Content uploaded by Douglas Casa
Author content
All content in this area was uploaded by Douglas Casa on Jun 14, 2014
Content may be subject to copyright.
Terms and Conditions for Use of PDF
The provision of PDFs for authors' personal use is subject to the following Terms & Conditions:
The PDF provided is protected by copyright. All rights not specifically granted in these Terms & Conditions are expressly
reserved. Printing and storage is for scholarly research and educational and personal use. Any copyright or other notices
or disclaimers must not be removed, obscured or modified. The PDF may not be posted on an open-access website
(including personal and university sites).
The PDF may be used as follows:
• to make copies of the article for your own personal use, including for your own classroom teaching use (this includes
posting on a closed website for exclusive use by course students);
• to make copies and distribute copies (including through e-mail) of the article to research colleagues, for the personal use
by such colleagues (but not commercially or systematically, e.g. via an e-mail list or list serve);
• to present the article at a meeting or conference and to distribute copies of such paper or article to the delegates
attending the meeting;
• to include the article in full or in part in a thesis or dissertation (provided that this is not to be published commercially).
This material is the copyright of the original publisher.
Unauthorised copying and distribution is prohibited.
2007, Vol. 37, No. 10 (pp. 907-921)
ISSN: 0112-1642
Review Article
Hydration and Muscle Performance
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Sports Med 2007; 37 (10): 907-921
R
EVIEW
A
RTICLE
0112-1642/07/0010-0907/$44.95/0
2007 Adis Data Information BV. All rights reserved.
Hydration and Muscular Performance
Does Fluid Balance Affect Strength, Power and
High-Intensity Endurance?
Daniel A. Judelson,
1,2
Carl M. Maresh,
1
Jeffrey M. Anderson,
1
Lawrence E. Armstrong,
1
Douglas J. Casa,
1
William J. Kraemer
1
and Jeff S. Volek
1
1 Human Performance Laboratory, Department of Kinesiology, University of Connecticut,
Storrs, Connecticut, USA
2 Department of Kinesiology, California State University, Fullerton, California, USA
Contents
Abstract .................................................................................... 907
1. Important Influences in Previous Research .................................................. 908
1.1 Exacerbating Factors ................................................................. 908
1.2 Masking Factors ..................................................................... 909
1.3 Other Potential Influences ............................................................ 910
1.4 Ecological Validity and Best Practices for Future Research ............................... 910
2. Effects of Hypohydration on Muscular Performance ......................................... 910
2.1 Strength ............................................................................ 912
2.2 Power .............................................................................. 914
2.3 High-Intensity Endurance ............................................................. 915
2.4 Comparisons and Relevance of Conclusions ........................................... 916
2.5 Important Considerations ............................................................. 917
3. Potential Mechanisms of Hypohydration .................................................... 917
3.1 Cardiovascular Mechanisms .......................................................... 917
3.2 Metabolic Mechanisms ............................................................... 918
3.3 Buffering Mechanisms ................................................................ 918
3.4 Neuromuscular Mechanisms .......................................................... 918
4. Conclusions ............................................................................. 919
Significant scientific evidence documents the deleterious effects of hypohydra-
Abstract
tion (reduced total body water) on endurance exercise performance; however, the
influence of hypohydration on muscular strength, power and high-intensity endur-
ance (maximal activities lasting >30 seconds but <2 minutes) is poorly understood
due to the inconsistent results produced by previous investigations. Several subtle
methodological choices that exacerbate or attenuate the apparent effects of
hypohydration explain much of this variability. After accounting for these factors,
hypohydration appears to consistently attenuate strength (by ≈2%), power (by
≈3%) and high-intensity endurance (by ~10%), suggesting alterations in total
body water affect some aspect of force generation. Unfortunately, the relation-
ships between performance decrement and crucial variables such as mode, degree
and rate of water loss remain unclear due to a lack of suitably uninfluenced data.
The physiological demands of strength, power and high-intensity endurance
couple with a lack of scientific support to argue against previous hypotheses that
suggest alterations in cardiovascular, metabolic and/or buffering function
represent the performance-reducing mechanism of hypohydration. On the other
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
908 Judelson et al.
hand, hypohydration might directly affect some component of the neuromuscular
system, but this possibility awaits thorough evaluation. A critical review of the
available literature suggests hypohydration limits strength, power and high-
intensity endurance and, therefore, is an important factor to consider when
attempting to maximise muscular performance in athletic, military and industrial
settings.
Some active individuals have difficulty in volun- tained through a systematic review of published
tarily maintaining euhydration during exercise and articles from Internet databases (e.g. PubMed) and
often fail to rehydrate properly between exercise reference lists from related original research, book
sessions,
[1-6]
leading to reductions in body water that chapters and review articles. Throughout this article,
affect an array of physiological processes and ulti- hypohydration refers to a state of reduced total body
mately limit exercise capacity. Significant research water, while dehydration refers to the process of
documents the effects of hypohydration on endur- reducing total body water (i.e. dehydration leads to
ance exercise performance,
[7-9]
with less attention hypohydration).
given to the influence of hydration status on muscu-
1. Important Influences in
lar strength (the maximal force a muscle or muscle
Previous Research
group can generate at a specified velocity),
[10]
peak
power (the power generated when a muscle engages
Many high-quality investigations that were not
in a maximal concentric action at the optimal short-
designed to examine isolated hypohydration have
ening velocity),
[10]
or high-intensity endurance
been inappropriately discussed or analysed in the
(maximal activities lasting >30 seconds but <2 min-
context of hypohydration. Generally, these studies
utes). In previous original research investigations,
employed specific research designs, subject popula-
hypohydration inconsistently affects muscle per-
tions and/or testing modalities that preclude a direct
formance; the use of interventions that impair exer-
application to only changes in hydration status.
cise performance independent of water loss (e.g.
Sometimes these influences magnified the effects of
exercise-heat stress) explains some of this inconsis-
hypohydration, which if interpreted only in the con-
tency, as does the failure of some studies to control
text of hydration would overemphasise the effects of
for factors that obscure the association between hy-
hypohydration (‘exacerbating factors’). In other
dration state and performance (e.g. caloric restric-
cases, these influences counteracted or attenuated
tion or training status).
the effects of hypohydration, which if interpreted
Although reviews and position statements dis-
only in the context of hypohydration would underes-
cussing bodyweight loss
[11-23]
and general hy-
timate the effects of hydration on high-intensity
pohydration
[7,24-26]
superficially discuss the effects
performance (‘masking factors’).
of hydration state on anaerobic performance, the
literature currently lacks a comprehensive review
1.1 Exacerbating Factors
describing the effects of hypohydration on strength,
power and high-intensity endurance. Therefore, the Because athletes who participate in weight-con-
purpose of this article is to objectively analyse the trol sports (e.g. wrestling and boxing) regularly alter
scientific literature examining the effects of hydra- their body mass, many studies examining the effects
tion state on muscular performance to determine if, of acute mass loss on performance used these ath-
and how, hypohydration affects muscular strength, letes as subjects. In the days or hours preceding a
power and high-intensity endurance. A major aim is competition, many weight-control athletes signifi-
to compare and contrast studies to better understand cantly reduce their body mass, typically by decreas-
how different methodological factors contribute to ing total body water and limiting caloric intake.
the relationship between hypohydration and per- Because not every study examining wrestlers or
formance. Scientific literature on this topic was ob- boxers was designed to evaluate hydration state,
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 909
weight-loss techniques were frequently uncontrolled tween lean body mass (and hence, reservoir of total
and undocumented. Although dehydration frequent- body water) and strength reductions following 1.7%
ly accounted for some mass loss in this research, the hypohydration. It appears that any condition (nutri-
effects of hypohydration are not easily separated tional or physiological) that increases total body
from the potential performance-reducing effects of water, including endurance training, helps counter-
caloric restriction.
[27-29]
Unfortunately, some authors act the effects of hypohydration because the body’s
failed to recognise the physiological divergence sep- greater fluid reservoir minimises the percentage of
arating weight loss from hypohydration and, there- fluid lost for any given decrease of total body water.
fore, inappropriately analysed and discussed acute Results of studies examining isolated hypohydration
weight loss solely in the context of hypohydration. on endurance-trained athletes
[41-43]
have rarely
demonstrated physiologically or statistically signifi-
Independent of hydration, increasing muscle and/
cant hypohydration-induced reductions of maximal
or core temperature above specific thresholds
muscular performance (see sections 2.1 and 2.2),
reduces muscle function, limits work capacity and
further supporting the conclusions of Caterisano
promotes fatigue.
[30-32]
Methodologically, studies
et al.
[39]
employing dehydration techniques that increased
muscle temperature (via exercise and/or heat expo-
Very little research examines the effect of hydra-
sure), but tested subjects before they adequately
tion on strength, power or high-intensity endurance
cooled, cannot isolate the effects of hypohydration
in women.
[33,44-46]
None of these studies, however,
from the performance-reducing effects of increased
controlled for subjects’ menstrual status. Although
core temperature. Similarly, many studies employed
menstrual status appears to exert little influence on
dehydration techniques causing muscular fatigue
strength or anaerobic exercise performance,
[47]
the
(primarily exercise); investigations that tested sub-
alterations in concentration and activity of the fluid
jects without allowing full recovery cannot separate
regulatory hormones across the reproductive cycle
the effects of hypohydration from the performance-
promote water retention during the luteal
reducing effects of muscle fatigue. Clearly, the spe-
phase.
[48,49]
This increased fluid reserve, as suggest-
cific methodology employed to dehydrate subjects
ed in the previous paragraph, likely provides a
in hydration studies is vital. If dehydration was
greater fluid reserve to defend against hypohydra-
coupled with caloric restriction and/or subjects were
tion-induced alterations of total body water. Al-
unable to completely recover from the stress of the
though no scientific investigations confirm this hy-
dehydration, the isolated effect of hydration cannot
pothesis, the physiological basis for this argument
be evaluated.
[14,15,30,33-37]
and parallel findings in endurance athletes suggest
results obtained from women without controlling for
1.2 Masking Factors
menstrual status must be cautiously interpreted.
Several authors have hypothesised that training Finally, several studies examining muscular
state significantly alters the effects of hydration on strength,
[50]
power
[44,51-56]
and high-intensity endur-
muscular performance,
[16,33,38]
and at least one study ance
[51,53-59]
employed measurements in which only
scientifically confirmed this conjecture. Caterisano the subject’s body mass resisted the testing move-
et al.
[39]
clearly demonstrated that 3% hypohydration ment (e.g. vertical jumping or short-distance sprint-
reduced isokinetic quadriceps muscular endurance ing). The decreased body mass characteristic of
(ability to maintain ≥50% maximal peak torque) in hypohydration might offset reduced muscular
power athletes and sedentary controls, but failed to strength and/or power, however, complicating the
affect performance in endurance athletes. They pro- interpretation of these studies.
[37,44]
For example, if
posed that the haemodynamic adaptations resulting hypohydration fails to reduce muscle force or pow-
from endurance training (primarily increased plas- er, vertical jump height will increase as total body
ma volume) provided an extra reserve of water to water decreases because the jumper must move less
offset the fluid shifts caused by dehydration. Schoff- body mass. Body mass based tests require less force
stall et al.
[40]
corroborated this hypothesis when they as hypohydration progresses; this reduction of phys-
discovered a significant inverse relationship be- iological demand promotes improved performance
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
910 Judelson et al.
and obscures the effects of hypohydration on muscle function, future research must recognise the follow-
function. ing three vital components of appropriate research
design: (i) dehydration technique; (ii) subject popu-
1.3 Other Potential Influences
lation; and (iii) performance measures. Scientists
can completely avoid the dehydration methods de-
In addition to the primary exacerbating (caloric
scribed in section 1.1 by using diuretics to reduce
restriction, increased muscle temperature and fa-
total body water (understanding the unique physio-
tigue) and masking (endurance training, menstrual
logical stresses of diuretic-induced hypohydra-
status and test type) factors, the subjects’ history of
tion
[64]
); however, exercise and heat exposure are
exercising while hypohydrated has also received
useful methods to dehydrate subjects. In using these
attention as a potential confounding variable. Sever-
latter techniques, future investigations must consid-
al authors hypothesised that subjects accustomed to
er the time duration between a physiologically
hypohydration (typically wrestlers) demonstrate in-
stressful dehydration protocol and the outcome per-
significant performance alterations due to their fa-
formance measure(s). Sufficient time must separate
miliarity with the characteristic physiological stress-
dehydration from performance to allow core tem-
es.
[16,60]
Subjects’ history of hypohydration is not
perature to stabilise and fatigue to dissipate. Our
considered an important influence in the present
laboratory typically dehydrates subjects via low-
review because (i) no scientific literature documents
intensity exercise in the heat the evening prior to a
a physiological adaptation to hypohydration; (ii) this
morning data collection;
[65-67]
the overnight rest pe-
effect, if present, would largely result from psycho-
riod drastically reduces the effects of the dehydra-
logical rather than physiological mechanisms; and
tion procedures on subsequent outcome measures.
(iii) research examining isolated hypohydration
To account for possible influences of subject
published after the presentation of this hypothesis
selection, future studies should attempt to maximise
(in the early 1980s) demonstrated significantly re-
the homogeneity of their subjects’ endurance train-
duced muscular performance in individuals with a
ing background. Hypohydration can (and should) be
history of rapid body mass loss.
[40,61]
studied in female populations, but authors must ac-
knowledge the potential influence of the menstrual
1.4 Ecological Validity and Best Practices for
cycle on fluid balance. While data collection might
Future Research
properly occur during any phase of the menstrual
cycle, (i) all subjects should be tested during a
Understanding the isolated effects of hypohydra-
common phase; and (ii) all data collection for re-
tion on strength, power and high-intensity endur-
peated measures studies (the most appropriate to
ance is important from a basic science perspective,
eliminate the effects of the dehydration protocol)
but this topic also merits attention due to high eco-
must occur during the same menstrual phase. In
logical validity. While some populations experience
terms of outcome measures, subjects must perform
the stress of hypohydration combined with another
against consistent workloads in all trials. This re-
factor (e.g. fatigue, caloric restriction or increased
quirement eliminates tests that rely primarily on the
core temperature), multiple groups regularly experi-
subject moving his or her body mass (e.g. vertical
ence only hypohydration. Training athletes who fail
jump or short distance sprinting) and mandates that
to adequately rehydrate during or immediately after
performance workloads are based upon euhydrated
an initial exercise bout
[1-6]
might initiate subsequent
subject characteristics (e.g. euhydrated one repeti-
exercise bouts in a hypohydrated state, but the hours
tion maximum or percentage of euhydrated body
between exercise limit the stress of increased core
mass).
temperature or fatigue. Other groups that require
peak muscle function for health and safety, such as
2. Effects of Hypohydration on
astronauts and the elderly, also frequently experi-
Muscular Performance
ence hypohydration.
[62,63]
Given the importance of determining the effect of Tables I–III comprehensively summarise the re-
isolated hypohydration on high-intensity muscle sults from studies that cannot be evaluated solely in
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 911
Table I. Effects of hypohydration on muscular strength
Study Dehydration Results
a
Primary factor
b
Studies with masking factors
Bosco et al.
[50]
–
2.5% via WD 5.3% ↓ strength to mass ratio BMB
Evetovich et al.
[33]
–
2.9% via WD 3.4% ↓ isometric forearm flexion strength UMS
2.1% ↓ isokinetic forearm flexion strength UMS
Saltin
[41]
–
3.8% via E-H 0.5% ↑ R knee extension strength ETS
2.9% ↑ L knee extension strength ETS
2.7% ↑ R elbow flexion strength ETS
0.7% ↓ L elbow flexion strength ETS
–
3.8% via S 0.2% ↑ R knee extension strength ETS
0.4% ↓ L knee extension strength ETS
2.3% ↑ R elbow flexion strength ETS
2.8% ↑ L elbow flexion strength ETS
Montain et al.
[45]
–
4.0% via E-H 4.4% ↑ knee extension strength UMS
Studies with exacerbating factors
Guti
´
errez et al.
[44]
–
1.8% via E 4.0% ↓ in handgrip strength Temperature
0.9% ↓ in row strength Temperature
Bijlani and Sharma
[68]
–
3.0% via E-H 0.0% ∆ elbow extensor strength Temperature
Viitasalo et al.
[52]
–
3.4% via S 7.8% ↓ knee extension strength* Temperature
Guastella et al.
[72]
–
4.2% via C 2.2% ↓ grip strength CR
Houston et al.
[57]
≈
–
4.5% via C 11.3% ↓ knee extension strength at 30°/sec* CR
11.5% ↓ knee extension strength at 180°/sec* CR
10.5% ↓ knee extension strength at 300°/sec* CR
Moore et al.
[69]
–
4.8% via E-S 8.9% ↓ knee extension strength at 180°/sec* Temperature
Webster et al.
[35]
–
4.9% via C 6.9% ↓ R knee extension strength – fast CR
10.2% ↑ R knee extension strength – slow CR
7.4% ↑ R knee flexion strength – fast CR
11.4% ↑ R knee flexion strength – slow CR
5.5% ↑ L knee extension strength – fast CR
2.7% ↑ L knee extension strength – slow CR
0.7% ↓ L knee flexion strength – fast CR
6.9% ↑ L knee flexion strength – slow CR
3.6% ↓ chest press strength – fast CR
6.6% ↓ chest press strength – slow* CR
5.2% ↓ chest row strength – fast CR
4.5% ↓ chest row strength – slow CR
6.6% ↓ shoulder push strength – fast CR
8.1% ↓ shoulder push strength – slow CR
8.9% ↓ shoulder pull strength – fast CR
4.5% ↓ shoulder pull strength – slow* CR
Viitasalo et al.
[52]
–
5.8% via C 7.7% ↓ knee extension strength* CR
Kraemer et al.
[73]
≈
–
6% via C 7.0% ↑ hip/back strength CR
11.4% ↓ grip strength* CR
1.1% ↑ bear hug strength CR
2.4% ↓ knee extension strength at 0°/sec CR
9.9% ↓ knee extension strength at 60°/sec CR
15.2% ↓ knee extension strength at 300°/sec* CR
Continued next page
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
912 Judelson et al.
Table I. Contd
Study Dehydration Results
a
Primary factor
b
6.3% ↓ knee flexion strength at 60°/sec CR
11.1% ↓ knee flexion strength at 300°/sec* CR
2.8% ↓ elbow flexion strength at 0°/sec CR
2.5% ↓ elbow flexion strength at 60°/sec CR
4.9% ↓ elbow flexion strength at 300°/sec CR
8.3% ↓ elbow extension strength at 60°/sec CR
4.5% ↓ elbow extension strength at 300°/sec CR
Studies difficult to interpret
Ahlman and Karvonen
[70]
Learning effect
Bell et al.
[74]
UWL
Ftaiti et al.
[75]
Temperature, fatigue, ETS
Greenleaf et al.
[38]
No euhydrated baseline
Greenleaf et al.
[46]
Temperature, fatigue, UMS
Guti
´
errez et al.
[44]
Temperature, UMS
¨
O
¨
opik et al.
[76]
UWL
Serfass et al.
[60]
UWL
Singer and Weiss
[77]
UWL
Tuttle
[78]
UWL, caloric restriction
Vallier et al.
[79]
No euhydrated baseline, ETS
Wenos and Amato
[59]
UWL
a Data are shown as percentage change from baseline. Results obtained from references
[33,35,38,41,44-46,50,52,57,59,60,68-70,72-79]
and findings
obtained from references
[38,50,57]
estimated from figures.
b Primary factor refers to the variable preventing an isolated analysis of the effects of hypohydration on muscular performance.
BMB = body mass based test; C = combination dehydration techniques; CR = caloric restriction; E = exercise; ETS = endurance-trained
subjects; H = heat exposure (36–41°C); L = left; R = right; S = sauna exposure (70–85°C); UMS = uncontrolled menstrual status; UWL =
uncontrolled weight loss; WD = water deprivation. ↑ indicates improvement; ↓ indicates decrement; ∆ indicates change; * p < 0.05.
the context of hypohydration, presenting investiga- take
[55,58,60,68-71]
or uncontrolled carbohydrate in-
take
[44]
during the rehydration.
tions that examined the effect of hypohydration on
Figures 1–3 display the results of the 11 pub-
muscular strength (table I), power (table II) and
lished, peer-reviewed studies
[34,36,37,39,40,50,52,61,81-83]
high-intensity endurance (table III), respectively.
that accurately assessed only the effects of hy-
Each table is divided into the following three sec-
pohydration on muscular strength (figure 1), power
tions: (i) research with masking factors (i.e. attenu-
(figure 2) and high-intensity endurance (figure 3).
ating hypohydration effects); (ii) research with ex-
Similar to tables I–III, these figures contain infor-
acerbating factors (i.e. magnifying hypohydration
mation relating only to initial dehydration and ig-
effects); and (iii) research that cannot be interpreted
nore subsequent rehydration.
[40,83]
To examine pos-
based on acknowledged limitations of research de-
sible muscle specificity, figures 1–3 present findings
sign (e.g. learning effect), lack of description or
from lower, upper and total body musculature sepa-
rately; whenever possible, results from similar mus-
control of the hypohydration techniques, and/or
cle groups/actions are juxtaposed for clarity.
combinations of masking and exacerbating factors.
Single publications appear in multiple sections and
2.1 Strength
on different tables if the methodology included sev-
eral different dehydration techniques, subject popu-
Table I and figure 1 present the effects of hy-
lations or exercise tasks. In those studies examining
pohydration on muscular strength (the maximal
the effects of dehydration and subsequent rehydra-
force a muscle or muscle group can generate at a
tion, only the initial dehydration was evaluated to
specified velocity).
[10]
Protocols used to evaluate
eliminate effects of ad libitum food and fluid in- strength typically measured single maximal effort
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 913
Table II. Effects of hypohydration on muscular power
Study Dehydration Results
a
Primary factor
b
Studies with masking factors
Hoffman et al.
[53]
–
1.1% via E 3.4% ↑ squat jump height BMB
3.0% ↑ countermovement jump height BMB
–
1.8% via E 0.0% ∆ squat jump height BMB
3.0% ↑ countermovement jump height BMB
Guti
´
errez et al.
[44]
–
1.8% via H 4.7% ↓ squat jump height BMB
3.8% ↓ countermovement jump height BMB
Walsh et al.
[42]
–
1.8% via E-H 0.1% ↓ cycling power ETS
Watson et al.
[51]
–
2.2% via D 0.1% ↑ 50m sprint BMB
1.0% ↑ 200m sprint BMB
–
2.5% via D 1.5% ↑ jump height BMB
Viitasalo et al.
[52]
–
2.5% via D 2.2% ↑ jumping power BMB
7.1% ↑ jump height* BMB
7.9% ↑ weighted (+20kg) jump height* BMB
8.9% ↑ weighted (+40kg) jump height* BMB
3.9% ↑ weighted (+60kg) jump height BMB
1.3% ↑ weighted (+80kg) jump height BMB
Fritzsche et al.
[43]
–
4.2% via E-H 4.7% ↓ cycling power ETS
Studies with exacerbating factors
Jacobs
[56]
–
2.0% via H 2.2% ↓ Wingate peak power Temperature
King et al.
[80]
–
3.0% via E-H 2.5% ↓ cycling peak power Temperature, fatigue
Viitasalo et al.
[52]
–
3.4% via S 16.1% ↓ knee extension rate of force development* Temperature
Jacobs
[56]
–
4.1% via H 2.1% ↓ Wingate peak power Temperature
Guastella et al.
[72]
–
4.2% via C 0.6% ↓ Wingate peak power CR
Webster et al.
[35]
–
4.9% via C 21.5% ↓ cycling power CR
Jacobs
[56]
–
5.0% via H 2.3% ↓ Wingate peak power Temperature
Viitasalo et al.
[52]
–
5.8% via C 19.0% ↓ knee extension rate of force development* CR
Kraemer et al.
[73]
~
–
6.0% via C 3.2% ↓ jumping power CR
Studies difficult to interpret
Bell et al.
[74]
UWL
Doscher
[54]
CR, BMB
Fogelholm et al.
[55]
CR, BMB
Guti
´
errez et al.
[44]
Temperature, BMB, UMS
Jacobs
[56]
Temperature, BMB
King et al.
[80]
Temperature, fatigue, ETS
¨
O
¨
opik et al.
[76]
UWL
Vallier et al.
[79]
No euhydrated baseline, ETS
Viitasalo et al.
[52]
CR or temperature, BMB
a Data are shown as percentage change from baseline. Results obtained from references
[35,42-44,51-56,72-74,76,79,80]
and findings obtained
from references
[43,53]
estimated from figures.
b Primary factor refers to the variable preventing an isolated analysis of the effects of hypohydration on muscular performance.
BMB = body mass based test; C = combination dehydration techniques; CR = caloric restriction; D = diuretic; E = exercise; ETS =
endurance-trained subjects; H = heat exposure (30–56°C); S = sauna exposure (70–85°C); UMS = uncontrolled menstrual status; UWL =
uncontrolled weight loss; ↑ indicates improvement; ↓ indicates decrement; ∆ indicates change; * p < 0.05.
isometric, isotonic and/or isokinetic force produc- and lower body (e.g. hip flexion, knee extension and
knee flexion).
tion of the upper body (e.g. back extension, bear
hug, bench press, row, elbow extension, elbow flex-
Numerical analysis supports the division of stud-
ion, forearm flexion, grip strength, shoulder abduc-
ies by external influence: the average loss of
tion, shoulder adduction and shoulder extension) strength was 2.3%, 0.3% and 3.8% for investiga-
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
914 Judelson et al.
Table III. Effects of hypohydration on muscular endurance (activities >30 seconds and <2 minutes)
Study Dehydration Results
a
Primary factor
b
Studies with masking factors
Hoffman et al.
[53]
–
1.1% via E 16.5% ↓ jumping power during 30 sec test BMB
7.2% ↓ jumps in 30 sec BMB
4.8% ↓ average jump height during 30 sec test BMB
–
1.8% via E 15.2% ↓ jumping power during 30 sec test BMB
10.5% ↓ jumps in 30 sec BMB
0.0% ∆ average jump height during 30 sec test BMB
Watson et al.
[51]
–
2.5% via D 0.6% ↓ 400m sprint BMB
Caterisano et al.
[39]
–
3.0% via H 1.2% ↑ knee extension endurance ETS
Studies with exacerbating factors
Jacobs
[56]
–
2.0% via H 0.8% ↑ average power during 30 sec Wingate Temperature
Fogelholm et al.
[55]
–
2.7% via C 3.4% ↑ average power during 1 min Wingate 1 (of 2) CR
0.3% ↑ average power during 1 min Wingate 2 (of 2) CR
Bijlani and Sharma
[68]
–
3.0% via E-H 31.8% ↓ elbow extensor endurance* Temperature
King et al.
[80]
–
3.0% via E-H 10.2% ↓ cycling work in 45 sec* Temperature, fatigue
8.5% ↓ cycling power at end of 45 sec Temperature, fatigue
3.2% ↓ cycling fatigue index Temperature, fatigue
Jacobs
[56]
–
4.1% via H 1.3% ↓ average power during 30 sec Wingate Temperature
Guastella et al.
[72]
–
4.2% via C 0.7% ↓ average power during 30 sec Wingate CR
Webster et al.
[35]
–
4.9% via C 9.7% ↓ cycling work in 40 sec* CR
Jacobs
[56]
–
5.0% via H 0.5% ↓ average power during 30 sec Wingate Temperature
Studies difficult to interpret
Bell et al.
[74]
UWL
Doscher
[54]
CR, BMB
Houston et al.
[57]
CR, BMB
Jacobs
[56]
Temperature, BMB
King et al.
[80]
Temperature, fatigue, ETS
Klinzing and Karpowicz
[58]
CR, BMB
Mnatzakanian and Undefined weight loss
Vaccaro
[71]
Wenos and Amato
[59]
UWL, BMB
a Data are shown as percentage change from baseline. Results obtained from references
[35,39,51,53-59,68,71,72,74,80]
and findings obtained
from references
[53,57]
estimated from figures.
b Primary factor refers to the variable preventing an isolated analysis of the effects of hypohydration on muscular performance.
BMB = body mass based test; C = combination dehydration techniques; CR = caloric restriction; E = exercise; ETS = endurance-trained
subjects; D = diuretic; H = heat exposure (40–58°C); UWL = uncontrolled weight loss; ↑ indicates improvement; ↓ indicates decrement; ∆
indicates change; * p < 0.05.
tions with no factors (i.e. those assessing only isolat- vergent results sometimes occur for the same muscle
(e.g. knee extension and elbow flexion). Although
ed hypohydration), masking factors and exacerbat-
some variability exists, more than two-thirds of un-
ing factors, respectively. Only 15 of the 70 total
influenced results show negative effects, suggesting
findings (21%) showed statistically significant per-
that 3–4% hypohydration reduces muscular strength
formance reductions. Given the relatively small ef-
by approximately 2%.
fect of hypohydration, the rarity of statistical signifi-
cance is not surprising considering the small sample
2.2 Power
sizes (mean sample size of uninfluenced studies =
ten) and sometimes insufficiently sensitive testing
Table II and figure 2 present the effects of hy-
modalities.
[84]
No specific muscle group or action
pohydration on muscular power (the power generat-
appears more susceptible to hypohydration, as di- ed when a muscle engages in a maximal concentric
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 915
Muscular strength (%)
–15
–10
–5
0
5
10
15
a b c d e f g h
Lower body
s
Total
body
i j k l m n o p q r
Upper body
*
*
*
Lower body
a–g: Knee extension
h: Leg extension
Upper body
i: Bench press
j–m: Elbow flexion
n–o: Handgrip
p–q: Shoulder extension
r: Trunk extension
s: Composite score
Fig. 1. Non-confounded effects of hypohydration on muscular strength. Data are presented as mean percentage change from baseline.
Results from: Bosco et al.
[50]
(a, h, j, n, o, r and s) [estimated from figures]; Greiwe et al.
[34]
(b and k); Viitasalo et al.
[52]
(c); Bosco et al.
[81]
(d,
e, l, m, p and q); Bigard et al.
[82]
(f and g); and Schoffstall et al.
[40]
(i). * p < 0.05.
action at the optimal shortening velocity).
[10]
Appro- centage increase in performance failed to match the
percentage decrease in body mass. Except for two
priate protocols used to evaluate peak power typical-
investigations examining short-distance sprint-
ly measured performance during maximal intensity
ing,
[51,55]
all of these studies examined power via
cycling and maximal knee extension (rate of force
lower body exercise (e.g. jumping or cycling), elim-
development). Numerical analysis again supports
inating an analysis of muscle specificity. Figure 2
the division of studies based on the type of external
displays some variability (more in magnitude than
influence: the average change in power was
–
3.2%,
direction) and uninfluenced findings require replica-
+1.8% and
–
7.7% for investigations with no factors,
tion in future studies, but the current literature sug-
masking factors and exacerbating factors, respec-
gests that 3–4% hypohydration reduces muscular
tively. Nine of the 47 total findings (19%) showed
power by approximately 3%.
statistically significant performance reductions. Un-
fortunately, the 21 results shown in figure 2 come
2.3 High-Intensity Endurance
from only four investigations, one of which was
published only in abstract form
[61]
(complete details
Table III and figure 3 present the effects of
of this research were obtained from the author of the
hypohydration on high-intensity muscular endur-
abstract: Smith SA, 2006, personal communication).
ance. Appropriate protocols used to evaluate high-
Studies with masking factors that used body mass
intensity endurance typically measured total work
based tests further corroborate the power-reducing
(number of repetitions) or average power main-
effect of hypohydration: in 8 of 15 cases, the per- tained during 30–120 seconds of repeated activities
a b c d e f g h i j k l m n o p q r s t u
Muscular power (%)
0
5
–20
–15
–10
–5
10
15
20
Lower body
*
*
*
*
*
*
*
Lower body
a–h: 10–15s Wingate Test
peak power
i–t: 10–15s Wingate Test
average power
u: Knee extension rate of
force development
Fig. 2. Non-confounded effects of hypohydration on muscular power. Data are presented as mean percentage change from baseline.
Results from: Smith et al.
[61]
(a–e, i–m); Cheuvront et al.
[37]
(f–h, n–p); Yoshida et al.
[36]
(q–t) [estimated from figures]; and Viitasalo et al.
[52]
(u). * p < 0.05.
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
916 Judelson et al.
a b c d e f g h
Muscular endurance (%)
–40
–30
–20
–10
0
10
20
30
40
Lower
body
Total
body
Upper
body
*
*
*
*
Lower body
a–d: Knee extension
Upper body
e: Elbow flexion
f: Sit-ups
Total body
g: Total body isometric
h: Total body isotonic
Fig. 3. Non-confounded effects of hypohydration on high-intensity muscular endurance (activities lasting >30 seconds but <120 seconds).
Data are presented as mean percentage change from baseline. Results from: Caterisano et al.
[39]
(a and b); Greiwe et al.
[34]
(c and e);
Bigard et al.
[82]
(d); Bosco et al.
[81]
(f); and Torranin et al.
[83]
(g and h). * p < 0.05.
(bench presses, rows, chin-ups, elbow extensions, 2.4 Comparisons and Relevance
of Conclusions
elbow flexions, knee extensions, knee flexions,
shoulder abductions, shoulder adductions and/or sit-
The previous conclusions suggest that hy-
ups); high-intensity cycling tasks were also evalu-
pohydration attenuates the performance of high-
ated. Division of studies based on external influence
intensity endurance to a much greater degree than
is less numerically convincing for this variable: the
strength and power exercises. The (i) detrimental
average loss of endurance was 15.0%, 6.7% and
effects of body water loss on traditional endurance
5.6% for studies with no factors, masking factors
exercises; and (ii) direct relationship between the
and exacerbating factors, respectively. Statistically
magnitude of hypohydration-induced performance
significant reductions in performance occurred in 7
decrement and exercise duration
[7,9]
support this hy-
of the 27 results (26%). The smaller total pool of
pothesis. A 10% reduction in high-intensity endur-
results (only 27 compared with 70 for strength and
ance performance produces clear decrements in ex-
47 for power) and/or the physiological differences
ercise outcome. The relative importance of 2–3%
separating high-intensity muscular endurance from
reductions in strength and peak power, however, is
less clear. These effects are unlikely to affect the
strength and power (as endurance relies more heavi-
casual resistance exerciser attempting to maintain
ly on cardiovascular function and muscle metabo-
health and reduce risk of disease, but small reduc-
lism; see sections 3.1 and 3.2) might explain the
tions in exercise performance significantly affect the
altered quantitative relationship among influences.
outcome of athletic competitions when vanishingly
Regardless, the consistent, statistically significant
small differences separate winning from losing.
[84]
reductions noted in the uninfluenced studies suggest
For example, results from the 1996, 2000 and 2004
that hypohydration detrimentally affects high-inten-
Olympic Games indicate the gold medalist in the
sity muscular endurance; visual evidence supports a
100m dash defeated the eighth place finisher by an
greater effect in the lower body than the upper body;
average of only 3%. Decrements in peak strength
however, the small number of results supporting this
and power also affect non-elite athletic events, mili-
hypothesis makes this conclusion tentative. Little
tary operations and civil servant activities (e.g. po-
variability exists in figure 3, suggesting that 3–4%
lice and fire personnel) when participants strive to
hypohydration reduces high-intensity muscular en-
maximise performance for personal satisfaction,
durance by approximately 10%. personal or public safety, and overall well-being.
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 917
Table IV. Methodological details of the non-confounded studies examining muscular strength, power and high-intensity endurance
Study Dehydration method Degree of hypohydration (%) Variable(s) assessed
Bigard et al.
[82]
Sauna
–
3.0 Isometric strength, endurance
Bosco et al.
[81]
Water deprivation
–
5.7 Isometric strength, endurance
Bosco et al.
[50]
Water deprivation
–
2.5 and
–
3.1 Isometric strength
Caterisano et al.
[39]
Heat
–
3.0 Endurance
Cheuvront et al.
[37]
Heat
–
2.7 Power
Greiwe et al.
[34]
Sauna
–
3.8 Isometric strength, endurance
Schoffstall et al.
[40]
Sauna
–
1.7 Isotonic strength
Smith et al.
[61]
Combination
–
4.5 Power
Torranin et al.
[83]
Sauna
–
3.9 and
–
4.0 Endurance
Viitasalo et al.
[52]
Diuretic
–
2.5 Isometric strength, power
Yoshida et al.
[36]
Exercise
–
0.7,
–
1.7,
–
2.5 and
–
3.9 Power
2.5 Important Considerations masking or exacerbating factor and four
[38,43,53,79]
accurately documented hydration status. Realistical-
ly, the limited data available from studies that accu-
The previous analysis omits three obviously rele-
rately documented the effects of only hypohydration
vant variables. Mode of dehydration,
[14-16,25,33,52,64]
(strength,
[34,40,50,52,81,82]
power,
[36,37,52,61]
endur-
degree of hypohydration
[16,25,38]
and rate of water
ance
[34,39,81-83]
) fail to provide a suitable number of
loss
[16,38,85]
likely alter the physiological response to
data points to accurately or reliably evaluate the
hypohydration. Despite their importance, several
relationship between degree of hypohydration and
reasons justify the intentional exclusion. Given the
change of muscle function. Evidence from an endur-
small number of uninfluenced results upon which
ance model clearly suggests that the technique used
the previous conclusions are largely based, compar-
to dehydrate subjects affects subsequent perform-
ing the effects of different dehydration methods and
ance outcomes and fluid biocompartmentation.
[64]
degrees of hypohydration becomes difficult (this
Presumably, mode of dehydration interacts with de-
information is provided for the uninfluenced studies
gree of hypohydration to determine the overall mag-
in table IV). A surprising lack of scientific evidence
nitude of performance decrement.
documenting hydration status further complicates
this assessment. Of the studies evaluated in this
3. Potential Mechanisms
review, approximately half verified hydration status
of Hypohydration
(pre- or post-dehydration) with any physiological
measurement other than body mass (e.g. urine spe-
How might hypohydration negatively influence
cific gravity or plasma osmolality). This verification
strength, power and high-intensity endurance? Un-
is vital, especially to ensure hydration indices indi-
fortunately, the inconsistent results described in sec-
cate that subjects’ baseline body masses represent a
tions 2.1–2.3 have precluded an extensive analysis
euhydrated state. Without the physiological verifi-
of the hypohydration mechanism. Instead, our cur-
cation that baseline body mass truly represents
rent state of knowledge results from a basic under-
euhydration, the degree of hypohydration post-de-
standing of exercise physiology and information
hydration cannot be quantified nor can the relation-
gleaned from studies examining hypohydration and
ship between the magnitude of hypohydration and
endurance performance.
decrement in muscle function be assessed.
Research examining the same subjects complet-
3.1 Cardiovascular Mechanisms
ing the same exercise bouts at multiple hypohydrat-
ed states most effectively analyses the effect of During endurance exercise, especially in a hot
degree of hypohydration; unfortunately, very few of environment, many of the deleterious effects of hy-
these studies exist. Nine published stud- pohydration result from altered cardiovascular func-
ies
[36,38,43,50,53,56,77,79,80]
examined multiple degrees of tion. Hypohydration reduces total plasma volume,
hypohydration, but only two
[36,50]
lack a major increasing submaximal heart rates and decreasing
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
918 Judelson et al.
maximal cardiac output.
[86,87]
Further, changes of lactate with hypohydration, the vast majority
muscle blood flow due to water loss can decrease demonstrate that hypohydration either failed to
nutrient delivery, decrease metabolite removal and change
[43,51,56,72,76,82,93]
or decreased
[41,64,69,80]
post-
alter cellular metabolism.
[88,89]
The degree to which exercise lactate. In many cases, the reduced blood
these cardiovascular alterations affect strength and lactate was hypothesised to result from decreased
power, however, is unclear. Brief strength and pow- work rate or work time,
[30,96]
rather than a physiolog-
er production occurs essentially independent of the ical effect of hypohydration on lactate production,
cardiovascular system because these exercises do efflux, or uptake.
[93]
On the other hand, decreased
not require peak cardiac output and largely rely lactate production might occur secondary to dehy-
upon stored intramuscular adenosine triphosphate dration-induced reductions of glycogen stores, not
(ATP) and creatine phosphate (CP) for energy. Al- because hypohydration fundamentally affects carbo-
though little research examining hypohydration and hydrate metabolism.
[13,14,76,97,98]
This final possibili-
muscular performance documents these variables, ty explains many findings, as all data demonstrating
the physiology of maximal performance suggests reduced post-exercise lactate resulted from subjects
that decreased cardiovascular function cannot ac- who either restricted caloric intake or increased their
count for reduced strength and power.
[13,14,45]
The core temperature (each of which promotes glycogen
importance of cardiovascular changes might in- depletion) during dehydration. Additionally, the de-
crease, however, during high-intensity endurance hydration protocols frequently stress subjects, stim-
performance.
[14,83]
Because repetitive exercises, no ulating the sympathetic nervous system. This ‘fight
matter how brief, require adequate delivery of oxy- or flight’ response promotes glycogenolysis;
[99]
pro-
gen to and removal of metabolic by-products from longed dehydration procedures might lead to glyco-
the active musculature, reductions of muscle blood gen depletion and subsequently reduced lactate pro-
flow might assume greater importance in dictating duction during performance testing.
[36]
Thus, the
performance reductions.
[13,36,43,83]
collective evidence suggests that isolated hy-
pohydration does not directly alter lactate kinetics or
3.2 Metabolic Mechanisms
carbohydrate metabolism. Further research is re-
quired to ascertain the effects of hypohydration on
Similar to cardiovascular mechanisms, the physi-
lipid and protein metabolism during exercise, but
ology of maximal performance suggests only a lim-
these factors appear unlikely to cause decrements in
ited role for muscle metabolism in reducing muscle
high-intensity muscular performance.
function, especially for strength and power.
[25]
Closer inspection of basic physiology, however,
3.3 Buffering Mechanisms
shows that hydration-induced changes in cell vol-
ume strongly influence cellular metabolism,
[90-92]
A third hypothesis proposes that hydration state
suggesting that hypohydration might fundamentally
affects the acid-base balance of the body. Optimal
disturb metabolism to affect even the briefest exer-
cellular functioning requires maintenance of appro-
cises.
[80,83]
Although altered lipid metabolism has
priate internal pH, causing several researchers to
been suggested as a possible mechanism explaining
suggest that hydration influences performance by
the effect of hypohydration on maximal muscle ac-
reducing buffer capacity.
[13,14,97]
Actual evidence ex-
tivity,
[93-95]
the majority of scientific attention and
amining muscle and blood, however, demonstrated
evidence examines potential changes of carbohy-
no hypohydration-induced changes of internal
drate metabolism.
pH
[69,80]
and bicarbonate
[82]
after exercise; therefore,
Experimental evidence, albeit limited, refutes the
acid-base balance is unlikely to represent the mecha-
possibility that hypohydration fundamentally
nism for hypohydration.
changes intramuscular stores of ATP and CP
[13,15,45]
or circulating concentrations of blood glucose.
[76,81]
3.4 Neuromuscular Mechanisms
Greater controversy exists over the effect of hy-
pohydration on post-exercise circulating lactate con- The three previous mechanisms (cardiovascular,
centrations; although one study
[51]
showed increased metabolic and buffering) appear insufficient to ex-
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 919
plain the effects of hydration on strength, power and Acknowledgements
high-intensity endurance, leaving a fourth possibili-
No funding sources were used in the preparation of this
ty, as stated by Coyle and Hamilton:
[24]
manuscript. Douglas J. Casa serves on the Board of Advisors,
has received grant funding and honoraria from Gatorade and
“It is unlikely that moderate reductions in muscle
has received honoraria from Camelbak, Inc. The authors wish
water alter force generation capability or energy
to thank Dr Sinclair A. Smith for his exceptional helpfulness
production when maximally stimulated. It is more
and Dr Barry A. Spiering for editorial contributions.
likely that the infrequently reported reductions in
strength following hypohydration are due to a di-
References
minished ability of the central nervous system to
1. Boudou P, Fiet J, Laureaux C, et al. Changes in several plasma
recruit motor units”.
and urinary components in marathon runners. Ann Biol Clin
1987; 45: 37-45
Many others similarly claimed that the loss of
2. Greenleaf JE, Sargent F. Voluntary dehydration in man. J Appl
total body water affects some component of the
Physiol 1965; 20: 719-24
3. Hubbard RW, Sandick BL, Matthew WT, et al. Voluntary
neuromuscular system.
[14,36,42,43,45,52,53,75,81,83]
Unfor-
dehydration and alliesthesia for water. J Appl Physiol 1984;
tunately, very little scientific evidence evaluates
57: 868-73
these hypotheses. Electromyographic data collected
4. Pitts GC, Johnson RE, Consolazio FC. Work in the heat as
affected by intake of water, salt and glucose. Am J Physiol
during maximal contractions are limited and incon-
1944; 142: 253-9
clusive,
[33,75,79,82]
and research examining the effect
5. Maughan RJ, Merson SJ, Broad NP, et al. Fluid and electrolyte
intake and loss in elite soccer players during training. Int J
of hypohydration on muscle membrane excitability
Sport Nutr Exerc Metab 2004; 14: 333-46
clearly argues against this hypothesis.
[100,101]
Al-
6. Cheuvront SN, Haymes EM. Ad libitum fluid intakes and ther-
though altered neuromuscular function is an appeal-
moregulatory responses of female distance runners in three
environments. J Sports Sci 2001; 19: 845-54
ing hypothesis, the literature currently lacks a well
7. Shirreffs SM. The importance of good hydration for work and
designed study evaluating the effect of hydration
exercise performance. Nutr Rev 2005; 63: S14-21
8. Sawka MN, Montain SJ, Latzka WA. Hydration effects on
state on a sensitive marker of central drive (e.g.
thermoregulation and performance in the heat. Comp Biochem
twitch interpolation or central activation ratio). Until
Physiol A Mol Integr Physiol 2001; 128: 679-90
this gap in the literature is filled, the importance of
9. Cheuvront SN, Carter R, Sawka MN. Fluid balance and endur-
ance performance. Curr Sports Med Rep 2003; 2: 202-8
neuromuscular alterations in mediating hypohydra-
10. Knuttgen HG, Kraemer WJ. Terminology and measurement in
tion-induced decrements of muscle function cannot
exercise performance. J Appl Sports Sci Res 1987; 1: 1-10
be accurately assessed.
11. American College of Sports Medicine. Position stand on weight
loss in wrestlers. Med Sci Sports Exerc 1976; 8: xi-xiii
12. American Medical Association. Wrestling and weight control.
JAMA 1967; 201: 131-3
4. Conclusions
13. Horswill CA. Applied physiology of amateur wrestling. Sports
Med 1992; 14: 114-43
14. Fogelholm M. Effects of bodyweight reduction on sports per-
When the masking and exacerbating influences
formance. Sports Med 1994; 18: 249-67
of dehydration procedure, test selection and subject
15. Horswill CA. Weight loss and weight cycling in amateur wres-
tlers: implications for performance and resting metabolic rate.
population have been accounted for, hypohydration
Int J Sport Nutr 1993; 3: 245-60
appears to negatively influence muscular strength,
16. Lopez R. Weight loss and diet in wrestling. Phys Educator 1980;
power and high-intensity endurance. After consider-
37: 131-9
17. Ribisl PM. When wrestlers shed pounds quickly. Phys Sport-
ing the important external factors, future research
smed 1974; 2: 30-5
should aim to elucidate the magnitude of hy-
18. Tipton CM, Oppliger RA. The Iowa Wrestling study: lessons for
pohydration effects, to clarify the mechanism of
physicians. Iowa Med 1984; 74 (9): 381-5
19. Tipton CM. Physiologic problems associated with the ‘making
these effects, and explore interrelationships with key
of weight’. Am J Sports Med 1980; 8: 449-50
modulators such as the degree of hypohydration and
20. Hansen NC. Wrestling with ‘making weight’. Phys Sportsmed
1978; 6: 105-11
mode of dehydration. Although further work re-
21. Keller HL, Tolly SE, Freedson PS. Weight loss in adolescent
mains to be completed, this critical review of the
wrestlers. Pediatr Exerc Sci 1994; 6: 212-24
available literature suggests hypohydration is an
22. Yarrows SA. Weight loss through dehydration in amateur wres-
tlers. J Am Diet Assoc 1988; 88: 491-3
important factor to consider when attempting to
23. Oppliger RA, Case S, Horswill CA, et al. American College of
maximise muscular performance in athletic, military
Sports Medicine Position Stand: weight loss in wrestlers. Med
and industrial settings.
Sci Sports Exerc 1996; 28: ix-xii
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
920 Judelson et al.
24. Coyle EF, Hamilton M. Fluid replacement during exercise: 44. Guti
´
errez A, Mesa JLM, Ruiz JR, et al. Sauna-induced rapid
effects on physiological homeostasis and performance. In: weight loss decreases explosive power in women but not in
Gisolfi CV, Lamb DR, editors. Perspectives in exercise sci- men. Int J Sports Med 2003; 24: 518-22
ence and sports medicine: fluid homeostasis during exercise.
45. Montain SJ, Smith SA, Mattot RP, et al. Hypohydration effects
Carmel (IN): Cooper Publishing Group, 1990: 281-308
on skeletal muscle performance and metabolism: a 31P-MRS
25. Sawka MN, Pandolf KB. Effects of body water loss on physio-
study. J Appl Physiol 1998; 84: 1889-94
logical function and exercise performance. In: Gisolfi CV,
46. Greenleaf JE, Prange EM, Averkin EG. Physical performance of
Lamb DR, editors. Perspectives in exercise science and sports
women following heat-exercise hypohydration. J Appl Physiol
medicine: fluid homeostasis during exercise. Carmel (IN):
1967; 22: 55-60
Cooper Publishing Group, 1990: 1-38
47. Janse de Jonge XA. Effects of the menstrual cycle on exercise
26. Casa DJ, Armstrong LE, Hillman SK, et al. National Athletic
performance. Sports Med 2003; 33: 833-51
Trainers Association Position Statement: fluid replacement for
48. Stachenfeld NS, DiPietro L, Kokoszka CA, et al. Physiological
athletes. J Athl Train 2000; 35: 212-24
variability of fluid-regulation hormones in young women. J
27. McMurray RG, Proctor CR, Wilson WL. Effect of caloric
Appl Physiol 1999; 86: 1092-6
deficit and dietary manipulation on aerobic and anaerobic
49. Maresh CM, Judelson DA. Alterations in arginine vasopressin
exercise. Int J Sports Med 1991; 12: 167-72
with exercise, environmental stress, and other modifying fac-
28. Maughan RJ, Greenhaff PL, Leiper JB, et al. Diet composition
tors. In: Kraemer WJ, Rogol AD, editors. The Olympic ency-
and the performance of high-intensity exercise. J Sports Sci
clopaedia of sports medicine volume XI: the endocrine system
1997; 15: 265-75
in sport and exercise. Malden (MA): Blackwell Publishing,
29. Rankin JW, Ocel JV, Craft LL. Effect of weight loss and
2005: 487-98
refeeding diet composition on anaerobic performance in wres-
50. Bosco JS, Terjung RL, Greenleaf JE. Effects of progressive
tlers. Med Sci Sports Exerc 1996; 28: 1292-9
hypohydration on maximal isometric muscular strength. J
30. Nielsen B, Kubica R, Bonnesen A, et al. Physical work capacity
Sports Med Phys Fitness 1968; 8: 81-6
after dehydration and hyperthermia: a comparison of the effect
51. Watson G, Judelson DA, Armstrong LE, et al. Influence of
of exercise versus passive heating and sauna and diuretic
diuretic-induced dehydration on competitive sprint and power
dehydration. Scand J Sports Sci 1981; 3: 2-10
performance. Med Sci Sports Exerc 2005; 37: 1168-74
31. Cheung SS, Sleivert GG. Multiple triggers for hyperthermic
52. Viitasalo JT, Kyrolainen H, Bosco C, et al. Effects of rapid
fatigue and exhaustion. Exerc Sport Sci Rev 2004; 32: 100-6
weight reduction on force production and vertical jumping
32. Thomas MM, Cheung SS, Elder GC, et al. Voluntary muscle
height. Int J Sports Med 1987; 8: 281-5
activation is impaired by core temperature rather than local
53. Hoffman JR, Stavsky H, Falk B. The effect of water restriction
muscle temperature. J Appl Physiol 2006; 100: 1361-9
on anaerobic power and vertical jumping height in basketball
33. Evetovich TK, Boyd JC, Drake SM, et al. Effect of moderate
players. Int J Sports Med 1995; 16: 214-8
dehydration on torque, electromyography, and mechanomy-
54. Doscher N. The effects of rapid weight loss upon the perform-
ography. Muscle Nerve 2002; 26: 225-31
ance of wrestlers and boxers, and upon the physical proficien-
34. Greiwe JS, Staffey KS, Melrose DR, et al. Effects of dehydra-
cy of college students. Res Q 1944; 15: 317-24
tion on isometric muscular strength and endurance. Med Sci
55. Fogelholm GM, Koskinen R, Laasko J, et al. Gradual and rapid
Sports Exerc 1998; 30: 284-8
weight loss: effects on nutrition and performance in male
35. Webster S, Rutt R, Weltman A. Physiological effects of a
athletes. Med Sci Sports Exerc 1993; 25: 371-7
weight loss regimen practiced by college wrestlers. Med Sci
56. Jacobs I. The effects of thermal dehydration on performance of
Sports Exerc 1990; 22: 229-34
the wingate anaerobic test. Int J Sports Med 1980; 1: 21-4
36. Yoshida T, Takanishi T, Nakai S, et al. The critical level of
57. Houston ME, Marrin DA, Green HJ, et al. The effect of rapid
water deficit causing a decrease in human exercise perform-
weight loss on physiological functions in wrestlers. Phys
ance: a practical field study. Eur J Appl Physiol 2002; 87:
Sportsmed 1981; 9: 73-8
529-34
58. Klinzing JE, Karpowicz W. The effects of rapid weight loss and
37. Cheuvront SN, Carter R, Haymes EM, et al. No effect of
rehydration on a wrestling performance test. J Sports Med
moderate hypohydration or hyperthermia on anaerobic exer-
1986; 26: 149-56
cise performance. Med Sci Sports Exerc 2006; 38: 1093-7
59. Wenos DL, Amato HK. Weight cycling alters muscular strength
38. Greenleaf JE, Matter M, Bosco JS, et al. Effects of hypohydra-
and endurance, ratings of perceived exertion, and total body
tion on work performance and tolerance to +G
Z
acceleration in
water in college wrestlers. Percept Mot Skills 1998; 87: 975-8
man. Aerosp Med 1966; 37: 34-9
60. Serfass RC, Stull GA, Alexander JF, et al. The effects of rapid
39. Caterisano A, Camaione DN, Murphy RT, et al. The effect of
weight loss and attempted rehydration on strength and endur-
differential training on isokinetic muscular endurance during
ance of the handgripping muscles in college wrestlers. Res Q
acute thermally induced hypohydration. Am J Sports Med
Exerc Sport 1984; 55: 46-52
1988; 16: 269-73
61. Smith SA, Williams JH, Ward CW, et al. Dehydration effects on
40. Schoffstall JE, Branch JD, Leutholtz BC, et al. Effects of
repeated bouts of short-term, high-intensity exercise in college
dehydration and rehydration on the one-repetition maximum
wrestlers [abstract]. Med Sci Sports Exerc 1991; 23: S67
bench press of weight-trained males. J Strength Cond Res
62. Smith SM, Krauhs JM, Leach CS. Regulation of body fluid
2001; 15: 102-8
volume and electrolyte concentrations in spaceflight. Adv
41. Saltin B. Aerobic and anaerobic work capacity after dehydra-
Space Biol Med 1997; 6: 123-65
tion. J Appl Physiol 1964; 19: 1114-8
63. Ferry M. Strategies for ensuring good hydration in the elderly.
42. Walsh RM, Noakes TD, Hawley JA, et al. Impaired high-
Nutr Rev 2005; 63: S22-9
intensity cycling performance time at low levels of dehydra-
64. Caldwell JE, Ahonen E, Nousiainen U. Differential effects of
tion. Int J Sports Med 1994; 15: 392-8
sauna-, diuretic-, and exercise-induced hypohydration. J Appl
43. Fritzsche RG, Switzer TW, Hodgkinson BJ, et al. Water and
Physiol 1984; 57: 1018-23
carbohydrate ingestion during prolonged exercise increase
maximal neuromuscular power. J Appl Physiol 2000; 88: 65. Maresh CM, Whittlesey MJ, Armstrong LE, et al. Effect of
730-7 hydration state on testosterone and cortisol responses to train-
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)
This material is
the copyright of the
original publisher.
Unauthorised copying
and distribution
is prohibited.
Hydration and Muscle Performance 921
ing-intensity exercise in collegiate runners. Int J Sports Med 84. Maughan RJ, Shirreffs SM, Leiper JB. Fluids and electrolytes
2006; 27: 765-70 during exercise. In: Garrett WE, Kirkendall DT, editors. Exer-
cise and sport science. Philadelphia (PA): Lippincott Williams
66. Casa DJ, Maresh CM, Armstrong LE, et al. Intravenous versus
& Wilkins, 2000: 413-24
oral rehydration during a brief period: stress hormone re-
sponses to subsequent exhaustive exercise in the heat. Int J
85. Ladell WSS. Effects on man of restricted water supply. Br Med
Sport Nutr Exerc Metab 2000; 10: 361-74
Bull 1947; 5: 9-13
67. Hoffman JR, Maresh CM, Armstrong LE, et al. Effects of
86. Gonzalez-Alonso J. Separate and combined influences of dehy-
hydration state on plasma testosterone, cortisol and catecho-
dration and hyperthermia on cardiovascular responses to exer-
lamine concentrations before and during mild exercise at ele-
cise. Int J Sports Med 1998; 19 Suppl. 2: S111-4
vated temperature. Eur J Appl Physiol Occup Physiol 1994;
87. Gonzalez-Alonso J, Mora-Rodriguez R, Below PR, et al. Dehy-
69: 294-300
dration reduces cardiac output and increases systemic and
68. Bijlani RL, Sharma KN. Effect of dehydration and a few re-
cutaneous vascular resistance during exercise. J Appl Physiol
gimes of rehydration on human performance. Indian J Physiol
1995; 79: 1487-96
Pharmacol 1980; 24: 255-66
88. Gonzalez-Alonso J, Calbet JA, Nielsen B. Muscle blood flow is
69. Moore BJ, King DS, Kesl L, et al. Effect of rapid dehydration
reduced with dehydration during prolonged exercise in
and rehydration on work capacity and muscle metabolism
humans. J Physiol 1998; 513: 895-905
during intense exercise in wrestlers [abstract]. Med Sci Sports
89. Gonzalez-Alonso J, Calbet JA, Nielsen B. Metabolic and ther-
Exerc 1992; 24: S95
modynamic responses to dehydration-induced reductions in
70. Ahlman K, Karvonen MJ. Weight reduction by sweating in
muscle blood flow in exercising humans. J Physiol 1999; 520:
wrestlers and its effects on physical fitness. J Sports Med Phys
577-89
Fitness 1961; 1: 58-62
90. Keller U, Szinnai G, Bilz S, et al. Effects of changes in hydra-
71. Mnatzakanian PA, Vaccaro P. Effects of 4% dehydration and
tion on protein, glucose and lipid metabolism in man: impact
rehydration on hematological profiles, urinary profiles, and
on health. Eur J Clin Nutr 2003; 57: S69-74
muscular endurance of college wrestlers [abstract]. Med Sci
91. Ritz P, Salle A, Simard G, et al. Effects of changes in water
Sports Exerc 1982; 14: 117
compartments on physiology and metabolism. Eur J Clin Nutr
72. Guastella P, Wygand J, Davy K, et al. The effects of rapid
2003; 57: S2-5
weight loss on anaerobic power in high school wrestlers [ab-
92. Waldegger S, Busch GL, Kaba NK, et al. Effect of cellular
stract]. Med Sci Sports Exerc 1988; 20: S2
hydration on protein metabolism. Miner Electrol Metab 1997;
73. Kraemer WJ, Fry AC, Rubin MR, et al. Physiological and
23: 201-5
performance responses to tournament wrestling. Med Sci
93. Armstrong LE, Costill DL, Fink WJ. Influence of diuretic-
Sports Exerc 2001; 33: 1367-78
induced dehydration on competitive running performance.
74. Bell D, Bemben M, Trew JA, et al. The effects of rapid weight
Med Sci Sports Exerc 1985; 17: 456-61
loss in college wrestlers. Aust J Sports Med Exerc Sci 1982;
94. Horswill CA, Hickner RC, Scott JR, et al. Weight loss, dietary
14: 27-30
carbohydrate modifications, and high intensity, physical per-
75. Ftaiti F, Gr
´
elot L, Coudreuse JM, et al. Combined effect of heat
formance. Med Sci Sports Exerc 1990; 22: 470-6
stress, dehydration and exercise on neuromuscular function in
95. Burge CM, Carey MF, Payne WR. Rowing performance, fluid
humans. Eur J Appl Physiol 2001; 84: 87-94
balance, and metabolic function following dehydration and
76.
¨
O
¨
opik V, P
¨
a
¨
asuke M, Sikku T, et al. Effect of rapid weight loss
rehydration. Med Sci Sports Exerc 1993; 25: 1358-64
on metabolism and isokinetic performance capacity: a case
96. Saltin B. Circulatory responses to submaximal and maximal
study of two well trained wrestlers. J Sports Med Phys Fitness
exercise after thermal dehydration. J Appl Physiol 1964; 19:
1996; 36: 127-31
1125-34
77. Singer RN, Weiss SA. Effects of weight reduction on selected
97. Hickner RC, Horswill CA, Welker JM, et al. Test development
anthropometric, physical, and performance measures of wres-
for the study of physical performance in wrestlers following
tlers. Res Q Exerc Sport 1968; 39: 361-9
weight loss. Int J Sports Med 1991; 12: 557-62
78. Tuttle WW. The effect of weight loss by dehydration and the
98. Maffulli N. Making weight: a case study of two elite wrestlers.
withholding of food on the physiologic responses of wrestlers.
Br J Sports Med 1992; 26: 107-10
Res Q 1943; 14: 158-66
99. Febbraio MA, Lambert DL, Starkie RL, et al. Effect of epineph-
79. Vallier JM, Grego F, Basset F, et al. Effect of fluid ingestion on
rine on muscle glycogenolysis during exercise in trained men.
neuromuscular function during prolonged cycling exercise. Br
J Appl Physiol 1998; 84: 465-70
J Sports Med 2005; 39: e17-22
100. Costill DL, Cot
´
e R, Fink W. Muscle water and electrolytes
80. King DS, Costill DL, Fink WJ, et al. Muscle metabolism during
following varied levels of dehydration in man. J Appl Physiol
exercise in the heat in unacclimatized and acclimatized
1976; 40: 6-11
humans. J Appl Physiol 1985; 59: 1350-4
81. Bosco JS, Greenleaf JE, Bernauer EM, et al. Effects of acute 101. Costill DL, Cot
´
e R, Fink WJ, et al. Muscle water and electrolyte
dehydration and starvation on muscular strength and endur- distribution during prolonged exercise. Int J Sports Med 1981;
ance. Acta Physiol Pol 1974; 25: 411-21 2: 130-4
82. Bigard AX, Sanchez H, Claveyrolas G, et al. Effects of dehydra-
tion and rehydration on EMG changes during fatiguing con-
Correspondence: Dr Daniel A. Judelson, Department of Ki-
tractions. Med Sci Sports Exerc 2001; 33: 1694-700
nesiology, California State University, 800 North State Col-
83. Torranin C, Smith DP, Byrd RJ. The effect of acute thermal
lege Boulevard, Fullerton, CA 92887, USA.
dehydration and rapid rehydration on isometric and isotonic
endurance. J Sports Med Phys Fitness 1979; 19: 1-9 E-mail: djudelson@fullerton.edu
2007 Adis Data Information BV. All rights reserved. Sports Med 2007; 37 (10)