presents the observed absolute VO2peak, relative VO2peak,
VEpeak, HRM, and TE for test 1 and test 2 and the difference
in these measures between tests. Absolute VO2peak, relative
VO2peak, and TE increased (mean ± SD) 0.04 ± 0.1 L·min-
1, 1 ± 1.1 ml·kg-1·min-1 and 28 ± 8.1
s respectively. HRM and VEpeak decreased by 3 ± 0.3 beats·min-1
and 2.8 ± 1.6 L·min-1 respectively.
Subjective feedback from participants suggested that the test accurately
simulated the actions used in competitive sparring situations. In
addition, participants reported that they "felt more motivated"
performing the new test than previous aerobic assessment tests.
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| DISCUSSION |
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At
present, this is the first sports specific test to assess the aerobic
fitness of competition Karate practitioners. The first thing to
detail is the fact that the new test simulates the actions used
in competition Karate. All participants are familiar with other
means of aerobic fitness testing, the most common being the multistage
fitness test or 'bleep' test (Léger et al., 1988).
Participants reported that the new test accurately simulated the
actions they used in competition sparring, and this in turn "increased
motivation" to perform well on the new test compared to previous
aerobic capacity testing.
The difference between test 1 and test 2 absolute VO2peak,
relative VO2peak, HRM, and TE was 0.04 L·min-1,
1 ml·kg-1·min-1, -3 beats·min-1,
and 28 s, respectively. These relatively small, non-significant
differences indicate that the newly developed test demonstrates
potential test re-test reliability in these variables. VEpeak
displayed a significant difference between the two tests, decreasing
2.8 L·min-1 in the second test. This finding indicates
the new test is potentially less reliable at assessing VEpeak.
There was a strong relationship between TE and relative VO2peak
(Figure 2) and potentially
a large percentage (59.3%) of the variance in TE is attributed to
relative VO2peak. Performance on the new test involves
weight-bearing exercise utilising both upper and lower limbs. It
is well established that relative VO2peak relates strongly
to performance for weight-bearing whole body exercise as witnessed
in the present study (Haug et al., 1999).
The present finding indicates that the new test potentially assesses
the appropriate capacity of the aerobic system.
In developing the new test, a format similar to that of Léger et
al., 1988
was used. The 20m shuttle run test was designed to increase to such
intensity that it was almost impossible, if not impossible, to complete.
It was our aim that the new test should also be of an intensity
that prevented completion. However, it is noticeable that one participant
completed the new test on both occasions, indicated by a TE of 1182
seconds. Another participant completed the test on the second testing
occasion, increasing time to exhaustion by 76 s. Both participants
had a VO2peak equal to or greater than 55 ml·kg-1·min-1.
Moreover, these participants reported that they could have continued
exercising longer had the test not ended.
Current guidelines for maximal aerobic capacity testing indicate
VO2peak should be achieved within 8 - 15 mins (BASES,
1997). In the present test, only one participant achieved VO2peak
within this time (Participant 4, Table
2). For those participants that did not complete the test (n
= 3), average time to achieve VO2peak was 16.9 mins and
17.2 mins for tests 1 and 2 respectively. This, coupled with the
fact that time to completion of the test is already 19 mins and
42 s (1182 s/60), indicates that the new test is perhaps already
too long. Further time additions (e.g. an increase in number of
exercises/stages) would be impractical. It would be more practical
to consider the new test to be of insufficient intensity to achieve
VO2peak within guideline duration. Likewise, the new
test appears of insufficient intensity for individuals with a VO2peak
55 ml·kg-1·min-1 or greater.
Implications
for test development
Due to the small n, consideration to the possible presence of both
type I and type II error needs to be given. A larger n would reduce
the possibility of these errors occurring and provide sufficiently
statistical significant results. This should be addressed accordingly
in continuation study of the new test. Additional further developments
to the test include a need to increase intensity at an earlier stage
in an effort to prevent completion of the test. This could be achieved
by eliminating early stages used as a warm up period, and increasing
the number of stages within each exercise. However, when performing
a maximal oxygen uptake test on a treadmill or cycle ergometer,
work rate or intensity progressively increases by either increasing
speed (treadmill) or workload (cycle) until volitional exhaustion.
One of the restrictions of the new Karate test is the fact that
work rate cannot be assessed nor altered in the same manner as treadmill
or cycle ergometry workload. In the new test participants are asked
to perform each technique with as much force as possible. Towards
the end of the test, it was noticeable that participants were not
able to maintain the same level of force as that of earlier stages.
The problem lies in distinguishing if participants are giving a
maximal effort each time they perform the activity bout. Test developments
will look to address this issue via methods of assessing power output
during the test. The use of force transducers within a boxing punch
bag (Karpitowski et al., 1994)
and boxing manikin (Smith et al., 2000)
to monitor strike forces has been shown to provide accurate and
reliable force and power outputs in boxers. The adoption of such
methods for assessment of force/power output in the new test warrants
further investigation.
Finally, subjective feedback provided information regarding the
effectiveness of the new test in simulating actions specific to
competitive karate. As a result, participants reported feeling "more
motivated" performing the new test compared to previous non-specific
aerobic assessment tests. The use of appropriate psychological inventories
(Reeve and Deci, 1996)
may have allowed for quantification of this improved motivation.
Further developments will look to employ such methods, providing
additional ecological validity to the work.
In summary, the new test accurately simulates the actions used in
competition Karate and anecdotal reports are that the test is more
motivating than other familiar methods of assessing aerobic capacity
in Karate practitioners. Time to exhaustion during the test was
strongly related to relative VO2peak. At present, the
new test does not allow us to quantitatively measure performance
effort, making it difficult to distinguish a 'true' VO2peak.
The use of force transducers could be assessed to address this issue.
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| KEY
POINTS |
- This
is the first attempt at an aerobic fitness test specific to competitive
Karate practitioners
- Anecdotal
reports are that the new test accurately simulates the actions
used in competition Karate
- Relative
VO2peak was significantly related to time to exhaustion, with
63.5% of the variance in time to exhaustion attributed to relative
VO2peak.
- Test
developments include the use of force plates and transducers to
assess force/power output during the test
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| AUTHOR
BIOGRAPHY |
David NUNAN
Employment: Director,
Human Performance Laboratory.
Degrees: MSc Sport Sciences, BSc Sports Science
Research interests: Applied sport/exercise physiology,
ergogenic aids, exercise induced muscle damage
E-mail: d.nunan@kingston.ac.uk |
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