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EFFECTS
OF RAPID WEIGHT LOSS ON BALANCE AND
REACTION TIME IN ELITE JUDO ATHLETES
Journal:
International Journal of Sports Physiology and Performance
Manuscript ID
IJSPP.2018-0089
Manuscript Type:
Original Investigation
Date Submitted by the Author:
03-Feb-2018
Complete List of Authors:
Morales, Jose; Ramon Llull University, Faculty of Psychology, Education
Sciences and Sport Blanquerna
Ubasart, Carla; Ramon Llull University, Faculty of Psychology, Education
Sciences and Sport Blanquerna
Solana-Tramunt, Mónica; Ramon Llull University, Faculty of Psychology,
Education Sciences and Sport Blanquerna
Villarrasa-Sapiña, Israel; Department of Physical Education and Sports,
University of Valencia, Valencia, Spain
González, Luis-Millán; University of Valencia, Department of Physical
Education and Sports
Franchini, Emerson; University of São Paulo, School of Physical Education
and Sport; Combat Centre, Australian Institute of Sport, Canberra,
Australia.
Fukuda, David; University of Central Florida, Educational & Human
Sciences
Keywords:
Combat sports, Dehydration, Perceptual motor skills, Judo performance,
Weight reduction strategies
Human Kinetics, 1607 N Market St, Champaign, IL 61825
International Journal of Sports Physiology and Performance
For Peer Review
TITLE PAGE
Title of the article:
EFFECTS OF RAPID WEIGHT LOSS ON BALANCE AND REACTION TIME IN ELITE JUDO ATHLETES
Submission type: Original investigation
Names of the authors:
Jose Morales
1
Carla Ubasart
1
Mónica Solana-Tramunt
1
Israel Villarrasa-Sapiña
2
Luis-Millán González
2
David Fukuda
3
Emerson Franchini
4
1
Faculty of Psychology, Education Sciences and Sport Blanquerna, Ramon Llull University,
Barcelona, Spain
2
Department of Physical Education and Sports, University of Valencia, Valencia, Spain
3
Institute of Exercise Physiology and Wellness, University of Central Florida, Orlando, Florida
4
Martial Arts and Combat Sports Research Group, Sport Department, School of Physical
Education and Sport, University of São Paulo, Brasil. Combat Centre, Australian Institute of
Sport, Canberra, Australia.
Corresponding author:
Dr. Jose Morales,
c/ Císter, 34, 08022 Barcelona, Spain.
Tel. +34 93 253 30 00 Fax: +34 93 253 30 31
E-mail: josema@blanquerna.url.edu
Running Head:
Rapid weight loss on balance performance
Abstract: 248 words
Text: 2891words
Number of figures: 3
Number of tables: 1
Page 1 of 18
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International Journal of Sports Physiology and Performance
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EFFECTS OF RAPID WEIGHT LOSS ON BALANCE AND REACTION TIME
1
IN ELITE JUDO ATHLETES
2
ABSTRACT
3
Balance, reaction time, and strength are key factors affecting judo performance. While
4
ample research exists examining potential strength changes caused by weight loss prior
5
to competition, changes in balance and reaction time, have been overlooked. Purpose:
6
The objective of this study was to examine the effects of rapid and progressive weight
7
loss (RWL and PWL) on balance, reaction time, and strength in a group of elite judo
8
athletes. Methods: 38 female and male judo athletes (age = 20.6 ± 2.6 years) completed
9
balance, reaction time, and strength assessments one week prior to an official weigh-in
10
(pre-test) and immediately after the weigh-in (post-test). The judo athletes were divided
11
into three groups, one control group who maintained regular training and eating habits,
12
one experimental group who engaged in PWL (<3% reductions in body mass) and a
13
second experimental group who used RWL techniques (>3% reductions in body mass).
14
Results: RWL group showed significant decreases (p<0.05) in balance performance
15
(Ellipse area: 4.83±0.87 vs. 6.31±1.39 mm
2
with eyes closed; Mean Mediolateral
16
Velocity: 2.07±0.2 vs. 2.52±0.45 mms
-1
with eyes closed; Mean Anteroposterior
17
Velocity: 2.25±0.20 vs. 2.51±0.32 mms
-1
with eyes open and 2.44±0.26 vs. 3.06±0.56
18
mms
-1
with eyes closed) and reaction time (0.38±0.04 vs. 0.42±0.06 seconds) with no
19
changes in strength from pre- to post-testing. The judo athletes in the progressive
20
weight loss and control groups maintained performance in all variables. Conclusion:
21
These findings demonstrate negative effects on perceptual motor skill performance in
22
judo athletes engaging in rapid weight loss strategies prior to competition.
23
24
KEY WORDS
25
Combat sports, dehydration, perceptual motor skills, judo performance, weight
26
reduction strategies.
27
INTRODUCTION
28
Olympic combat sports (i.e., wrestling, boxing, judo, taekwondo, and karate) separate
29
athletes into weight categories in order to promote equal competitive conditions among
30
contestants and to reduce the risk of injuries.
1
However, weight categorization may
31
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result in an advantage for those contestants that reduce their body mass to compete in an
32
inferior category where they would potentially encounter lighter and weaker
33
opponents.
2
Notably, official weigh-ins usually occur six to 24 hours before competition
34
leading many athletes to pursue very aggressive rapid weight loss (RWL) strategies,
1
35
such as severe energy restriction or dehydration via plastic suits and sauna usage,
3
that
36
may have negative health consequences.
4
Potential health implications of RWL include
37
cardiovascular problems due to plasma volume reduction and increased blood volume,
5
38
chronic hormonal imbalances, immune suppression
6
, mood alterations, and eating
39
disorders.
7,8
40
41
Approximately 90% of judo athletes, excluding those in the heavyweight category, have
42
lost weight to compete
3
usually losing between 2 and 10% of their body mass in the last
43
2 to 3 days prior to competition.
2,7
With a large number of competitions occurring
44
throughout a season, these contestants’ bodies are exposed to constant cycles of weight
45
loss. In 1997, the National Collegiate Athletic Association (NCAA) attempted to
46
regulate RWL in wrestling and thus preserve the athletes’ health by establishing
47
minimum hydration status and body fat percentage requirements.
9
According to some
48
authors, weight loss before a competition can be achieved almost exclusively with acute
49
dehydration
4
and those athletes reporting a 3% weight reduction during the week prior
50
to competing may be defined as having engaged in RWL.
8
51
52
Results from examinations of the impact of RWL on physical performance are
53
controversial and appear to depend on the skills assessed and the recovery time between
54
the assessments and weigh-in procedures.
2,7
In general, combat sports require a high
55
level of fitness that allows athletes to efficiently develop motor control and cognitive
56
skills.
10
Specific physical aspects concerning performance in judo, include maximum
57
isometric strength, reaction time (RT), and balance.
11,12
Few studies have indicated a
58
decrease in maximal isometric strength after RWL in grappling combat sports,
13,14
while
59
the majority of studies reviewed did not report significant changes in this variable after
60
RWL in combat sports athletes.
2
While many studies have explored the influence of
61
RWL on strength and power in judo, there is a lack of research focusing on perceptual
62
motor skills, such as RT and balance.
63
64
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Balance is a complex sensorimotor function that allows orientation of the body in space
65
and assists in postural stabilization. By stimulating muscular, articular, and cutaneous
66
mechanoreceptors, athletes can adapt to the constant modifications of posture, support,
67
ground, and opponent.
15,16
In judo, keeping balance while standing is a key factor to
68
carry out technical and tactical movements
17
aimed at disturbing the opponent’s balance
69
by creating instable dynamic situations. The effects of balance on judo athletes have
70
been examined with respect to age categories,
18
training status,
17
and competitive
71
level.
19
While no studies have been conducted on the effect of dehydration due to RWL
72
on balance in judo athletes, Lion et al
15
explained that exercise-induced dehydration
73
increases proteinemia which may lead to compromised balance. This lack of balance
74
control could be explained by metabolic modifications induced by dehydration affecting
75
postural control regulation, particularly at the vestibular level.
20
76
77
RT is the time between the initiation of a specific stimulus and the subsequent response.
78
The speed at which technical skills are applied in combat sports require that the time
79
between the beginning of a mechanical or visual stimulus and the beginning of the
80
movement response be minimal in order to maintain a competitive advantage.
12,21
81
However, examinations of RT following weight loss in wrestling
14
and karate
21
athletes,
82
as well as jockeys,
22
who commonly engage in RWL, have not confirmed decreases in
83
RT. Nonetheless, research on the effect of RWL on RT in judo athletes is needed.
84
85
The objective of this study was to examine RT, balance, isometric hand grip strength
86
(IGS), and isometric trunk traction strength (ITTS) in judo athletes that engaged in
87
progress weight loss (PWL) and RWL prior to competition. We hypothesized that the
88
group using RWL would experience greater decrements in performance.
89
METHODS
90
This investigation utilized a quasi-experimental design and was conducted prior to an
91
international-level judo competition held in Barcelona. Balance, RT, and strength tests
92
were conducted one week prior to the official weigh-in (pre-test) and immediately after
93
the weigh-in (post-test). The athletes in the experimental groups (PWL and RWL)
94
followed their standard competition preparation routines and weight loss strategies,
95
while a control group (CG) of athletes was established, who followed their standard
96
competition routines while maintaining their body weight without using any weight loss
97
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strategies. The athletes in the experimental groups were divided into athletes who lost
98
less than 3% of their body mass, deemed PWL, and athletes who lost more than 3% of
99
their body mass, deemed RWL, between the pre- and post-test data collection sessions.
100
After the weigh-in, the athletes were interviewed about their weight loss strategies and it
101
was confirmed that the RWL group had undertaken greater than 3% body mass
102
reductions via dehydration and energy restriction in the 48 hours prior to the weigh-in.
103
The order of execution of the tests was randomized and all of the judo athletes that took
104
part in the study were familiarized with the measurement procedures not more than an
105
hour before data collection in order to minimize possible learning effects.
106
107
SUBJECTS
108
109
38 national and international judo athletes (12 women and 26 men; age 20.6 ± 2.6 years;
110
height: 1.69 ± 0.11 m; body mass: 66.5 ± 13.1 kg), who were members of the Catalan
111
Judo Federation, volunteered to participate in the study. Inclusion criteria were to be a
112
participant in the final phase of the national championship. The athletes in the sample
113
had a mean of ten years of experience in judo, 5 years in competition, and engaged in
114
16.1 + 3.2 hours of training per week. Table 1 presents the descriptive characteristics of
115
the sample. All of the participants signed an informed consent prior to engaging in the
116
study, which was approved by the ethical committee of Ramon Llull University
117
(Barcelona).
118
119
Table1. ***Aprox. here***
120
121
INSTRUMENTS
122
Balance
123
The judo athletes’ balance was evaluated from centre of pressure (COP) data that were
124
collected using the Wii Balance board. The Wii Balance board contains a uniaxial
125
vertical force transducer on every corner and has been validated to analyse postural
126
control in several studies.
23–25
Raw data were collected using WiiLab software
127
(University of Colorado Boulder, Colorado, USA) for Matlab R2007 (Mathworks Inc,
128
Natick, USA) with 40Hz frequency and connected to a laptop via Bluetooth.
129
The Wii Balance board was put on the ground in a stable position, and participants were
130
asked to maintain an upright posture with feet in line with shoulders, and arms relaxed
131
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while standing for period of 30 seconds with their open eyes and for an additional 30
132
seconds with eyes closed. The first 5 seconds of each assessment were excluded from
133
analysis. The area of the 95% ellipse (AE), mean anteroposterior velocity (MAPV), and
134
mean mediolateral velocity (MMLV) were collected from the remaining 25 seconds of
135
the COP signal.
136
137
Reaction time
138
Simple RT was measured with a contact platform (Chronojump, Barcelona, Spain)
139
connected to a microcontroller (Arduino Duemilanove, Italy) and a laptop computer was
140
used to display the results. The emission of a light signal was programmed to randomly
141
occur at intervals of 6 to 9 seconds for a period of 40 seconds. While in a standing
142
position, participants were instructed to step on the contact platform, placed at a
143
distance of 20 cm, with their dominant foot as quickly as possible whenever the light
144
stimulus appeared. The lowest time from all attempts was recorded. Values below 150
145
ms were excluded from in order to avoid anticipation effects.
146
147
Isometric strength
148
All participants carried out standard tests for isometric hand grip strength (IGS) and
149
isometric trunk traction strength (ITTS) for 3 seconds. IGS was measured with a hand
150
dynamometer (TKK 5401, Grip-D, Takei, Tokyo, Japan) adjusted to the hands size of
151
each participant. ITTS was measured with a leg and back dynamometer (TKK 5402,
152
Back-D, Takei, Tokyo, Japan), with the participants extending their legs and placing
153
their trunk at 30º of lumbar flexion, while maximally pulling with their hands.
154
Each participant had two attempts per test with a minimum of 90 seconds of recovery
155
and the best result was recorded.
156
157
Statistical analysis
158
All descriptive data are presented as mean ± standard deviation (SD). The normal
159
distribution of the dependent variables were checked using the Shapiro-Wilk test. Due
160
to violations of the assumption of normality, the balance variables were transformed
161
using the ln (1+x) transformation to normalize the data and avoid negative results.
162
To contrast the hypotheses, a mixed model [Time (2: PRE, POST) × Group (3:
163
CONTROL, PWL, RWL)] analysis of variance (ANOVA) with Bonferroni post-hoc
164
testing was applied. Analyses were carried out by using the Statistical Package for
165
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Social Science software, version 22.0 (SPSS, Inc., Chicago, IL, USA) and the level of
166
significance was established at p<0.05.
167
RESULTS
168
Balance
169
Figure 1 shows the descriptive results for balance measures and the significant
170
differences between pre-test and post-test for all of the groups included in the study. A
171
significant time x group interaction (F
2,30
=5.108; p=0.02) was shown for AE with eyes
172
closed, while no interaction or main effect was shown for AE with eyes open. Paired
173
comparisons demonstrated that AE with eyes closed was significantly higher (p<0.05)
174
during the post-test than the pre-test in the RWL group, whereas no differences between
175
pre-test and post-test were found in the PWL and CG groups.
176
A significant main effect (F
2,30
=4.299; p=0.04) was shown for MAPV with eyes open,
177
and a significant time x group interaction (F
2,30
=3.403; p=0.04) was shown for MAPV
178
with eyes closed. Paired comparisons demonstrated that MAPV with eyes open and
179
eyes closed were significantly higher (p<0.05) during the post-test than the pre-test in
180
the RWL group, whereas no differences between pre-test and post-test were found in the
181
PWL and CG groups.
182
A significant time x group interaction effect of (F
2,30
=4.140; p=0.02) was shown for
183
MMLV with eyes closed, while no interaction or main effect was shown for MMLV
184
with eyes open. Paired comparisons demonstrated that MMLV with eyes closed was
185
significantly higher (p<0.05) during post-test than pre-test in the RWL group, whereas
186
no differences between pre-test and post-test were found in the PWL and CG groups.
187
188
Figure 1. ***Aprox. here***
189
Reaction time
190
Figure 2 shows the descriptive results for RT measures and the significant differences
191
between pre-test and post-test for all of the groups included in the study. RT showed a
192
main effect (F
2,30
=7.57; p=0.01), while no significant interaction effect was found in the
193
multivariate contrast. Paired comparisons demonstrated that RT was significantly higher
194
(p<0.05) during post-test than pre-test; whereas no differences were found in the PWL
195
and CG groups.
196
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197
Figure 2. ***Aprox. here***
198
Isometric strength
199
Figure 4 shows the descriptive results for IGGS and IGS measures for all of the groups
200
included in the study. No significant interaction or main effect was shown for IGS or
201
ITTS.
202
Figure 3. ***Aprox. here***
203
DISCUSSION
204
The main objective of this study was to compare performance changes in judo athletes
205
adjusting their weight for competition. Based on the scientific literature, we wanted to
206
determine if RWL, defined as ≥ 3% within the week prior to competition as suggested
207
by Koral and Dosseville,
8
results in performance deficits, particularly balance and RT.
208
The findings in this study partially confirm the initial hypothesis that balance (AE,
209
MAPV, and MMLV) and RT are altered by RWL, whereas isometric strength is
210
maintained.
211
While balance has been shown to improve with age and training/competitive status in
212
judo athletes,
17–19
the effects of RWL were previously unexplored. Several examples
213
from athletes engaging in RWL have also been conducted using field-based balance
214
assessments. Jlid et al
20
studied the alterations in postural control in wrestlers following
215
RWL and found significantly lower values in some positions on their right leg in the
216
Star Excursion Balance Test (SEBT). Conversely, jockeys who undertook a 4%
217
dehydration-based reduction in body mass over 48 hours showed no significant
218
differences in the Y Balance Test. The results of the current investigation demonstrated
219
RWL-related declines in AE, MAPV, and MML measures using the Wii Balance board
220
with eyes closed and in MAPV with eyes open.
221
In a study conducted by Perrin et al,
16
judo athletes were found to have balance
222
performance with eyes closed than ballet dancers, suggesting a lower dependence on
223
visual inputs. These results, along with the current findings, highlight the influence of
224
proprioception during the complex motor tasks associated with judo
26
and the potential
225
alterations that may occur during RWL prior to competition..
226
One of the factors that can explain the decreased balance performance may be the
227
dehydration that likely occurred during RWL. In support, Lion et al
15
noted that
228
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dehydration affected sensory organization likely through impairments of the vestibular
229
system and that the level of dehydration is correlated with the use of the vestibular
230
input.
231
To our knowledge, this is the first study to show a reduction in cognitive function via
232
RT following RWL in judo athletes. Examples from the combat sports research
233
literature show limited support for changes in RT following weight adjustment or food
234
restriction. Kraemer et al
14
observed that RT performance in wrestlers was neither
235
affected by weight loss nor by competition; however, the conditions of the study are not
236
comparable as RT measurement during competition likely involves a much higher level
237
of attention than when measured the day before competition. Furthermore, food
238
restriction due to Ramadan did not influence RT values in elite karate athletes,
21
though
239
this practice differs greatly from RWL strategies in judo that likely include dehydration
240
and exercise in rubber or plastic suits.
7
In the case of jockeys, there are no results that
241
support our study either, as research in this field shows that RT is maintained following
242
RWL.
22,27
243
The effect of RWL on performance is a controversial issue potentially due to the
244
difference between the physical qualities being evaluated and the recovery period
245
between the assessments and the official weigh-in.
7
While the isometric strength
246
assessment was not the main objective of this study, the observation of this parameter
247
was included in order to contrast with balance and RT measures that likely have greater
248
influence on perceptual motor skills.
249
Strength changes in response to RWL have been commonly examined in combat sports.
250
In our study, IGS and ITTS tests were not affected by PWL or RWs. Several studies
251
support these findings as strength and power were not affected by RWL regardless of
252
the following recovery period
8,28
and a review by Franchini et al
2
showed that maximum
253
strength does not seem to be acutely affected by RWL. In contrast, some studies have
254
shown the opposite. For instance, Silva et al
29
demonstrated that judo athletes with more
255
than a 2.7% reduction of total body water lost 2% or more IGS. Some older studies
13,30
256
have shown significantly reduced strength levels after RWL in combat sports athletes;
257
however, anecdotal observations suggest that physical fitness in judo athletes has
258
improved in the last few years, which may help to explain why more recent studies
259
show limited decrements in strength following RWL.
260
One of the main limitations of this study is that post-test assessments were conducted
261
immediately following the official weigh-in rather than prior to the competition. The
262
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approximately 12-hour difference between weigh-in and competition likely allowed the
263
athletes to regain some of the previously lost body weight; however, the current
264
International Judo Federation regulations state that athletes must be within 5% of the
265
maximum weight limit of their category on the day of competition. Furthermore,
266
completing data collection procedures during this time period is difficult due to the
267
potential distraction of the athletes prior to competition or other perceived negative
268
influences on performance. Considering the current findings, future investigations
269
examining the effects of weight loss on non-fatiguing assessments requiring minimal
270
effort and time, such as balance tests, immediately prior to the competition and between
271
matches may be warranted.
272
273
PRACTICAL APPLICATIONS
274
The currently presented findings highlight the potentially negative impact of RWL on
275
perceptual motor skills and performance in judo. As scoring actions are based on
276
unbalance and reaction time is important to perform defensive action in judo, the rapid
277
weight loss should be avoided. Conversely, progressive weight loss did not negatively
278
affect balance and could be used to achieve a specific weight limit. Thus, a proper
279
combination of diet and exercise is needed to avoid these negative effects. Accordingly,
280
coaches and sports medicine professionals must consider appropriate oversight and
281
education for their athletes in order to safely engage in weight loss prior to competition.
282
Moreover, the national and international federations responsible for organizing
283
competitions and weigh-ins should examine strategies that minimize the negative
284
effects of RWL on athletes and the quality of competition.
285
CONCLUSIONS
286
Despite an abundance of research examining RWL in combat sports, the effects on
287
physical performance were previously equivocal. Based on the current results, judo
288
athletes engaging in RWL before competition experience negative alterations to balance
289
and RT, while isometric strength is unaffected. Additionally, judo athletes engaging in
290
PWL or weight maintenance balance and RT were maintained before competition.
291
Along with general health concerns, these findings provide support for less extreme
292
weight loss strategies prior to competition in order to maintain perceptual motor skill
293
performance in judo athletes.
294
295
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ACKNOWLEDGMENTS
296
We would like to acknowledge the technical and material support of the Catalonian
297
Judo Federation. We would also like to thank the work carried out by Ainhoa Nieto and
298
Alba Acevedo during data collection.
299
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FIGURE CAPTIONS 389
Figure 1. Balance results for the control, progressive weight loss (PWL), and rapid
390
weight loss (RWL) groups.
391
MAPV = mean anteroposterior velocity; MMLV = mean mediolateral velocity. *
392
denotes significant differences (P<0.05) between pre-test and post-test.
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394
Figure 2. Reaction time results for the control, progressive weight loss (PWL), and
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rapid weight loss (RWL) groups.
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* denotes significant differences (P<0.05) between pre-test and post-test.
397
398
Figure 3. Maximal isometric strength results for the control, progressive weight
399
loss (PWL), and rapid weight loss (RWL) groups.
400
401
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Table 1. Descriptive statistics for the control, progressive weight loss (PWL), and
rapid weight loss (RWL) groups.
Gender Group N Age (years) Body mass (kg) Height (m)
WOMEN CONTROL
3 20.67 (3.79)
58.33 (4.16) 1.60 (0.05)
PWL 4 18.80 (1.30)
56.60 (12.52) 1.57 (0.03)
RWL 5 21.25 (2.22)
55.00 (6.48) 1.60 (0.09)
MEN CONTROL
6 19.67 (1.75)
67.83 (14.89) 1.70 (0.10)
PWL 9 22.00 (3.29)
80.83 (13.76) 1.82 (0.07)
RWL 11 21.00 (2.67)
69.00 (5.94) 1.72 (0.06)
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Figure 1. Balance results for the control, progressive weight loss (PWL), and rapid weight loss (RWL) groups.
MAPV = mean anteroposterior velocity; MMLV = mean mediolateral velocity. * denotes significant
differences (P<0.05) between pre-test and post-test.
215x355mm (300 x 300 DPI)
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Figure 2. Reaction time results for the control, progressive weight loss (PWL), and rapid weight loss (RWL)
groups.
* denotes significant differences (P<0.05) between pre-test and post-test.
299x199mm (300 x 300 DPI)
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Figure 3. Maximal isometric strength results for the control, progressive weight loss (PWL), and rapid weight
loss (RWL) groups.
297x210mm (300 x 300 DPI)
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