ArticlePDF AvailableLiterature Review

Hydration and muscular performance: Does fluid balance affect strength, power and high-intensity endurance?

January 2007
Sports Medicine 37(10):907-21

Source
PubMed

Authors:

Carl M Maresh

University of Connecticut

Jeffrey Anderson

University of Connecticut

Lawrence Armstrong

Hampton VA

Show all 7 authorsHide

Significant scientific evidence documents the deleterious effects of hypohydration (reduced total body water) on endurance exercise performance; however, the influence of hypohydration on muscular strength, power and high-intensity endurance (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 approximately 2%), power (by approximately 3%) and high-intensity endurance (by approximately 10%), suggesting alterations in total body water affect some aspect of force generation. Unfortunately, the relationships 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 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.

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.

…

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.

…

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.

…

Figures - uploaded by Douglas Casa

Content may be subject to copyright.

Content uploaded by Douglas Casa

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

EVIEW

RTICLE

0112-1642/07/0010-0907/$44.95/0

Hydration and Muscular Performance

Does Fluid Balance Affect Strength, Power and

High-Intensity Endurance?

Daniel A. Judelson,

1,2

Carl M. Maresh,

Jeffrey M. Anderson,

Lawrence E. Armstrong,

Douglas J. Casa,

William J. Kraemer

and Jeff S. Volek

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,

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

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

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

Primary factor

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

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

Primary factor

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

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

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

Primary factor

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

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-

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

Primary factor

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

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

a b c d e f g h

Lower body

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 (%)

–20

–15

–10

–5

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.

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

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.

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

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.

[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-

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

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

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-

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.

opik V, P

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

Article

Full-text available

Dec 2022
PLOS ONE

Hemoconcentration during exercise is a well-known phenomenon, however, the extent to which dehydration is involved is unclear. In our study, the effect of dehydration on exercise-induced hemoconcentration was examined in 12 elite Hungarian kayak-canoe athletes. The changes of blood markers were examined during acute maximal workload in hydrated and dehydrated states. Dehydration was achieved by exercise, during a 120-minute extensive-aerobic preload. Our research is one of the first studies in which the changes in blood components were examined with a higher time resolution and a wider range of the measured parameters. Hydration status had no effect on the dynamics of hemoconcentration during both the hydrated (HS) and dehydrated (DHS) load, although lower maximal power output were measured after the 120-minute preload [HS Hemoglobin(Hgb)Max median 17.4 (q1 17.03; q3 17.9) g/dl vs. DHS HgbMax median 16.9 (q1 16.43; q3 17.6) g/dl (n.s); HS Hematocrit(Hct)Max 53.50 (q1 52.28; q3 54.8) % vs. DHS HctMax 51.90 (q1 50.35; q3 53.93) % (n.s)]. Thirty minutes after the maximal loading, complete hemodilution was confirmed in both exercises. Dehydration had no effect on hemoconcentration or hemodilution in the recovery period [HS HgbR30' 15.7 (q1 15.15; q3 16.05) g/dl (n.s.) vs. DHS HgbR30' 15.75 (q1 15.48; q3 16.13) g/dl (n.s.), HS HctR30' 48.15 (q1 46.5; q3 49.2) % vs. DHS HctR30' 48.25 (q1 47.48; q3 49.45) % (n.s.)], however, plasma osmolality did not follow a corresponding decrease in hemoglobin and hematocrit in the dehydrated group. Based on our data, metabolic products (glucose, lactate, sodium, potassium, chloride, bicarbonate ion, blood urea nitrogen) induced osmolality may not play a major role in the regulation of hemoconcentration and post-exercise hemodilution. From our results, we can conclude that hemoconcentration depends mainly on the intensity of the exercise.

The effects of passive dehydration on motor unit firing rates of the vastus lateralis in males

Article

Full-text available

Nov 2022
Sport Sci Health

PurposeThe purpose of the present study was to examine the effects of dehydration on strength and motor unit (MU) firing rates of the vastus lateralis (VL) during submaximal contractions.Methods Eight resistance trained, healthy males (mean ± SD; age = 27.6 ± 3.2 years, mass = 98.7 ± 15.1 kg, stature = 181.0 ± 3.8 cm) performed submaximal leg extension contractions at 70% of maximal voluntary contraction (MVC) before and after a passive dehydration protocol to a 5% loss in body weight. Surface EMG signals of the VL were collected and decomposed into their constituent MU action potential trains and linear mean firing rate (pps) vs. recruitment threshold [expressed as a percentage of MVC (%MVC)] relationships were analyzed for each subject and hydration condition.ResultsThe MVC torque was higher during euhydration (269.3 ± 58.9 Nm) than during hypohydration (242.8 ± 60.8 Nm) while there were no differences between the slopes (euhydrated = -0.43 ± 0.23 pps/%MVC; hypohydrated = -0.50 ± 0.28 pps/%MVC; p = 0.23) or the y-intercepts (euhydrated = 30.43 ± 10.47 pps; hypohydrated = 35.22 ± 14.58 pps; p = 0.078) between conditions.Conclusion The 9.8% decrease in strength during hypohydration might be caused by a decrease in the contractile force of the active muscle fibers rather than decreased activation of the MU pool.

Countermovement jump, handgrip, and balance performance change during euhydration, mild-dehydration, rehydration, and ad libitum drinking

Article

Full-text available

Aug 2022
J EXERC SCI FIT

Objective To examine the effects of euhydration, mild-dehydration, rehydration, and ad libitum drinking on countermovement jump (CMJ), handgrip strength, and performance of balance error scoring system test (BESS). Methods Eighteen healthy male subjects (mean[M]±standard deviation[SD]; age, 23±3y; body mass, 80.1 ± 9.7 kg; height, 175.8 ± 5.7 cm) participated in this study. Participants reported to the laboratory to perform CMJ, handgrip strength, and BESS with different hydration statuses (euhydrated, EUH; when they initially sensed thirst, THIRST; dehydrated, DEH; following 30 minutes of rehydration, REH; and following 24-h ad libitum drinking, AD). Results CMJ at EUH (M±SD; 54.6 ± 3.0 cm) was significantly higher than DEH (52.8 ± 3.0 cm, p = 0.027) and REH (52.6 ± 2.8 cm, p < 0.001). However, there was no difference between DEH and REH (p = 0.643). CMJ at THIRST (54.9 ± 3.0 cm, p = 0.004) was higher than REH. Also, AD (53.8 ± 2.8 cm, p = 0.027) was higher than REH. In left handgrip strength, THIRST (48.6 ± 9.5 kg) was higher than EUH (46.7 ± 10.1 kg, p = 0.018), DEH (45.8 ± 10.0 kg, p = 0.013), REH (46.1 ± 9.5 kg, p = 0.004), and AD (47.1 ± 9.7 kg, p = 0.05). Additionally, in the single-leg stance on a foam pad, more BESS errors were found at THIRST (6 ± 2) compared to EUH (5 ± 2, p = 0.007) and AD (5 ± 2, p = 0.002). Conclusion The findings of this study were: ∼2% of mild dehydration induced by 24-h fluid restriction decreased lower body power measured by CMJ, acute rehydration did not restore the loss of lower body power induced by dehydration, and ∼0.5–0.9% of dehydration did not decrease lower body power.

Effects of Different Rapid Weight Loss Strategies and Percentages on Performance-Related Parameters in Combat Sports: An Updated Systematic Review

Article

Full-text available

Jan 2023

Most combat sports (CS) are structured in weight categories, and it is very common to carry out body weight adjustment strategies in order to compete in lower weight categories. For this reason, different rapid weight loss (RWL) strategies are usually performed to pass the pre-competition weigh-in test, and then a replenishment of fluids and carbohydrate-rich foods is conducted in an attempt to recover the weight and avoid a performance loss. In this context, no clear references have been found on whether these types of strategies have negative effects, impairing the athlete's combat and/or physical performance. For this reason, the aim of this study was to review the scientific literature on the effect of rapid weight reduction strategies on the performance of CS athletes. A literature search was performed through four different databases (PubMed, SPORTDiscus, Web of Science and ScienceDirect). Four inclusion criteria were established as follows: (1) the subjects had to be competitors in the CS and carry out RWL strategies; (2) at least two measurement points, that is, normal conditions and dehydration condition; (3) measurements in a real competition or simulating the same conditions; (4) original research articles written in English or Spanish and available in full text. Finally, a total of 16 articles were finally included in this research. All subjects (n = 184) were athletes from combat disciplines, with a minimum of 3-4 years of practice, as well as with certain experience in RWL. Six of the studies reported that an RWL strategy of around 5% of body weight loss did not affect performance parameters. However, the other ten studies with RWL between 3 and 6% or even higher reported negative effects or impairments on different parameters related to performance and/or athlete's psychophysiology, such as perceived fatigue, mood states, strength and power production, as well as changes in hormonal, blood and urine parameters, body composition, or the kinematics of the technical gesture. Although there is still no clear answer to the issue approached in this research, in general terms, it seems that in order to guarantee an acceptable athletic performance of the competitor, the weight loss should not exceed 3% to ≤5% of body weight together with ≥24 h for adequate (or at least partial) recovery and rehydration processes. In addition, it is highly recommended to lose weight progressively over several weeks, especially focusing on competitions lasting several days, as well as multiple rounds or qualifying stages.

Effects of Different Rapid Weight Loss Strategies and Percentages on Performance-Related Parameters in Combat Sports: An Updated Systematic Review

Article

Full-text available

Mar 2023
Int J Environ Res Publ Health

Personalizing Resistance Training Mitigates Neuromuscular and Perceived Fatigue: The Autoregulation Cluster Training Method

Article

Feb 2023
Int J Sports Physiol Perform

Purpose: To compare predetermined and autoregulated resistance training sessions on velocity loss and perceived fatigue. Methods: Twenty-six resistance-trained men completed 3 sessions including the back-squat and bench-press exercises matched for load (75% of 1-repetition maximum), volume (24 repetitions), and total rest (240 s). Sessions were randomly performed as traditional set (TRA), 3 sets of 8 repetitions with 120-second interset rests; cluster interset-rest redistribution (IRR), 6 clusters of 4 repetitions with 48-second between-clusters rests; and autoregulation cluster training (ACT), a personalized combination of clusters, repetitions per cluster, and between-clusters rest regulated on a velocity loss threshold. The comparative effects were evaluated on velocity loss outputs measured with a linear encoder and perceived fatigue responses reported using a single-item scale. Results: IRR and ACT induced less velocity loss than TRA (b = -2.09, P < .001). ACT also mitigated velocity loss more than IRR (b = -2.31, P < .001). The back squat resulted in greater velocity loss compared to the bench press (b = 1.83, P < .001). Perceived fatigue responses mirrored the pattern observed for the velocity loss outputs (IRR and ACT vs TRA: b = -0.64, P < .001; ACT vs IRR: b = -1.05, P < .001; back squat vs bench press: b = 0.46, P = .005). Conclusions: IRR and ACT reduced neuromuscular and perceived fatigue, likely due to their cluster-set structures' embedding frequent windows of interset rest. However, the ACT was overall more effective, presumably given its personalized structure.

A questionnaire study on the knowledge, attitudes, and practices of fluid replacement and urination among Chinese elite athletes

Article

Full-text available

Oct 2022
PLOS ONE

Objective To evaluate the knowledge, attitudes and practices (KAP) of Chinese elite athletes about fluid replacement and urination.MethodsA cross-section study was carried out among Chinese national and national youth teams from March to April 2020, using a pretested questionnaire. The 42-questions questionnaire was designed to assess the KAP regarding fluid replacement and urination. The questionnaire included knowledge of fluid replacement (KFR), attitudes of fluid replacement (AFR), knowledge of urination (KU), and attitudes of urination (AU), which were awarded 20 scoring points. Descriptive statistics, independent samples t-tests, one-way ANOVA, Pearson's correlation analysis, Multiple linear stepwise regression and Chi-square test were performed.ResultsA total of 779 valid questionnaires were collected and the effective rate is 98.4%. We finally conducted an assessment of 646 questionnaires of elite athletes. The mean score for KFR, AFR, KU, and AU was 2.8±1.3, 2.3±0.6, 3.0±1.5, and 2.1±0.8, respectively, with higher scores indicating positive hydration knowledge and attitudes. KFR and AFR scores of winter sports athletes were higher than those of summer sports athletes(P

Analysis of potential hydration opportunities during future football tournaments based on data from the 2018 FIFA World Cup

Article

Oct 2022

The World Cup is traditionally held during the hot summer months which requires playing in oppressive thermal conditions. Therefore, teams should follow heat strain mitigation strategies, such as acclimatization, pre-exercise cooling, and optimal fluid ingestion. Even though the 2022 World Cup in Qatar is being moved to the autumn to reduce environmental stress, many challenges will remain. The objective of this analysis was to assess and visually communicate match-based World Cup player hydration opportunities and behaviors. Broadcast recordings of the 2018 World Cup (June-July) were analyzed. Descriptive data were reported for match duration, the number, type, and duration of breaks, and player-initiated hydration moments, as well as data reporting environmental conditions using the Universal Thermal Climate Index (UTCI), with matches categorized as "no thermal stress" and "thermal heat stress." The median number and interquartile range of total match breaks were 7 [5-8] during official breaks, with a duration of 42 [23-72] seconds. There were 2 [1-3] player-initiated hydration moments per game, with a duration of 77 [55 to 100] seconds. On top of the 29% (#126) of breaks in which drinking occurred, an additional 26% (#33) of self-initiated drinking was registered with a duration of 7 [4-28] seconds without an official break. There was no significant difference (P=0.22) in self-initiated hydration between matches played under the two thermal conditions. Relative percentages showed suboptimal use of substitution (14%) and VAR (38%) breaks vs. injury breaks (75%). In conclusion, football players did not sufficiently use available breaks to hydrate.

A comparison of body composition and blood lipid indices among Kho-Kho players based on water intake pattern

Article

Jan 2022

Comparison between digital and paper urine color to assess hydration status

Article

Feb 2023
EUR J NUTR

Purpose: The purpose of this study was to investigate associations between digital urine color and paper urine color with other urine indices to assess hydration status. Methods: Twelve male subjects (mean ± standard deviation; age, 26 ± 8 years; body mass, 57.8 ± 5.3 kg; height, 177.5 ± 8.9 cm; VO2max, 57.8 ± 5.8 ml·kg-1·min-1) performed four exercise trials in the heat. Before and following exercise trials, subjects provide urine samples. Urine samples were measured using a digital urine color chart on a portable device screen. Urine samples were also assessed with urine specific gravity (USG), urine osmolality (UOsmo), and a validated paper urine color chart. Results: There were extremely large associations found between digital urine color and paper urine color (r = 0.926, p < 0.001). Correlation coefficients showing associations with USG and UOsmo were similar between digital urine color (USG, r = 0.695, p < 0.001; UOsmo, r = 0.555, p < 0.001) and paper urine color (USG, r = 0.713, p < 0.001; UOsmo, r = 0.570, p < 0.001). Bland-Altman analysis indicated that no proportional bias was observed between digital and paper urine colors (bias, - 0.148; SD of bias, 0.492; 95% LOA, - 1.11, 0.817; p = 0.094). Conclusions: Strong associations were found between digital and paper urine colors with no proportional bias. Furthermore, the degree of associations with USG and UOsmo was similar between digital and paper urine color. These results indicate that digital urine color is a useful tool to assess hydration status and this method could be used as an alternative method to using paper urine color.

Combined effect of heat stress, dehydration and exercise on neuromuscular function in humans

Article

Full-text available

Feb 2001

This study examined the combined effect of exercise induced hyperthermia and dehydration on neuromuscular function in human subjects. Six trained male runners ran for 40 min on a treadmill at 65% of their maximal aerobic velocity while wearing a tracksuit covered with an impermeable jacket and pants to impair the evaporation of sweat. These stressful experimental running conditions led the runners to a physiological status close to exhaustion. On average, the 40 min run ended at a heart rate of 196 (SD 8) beats · min−1, a tympanic temperature of 40 (SD 0.3) °C and with a loss of body mass of 2 (SD 0.5)%. Pre- and post-running strength tests included measurements of maximal knee extension and flexion torques in both isometric and isokinetic (at 60 and 240° · s−1) conditions. A 20 s endurance test at 240° · s−1 was also performed. Surface electromyographic (EMG) activity was recorded from six knee extensor and flexor muscles during the entire protocol. The treadmill run led to clear decrements in maximal extension torque and EMG activity both in isometric and at the slowest isokinetic velocity (60° · s−1). However, no differences in these parameters were observed at 240° · s−1. Furthermore, the EMG patterns of the major knee extensor and flexor muscles remained remarkably stable during the treadmill run. These results demonstrate that the exercise-induced hyperthermia and dehydration in the present experiments had only minor effects on the neuromuscular performance. However, it is also suggested that high internal body temperature per se could limit the production of high force levels.

Physiological and performance responses to tournament wrestling

Article

Full-text available

Sep 2001

The purpose of this study was to investigate the physiological and performance responses to a simulated freestyle wrestling tournament after typical weight loss techniques used by amateur wrestlers. Twelve Division I collegiate wrestlers (mean +/- SD;19.33 +/- 1.16 yr) lost 6% of total body weight during the week before a simulated, 2-d freestyle wrestling tournament. A battery of tests was performed at baseline and before and immediately after each individual match of the tournament. The test battery included assessment for body composition, reaction/movement time, lower and upper body power and isokinetic strength, and a venous blood sample. Lower body power and upper body isometric strength were significantly reduced as the tournament progressed (P < or = 0.05). Significant elevations in testosterone, cortisol, and lactate were observed after each match (P < or = 0.05). However, there was a significant reduction (P < or = 0.05) in resting testosterone values in the later matches. Norepinephrine increased significantly (P < or = 0.05) after each match, whereas epinephrine increased significantly (P < or = 0.05) after each match except the last match of each day. Plasma osmolality was consistently higher than normal values at all times including baseline, with significant increases observed after each match (P < or = 0.05). Tournament wrestling augments the physiological and performance decrements of weight loss and its impact is progressive over 2 d of competition. The combined effects of these stresses may ultimately be reflected in a wrestler's ability to maintain physical performance throughout a tournament.

The Effect of Rapid Weight Loss on Physiological Functions in Wrestlers

Article

Nov 1981

To assess the effects of rapid weight reduction, four university wrestlers decreased their body weight by 8% over a four-day period by food and liquid intake reductions. Significant decreases in muscle glycogen concentration and dynamic strength, but not aerobic or anaerobic capacity, accompanied weight loss. A three-hour rehydration period did not improve glycogen levels or strength performance. These results suggest that rapid weight reduction may impair wrestling performance.

Physical work capacity after dehydration and hyperthermia. A comparison of the effect of exercise versus passive heating and sauna and diuretic dehydration

Article

Jan 1981

Physical work capacity was measured in a standard exercise test on a bicycle ergometer: 50% of VO2 max (maximal oxygen uptake) for 8 min, 70% for 5 min, and 105% until exhaustion. The amount of work performed in the last bout was used as an index of physical work capacity. The subjects performed the test under normal (control) conditions and after: prolonged (90-160 min) bicycle exercise (50% of VO2 max); passive heating in water until a rectal temperature of 38°C was achieved; sauna dehydration until body weight loss and rectal temperature were the same as after prolonged exercise; and after diuretic dehydration to the same weight loss as that obtained in the prolonged exercise. Heart rate, oxygen consumption, rectal and muscle temperatures, and weight loss were measured. Blood samples were taken for determinations of hematocrit, hemoglobin concentration, plasma levels of sodium, potassium and chloride, osmolarity, and blood lactate. It was concluded that the reduction in physical work capacity following prolonged exercise was the result of changes in many variables, partly the depletion of energy stores. However, dehydration and hyperthermia had separate effects in reducing work capacity. Electrolyte shifts and plasma volume changes were also associated with changes in work capacity. For all pretreatments taken together, the best indicator of physical work capacity was the difference between maximal heart rate and the heart rate obtained at 70% of VO2 max in the standard test.

The Effects of Thermal Dehydration on Performance of the Wingate Anaerobic Test

Article

Feb 1980

Ira Jacobs

Dehydration by means of exercise, heat, diuretics, semistarvation, or a combination of these is common practice among competitors in weight class sports. Many studies have demonstrated a reduced aerobic work capacity following each of these forms of dehydration. The effects of these practices on performance that requires energy derived primarily from anaerobic sources is not well documented. The purpose of this study was to examine the effects of progressive, acute, thermal dehydration on performance of an anaerobic criterion task. Eleven collegiate wrestlers performed the Wingate Anaerobic Test (WAnT) prior to and after each of the following mean weight losses: 2%, 4%, and 5%. Weight loss was induced by passive thermal dehydration (56°C, 15% RH). Approximately 2 h were required in the environmental chamber to lose the required weight at each stage. There was no significant change (P > 0.05) in the ability to perform the WAnT or its various indices at any stage of dehydration, nor were blood lactate concentrations post WAnT significantly different from predehydration levels. This suggests that anaerobic performance may not be impaired to the extent that aerobic performance is by passive, thermal dehydration to a 5% body weight loss. However, deleterious physiologic effects may result from dehydration practices even though performance levels are maintained.

Effects of dehydration and rehydration on EMG changes during fatiguing contractions

Article

Oct 2001
MED SCI SPORT EXER

Purpose: This study measured the effects of sauna-induced dehydration (Dhy) and the effectiveness of rapid rehydration on muscle performance and EMG frequency spectrum changes associated with fatigue during isometric contractions. Methods: Knee extensor muscle strength during isometric maximal voluntary contraction (MVC) and endurance time at 25% and 70% of MVC (ET25 and ET70, respectively) were measured three times in 11 healthy male subjects, under euhydration conditions (Eu), after Dhy, and after rehydration following Dhy (Rhy). Results: Dhy led to a decrease in body weight by 2.95 +/- 0.05%. No significant effect of the hydration status was shown on MVC values. A 23% decrease in ET25 was recorded during Dhy (P < 0.01), whereas ET70 only tended to decrease (-13%, P = 0.06). ET25 was higher during Rhy than Dhy (8%, P < 0.05) but remained lower than during Eu (-17%, P < 0.05). The EMG root mean square (RMS) increased earlier during Dhy than Eu. Opposite changes were shown for the mean power frequency (MPF) of EMG, and Dhy resulted in an accelerated fall in MPF. However, because ET25 decreased with dehydration, RMS and MPF changes were similar during Eu and Dhy when reported to normalized contraction time, exhaustion was thus associated with similar values of RMS and MPF for all conditions. RMS and MPF changes during Rhy showed an intermediate pattern between Eu and Dhy. Conclusions: Dhy induced an increase in muscle fatigue, associated with early changes in EMG spectral parameters. It is not clear whether these alterations could be attributed to biochemical modifications, and the role of increased perception of effort when subjects were dehydrated should be clarified.

Effect of Rapid Dehydration and Rehydration on Work Capacity and Muscle Metabolism During Intense Exercise in Wrestlers: 568

Article

May 1992
MED SCI SPORT EXER

Muscle blood flow is reduced with dehydration during prolonged exercise in humans

Article

Sep 2004
J PHYSIOL-LONDON

This is the first study to demonstrate significant reductions in blood flow to exercising skeletal muscle during prolonged exercise in humans. Previous studies in humans (Kirwan et al. 1987; Nielsen et al. 1990, 1993, 1997), rats (Laughlin & Armstrong, 1983) and miniature swine (Armstrong et al. 1987; McKirnan et al. 1989) have shown that blood flow to active muscles is either maintained or increased when heat stress is superimposed during exercise. This is in contrast to the significant reductions in blood flow to some exercising muscles found in sheep with heat stress (Bell et al. 1983). The main reason for the discrepancy might be that the heat stress used in human and most animal studies did not reduce cardiac output unlike the present study with dehydration and Bell et al. (1983). In previous human studies from this laboratory, it was shown that muscle blood flow in the working leg was not reduced compared with control values when heat stress was imposed during prolonged walking (Nielsen et al. 1990), knee-extension exercise (Savard et al. 1988) or moderate- and high-intensity bicycling exercise in the semirecumbent position (Nielsen et al. 1993, 1997). In all studies, the cardiovascular system responded adequately to the additional demand of an elevated skin blood flow by increasing cardiac output (1–3 l min−1) and possibly reducing splanchnic and renal blood flow as shown by others (Rowell et al. 1965, 1971; Ho et al. 1997). Further support for unaltered muscle perfusion in these previous studies was found in the observations that femoral a-vO2 difference, leg V̇O2 and lactate release were unchanged (Savard et al. 1988; Nielsen et al. 1990, 1993, 1997). The present design used upright, moderately intense prolonged exercise in the heat with the aim of taxing the cardiovascular system to the extent where cardiac output declines markedly (Sawka et al. 1979; Montain & Coyle, 1992; González-Alonso et al. 1995).

Effects of dehydration on isometric muscular strength and endurance

Article

Feb 1998
MED SCI SPORT EXER

To examine the effects of rapid dehydration on isometric muscular strength and endurance, seven men were tested at baseline (control) and after a dehydration (dHST) and a euhydration (eHST) heat stress trial. The dHST consisted of intermittent sauna exposure until 4% of body mass was lost, whereas the eHST consisted of intermittent sauna exposure (same duration as dHST) with water replacement. Peak torque was determined for the knee extensors and elbow flexors during three isometric maximal voluntary contractions. Time to fatigue was determined by holding a maximal voluntary contraction until torque dropped below 50% peak torque for 5 s. Strength and endurance were assessed 3.5 h after the HSTs (no food or water intake). Body mass was decreased 3.8+/-0.4% post dHST and 0.4+/-0.3% post eHST. Plasma volume was decreased 7.5+/-4.6% and 5.7+/-4.4%, 60 and 120 min post dHST, respectively. A small (1.6 mEq x L[-1]) but significant increase was found for serum Na+ concentration 60 min post dHST but had returned to predehydration level 120 min post dHST. Serum K+ and myoglobin concentrations were not affected by HSTs. Peak torque was not different (P > 0.05) among control, dHST, and eHST for the knee extensors (Mean (Nm)+/-SD, 285+/-79, 311+/-113, and 297+/-79) and elbow flexors (79+/-12, 83+/-15, and 80+/-12). Time to fatigue was not different (P > 0.05) among control, dHST and eHST for the knee extensors (Mean (s)+/-SD. 42.4+/-11.5, 45.3+/-7.6, and 41.8+/-6.0) and elbow flexors (48.2+/-8.9, 44.0+/-9.4, and 46.0+/-6.4). These results provide evidence that isometric strength and endurance are unaffected 3.5 h after dehydration of approximately 4% body mass.

Effects on man of restricted water-supply.

Article

Jan 1947

W S S LADELL

Hydration and muscular performance: Does fluid balance affect strength, power and high-intensity endurance?

Abstract and Figures

Recommendations

R.E.P.S

Resistance Exercise and Coagulation (REC) Study

Musculoskeletal Complaints and Repetition Number

F.A.S.T.E.R.

Fluid Balance and Endurance Exercise Performance

Hydration and Muscular Performance

Effect of Hydration State on Strength, Power, and Resistance Exercise Performance

The effects of progressive dehydration on strength and power: Is there a dose response?

Fluid needs for training and competition in athletics