Field study of anthropomorphic and muscle performance changes among elite skippers following a transoceanic race

Abstract

Background:
Ocean racing has become increasingly demanding, both physically and psychologically. The aim of the study was to assess global changes after a transoceanic race.

Materials and methods:
Eight male sailors were evaluated pre- and post-race through anthropometric measurements (weight, skinfold, girth at different level and estimated body fat percentage), multifrequency tetrapolar bioelectrical impedance, muscular performance, visual analogic scale for perceived fatigue and Critical Flicker Fusion Frequencies for cerebral arousal.

Results:
Compared to pre-race values, a significant decrease in body weight (-3.6 ± 1.4%, p = 0.0002) and body composition with reduction of body fat percentage (-15.1 ± 3.5%, p < 0.0001) and fat mass (-36.4 ± 31.4%, p = 0.022) was observed. Muscle performance of the upper limb was preserved. In the lower limb, monohulls skippers showed a significant reduction of jump height (-6.6 ± 4.8%, p = 0.022), power (-11.7 ± 7.3%, p = 0.011) and speed (-14.6 ± 7.4%, p = 0.0006) while a multihulls skipper showed a gain in speed (+0.87%), power (+8.52%), force (+11%) resulting in a higher jump height (+1.12%). These changes were inversely correlated with sea days (Pearson r of -0.81, -0.96 and -0.90, respectively, p < 0.01).

Conclusions:
Changes in body weight and composition are consistent with previous data indicating a probable negative energy balance. The main finding demonstrates a difference in muscular conditioning between upper and lower limbs that might be explained by differential workload related to boat architecture (trampolines) or handling.

Full text

Pierre Lafère, PhD, Department of Anaesthesiology, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium,
e-mail:
pierre.lafere@erasme.ulb.ac.be

www.intmarhealth.pl
Int Marit Health
2020; 71, 1: 20–27
10.5603/IMH.2020.0007
www.intmarhealth.pl
Copyright © 2020 PSMTTM
ISSN 1641–9251
ORIGINAL ARTICLE
20
Field study of anthropomorphic and muscle
performance changes among elite skippers
following a transoceanic race
Pierre Lafère1, 2, 3 , Yann Gatzoff4, François Guerrero2,
Steven Provyn3, 5, 6 , Costantino Balestra3, 5, 6, 7
1Department of Anaesthesiology, Erasme University Hospital, Université Libre de Bruxelles, Brussels, Belgium
2ORPHY Laboratory EA4324, Université de Bretagne Occidentale, Brest, France
3Environmental, Occupational, Ageing (Integrative) Physiology Laboratory, Haute Ecole Bruxelles-Brabant (HE2B), Brussels, Belgium
4Geneva University Hospitals, Geneva, Switzerland
5Anatomical Research Training and Education (ARTE), Vrije Universiteit Brussel (V.U.B.), Brussels, Belgium
6Anatomical Research and Clinical Studies (ARCS), Vrije Universiteit Brussel (V.U.B.), Brussels, Belgium
7Motor Sciences, Université Libre de Bruxelles (U.L.B.), Brussels, Belgium
ABSTRACT
Background:
Ocean racing has become increasingly demanding, both physically and psychologically. The
aim of the study was to assess global changes after a transoceanic race.
Materials and methods:
Eight male sailors were evaluated pre- and post-race through anthropometric me-
asurements (weight, skinfold, girth at different level and estimated body fat percentage), multifrequency
tetrapolar bioelectrical impedance, muscular performance, visual analogic scale for perceived fatigue and
Critical Flicker Fusion Frequencies for cerebral arousal.
Results:
Compared to pre-race values, a significant decrease in body weight (–3.6 ± 1.4%, p = 0.0002)
and body composition with reduction of body fat percentage (–15.1 ± 3.5%, p < 0.0001) and fat mass
(–36.4 ± 31.4%, p = 0.022) was observed. Muscle performance of the upper limb was preserved.
In the lower limb, monohulls skippers showed a significant reduction of jump height (–6.6 ± 4.8%,
p = 0.022), power (–11.7 ± 7.3%, p = 0.011) and speed (–14.6 ± 7.4%, p = 0.0006) while a multihulls
skipper showed a gain in speed (+0.87%), power (+8.52%), force (+11%) resulting in a higher jump height
(+1.12%). These changes were inversely correlated with sea days (Pearson r of –0.81, –0.96 and –0.90,
respectively, p < 0.01).
Conclusions:
Changes in body weight and composition are consistent with previous data indicating
a probable negative energy balance. The main finding demonstrates a difference in muscular conditioning
between upper and lower limbs that might be explained by differential workload related to boat architecture
(trampolines) or handling.
(Int Marit Health 2020; 71, 1: 20–27)
Key words: anthropometry, skinfold thickness, impedance, bioelectrical, weight loss, icker fusion,
muscle strength
INTRODUCTION
Ocean racing has changed a lot in the last 30 years. Boat
designers have tried to find ways to increase power, while
reducing weight, however with few concessions to sailor’s
comfort. Therefore, these high-performance racing boats
tend to go faster. For instance, 60-feet monohulls boat
from the International Monohulls Open Class Association
(IMOCA), completing the round-the-world solo race (“Vendee
Globe”: 21,638 nautical miles), decreased the time needed
from under 100 days in 2001, down to 90 days in 2005,

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Pierre Lafère et al., Differential effect of offshore race on limbs
below 85 days in 2009, 78 days in 2013 and to finally reach
74 days in 2017.
Consequently, boats handling has become increasingly
demanding, both physically and psychologically. Indeed,
offshore racing is an arduous activity involving hard mental
and physical work carried out in strenuous environmental
conditions. The watch system makes it impossible to get
a full night sleep deterring physical and mental performance
as well as meal frequency [1]. Also, according to the nature
of their sport, sailors involved in offshore racing can be
exposed to injuries and other health problems that can
endanger their lives [2]. Unfortunately, the distance from
onshore health facilities and lack of professional presence
on board might explain why only scarce scientific data are
available. A review based on a systematic search of medical
databases employing predefined criteria, using the terms
offshore racing/sailing, solo sailing or open sea racing could
only identified less than 20 publications on the subject over
the last 40 years [2–15]. All those studies only included
a very limited number of subjects (case report to a dozen
individuals), albeit a very specific population (Caucasian
males in their mid-thirties) and were mostly focused on
energy expenditure/intake and sleep deprivation.
More data are available about the physiological chal-
lenges of competitive sailing, for instance related to the
America’s Cup [16, 17], albeit this is not the exact same
sailing discipline as the later ignores the continuous de-
manding efforts of long-haul sailing. According to a recent
review [18], the most influential factors in determining
sailing performance, including dinghy sailing with smaller
boats like Laser or the “America’s Cup” with large boats,
are related to the sailor’s physical characteristics, sailing
techniques, decision-making abilities, tactical skills or psy-
chological characteristics.
In competitive sailing, there are different types of boats
that demand various types of effort by the sailor, which is
why knowledge of their specific physical and physiological
features for each type of vessel is necessary. Unfortunately,
the field of ocean racing remains mostly unexplored. To find
out more about this issue, the Pen Duick company (Paris,
France) gave us the opportunity to carry out measurements
on skippers participating in the two-handed 2009 “Tran-
sat Jacques Vabre” between Le Havre, France and Puerto
Limón, Costa Rica (4335 nautical miles).
Therefore, the aim of the study was to assess global
physical changes among offshore skippers with a specific
focus on muscular strength after a transoceanic race.
MATERIALS AND METHODS
After being informed of the purpose and experimen-
tal procedures of the study, 8 Caucasian male skippers
without any of them paired on the same boat (7 sailing
an IMOCA and 1 sailing a Multi 50) volunteered to partic-
ipate and signed a written informed consent.
The study
was approved by the local Academic Bio-Ethical Committee
of Brussels (CE2008/66) and was conducted in accordance
with the Declaration of Helsinki [19]. All participants were
subjected to the same data collection procedure, which was
applied before the race and within 6 hours after arrival in
Puerto Limón. Therefore, each skipper is his own control.
Anthropometric measurements performed by the same
qualified investigator with 5 years of experience followed the
protocol of the International Society for the Advancement
of Kinanthropometry (ISAK) [20] and include body mass
measured to the nearest 0.05 kg with a digital scale (SECA
220, Seca gmbh & Co., Hamburg, Germany), skinfolds at six
different sites (triceps, subscapular, supra-spinal, abdominal
[umbilical], anterior tight, medium calf) using a Harpenden
calliper (Harpenden skinfold calliper, Bay international, West
Sussex, England), and girths at six different sites (arm girth
relaxed, forearm, supra-patellar, thigh, mid-thigh, medial calf)
with a flexible anthropometric steel tape (Lufkin W606PM,
cooper industries, Ohio, United States) to the nearest 0.1cm.
By convention, all anthropometrical measurements were taken
on the right side of the body (all skippers were right-handed).
Each measurement was taken twice. If the difference be-
tween the first and the second reading was > 5% for skinfolds
and > 1% for girths, a third measurement was taken and the
mean of the two nearest measurements was calculated as
the final value. Percentage body fat (%BF) was calculated
using the Yuhasz formula (%BF = 0.1051 × (∑6 skinfolds)
+ 2.585) [21], because it was designed for athletes and fit
individuals, which is the case of our population [22].
Since biometrical multifrequency impedance analysis
(BIA) is a widely accepted method for the determination of
body composition (total body water [TBW], extracellular fluid
[ECF] and intracellular fluid [ICF]) due to its simplicity, speed
and non-invasive nature [23], we used a single channel,
tetra polar bioimpedance spectroscopy device that scans
256 frequencies between 4 kHz and 1000 kHz for the es-
timation of body composition in healthy individuals (SFB7,
Impedimed Inc., Carlsbad, USA). Fat-free mass (FFM) and
fat mass (FM) are then calculated on the device.
Strength assessment included measurement of the
maximal voluntary handgrip strength (HGS) and the vertical
jump performance [24]. To avoid injury, a standard warm-up
routine, consisting of jumping, stretching and gripping at
submaximal intensity preceded the actual tests. HGS was
measured three times with an electronic hand dynamometer
(Newgen medical EH101, Pearl, Buggingen, Germany) [25]
and the mean value was used for analysis and compari-
son. Vertical counter movement jump performance was
assessed using an accelerometer (Myotest, Myotest Inc.,
Sion, Switzerland) [26]. A total of 5 maximal vertical jumps

Int Marit Health 2020; 71, 1: 20–27
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22
were evaluated and accelerometric data were stored during
the assessments and subsequently downloaded for jump
height (cm), power (w/kg), force (N/kg), and speed (cm/s)
calculations. The mean for each value, calculated on the
three highest jumps, was used for analysis and comparison.
In the present study, non-muscular fatigue (central)
was assessed by means of Critical Flicker Fusion Frequen-
cy (CFFF) and by a 100-mm visual analogue scale (VAS).
CFFF was assessed with a specific watertight device (Hu-
man Breathing Technology, Trieste, Italy) previously fully
described by Balestra et al. [27]. Thanks to the design of the
device, it is impossible for the subjects to be aware of the
actual flicker frequency through the whole test. When there
is a change in LED light from fusion to flicker (or flicker to
fusion), the subject acknowledges it to the investigator and
the reached frequency is recorded. For each sample, the
mean of three consecutive tests was calculated and used for
analysis. For VAS testing, we used the same methodology as
in Lafère et al. [28] where the same VAS scale is presented
twice but in opposite directions: one asked to evaluate the
‘energy level’ (from sleepy/0 to energetic/10), the second
asked to evaluate the “tiredness level” (from energetic/0 to
sleepy/10). Should the difference between the first and the
second reading be > 10%, a third measurement (“tiredness
level”) was taken and the mean of the two nearest mea-
surements was calculated as the final value.
Since all data passed the Kolmogorov-Smirnov test,
allowing us to assume a Gaussian distribution, they were
analysed with a Student’s paired t-test or a one-way ANOVA
with Bonferroni post-hoc test.
Since each skipper is his own control, taking the pre-race
values as 100%, percentage changes were calculated for
each parameter, allowing an appreciation of the magnitude
of change between each measurement rather than the
absolute values.
Existing correlation between significant statistical re-
sults and age, initial weight or days at sea was assessed
through a Pearson correlation coefficient test and linear
regression when possible.
All tests were performed using a standard computer sta-
tistical package, GraphPad Prism version 5.00 for Windows
(GraphPad Software, San Diego California USA). A threshold
of p < 0.05 was considered statistically significant. All data
are presented as mean ± standard deviation (SD).
RESULTS
The mean age of the 8 subjects was 39.7 ± 5.3 years
and height 1.79 ± 0.97 m. All other anthropometric char-
acteristics pre- and post-race are summarised in Table 1.
We observed a significant decrease in body weight (–3.6±
± 1.4%) from 81.8 ± 10.1 to 78.9 ± 10.1 kg (p = 0.0002,
paired t-test, df = 7) and a similar significant reduction of
Table 1. Pre- and post-transoceanic race anthropometric data of offshore sailors (n = 8)
Pre-race Post-race P (Paired t test)
Weight [kg] 81.8 ± 10.1 78.9 ± 10.1 0.0002**
Body mass index [kg/m2] 25.4 ± 1.1 24.5 ± 1.3 0.0001**
Percentage of body fat [%BF]#12.2 ± 2.4 10.4 ± 2.3 < 0.0001**
Skinfold [mm]:
Triceps 13.9 ± 5.2 10.6 ± 3.7 0.0019*
Subscapular 18.5 ± 5.2 15.0 ± 4.5 0.0011*
Supra-spinal 17.6 ± 6.2 14.9 ± 5.9 < 0.0001**
Umbilical 25.6 ± 6.7 18.7 ± 7.9 0.0002**
Front tight 9.7 ± 2.8 9.5 ± 2.5 0.516
Medium calf 6.4 ± 2.6 5.9 ± 2.6 0.227
Girth [cm]:
Forearm 29.7 ± 1.7 29.8 ± 1.4 0.557
Arm 29.9 ± 1.9 30.3 ± 1.5 0.161
Thigh 53.2 ± 2.7 51.7 ± 3.0 0.0025*
Mid-thigh 45.6 ± 3.5 44.2 ± 3.7 0.0095*
Supra-patellar 39.4 ± 3.2 39.1 ± 3.2 0.139
Medium calf 38.0 ± 1.3 37.6 ± 1.1 0.111
*p < 0.01; **p < 0.001; #Calculated according the Yuhasz formula (%BF = 0.1051 × (∑6 skinfolds) + 2.585)

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Pierre Lafère et al., Differential effect of offshore race on limbs
the body mass index (BMI: –3.2 ± 1.7%) from 25.4 ± 1.1 to
24.5 ± 10.3 kg/m2 (p = 0.0001, paired t-test, df = 7). Based
on skinfold measurements and the Yuhasz formula, this
weight reduction seems to be associated with a modification
of body composition with a significant reduction of the %BF
(–15.1 ± 3.5%) from 12.2 ± 2.4 to 10.4 ± 2.3 % (p < 0.0001,
paired t-test, df = 7). However, this modification seems to
be at the expense of the upper body with some significant
decreased skinfolds at tricipital, subscapular, supra-spinal
and umbilical level. No significant changes were identified
on the lower limb. Unlike skinfold measurement, muscle
circumference did not show significant change in the upper
limb, while a significant decrease was noticed in the lower
limb at mid-tight and maximal thigh level.
Analysis of body composition by BIA (Fig. 1) showed no
difference in hydration (TBW: from 55.4 ± 6.0 to 55.8 ± 5.3%
of total weight, p = 0.571; ECF: from 22.7 ± 3.0 to 23.3±
± 3.8% of total weight, p = 0.307; ICF: 32.7 ± 3.2 to 32.4±
± 1.6% of total weight, p = 0.878, paired t-test, df = 6) and
FFM values (75.7 ± 8.2 to 75.7 ± 7.2 kg, p = 0.878 paired
t-test, df = 6). However, we observed a significant reduc-
tion of FM (–36.4 ± 31.4%) from 6.6 ± 4.1 to 3.2 ± 0.9 kg
(p = 0.022 paired t-test, df = 6). Segmental impedance in-
dicated that this reduction in fat mass is evenly distributed
between the different segments of the body. Although the
trunk presented the greater reduction of fat mass (–48.3±
± 28.1%), this result is not significant (p = 0.247, one-way
ANOVA, F (4, 30) = 1,433).
60 40
80 60
100 80
120A100B
% of control values
% of control values
TBW ECF ICF FFM FM Right
leg
Right
arm
Left
leg
Left
arm
Trunk
*
***
***
*** ***
**
Figure 1.
Percentage variation of global impedancemetry (A) and segmental fat mass (B) after a transoceanic race
(n = 8).
Pre
-race value is taken as 100%. Each subject
is compared to his own pre-race value. Means and standard deviations are shown in
graph; ***p < 0.001; **p < 0.01; *p < 0.05; TBW — total body water; ECF — extracellular fluid; ICF — intracellular fluid; FFM — free fat
mass; FM — fat mass
80
90
100
110
% of control values
Jump height
**
*
*
Speed Power Force
*
50
100
150
% of control values
CFFF
*
**
VAS
Figure 2. Percentage variation of lower limb muscle performan-
ce
after a trans-oceanic race
(n = 8).
Pre-race value is taken
as 100%. Each subject
is compared to his own pre-race
value. Means and standard deviations are shown in graph;
**p < 0.001; *p < 0.05
Figure 3. Percentage variation of perceived fatigue
after
a trans-oceanic race
(n = 8).
Pre-race value is taken as 100%.
Each subject
is compared to his own pre-race value. Means and
standard deviations are shown in graph; **p < 0.001; *p < 0.05;
CFFF — Critical Flicker Fusion Frequency; VAS — Visual Analog Scale

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24
Muscle performance of the upper limb seemed to be
preserved as HGS values did not change significantly after
the race from 53.6 ± 8.3 to 51.8 ± 8.7 N (p = 0.228, paired
t-test, df = 7). On the contrary, results of the lower limb
showed significant impairment (Fig. 2). The speed (–6.6±
± 4.8%) and power (–11.7 ± 7.3%) developed by the exten-
sor muscles of the lower limbs during counter movement
jumps decreased from 237.8 ± 30.3 to 221.8 ± 28.0 cm/s
(p
= 0.022, paired t-test, df = 7) and from 44.8
± 7.8 to
39.7 ± 8.9 w/kg (p
= 0.011, paired t-test, df = 5). J
ump
height was also significantly decreased (–15.5 ± 7.4%)
from 29.3 ± 6.3 to 25.4 ± 6.1 cm (p = 0.0006, paired t-test,
df = 7). However, the force (N/kg) developed by the same
muscles, did not show any significant difference between
measurements made before and after the race (Force: 22.8±
± 3.1 vs. 22.4 ± 2.0 N/kg, p = 0.930, paired t-test, df = 7).
Perceived fatigue was significantly higher after the race
(Fig. 3). Subjective evaluation (VAS) showed an increase of
25.9 ± 19.3% in the level of tiredness at 126 ± 19.3% of
pre-race value (p = 0.0067, paired t-test, df = 7), while ob-
jective evaluation of cerebral arousal showed a consistent
decrease in CFFF by 5.6 ± 5.7% of CFFF at 94.4 ± 5.8% of
pre-race value (p = 0.028, paired t-test, df = 7).
To depict the magnitude of the race, the first multi
50 raced for 5050 nautical miles and crossed the line
after 15 days 15 hours, 31 minutes while the first IMOCA
crossed the line a few hours later after 15 days 19 hours and
22 minutes and 4730 nautical miles of travelled distance.
Our last volunteer crossed the finish line after 18 days
13 hours and 26 minutes. A Pearson correlation calculation
demonstrated that the magnitude of umbilical skinfold, %BF,
jump height and speed changes were inversely correlated
with days at sea (Pearson r of –0.87, –0.81, –0.96 and
–0.90, respectively; Fig. 4). Since all differences reached
statistical significance (p < 0.01), we can reject the idea
that the correlation is due simply to random sampling. This
relation is further confirmed by linear regression. No other
correlation could be found between statistically significant
results and age or initial weight.
DISCUSSION
Measuring physiological parameters during sailing rac-
es is technically and logistically difficult. Nonetheless, this
study contributed valuable data on global physical changes
in the 2009 “Transat Jacques Vabre”, a two-handed offshore
sailing race.
Previous studies demonstrated t
hat professional sail-
ors incur severe sleep loss with marked performance im-
pairment [8–11]. In case of prolonged sleep restriction, the
balance between sleep homeostasis and circadian rhythm
Figure 4
. Correlation calculation and linear regression of the magnitude umbilical skinfold (A), body fat (%BF) (B), jump height (C) and
speed (D) changes and days at sea (n = 8).
–50
–40 –20
–30
–30 –30
–20
–20 –20
–10
–10
–10 –10
0
0 0
0
10
10 10
10
16
16 16
16
17
17 17
17
Days at sea
Days at sea Days at sea
Days at sea
18
18 18
18
19
19 19
19
–60 –30
Slope: –11.6 ± 2.57
R2: 0.77, P = 0.004
Slope: –6.27 ± 0.7
R2: 0.93, P = 0.0001
Slope: –5.62 ± 2.01
R2: 0.82, P = 0.002
Slope: –2.48 ± 0.74
R2: 0.65, P = 0.015
Variation [%]
Variation [%]
Variation [%]
Variation [%]
A
C
B
D

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Pierre Lafère et al., Differential effect of offshore race on limbs
process is disturbed, which induces an adaptive response.
Pressure for sleep during wakefulness increases and dis-
sipates exponentially during subsequent sleep, hence the
efficacy of brief periods of sleep providing significant perfor-
mance recuperation. However, sleep restriction practiced
on a chronic basis induces cumulative performance deficits
[29]. Our results confirmed an increased perceived fatigue
both on subjective (VAS) and objective assessment (CFFF).
Indeed, CFFF has been used with success in several models
of extreme exposure such as divers [28, 30], pilots [31] or
parabonauts [32] and has been seen as a global index of
cerebral arousal, however with an easier set-up. Since, it
was demonstrated on short races that it was possible to
minimise anxiety and perceived fatigue with adequate sleep
to optimise performance and efficiency [8], it implies that
an improved arousal may be a surrogate of an improved
performance. We therefore advocate introducing CFFF mea-
surement into skipper’s individual assessment to better
identify the optimal moment or need for sleep.
As already demonstrated in several studies [4, 5, 7, 33],
we observed a significant reduction of bodyweight
(–3.6
±
± 1.4%) at the expense of FM (–36.4 ± 31.4%). According
to segmental BIA of FM, the reduction of fat mass was more
pronounced in the abdomen (–48.3 ± 28.1%) than in the
limbs (–25.1 ± 22.5%). Although not statistically significant,
this trend makes sense as abdominal adipose tissue (both
visceral and subcutaneous) represents about 45% of the total
adipose tissue volume among lean men between 39 and
49 years [34]. Since it was not possible to assess the daily
nutritional intake, we can only assume a negative energy
balance. The hypothesis of negative energy balance makes
sense in regards of the significant reduction of waist circum-
ference. Indeed, according to different studies the mean
total daily energy expenditure during offshore race may vary
between 14.5 [33] and 19.3 MJ/d [4], which is very high.
More, it was demonstrated on an offshore race of 500 nau-
tical miles long that the time spent performing sedentary
(< 1.5 METs, excluding sleeping) or light activity (between
1.5 and 2.9 METs) predominates with an average of 92% of
the wake time [11]. This may be assimilated to an endurance
exercise known to increase the maximum consumed oxygen,
improve the capability of skeletal muscles to produce energy
via the aerobic system and to reduce weight [35].
The main finding of our study reports a difference in
muscular conditioning between upper and lower limbs.
Indeed, no loss of HGS was noticed while there is a clear
and significant impairment of the leg physical capacity
with a reduction of jump height, speed and power. A recent
case report has produced similar result after an oceanic
race that lasted 64 days [1]. According to this report, this
is explained by a leg disuse responsible for a decreased
maximum oxygen uptake and maximum workload during
cycling measured 10 days after completion of the race.
A deeper look at skinfolds and muscle circumferences
could explain this difference. In the upper limb, we noticed
a significant reduction of skinfolds, confirming the loss of
fat, while arm and forearm circumferences are not modi-
fied suggesting a gain of muscle. On the opposite, in the
lower limbs, the skinfolds are not modified, while there is
a significant reduction of the circumference of the thigh sug-
gesting a loss of muscle. Analysis of the different muscular
activities when on board, could explain these results. Activity
of the lower limbs is essentially static, often sub-maximal
whereas upper limbs activity, during race, is explosive and
often maximal (using grinders and winches to shape the
sails in coordination with the trimmers boat) [36]. When
outside, sailors usually stay in the cockpit located at the
helm, where the majority of ropes are positioned, allowing
for sails adjustments. Except in the event of changing and
reefing sails, skippers avoid moving towards the bow. When
inside, the available room does not allow the skippers to
maintain an upright position, except for the smaller ones or
when the boat goes upwind. They remain seated in front of
the chart table, in order to receive and study the weather
forecasts, calculate the best route, or during bad weather
conditions. This can be clearly considered as a lower limb
detraining [37]. Indeed, it is agreed that if activity is suffi-
ciently reduced, muscle atrophy will ensue with associated
loss of force and power [38, 39]. It is further interesting to
note that all of the participants within the study decreased
their performance (i.e. losing strength in the lower limb)
with one exception. Indeed, the only skipper of our sample
engaged in multi 50 conserved his leg functionalities. He
even ameliorated them with a gain in speed (+0.87%), power
(+8.52%) and force (+11%) resulting in a higher jump height
(+1.12%). A shorter stay at sea compared to the other sailors
might explain this. However, when compared to the fastest
IMOCA participants, who arrived within hours of the multi
50 (difference of 3 h 50 min 20 s), the slope of the curve
between pre- and postrace results are significantly different.
We can hypothesize that the presence of “trampolines” set
between the portside/starboard hulls and the main hull
could be responsible for this. Indeed, continuously crossing
of the trampolines to manoeuvre the boat requires greater
range of motion in lower limbs, with increased torque and
bigger flexion allowing more intense muscular recruitment
in this type of activity [40] preserving leg physical capacity.
Although both fatigue and loss of weight after an offshore
race were previously demonstrated, this provides some ex-
ternal validity to our results. However, we were surprised
by the extent of the reported changes and the difference
that a few days can make in weight, body composition and
performance. Since we were limited by logistical constraint
and a very specific population, our sample was small. This

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26
may have biased our results. However, using each skipper
as his own control mitigated any risks of underestimating
or overestimating the magnitude of the changes.
CONCLUSIONS
Even if our sample size was small, including only 20%
of skippers engaged in the race, we showed race-induced
impairment of fatigue, body weight, body composition, and
leg physical capacity. The results of this study confirmed
previous data but on a larger scale same race. Although
it does not allow us to determinate which phenomena are
directly implicated, we could say that the subjective feeling
of weakness of the lower limbs experienced by sailors seems
to be multifactorial: nervous system plasticity, loss and/or
fibre modifications.
The results of our study lead to a reflexion on the neces-
sity of conceiving specific trainings for IMOCA class sailors.
Indeed several factors (sleep time, eating habits, sufficient
hydration, etc.), have become essential in preparation, and
for success of ocean racing. In addition to these factors
biometrical and strength changes induced by this type of
competition should be considered. This could help the de-
velopment of specific training program or exercises while
at sea to prevent such leg detraining.
ACKNOWLEDGEMENTS
This study was carried out on own funds and did not
benefit from any external funding.
The authors wish to thank all the skippers who took the
time to participate to this study, especially among arrival
after a long stay at sea, even before reuniting with their
family and friends.
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