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Journal of Exercise Physiologyonline
August 2014
Volume 17 Number 4
Editor-in-Chief
Official Research Journal of
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the American
Boone, PhD,
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Exercise
Physiologists
Todd Astorino, PhD
Julien Baker,
ISSN 1097-9751
PhD
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Eric Goulet, PhD
Robert Gotshall, PhD
Alexander Hutchison, PhD
M. Knight-Maloney, PhD
Len Kravitz, PhD
James Laskin, PhD
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Dale Wagner, PhD
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Ben Zhou, PhD
Official Research Journal
of the American Society of
Exercise Physiologists
ISSN 1097-9751
JEPonline
Correlations between Performance and 4-Min
Maximum Efforts in Olympic Kayaking Athletes
João Paulo Loures3, Heros Ribeiro Ferreira1,2, Rafael Mendonça
Rocha Oliveira3, Pamela Gill2, Luiz Cláudio Fernandes1
1Laboratory
of Cell Metabolism - Federal University of Paraná,
of Medical Sciences of Santa Casa - São Paulo, 3Brazilian
Canoeing Academy - Curitiba
2Faculty
ABSTRACT
Loures JP, Ferreira HR, Oliveira RMR, Gill P, Fernandes LC.
Correlations between Performance and 4-Min Maximum Efforts in
Olympic Kayaking Athletes. JEPonline 2014;17(4)34-41. The aim
of this study was to investigate the VO2 peak, lactate concentration,
and force responses after a maximum 4-min effort on specialized
ergometers and the possible relationship of these responses with
performance in a 1000 m race. The study consisted of 28 elite
kayakers divided into two groups: (a) 21 males, 21.25 ± 5.71 yrs,
173.50 ± 8.50 cm, 69.93 ± 10.36 kg; and (b) 7 females, 21.57 ±
6.17 yrs, 172.81 ± 9.27 cm, 68.90 ± 11.50 kg). All subjects
performed a 4-min maximal effort while VO2 peak values were
verified both prior to and after the exercise along with the collection
of 25 μL of blood from the earlobe for analysis of lactate [Lac].
Performance was observed 72 hrs later in a 1000 m race in an
individual Olympic kayak (K1). Pearson correlation was used for
possible associations between VO2 peak, [Lac] peak, the
parameters of the force-time curve and the performance in the K1
1000 m. Results revealed that of all the parameters analyzed, only
the fatigue index (FI), which was observed from the force-time
curve data, showed a significant correlation (r = 0.46). Thus, based
on these results we conclude that in K1 1000 m races the kayakers
who tend to maintain the distribution of force peaks during the race
appear to have a greater chance of success.
Key Words: Kayakers, VO2 max, Fatigue Index
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INTRODUCTION
Several physiological tests have been used to assess the conditions of Olympic kayakers. Of
these, the tests that stand out are those using specific ergometers (2,4,7) and performed in water
(9,19), in addition to the tests that analyze force and its relationship with performance (7,8,18).
Kayakers depend primarily on aerobic metabolism of which they remain at an intensity of ~90% of
their aerobic capacity throughout a trial (11). In agreement, Bishop et al. (3) indicate that kayaking
athletes remain at or near peak oxygen consumption (peak VO2) for the majority of a race. When
expressed as a fraction of VO2 max, the aerobic contribution during the 500 m race and 1000 m
race is 73% and 85%, respectively, with a time for each race of around 1 min and 45 sec and 3
min and 45 sec (13).
Tesch (17) observed high levels of lactic acid in a kayaking test. Bishop et al. (4) indicated that a
500 m kayaking speed effort requires ~35% from anaerobic metabolism and ~65% from the
aerobic system. This suggests the importance of the anaerobic contribution for success in
kayaking. Both Bishop (3) and Fernandez and colleagues (5) indicate that kayaking requires a high
level of anaerobic and aerobic fitness to realize a successful performance.
Interestingly, most studies that investigate the potential relationships between force parameters,
VO2, lactate concentration ([Lac]) and performance over 1000 m use non-specific methods for
kayakers (such as weight lifting or a cycle ergometer for the upper limbs). Thus, the purpose of this
study was to determine the force produced on a specific ergometer for kayakers during a 4-min
test to verify the possible relationships between VO2, [Lac], and test performance over 1000 m.
METHODS
Subjects
The sample consisted of 28 elite kayakers: 21 males (21.25 ± 5.71 yrs, 173.50 ± 8.50 cm, 69.93 ±
10.36 kg) and 7 females (21.57 ± 6.17 yrs, 172.81 ± 9.27 cm, 68.90 ± 11.50 kg) who volunteered
to participate in the study. All subjects had at least 3 yrs of competitive experience at the
international level, with some being finalists in world and continental championships. All athletes
trained in individual kayak boats (K1). The subjects were informed of the procedures and signed
an informed consent form prior to inclusion in the study. The study was approved by the ethics
committee of the Federal University of Parana. The evaluation period was at the beginning of the
season.
Procedures
The ergometer used was a Speedstroke GYM from Kayakpro®. This ergometer has been used in
recent years by the British, French, and Americans in indoor kayaking championships. The
ergometer allows the athlete to adopt the same posture as in a boat, and it is configured so that
the athlete performs the same movements as in the water. The ergometer paddle has an axis,
which is fixed at the ends and connected by cables to a force transducer, where resistance can be
altered and fully controlled by a computer.
Experimental Approach to the Problem
The subjects were familiarized with the ergometer and procedures. Prior to the 4-min maximum
effort the subjects performed a 10-min warm-up divided into two parts, followed by a passive
36
interval of 2 min. The process for data acquisition was carried out by drawing lots in random order.
Seventy-two hrs after the ergometer tests the subjects participated in a national championship
where it was possible to verify their performances in the K1 1000 m (D1000).
Ergometer 4-Min Test
The goal of the 4-min kayak ergometer test (KE) was that the subjects performed at maximum
level throughout the test, without the use of strategies. The subjects performed a 5-min
unstructured joint warm-up and a 5-min specific warm-up on the ergometer with a load of 40 W,
which was followed by a passive interval of 2 min. Then, at a command from the researcher the KE
test started on a stationary ergometer.
During the specific warm-up, the actual test, and 5 min after the test (recovery), gas exchange was
analyzed using a metabolic system K4b2 (Cosmed, Rome, Italy) that was calibrated using a 3 L
syringe and gases of known concentrations. The physiological variables of interest included peak
VO2 and heart rate (HR). Prior to and immediately after the KE, blood was collected from the
earlobe to determine [Lac], using disposable microspears (Roche®, Soflix®) and reagent strips for
lactate (Roche®, lactate test strip) in a portable Accusport analyzer (Roche®). The HR data were
collected and recorded using a Polar® system of information transmission. All data were stored in
the equipment and subsequently filtered and analyzed using specific software.
Data collected during the KE test were amplified and transmitted using an analog/digital converter
(A/D) (National Instruments, NI6218) with 1 kHz sampling and, then, analyzed using a specific
program (Lab View Signal Express 3.0 mark National Instruments). A Butterworth 2nd order filter
with a filter cutoff frequency of 20 Hz was used, and the data were processed in a Matlab 7.9
(Matlab, The Matchworks) program using a routine created specifically for the study. The “force”
variables for each stroke and each hemisphere (right and left) were determined from the
components of the resulting force-time curve: the average force (MF), peak force (PF), rate of force
development (RFD), impulse (IMP), and fatigue index (FI).
Performance Test K1 1000 m (D100)
Before beginning the test, the subjects performed a warm-up, which involved paddling for 3000 m
at intensity of 70-75% of maximal aerobic capacity. Heart rate for each warm-up was individually
monitored using a frequency meter (Polar®, Finland), model S601i. The subjects used the same
frequency meter to monitor HR during both the test and subsequent analysis. After the warm-up,
the 1000 m national championship race was initiated during which performances were verified
through time taken to complete the course.
Statistical Analyses
The results are presented as mean ± standard deviation. Normality was confirmed using the
Kolmogorov-Smirnov test. The Pearson correlation test was used for all possible combinations of
performance parameters analyzed. The level of significance was set at P≤0.05.
RESULTS
The force behavior during the KE test is shown in Figure 1. Average VO2, lactate, HR, and
performance of the male and the female groups are presented in Table 1. The force data for both
groups are shown in Table 2. When analyzing all parameters and relationships with performance in
the 1000 m race (D1000 m), only FI for the male group showed a significant correlation (Table 3).
37
220
200
180
160
force(N)
140
120
100
80
60
40
20
0
50
100
150
200
250
Time(s)
Figure 1. The Behavior of the Force of a Subject during the 4-Min Maximum Effort.
Table 1. Average VO2, Lactate, HR, and Performance of Both Groups.
VO2
VO2
[Lac]
HR
D1000 m
(L·min-1)
(ml·kg-1·min-1)
(mmol·L-1)
(beats·min-1)
(sec)
Male
2.73 ± 0.66
37.69 ± 8.25
8.03 ± 1.30
181.21 ± 19.96
250.93 ± 17.67
Female
1.91 ± 0.65
31.16 ± 9.59
8.41 ± 0.73
174.98 ± 19.12
255.35 ± 7.25
Table 2: The Force Data for Both Groups during the 4-Min Maximum Effort.
MF
PF
FI
IMP
(N)
(N)
(%)
(N)
Male
250.99 ± 77.33
420.45 ± 133.48
70.88 ± 8.27
387.22 ± 110.57
Female
199.17 ± 78.05
301.86 ± 139.56
64.07 ± 11.77
367.50 ± 109.93
MF = Average Force; PF = Peak Force; FI = Fatigue Index; IMP = Impulse
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Table 3. Coefficient of Correlation between the 1000 m Performance and the Parameters
Analyzed on the Specific Ergometer for Kayakers.
VO2 (L·min-1)
VO2 (ml·kg-1·min-1)
Lac (mmol·L-1)
MF (N)
PF (N)
FI (%)
IMP (N)
Males
Females
-0.28
0.27
-0.14
-0.36
-0.14
0.46*
-0.24
-0.67
-0.66
0.25
-0.19
-0.06
0.16
-0.27
MF = Average Force; PF = Peak Force; FI = Fatigue Index; IMP = Impulse. *P≤0.05 correlation with
performance D1000 m
DISCUSSION
The major finding of this study was the correlation (r = 0.46) observed between the FI and D1000
m for male kayakers. Although the correlation is a weak positive association between the two
variables and even though correlation does not imply causation, this finding suggests that success
is not in producing a large production of force but in keeping the force maintained throughout the
race.
The observed values of VO2 (absolute and relative) in the present study are low for elite athletes.
Fry and Morton (7) reported a value of 59.2 ± 7.1 ml·kg-1·min-1 for elite athletes, and Tesch (17)
reported 58.4 ± 3.1 ml·kg-1·min-1. Both studies were conducted on specific ergometers for
kayakers. More recently, Nakamura et al. (14) on a cycle ergometer for upper limbs also observed
higher values (51.9 ± 5.6 ml·kg-1·min-1) than those presented in the present study.
Even though the studies by Fry and Morton (7) and Nakamura et al. (14) demonstrated VO2 peak
values which were much higher than the values we observed, when comparing performances in
the D1000 m, the results of the subjects (i.e., athletes) in the present study were found to be on the
same level as the athletes of the Fry and Morton study (7) (249.06 ± 19:25 ml·kg-1·min-1) and
better than both the national athletes of Nakamura et al. (14) (269.5 ± 12.6 ml·kg-1·min-1) and the
top-class athletes of Van Someren and Palmer (18) (262.56 ± 36.44 ml·kg-1·min-1).
Several studies have demonstrated a positive correlation between the parameters of peak VO2 and
the D1000 m (6,7,18). In contrast, we found no correlation between VO2 (absolute and relative)
and D1000 m, corroborating the findings of Nakamura et al. (14) who found no correlation between
peak VO2 (ml·kg-1·min-1) and performance. In addition, Van Someren and Palmer (18) found no
correlation between either VO2 max or maximal aerobic power and the D1000 m in experienced
male kayakers.
It has been suggested by several authors investigating kayakers that the anaerobic pathway plays
a crucial role in performance. van Someren and Palmer (18) observed a correlation between total
work performed during a 30 sec performance and a 1000 m performance that suggested the
relevance of the anaerobic pathway in kayaking. However, no relationship was observed between
39
[Lac] peak and performance thereby corroborating with the present study. In a literature review,
Michael et al. (13) suggested that the average [Lac] peak concentration found in laboratory and
water tests is approximately 12 mmol·L-1. Nakamura et al. (15) in a study consisting of female
paddlers showed a lactate peak concentration of 10.2 ± 0.8 mmol·L-1 over a distance of 500 m.
The values (males, 8.03 mmol·L-1 and females, 8.41 mmol·L-1) we observed are lower than those
found in the literature.
Hartmann et al. (10) analyzed paddling athletes and found that PF decreased from the first stroke
to the last stroke, which is similar to the present study. Using a 1 RM bench press and bench pull
to determine the force of kayakers, Forbes et al. (6) found positive correlations with the D1000 m.
But, they pointed out that other factors are necessary for successful performance, given that after
3 to 4 wks of training there was no change in force even though the athletes' performance had
improved.
Contrary to other studies (7,18) that analyzed isokinetic torque and power, correlations have been
observed between performances in tests of 500 m and 200 m, respectively. Although these forms
of force analysis have acceptable reliability, Abernethy and colleagues questioned the external
validity (1), which supports the relevance of the present study. This seems appropriate since most
studies that analyzed the force of kayakers did not carry out the analysis throughout the duration of
the test and/or in a specific manner, thus making it impossible to verify the behavior.
To our knowledge, the present study is the first to examine force throughout a test (4 min). Of all
the parameters analyzed, only the FI variable presented a positive correlation with performance for
the male group. This finding suggests that the athlete who has the greatest chance of success in a
competition is not the one who produces the highest PF but the one who maintains the distribution
of force peaks in the force-time curve. One explanation for this relationship not being found in the
female group is the small number of subjects. In this regard, Steinacker et al. (16) and Lawton (12)
analyzed rowing athletes. They observed that as the level of force declined over the test, it was
replaced by both speed and rate of stroke in order to maintain high power until the end of the event
(~6 min). This could be a technique used by athletes in kayaking.
CONCLUSIONS
Although the VO2 and lactate values of the Olympic kayaking athletes were lower than the values
reported in the literature, their performances were similar or better. This finding indicates that other
factors must influence the success of kayakers as well as the force distribution during the race. In
consideration of this point, it is reasonable to speculate that the key to successful kayaking is being
able to not only apply high force, but also to maintain force generation stroke by stroke.
ACKNOWLEDGMENTS
The authors would like to thank all the participating athletes who were essential for this study and
finally the UFPR, ABraCan, and CBCa.
Address for correspondence: Heros Ribeiro Ferreira, PhD, Sports Science Department –
Brazilian Canoe Federation, 4350 Visconde de Guarapuava Avenue, Apartment 507, Curitiba City,
Paraná State, Brazil, zip-code 84250-220. Email: heros.ferreira@canaogem.org.br
40
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