Assessment of physiological demand in kitesurfing

Abstract

To evaluate the physiological demands of kitesurfing, ten elite subjects performed an incremental running test on a 400-m track and a 30-min on-water crossing trial during a light crosswind (LW, 12-15 knots). Oxygen uptake (V(O)(2)) was estimated from the heart rate (HR) recorded during the crossing trial using the individual HR-V(O)(2) relationship determined during the incremental test. Blood lactate concentration [La(b)] was measured at rest and 3 min after the exercise completion. Mean HR and estimated V(O)(2) values represented, respectively 80.6 +/- 7.5% of maximal heart rate and 69.8 +/- 11.7% of maximal oxygen uptake for board speeds ranging from 15 to 17 knots. Low values for [La(b)] were observed at the end of crossing trial (2.1 +/- 1.2 mmol l(-1). This first analysis of kitesurfing suggests that the energy demand is mainly sustained by aerobic metabolism during a LW condition.

Full text

ORIGINAL ARTICLE
Assessment of physiological demand in kitesurfing
F. Vercruyssen ÆN. Blin ÆD. L’Huillier Æ
J. Brisswalter
Accepted: 17 September 2008 / Published online: 8 October 2008
ÓSpringer-Verlag 2008
Abstract To evaluate the physiological demands of
kitesurfing, ten elite subjects performed an incremental
running test on a 400-m track and a 30-min on-water
crossing trial during a light crosswind (LW, 12–15 knots).
Oxygen uptake _
VO2

was estimated from the heart rate
(HR) recorded during the crossing trial using the individual
HR- _
VO2relationship determined during the incremental
test. Blood lactate concentration [La
b
] was measured at rest
and 3 min after the exercise completion. Mean HR and
estimated _
VO2values represented, respectively 80.6 ±
7.5% of maximal heart rate and 69.8 ±11.7% of maximal
oxygen uptake for board speeds ranging from 15 to
17 knots. Low values for [La
b
] were observed at the end of
crossing trial (2.1 ±1.2 mmol l
-1
. This first analysis of
kitesurfing suggests that the energy demand is mainly
sustained by aerobic metabolism during a LW condition.
Keywords Kitesurfing Heart rate 
Estimated oxygen uptake Isometric effort Training 
Aerobic activity
Introduction
Kitesurfing is a technical extreme sport that is growing in
popularity and which combines aspects of several water
sports such as surfing, windsurfing, wakeboarding and
powerkiting. During this activity, the athlete propels him-
self and his board across the water by transfering the
energy of the wind into speed by a large controllable kite
(from 9 to 16 m
2
) situated at *25 m in the air zone. The
kitesurfer is able to move downwind and upwind with a
speed of approximately 15–30 knots depending on the
wind strength, the kite size and/or the water profile (flat vs.
with waves). The sail pumping action, observed during
windsurfing velocities up to 15 knots to increase the board
speed when the wind is not strong enough (Vogiatzis et al.
2002), is less practised and less strenuous in kitesurfing.
During light (LW, 9–15 knots) and moderate wind speeds
(MW, 15–25 knots), the pumping action in kitesurfing is
characterized by the completion of repetitive kite move-
ments up and down in order to increase the speed across the
water.
Freestyle, speed and crossing trials represent the main
disciplines of kitesurfing racing and thus, determine the
training modalities associated with the required energy
demand in competitive sailors. Recently, the world speed
record in kitesurfing has been officially recognized at
49.84 knots over a distance of 500 m with a wind speed of
40 knots. In the crossing event, comprising exercise dura-
tions of more than 30 min, kitesurfers must cover a fixed
distance while reducing sailing time. During kitesurfing
racing, especially in crossing, the sailor exhibits repetitive
and prolonged movements on the board characterized by
persistent isometric efforts of the lower- (knee flexion
within the range of 135–150°) and upper-limb muscles
(elbow flexion at &90°) with an elevated position of the
F. Vercruyssen (&)J. Brisswalter
Laboratoire Handibio, groupe ‘‘Mouvement alte
´re
´et efficience
e
´nerge
´tique’’, UFR STAPS, Universite
´de Toulon-Var,
83957 La Garde Cedex, France
e-mail: vercruyssen@univ-tln.fr
N. Blin
Direction de
´partementale et re
´gionale de Paris, Ile de France,
6/8 rue Euge
`ne Oudine
´, 75013 Paris, France
D. L’Huillier
DLS Kiteboarding Company,
85 470 Bre
´tignolles sur mer, France
123
Eur J Appl Physiol (2009) 105:103–109
DOI 10.1007/s00421-008-0879-3

forearms to manipulate the kite. To reduce the develop-
ment of potential muscular fatigue during crossing,
kitesurfers perform various intervals of short dynamic
actions superimposed on repeated isometric contractions.
Indeed, based on anecdotal reports, the quadriceps’ dis-
comfort has often been evoked in trained kitesurfers and
appears to be a limiting factor to performance close to that
identified in Laser sailors (e.g., Spurway 2007). Only
prospective studies specific to the trauma or injury patterns
and prevention measures have been recently published in
kitesurfing science (Petersen et al. 2002,2005; Nickel et al.
2004; Spanjersberg et al. 2007). To date, no scientific
reports regarding the physiological demand of kitesurfing
are available in the literature.
The physiological responses of sailing sports have
previously been described using direct measures of oxygen
uptake _
VO2

(De Vito et al. 1997; Vogiatzis et al. 2002;
Castagna and Brisswalter 2007; Castagna et al. 2007),
heart rate (HR) or blood lactate concentration ([La
b
])
(Gue
´vel et al. 1999; Chamari et al. 2003). For instance,
given the relative stability of the windsurfer on the board
(with or without pumping), the energy demand was eval-
uated using gas exchange telemetric analysers (Vogiatzis
et al. 2002; Castagna and Brisswalter 2007). The lack of
stability in kitesurfing, whatever the racing event, makes
the direct evaluation of energy demand difficult. More-
over, numerous investigators have shown that it was
possible to estimate physical activity oxygen demand
without bias and with reasonable accuracy from the HR
monitoring (e.g., Bernard et al. 1997; Keytel et al. 2005).
In addition, the [La
b
] has previously been used to estimate
the aerobic and anaerobic pathways to metabolism in
studies of Olympic boardsailing and windsurfing (e.g.,
Gue
´vel et al. 1999; Castagna et al. 2007). A greater
understanding of these physiological requirements will
provide any important information to characterize the
intensity level in kitesurfing. Within this framework, the
crossing trial (i.e., continuous sailing [30 min) appears to
be relevant in the analysis of kitesurfing since the exercise
duration and the prolonged isometric contractions may
induce a physiological demand close to those previously
evaluated in water sports such as dinghy sailing. Consid-
ering the duration of a typical kitesurfing event and the
isometric nature of muscle contraction sustained by large
muscles during a crossing event, it was hypothesized that
the energy demand of kitesurfers is similar to that recor-
ded in dinghy sailors, who like kitesurfers undergo
isometric efforts, but lower than the energy demand in
windsurfing which principally involves dynamic muscle
activity. Therefore, the objective of this study was to
assess the physiological demand of competitive sailors
during a simulated crossing event of kitesurfing in a LW
condition.
Materials and methods
Subjects
Ten highly competitive male (n=9) and female (n=1)
kitesurfers of national and international calibre volunteered
to participate in the study and provided written informed
consent. The mean age, height, body mass were 30.3 ±
3.9 years, 177.0 ±6.9 cm and 69.5 ±9.5 kg, respec-
tively. Subjects had regularly competed in two to four
national and international events per year for at least the
previous 2 years. Sailors average weekly training programs
including at least one running or muscle-building exercise,
and two to four kitesurfing sessions––especially in freestyle
and crossing.
Incremental testing protocol
Although the running protocol induces muscular contrac-
tions different from those observed in kitesurfing, such
protocols appear to be the most relevant to describe aerobic
fitness level and to make inferences about the physiological
responses induced on water in our group of trained subjects
(e.g., Chamari et al. 2003; Castagna and Brisswalter 2007;
Castagna et al. 2007). All kitesurfers first performed a
multistage incremental test on an outdoor 400-m running
track to determine the maximal _
VO2_
VO2 max

;maximal
HR (HR
max
) and maximal blood lactate concentration
([La
bmax
]), but also to calibre the individual HR- _
VO2
relationship. The 400-m running track was marked every
25-m and the running pace was given by sounds emitted
through a speaker controlled by a computer software pro-
gram to ensure precise control of speed by setting an
audible cadence. The warm-up was included in the running
track exercise because of the long step duration. Therefore,
the testing protocol began at an initial speed of 9 km h
-1
and was increased by 1 km h
-1
until volitional exhaustion.
Each stage consisted of a 3-min exercise period followed
by a 1-min recovery. Each subject was encouraged to exert
a maximal effort. The end of the running test was dictated
by the inability of subject to maintain the required velocity.
m
peak
was taken as the running speed obtained during the
last minute of exercise. Gas and respiratory parameters
were recorded breath-by-breath and HR was monitored
continuously during the whole test, using a telemetric
Cosmed K4 b2 gas analyser (Roma, Italy) previously val-
idated by McLaughlin et al. (2001). Following a 45 min
warm-up, the K4 b2 was calibrated immediately prior to
the testing of each subject according to the specifications of
the manufacturer. The 5% CO
2
and 15% O
2
gas used for
the calibration of the criterion gas analysers was used to set
the span for the portable unit, and the flowmeter of the k4
b2 was calibrated using a 3.00 liter syringe (Hans-Rudolph
104 Eur J Appl Physiol (2009) 105:103–109
123

Inc., Kansas City, MO). Immediately following the testing
bout, calibration gas was run through the portable system to
check for analyser drift over the course of the continuous
measurement period.
Furthermore, the following criteria were used to define
the maximal values for the exercise: a respiratory exchange
ratio (RER) [1.1, an increase in running speed without a
_
VO2increase and attainment of the theoretical HR
max
value
(220-age) (Howley et al. 1995). These criteria were eval-
uated during the running protocol by the telemetric system
of data transmission (i.e., K4b2-computer). The [La
b
] was
obtained using a Lactate Pro
Ò
analyser (Akray, Kyoto,
Japan), previously validated by Pyne et al. (2000), from
5ll samples of blood taken from the earlobe at rest and
3 min after the exercise [La
bmax
]. Subsequently, _
VO2and
HR values were analysed during the last minute of each 3-
min step (i.e., during steady state) and at the end of the
protocol to determine each participant’s HR- _
VO2regres-
sion equation. The four highest consecutive _
VO2values
were summed during the last minute of the exercise to
determine _
VO2 max:Individual HR
max
was taken as the
highest HR recorded from the incremental running test.
Maximal parameters obtained from the incremental run-
ning session are presented in Table 1.
On-water measurements
At least 2 days after the incremental running test, each
subject was evaluated on the ocean in Bre
´tignolles sur mer,
France, during a simulated crossing event of kitesurfing in
a LW condition ranging from 12 to 15 knots (6.2–
7.7 m s
-1
). With respect to this wind intensity frequently
observed during the experimental period (November),
athletes used kite sizes ranging from 12 to 15 m
2
to opti-
mize their crossing speed. Wind speed was measured with
an anemometer (Windmaster
Ò
) at the beginning of the
crossing trial and every 10 min throughout the exercise.
These values were then averaged to obtain the mean
crossing wind speed at 13 (1.3) knots [6.7 (0.7) m s
-1
].
The ambient temperature ranged from 14 to 17°C during
the experiment.
In the LW crossing trial, the subjects were instructed to
sail three sessions of 10-min during a reaching leg char-
acterized by a crosswind movement and with the kite-
athlete position at 90°to the wind direction (Fig. 1). For
each LW crossing trial, two sailors took the start behind the
virtual line represented by two buoys and were instructed
to sail as quickly as possible in order to reproduce the race
conditions. After 10 min of each crossing session, each
kitesurfer had to turn whatever their position on the water
and to sail towards the start point. A motorboat was sys-
tematically situated at approximately 50 m from the
kitesurfers to allow them to keep the optimal reaching leg
condition. This crossing duration has been selected
according to the time usually recorded during an official
race. During the 30-min of kitesurfing crossing, HR, speed
and distance were continuously monitored using the
FRWD
Ò
system (B100, Matsport training) fixed on the arm
of each subject. Each recorded HR on water was expressed
as a percentage of individual HR
max
to provide a measure
of relative intensity. _
VO2values were extrapolated from
individual HR values measured during the 30-min crossing
and combined with each participant’s HR- _
VO2regression
equation from the incremental session. Blood samples for
the determination of [La
b
] value were drawn from the
earlobe 3 min after the end of crossing trial and were
immediately analysed using the portable lactate pro ana-
lyser. HR, _
VO2;speed and distance were averaged every
5 min, at the following time periods: T1 (0–5 min), T2 (5–
10 min), T3 (10–15 min), T4 (15–20 min), T5 (20–25 min)
and T6 (25–30 min). T0 represents the rest period before
sailing.
Statistical analysis
Values are expressed as mean (standard deviation). Dif-
ferences in HR and %HR
max
, estimated _
VO2and
%_
VO2 max;speeds between the time periods of the crossing
trial were analysed using a one-way ANOVA with repeated
Table 1 Maximal values of physiological parameters obtained dur-
ing the incremental running exercise
_
VE max
(l min
-1
)
_
VO2 max
(ml kg
-1
min
-1
)
HR
max
(bpm)
[La
bmax
]
(mmol l
-1
)
m
peak
(km h
-1
)
134.1 (19.3) 54.8 (3.3) 191 (10.6) 7.6 (1.9) 15.7 (1.2)
Values are presented as means (SD)
Start: T0
Finish: T6
Duration: 3 x 10 min
(HR measurement)
Lactate
measurement-post
Lactate
measurement-pre
Wind
direction
buoys
Start: T0
Finish: T6
Duration: 3 x 10 min
(HR measurement)
Lactate
measurement-post
Lactate
measurement-pre
Wind
direction
buoys
Fig. 1 On-water kitesurfing protocol
Eur J Appl Physiol (2009) 105:103–109 105
123

measures. The Tukey post-hoc test analysis was applied to
determine significant differences over time. Moreover, the
linear regression analysis between _
VO2and HR was per-
formed for each subject during the incremental running
test. A Pearson correlation coefficient and linear regression
analysis were performed between the distance covered
during the crossing trial and physiological variables. Dif-
ferences in [La
b
] values between the pre and post crossing
trials (T0 and T6) were identified using paired Student’s t-
tests. Statistical significance was established at a level of
P\0.05.
Results
Mean values for maximal ventilation _
VEmax

;_
VO2 max;
HR
max
, [La
bmax
] and m
peak
obtained from all ten kitesurfers
are shown in Table 1. The linear relationship between _
VO2
and HR during the incremental running test was observed
in all ten kitesurfers (r=0.92–0.98 range, P\0.05)
and was related by the following formula: Estimated
_
VO2¼0:44 HRðÞ28:96:
During the LW condition, the statistical analysis indi-
cates an effect of time period on HR and %HR
max
,
estimated _
VO2and %_
VO2max (P\0.05, Table 2) charac-
terized by significant higher values in these variables
during the crossing trial at T1 compared to T4. The mean
values of sailing speeds were ranged from 14.9 to 17.0
knots during the 30-min crossing trial (Table 2). The mean
values of maximal sailing speed and covered distance were
respectively 21.0 (1.5) knots and 14.238 (973) m during
the crossing trial. Mean values in [La
b
] ranging from 1.2 to
4.4 mmol l
-1
were significantly more elevated after
30 min of crossing trial [2.1 (1.2) mmol l
-1
] compared
to the T0 measurement [1.2 (0.2) mmol l
-1
]. Moreover,
the only linear relationship was demonstrated between
the distance covered during the crossing trial and
_
VO2max values obtained in kitesurfers (r=0.83, P\0.05,
Fig. 2).
Discussion
The present study is the first to use HR and [La
b
] responses
to assess the physiological demands in elite kitesurfers
during a simulated crossing trial close to the race condi-
tions. The observation of low values for estimated fraction
of _
VO2max;[La
b
] and HR is in agreement with our
hypothesis and indicates that the completion of kitesurfing
exercise in a LW condition is predominately aerobic, as
previously reported in dinghy sailing. The current findings
from the HR monitoring provide relevant and valuable
information on the intensity level that may be used by elite
kitesurfers for the preparation of a specific training pro-
gramme. However, the lack of actual _
VO2measurements
during the on-water testing trials constitutes a major limi-
tation of our study and makes it difficult to compare this
physiological variable with those reported in the literature.
Given the absence of scientific data related to kitesur-
fing, we compared the physiological responses of our elite
group of kitesurfers with that observed in highly trained
Table 2 Mean values for HR, %HRmax, estimated _
VO2;%_
VO2max;and sailing speed obtained during the time periods (from T1toT6) of the
crossing event
Time periods T1T2T3T4T5T6
HR (bpm) 159 (11)
a
158 (16) 154 (20) 149 (18) 150 (19) 153 (18)
%HR
max
83.3 (3.7)
a
82.8 (6.1) 80.9 (9.2) 78.0 (7.3) 78.7 (7.2) 80.0 (7.3)
_
VO2(ml min
-1
kg
-1
) 40.7 (3.2)
a
40.1 (6.5) 38.3 (9.0) 35.9 (8.3) 36.8 (7.8) 37.7 (8.0)
%_
VO2 max 74.3 (5.4)
a
73.2 (11.0)
a
70.1 (16.6) 65.5 (14.5) 67.2 (13.0) 68.8 (13.8)
Sailing speed (knots) 16.1 (1.4) 15.0 (1.3) 16.2 (1.9) 15.4 (1.3) 14.9 (1.5) 17.0 (1.4)
b
Values are presented as means (SD)
a
Significantly different from values obtained during the crossing trial at T4
b
Significantly different from values obtained during the crossing trials at T2, T4 and T5
y = 249,01x + 594,58
R2 = 0.70
12000
12500
13000
13500
14000
14500
15000
15500
16000
16500
45
VO2max
(ml. min
Distance covered (m)
-1
. kg-1
)
50 55 60 65
Fig. 2 Linear regression between the distances covered during the
crossing trial and the maximal oxygen uptake _
VO2max

106 Eur J Appl Physiol (2009) 105:103–109
123

windsurfers and Laser sailors (see Table 3). The mean
aerobic fitness level i:e:; _
VO2max

of our subjects is similar
to that reported in elite Laser sailors (*55 ml min
-1
kg
-1
)
(e.g., Vogiatzis et al. 1995; De Vito et al. 1996; Castagna
and Brisswalter 2007), but lower than that observed in
trained windsurfers ([60 ml min
-1
kg
-1
) (e.g., De Vito
et al. 1997; Gue
´vel et al. 1999; Chamari et al. 2003;
Castagna et al. 2007). The differences in _
VO2max values
between trained windsurfers and our subjects might be
related to the specificity of training, but also the nature of
the muscular contractions required during sailing. Wind-
surfing requires extensive dynamic upper- and lower-body
activity, whereas kitesurfing comprises more static activa-
tion of upper- and lower-body muscles as previously
observed in Laser sailing. Within this framework, Castagna
et al. (2007) have reported a high _
VO2max (e.g.,
63.7 ml min
-1
kg
-1
) in windsurfers and also a high train-
ing volume per week ([25 h comprising sailing, endurance
training and bodybuilding). Therefore, trained kitesurfers
might adopt a similar training program to that of windsur-
fers, by including more sailing, endurance and strength
training in an attempt to enhance the physical fitness level
and thus, the crossing performance. Interestingly, we found
a significant correlation between _
VO2max and the distance
covered during the simulated crossing event (Fig. 2) indi-
cating that kitesurfers with higher _
VO2max values increased
their distance and thereby, their performance. Although
multiple factors are correlated with successful endurance
sports (e.g., Schabort et al. 2000), our results suggest that a
good level of physical fitness constitutes a useful predictor
of kitesurfing performance. Further investigation is needed
in a large population of elite kitesurfers during crossing
racing to confirm these aforementioned considerations.
During sailing, HR monitoring provides an interesting
tool to estimate the cardiorespiratory responses and to
characterize the intensity level (Gue
´veletal.1999; Cha-
mari et al. 2003). It was shown that the HR expressed as a
percentage of HR
max
is more representative of exercise
intensity than the absolute HR values (Chamari et al.
2003). The current findings indicate that kitesurfers sailed
for 30 min with a mean HR value representing approxi-
mately 81% of HR
max
in a LW condition (Table 2). More
precisely, the %HR
max
tends to decrease from the T1
(&83%) to the T3 period (&81%) and this reduction has
been reported to be significant from the T4 period (78.0%).
Given the relative stability of wind intensity during all
crossing trials (12–15 knots), we hypothesize that the car-
diovascular adaptation which occurred from the T2 to the
T4 sailing period is linked to the ability of our subjects to
seek, for a given crossing speed, the most comfortable
position on the board and thus allowing them to manipulate
the kite with a great effectiveness. In addition, the higher
%HR
max
obtained during the T1 period compared to the
middle of the crossing trial may be linked to the strategic
goal of kitesurfers to sail as fast as possible at the start to
get the best position on water. As reported in Table 3, the
characteristics of experimental design associated with the
specificity of sailing mode make it difficult to compare the
HR responses in kitesurfing with those observed in wind-
surfing and Laser sailing (Gue
´vel et al. 1999; Chamari et al.
2003; Castagna and Brisswalter 2007). However, while it
has been acknowledged that the pumping action in wind-
surfing is considered as a highly demanding aerobic
activity (De Vito et al. 1997; Vogiatzis et al. 2002)in
comparison with specific manoeuvres observed in kitesur-
fing or Laser sailing, the mean HR responses of these
sailing sports are comprised within a range of 72–85%
HR
max
(Table 3).
The lack of actual _
VO2measurement during the on-
water testing trials constitutes a major limitation of the
current work. Given the high difficulty of using a gas
exchange analyser in our experimental design (e.g., trunk
position in the water before starting, unstable position on
the board) compared to Laser sailing or windsurfing, it is
important to consider the validity of the _
VO2values esti-
mated from the HR- _
VO2relationship. Within this
framework, it was observed that relatively large increases
in mean HR (&75% HR
max
) were accompanied by only
modest increments in measured _
VO235%_
VO2max

during Laser sailing (Vogiatzis et al. 1994,1995; De Vito
Table 3 Mean values in physiological parameters of highly trained sailors during various outdoor experimental sessions reported in the
literature compared to our study
Sailing sport Wind
(knots)
_
VO2 max
(ml min
-1
kg
-1
)
Sailing duration
(min)
HR sailing
(beats min
-1
)
%HR
max
Final [La
b
]
(mmol l
-1
)
Our study Kitesurfing 11–15 54.8 30 154 80.6 2.1
Chamari et al. (2003) Windsurfing 14 62.5 40 148 76.2 5.2
Gue
´vel et al. (1999) Windsurfing 9–13 66.8 33 167 82.9 5.7
Castagna and Brisswalter (2007) Laser 12 58.2 30 139 72.2 3.3
De Vito et al. (1996) Laser 6–8 53.4 15 132 72.0 NA
Vogiatzis et al. (1995) Laser 8–16 52.0 10 135 69.0 3.0
NA not available
Eur J Appl Physiol (2009) 105:103–109 107
123

et al. 1996). This has been explained as the results of the
persistent isometric efforts of the lower- and upper-limb
muscles during which the muscle perfusion is impaired by
mechanical compression from the contracting skeletal
muscles (e.g., Vogiatzis and Roach 1993; Felici et al. 1999;
Castagna and Brisswalter 2007). During a kitesurfing
crossing event, the muscular activity is mostly isometric for
the lower- and upper-body muscles, close to those observed
in Laser sailing, and the upper limbs of the kitesurfer are in
an elevated position which may induce specific cardio-
vascular responses resulting in a disproportionate increase
in HR values (e.g., Felici et al. 1999). Additionally, the
formula used in our study to predict the _
VO2from the HR
monitoring during sailing is similar to those published
using treadmill and cycling protocols (e.g., Bernard et al.
1997). Considering these previous reports, it is likely that
the predicted mean _
VO2values on water 70%_
VO2max

was overestimated in our study. This might partly explain
why the estimated _
VO2values on water in our kitesurfers
were substantially higher than those previously measured
in Laser sailing (e.g., De Vito et al. 1996; Castagna and
Brisswalter 2007).
An interesting finding in the current study is linked to
the low values of [La
b
] observed at the end of crossing
exercise as recently reported during Laser sailing
(Table 3). During kitesurfing exercise, the sailor adopts a
prolonged high-force isometric effort of the quadriceps
muscle group to manipulate his kite and to move across the
water. Consequently, the [La
b
] values may be related to the
specific isometric effort component which characterizes the
kitesurfing position. In the present study, the [La
b
]
responses are in good agreement with those reported in
dinghy sailing during which [La
b
] values hardly exceed
3 mmol l
-1
either on water or in the laboratory, suggesting
a limited oxygen deficit (e.g., Vogiatzis et al. 1995,1996).
Within this framework, Spurway (2007) recently indicated
that the prolonged isometric effort resulted in a large
increase in blood pressure and HR commonly accompanied
by low or moderate increments in _
VO2and [La
b
] respon-
ses. A possible explanation for the low [La
b
] values
observed during kitesurfing crossing might be associated
with the discontinuous nature of the isometric effort owing
to the relief intervals (in the range of 10–20 s). These
intervals would occur when kitesurfers perform leg
movement up and down on the board, so some degree of
muscle relaxation is temporally achieved. Based on a
recent study by Vogiatzis et al. (2008), we hypothesize that
these rest intervals would allow partial restoration of the
muscles’ oxygen accessibility, thus promoting a more
oxidative degradation of glycogen and a low lactate con-
centration. Based on these reports, it is likely that during a
typical race, lasting 30–40 min, the prolonged isometric
effort might present a limiting factor to kitesurfing
performance even if the isometric effort can be sustained
during relatively long periods of time by the introduction of
brief periods of muscle relaxation. This analysis of the
kitesurfing activity may be of a great interest for physical
fitness training and improving crossing performance. Elite
kitesurfers should adopt a training programme based on the
development of physical fitness level including the inte-
gration of bodybuilding sessions to enhance the strength
component of the upper- and lower-limb muscles.
According to the ‘‘intermittent’’ nature of the isometric
effort observed on water, elite kitesurfers should regularly
train by introducing brief periods of body movement so as
to temporally relax to some degree the lower limb muscles,
thus faciliting muscle perfusion and performance during
sailing. Further investigation is required concerning the
analysis of kitesurfer position on the board and the effects
on physiological parameters during a simulated crossing
trial in laboratory to identify the metabolic and biome-
chanical determinants of this water sport.
In conclusion, the crossing event of kitesurfing may be
considered as a moderately intense activity characterized
by low increments in [La
b
] and estimated _
VO2but higher
increments in HR values during a LW condition ranging
from 12 to 15 knots. Nevertheless, kitesurfers should
consider these findings when planning their physical
training programmes. Future investigation is needed to
analyse the physiological demands in elite kitesurfers
during different wind speeds and throughout the other
events of kitesurfing which characterize this new extreme
sailing sport.
Acknowledgments The authors gratefully acknowledge the DLS
kiteboarding company and all kitesurfers who took part in the
experiment for their high cooperation and motivation.
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