The effects of fluid loss on physical performance: A critical review

Abstract

Purpose: The purpose of this review was to critically analyse the current evidence investigating the effect of an athlete's hydration status on physical performance.
Methods: A literature search of multiple databases was used to identify studies that met the inclusion criteria for this review. The included studies were then critically appraised using the Downs and Black protocol.
Results: Nine articles were found to meet the inclusion criteria, with an average score of 79% for methodological quality representative of a “high” standard of research.
Conclusion: The evidence suggests that dehydration has a negative impact on physical performance for activities lasting more than 30 s in duration. However dehydration was found to have no significant impact on physical performance for activities lasting less than 15 s in duration.

Full text

Review
The effects of fluid loss on physical performance: A critical review
Q3 Andrew Carlton, Robin Marc Orr*
Faculty of Health Sciences and Medicine, Bond Institute of Health and Sport, Gold Coast, Queensland 4226, Australia
Received 21 March 2014; revised 27 May 2014; accepted 17 September 2014
Abstract
Purpose: The purpose of this review was to critically analyse the current evidence investigating the effect of an athlete’s hydration status on
physical performance.
Methods: A literature search of multiple databases was used to identify studies that met the inclusion criteria for this review. The included studies
were then critically appraised using the Downs and Black protocol.
Results: Nine articles were found to meet the inclusion criteria, with an average score of 79% for methodological quality representative of a
“high”standard of research.
Discussion: The evidence suggests that dehydration has a negative impact son physical performance for activities lasting more than 30 s in
duration. However dehydration was found to have no significant impact on physical performance for activities lasting less than 15 s in duration.
Copyright Ó2015, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.
Keywords: Athlete; Dehydration; Euhydration; Hydration; Performance
1. Introduction
The idea that bodily fluid loss, in the form of dehydration,
impairs an athlete’s physical performance is not new. In 1955,
Buskirk et al.
1
discussed the negative impact dehydration had
on VO
2max
. Since this research, evidence supporting dehy-
dration related impairments in aerobic performance,
2
anaer-
obic performance,
3,4
and cognitive performance,
5
have been
published, as have incidents whereby athlete dehydration has
led to the risk of fatality.
6
A state of dehydration can be induced though physical
activity (PA).
7
However, the level of dehydration induced can
be dependent upon a number of variables including the type,
intensity, and duration of the PA and the temperature and
humidity of the environment.
8
Hence studies have been un-
dertaken to investigate the impact that PA has on dehydration,
and conversely the impact that different levels of dehydration
have on physical performance. The intent of these studies
being to better understand the need for an athlete to maintain a
state of euhydration (absence of dehydration).
8
As an athlete’s
performance essentially requires a degree of PA and PA is
known to potentially induce a state dehydration and reduce an
athlete’s performance, an understanding of the relationship
between PA and hydration status is important if a coach wishes
to optimize their athlete’s performance and prevent a poten-
tially life threatening incidence. On this basis, the purpose of
this review was to critically analyse the current literature
investigating the effect of dehydration on physical
performance.
2. Methods
A two-layered search strategy was utilized for the review.
Firstly, a comprehensive search of online databases including
PubMed, CINHAL, Web of Science, SPORTSDiscus, and
EBSCO Academic Search was completed. The search terms
and filters used for the searches of these databases are detailed
in Table 1. All articles noted from the original database search
were checked for duplicates, and these were subsequently
removed. Secondly, the reference lists of articles from the
* Corresponding author.
E-mail address: rorr@bond.edu.au (R.M. Orr)
Peer review under responsibility of Shanghai University of Sport.
Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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2095-2546/$ - see front matter Copyright Ó2015, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jshs.2014.09.004

database search that were retrieved in full text were cross-
checked against the list of initial database articles and all
new articles were noted and sourced.
All articles were then subjected to key inclusion criteria,
these being: (1) the article specifically investigated the effect
of dehydration on physical task performance; (2) the article
was published within the last 10years; (3) the research
involved human participants; (4) the article was published in
English; and (5) the article was an original research article. For
the purpose of this review, dehydration was defined as an in-
crease in osmolality or similarly a decrease in body mass from
a single exercise session/heat exposure. Physical tasks were
defined as tasks that require physical exertion or activities that
challenge the participant in a physical capacity.
The methodological quality of selected articles were
assessed using the Downs and Black protocol.
9
The Downs
and Black protocol employs a 27-question checklist to assess
five key areas of methodological quality: statistical power,
internal validity (bias and confounding), external validity, and
reporting quality. The checklist comprised closed answer
questions, where a “yes” is awarded 1 point and a “no” or
“unable to determine” is award 0 points. There are two
questions that have more points assigned to them. Question 5,
reporting of confounding factors associated with the partici-
pants, is scored out of two (0 ¼No list, 1 ¼a partial list, 2 ¼a
complete list of principle confounders). Question 27, a sta-
tistical power question, has scores derived from the number of
participants involved in the clinical trial and is scored out of
five. Scores were converted to a percentage of the total score
by dividing each article’s score by 32 (total possible score) and
multiplying by 100. All studies were independently rated by
the authors with the level of agreement measured using a
Cohen’s Kappa (k) analysis of all raw scores (27 scores per
paper). For final scores, any disagreements in points awarded
were settled by consensus.
3. Results
From the initial search, 124 possible articles were identified
from the database searches (Fig. 1). Of these articles, 108 were
removed following review of the titles and abstracts against
the five inclusion criteria. An additional seven articles were
removed due to duplication. Six articles were added from the
search of reference lists which identified previously uniden-
tified articles. The remaining 15 articles were then reviewed in
detail and considered against the inclusion criteria with nine
papers retained for critical review.
The participants, methods, main findings and critical
appraisal of the articles are shown in Table 2. The kappa
statistic for inter-tester agreement of the methodological
quality of the studies indicated a “substantial” agreement
(k¼0.744).
10
The critical appraisal measures of power,
quality of reporting, internal validity and external validity of
the selected research articles were found to have reasonably
high methodological scores (mean ¼79% 4%) ranging
from 72% to 81% using the Downs and Black checklist.
9
These scores are considered to represent a high standard of
research.
11
Both the inability to blind the participants and the
researchers, and poorly represented populations were identi-
fied as the main limitations of the studies identified for review.
Table 1
Details of literature search: databases used, search terms, and filters.
Database Search terms Filters Number after
exclusion
Number after
inclusion
Total
number
Duplicates New
articles
PubMed “fluid loss” or “exercise induced dehydration”
and “performance” and “physical task” or
“exercise”
2003e2013
Human
English
Clinical Trial
RCT
43 303
CINHAL “fluid loss” or “exercise induced dehydration”
and “performance” and “physical task” or
“exercise”
2003e2013
Human
English
Research article
Peer reviewed
RCT
11 110
Web of Science “fluid loss” or “exercise induced dehydration”
and “performance” and “physical task” or
“exercise”
Article
English
2003e2013
72 8 8 5 6
SPORTDiscus “fluid loss” or “exercise induced dehydration”
and “performance” and “physical task” or
“exercise”
Journal article
peer reviewed
English
2003e2013
24 2 2 2 0
EBSCO:
Academic
Search
Complete
“fluid loss” or “exercise induced dehydration”
and “performance” and “physical task” or
“exercise”
Scholarly (peer
reviewed)
journals
2003e2013
Article
English
23 2 2 2 0
2 A. Carlton and R.M. Orr
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Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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The populations of the studies were all males, who were
classified as healthy and active. Some of the participants were
involved in specific sports including cycling,
8,12
rugby,
2
golf,
13
soccer,
14
and triathlon
7
with the remaining participants from
the general population.
3,4,15
The average population size for
the studies was nine participants ranging from seven to 12
participants. Seven of the nine studies
2,7,8,12e15
utilized a
randomized crossover trial to allow for the capture of results
from all participants across conditions whilst removing con-
founding effects in both learning and fatigue. The remaining
two studies
3,4
used a one-day trial where the participants
started in an euhydration state with exercise or heat exposure
prescribed to achieve the dehydration condition for post-
testing. There were a number of different approaches
employed by the studies to achieve a dehydrated state
including; heat exposure,
2e4
fluid restriction,
2,7,8,12,13
and
exercise.
7,12,14
There was one study that directly considered
the effect of dehydration on aerobic performance,
2
whilst most
looked at its effect on anaerobic performance.
3,4,7,8,12e15
Two
of these anaerobic studies did however consider the effect
dehydration had on the aerobic exercise that was undertaken to
induce a dehydrated state.
8,12
Two studies used sport specific skills to assess perfor-
mance,
13,14
two the Wingate test,
3,15
and another two a graded
exercise test to exhaustion.
7,12
One study looked at distance
travelled in 30 min
2
while another used a 5-km time trial to
determine performance impacts.
8
In the remaining study,
4
knee strength and standing vertical jump were used to deter-
mine the effect of dehydration on performance. Given these
outcomes measure, the majority of the studies came to the
conclusion that dehydration decreases perform-
ance
2e4,7,8,12e14
although one study found no difference be-
tween the euhydration and hypohydration trials.
15
Four studies found that with dehydration there was an
associated decrease in power output.
3,7,8,12
In addition, the
captured studies noted increases in relative VO
2
and heart rate
with dehydration,
2
decreased gross efficiency,
7
decreased
speed,
8
decreased time to exhaustion,
12
and decreased sport-
specific skills.
13
Two studies identified an increase in “Rat-
ings of Perceived Exertion” levels with dehydration
2,14
with a
third study noting a 70% increase in the severity of fatigue
with dehydration.
3
In contrast, one study did find only a slight,
non-significant increase in fatigue severity with dehydration.
15
4. Discussion
Fluid loss due to PA is a daily occurrence for humans.
Without replacement this fluid loss can lead to a state of
dehydration. With the methodological scores of the evidence
considered in this review found to be of good standard, the
majority of research suggests that dehydration has a detri-
mental effect on physical performance, with the potential
exception of activities lasting less than 15 s. This is unsur-
prising given evidence suggesting that a decrease in hydration
of 3% has been shown to have an effect on the performance of
further physical activities.
3
Upon investigating the impact of dehydration on aerobic
performance most studies were found to only consider an
aerobic exercise section as a segue between pre- and post-
testing. Aerobic exercise was used to help achieve the level of
dehydration that the researches had set as their
criteria.
4,7,8,12,14
However, some studies did utilize aerobic
exercise as an outcome measure and not merely an interven-
tion.
8,12
During these latter investigations the researchers
found a decrease in aerobic performance with the participants
that were in a hypohydrated or dehydrated state compared to
baseline or euhydration state. Hillman et al.
8
discovered that
with the reduced hydration in a warm climate (33.9 0.9 vs.
23.0 1.0 C) the distance covered in their 90 min of cycling
on a stationary ergometer significantly decreased ( p<0.03)
when compared to an euhydrated state in the same participant.
Ebert et al.
12
found similar results. In their study, riders
were allocated a low hydration restriction protocol of 50mLper
15 min or a high hydration protocol of 300mLper 15 min. The
investigators note that during and following 120 min of sub-
maximal riding there was a significant increase in the heart
rates (low hydration 187 146 bpm; high hydration
183 146 bpm; p¼0.02) and core body temperatures (low
hydration: 39.5 0.3 C; high hydration: 39.1 0.3 C;
p<0.001) of the low hydration riders. Both the increased
heart rate and increased body temperature are considered to be
detrimental to performance.
12
There was one study that
investigated just the aerobic performance on participants.
2
Aldridge et al.
2
explored the impact of dehydration on heart
rate, perceived rating of exertion, and mean VO
2
. They found
significant differences in all three variables when comparing
euhydration condition to the dehydration condition ( p0.01,
p0.05, p0.001, respectively).
As opposed to aerobic exercise, the majority of studies
investigated the effect of dehydration on anaerobic exer-
cise.
3,4,7,8,12e15
Unlike the aerobic exercise studies, which had
consistent findings, the studies investigating anaerobic
Fig. 1. A flow chart of the process used for the literature review.
Fluid loss and physical performance 3
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Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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Table 2
Summary of the critical appraisal of included articles in this review.
Authors Participants Variables Intervention Main findings Critical appraisal
score (%)
Aldridge et al.
2
Eight regularly active male
athletes euniversity rugby
players
Independent:
hydration status (EUH/HYPO)
Dependent:
aerobic exercise performance
Randomised Crossover
1. 1 30 min cycle ergometer at 75 W
UOsm values for EUH and HYPO
conditions were 385 184 mOsm/kg
and 815 110 mOsm/kg respectively.
There was significant increases
between EUH and HYPO conditions in
mean VO
2
(p0.001), HR
(p0.01), RPE (p0.05) at the
30 min point of the test
81
Cheuvront et al.
15
Eight healthy and physically
active male subjects
Independent:
hydration status (EUH/HYPO)
Dependent:
anaerobic exercise performance
Randomised crossover
1. 1 15 s Wingate (WAnT)
2. 3 h passive heat exposure
3. 3 WAnT’s at 0, 30 and 60 min’s
post heat exposure
HYPO condition had a significantly
decreased body mass compared to
EUH ( p<0.001)
No significant differences seen in
relative peak power output between
EUH and HYPO conditions
(11.4 1.0 and 11.7 1.3 W/kg)
81
Ebert et al.
12
Eight well-trained male cyclists Independent:
hydration status (HIGH CHO/LOW
CHO)
Dependent:
cycling hill climbing performance
1maximal graded cycling test on a
stationary ergometer to determine
MAP
Randomised crossover
1. 2 h ride on a stationary ergometer at
53% MAP
2. Hill climb time-to-exhaustion at
88% MAP, own their own bike on an
8% inclined treadmill
Significant difference between LOW
CHO and HIGH CHO conditions in
body mass loss (3.6 0.6 and
1.3 0.5% body mass respectively,
p<0.05)
Significant difference in time to
exhaustion on hill climb test between
LOW CHO and HIGH CHO conditions
(p¼0.002), with a 28.6% 13.8%
decrease in times in the LOW group
72
Edwards et al.
14
Eleven moderately active male
soccer players (2 players did not
complete MR conditions)
Independent:
(FI, NF, and MR)
Dependent:
Soccer match play and fitness
variables
Randomised crossover
1. 45 min pre-match cycle ergometer
(90% VT)
2. Completion of a 45 min soccer
match
3. Immediate post-match sport-specific
and mental concentration tests
U
SGM
significantly increased
(p<0.05) post-match compared to
pre-match in the NF test, however no
significant change in the FI andMR
tests
A significant decrease in both NF and
MR (13% and 15% respectively) in
distance covered in the post-match
performance test when compared to the
FI test
75
Hayes et al.
4
Twelve male university students Independent:
hydration status
increasing levels of HYPO
Dependent:
strength, jump capacity, and
neuromuscular function
Six resistance exercise bouts Heat
exposure between each bout
Heat exposure of20 min jogging in a
warm environment chamber
Resistance exercise bouts consisted of
a unilateral knee extension in isometric
and isokinetic concentric conditions
and a standing vertical jump
Subjects had a significant decrease in
body mass, maximal isometric and
isokinetic strength during the study
(p<0.001, p<0.05, p<0.05
respectively)
However no significant change was
seen in jump height, EMG, or maximal
isokinetic strength at 120/s
75
(continued on next page)
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Table 2 (continued)
Authors Participants Variables Intervention Main findings Critical appraisal
score (%)
Hillman et al.
8
Seven competitive
male cyclists
Independent:
hydration status (EUH and DE in W
and T conditions)
Dependent:
5 km cycling TT
Randomised crossover
1. 90 min cycling at 95% lactate
threshold
2. 5 km TT
% DE significantly increased in the
DEeW condition compared to pre-
exercise ( p<0.01)
DEeW also had significant decreases
in power output compared to all other
conditions in both the 90 min cycle and
5kmTT(p<0.03, p<0.02)
81
Jones et al.
3
Seven healthy males Independent:
hydration status (EUH/HYPO)
Dependent:
UL, and LLPO
1. 2 UL and LL e30 swingate tests
2. Heat exposure until dehydration of
3.0% body mass loss was achieved
3. 2 UL and LL e30 s Wingate tests
UL and LL mean PO were significantly
decreased between EUH and HYPO
(7.17%, p¼0.016; 19.20%, p¼0.002)
UL and LL peak PO were significantly
decreased between EUH and HYPO
(14.48%, p¼0.013; 18.36%,
p¼0.013)
81
Smith et al.
13
Seven athletic low-handicap
experienced male golfers
Independent:
hydration status (EUH/DE)
Dependent:
sport-specific and cognitive motor
performance
Randomised crossover
1. Sport-specific performance test:
hitting 30 golf balls in a laboratory-
based netted, enclosed swing area
2. Cognitive ability test: distance
judgment
Body mass in the DE condition was
significantly reduced when compared
to base line ( p<0.01)
Shot distance and off target accuracy
were both significantly different
between the EUH and DE conditions.
(14.1%, p<0.001; þ3.8%,
p¼0.001)
There was also a significant decrease
between EU and DE conditions in the
cognitive tests ( p<0.001)
81
Van Schuylenbergh
et al.
7
Nine national level
male triathletes
Independent:
hydration status (EUH/DE)
Dependent:
HR, PO, RER
Randomised crossover
1. Graded cycling test to exhaustion
2. 2 h endurance exercise bout
(including fluid replacement for the EH
condition)
3. Graded cycling test to exhaustion
DE post-exercise test was significantly
shorter and had reduced PO than the
other tests ( p<0.05, p<0.05)
Oxygen uptake was not significantly
different and RER was significantly
decreased in all post-exercise test
conditions ( p<0.05)
81
Abbreviations: EUH ¼euhydration; HYPODE ¼hypohydration/dehydration; HIGH CHO ¼high carbohydrate; LOW CHO ¼low carbohydrate; HR ¼heart rate; sRPE ¼rating of perceived exertion;
MAP ¼maximal aerobic power; VT ¼ventilatory threshold; W ¼warm; T ¼thermoneutral; TT ¼time trial; PO ¼power output; UL ¼upper limb; LL ¼lower limb; RER ¼respiratory gas exchange ratio;
MR ¼mouth rinse; FI ¼fluid intake; NF ¼no fluid.
Fluid loss and physical performance 5
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Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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exercise produced varying results. In the performance tests
that lasted for longer periods of time (30 s) the investigators
found that dehydration had a negative effect on perform-
ance.
3,4,7,8,12e14
However, for tests that lasted shorter than
15 s, including the standing vertical jump and 15 s Wingate
anaerobic test there were no observed changes in perfor-
mance.
4,15
A reason for these differences may relate to the
energy system predominately used for each test. There are two
main energy components that contribute to anaerobic perfor-
mance, the alactic and anaerobic glycolytic (lactic) compo-
nents.
16
These components work in conjunction with the
aerobic energy system to meet the energy demand during
exercise. Each energy system is active throughout exercise
however one is usually more dominant than the others with the
duration and intensity of the exercise influencing this.
16
For
high intensity exercise that lasts up to 15e20 s the body
predominately utilizes the alactic component
16
; this system
does not require water.
17
For high intensity activity that lasts
up to 2e3 min the body predominately uses the anaerobic
glycolytic component
16
; a system that utilizes water to help in
energy synthesis.
17
Water is used in the anaerobic glycolytic
energy system to resynthesize pyruvate into glucose so that it
can be recycled through the energy systems to create more
energy, likewise the hydrogen ions stripped from the water
produces energy when shuttled through the electron transport
chain.
17,18
Water is utilized by the aerobic energy system to
perform the same roles.
17
As such, a dehydrated state, where
bodily water is limited, may reduce the ability of the anaerobic
glycolytic and aerobic energy pathways to produce energy,
and as such, have a negative impact on performance of tasks
lasting 30 s or longer in duration.
The general findings from the reviewed research follow
earlier studies prior to the review period. In regards to aerobic
performance, previous research has typically found dehydra-
tion to negatively impact performance.
19e22
One study, by
Dengel et al.
23
did however fail to find changes in aerobic
performance with hypohydration. It should be noted that
participants in this study cycled at sub maximal intensities
(50% VO
2max
) for the duration. Similarly, findings investi-
gating anaerobic performance were mixed.
20
Where one study
by Greiwe at al.
24
found no change in isometric strength or
muscle endurance following a sauna induced state of hypo-
hydration, a study by Torranin et al.
25
did find a decrease in
muscle strength-endurance likewise following a sauna induced
hypohydration state.
Given the findings of this review and consideration of
earlier research, research suggests that athletes participating in
exercise of greater than 30 s in duration would benefit from
pre-hydrating to a state of euhydration prior to their event, and
to continually ingest fluids to match those lost during exercise
to maintain a state of euhydration. While coaches often
broadly consider hydration status (potentially more often
during games as opposed to training), they many not fully
appreciate the impact a dehydrated state could have on per-
formance or the potentially life threatening incidence that may
arise from this physiological state. As such, through main-
taining a state of euhydration, the athlete’s level of fatigue may
be decreased, as may their relative VO
2
, heart rate, and rating
of perceived exertion, the consequences of which will see an
increased level of performance.
Urine specific gravity (USG) presents one means moni-
toring an athlete’s level of hydration. Typically a quick and
easy method, USG can be captured though various means
including hydrometry, reagent strips, and refractometry with
refractometry considered the more accurate.
26
USG scores
from these measures can then be compared to ratings tables
(like those provided by Casa et al.
27
) to measure an athlete’s
level of hydration. Apart from USG, there are some other
methods for measuring hydration status including urine
osmolality (laboratory measure) and pre- and post-body
weight mass (field measure). Urine osmolality measures may
be more timely and delayed
28,29
and are considered inter-
changeable with USG measures.
29
In the field, body mass
measures can provide a guide as to fluid loss through sweat
loss. As a general guide, a loss of more than 1%e2% of body
mass indicates that the athlete did not ingest sufficient fluid
during the event.
30
Conversely, if body mass loss was lower
than this amount fluid intake may have been more than was
required for the event or activity.
30
It should be noted, how-
ever, that changes in body weight do not account for athletes
that are dehydrated on their initial their pre activity measure.
As such, the latter statement regarding limited body mass
changes and sufficient hydration may be misleading.
30
When considering the research presented and choice of
hydration measures, the coach should consider the potential
differences in athlete sweat rates. Research does suggest that
sweat rates differ from person to person, through factors like
fitness and percentage of body fat.
30,31
Furthermore, higher
intensity exercise or higher ambient temperature and humidity
may likewise influence sweat rates,
30
as may the nature of the
activity being undertaken.
32
When discussing the real world implications of these
finding both the nature of the PA being conducted (duration
and intensity) and the environments in which it is undertaken
must be considered. In the majority of the studies reviewed the
PA was cycling on either an ergometer or a personal bicycle on
an incline treadmill. Considering this, only three studies had
participants from a trained cyclist population. In one study
2
the researchers used cycling as the outcome measure on a
population trained to play rugby. As such the outcome mea-
sure lacked sport specificity and could not be considered a true
representation of the general population. Furthermore, in all
but one study,
14
the research was completed in a laboratory
setting and hence a controlled environment which may limit
the true impacts of the PA on levels of hydration as they
exclude environmental conditions (like breeze, surface tem-
perature, etc.) which may further influence the hydration of the
athlete.
Three key limitations identified for this review were 1) the
small number of “current”research studies that met the in-
clusion criteria, 2) the differences between protocols for the
studies, and 3) the differences in subjects and their training
histories. With only nine studies meeting the inclusion criteria
for critical review, drawing firm conclusions from their results
6 A. Carlton and R.M. Orr
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Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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was difficult especially given the variability in protocols and
outcome measures. Secondly, the variance in outcome mea-
sures across the studies limited the drawing of dedicated
recommendations. Thirdly, the subjects from each study varied
completing different activities, factors known to influence
sweat rates and hence potential hydration status.
32
5. Conclusion
In conclusion, dehydration appears to have a negative
impact on physical performances that are longer than 30 s in
duration. Even though there is no significant negative impact
on tasks lasting less than 15 s in duration, a state of euhy-
dration is suggested to be maintained during all PA. It is also a
suggestion of this review that further research be conducted
into the impacts of dehydration on physical performance
within the specific task environment while employing perfor-
mance outcome measures that closely mimic the athlete’s key
physical tasks.
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Fluid loss and physical performance 7
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Please cite this article in press as: Carlton A, Orr RM, The effects of fluid loss on physical performance: A critical review, Journal of Sport and Health Science
(2015), http://dx.doi.org/10.1016/j.jshs.2014.09.004
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