What Do Athletes Drink During Competitive Sporting Activities?

REVIEW ARTICLE

What Do Athletes Drink During Competitive Sporting Activities?

Alison K. Garth • Louise M. Burke

Published online: 26 March 2013

� Springer International Publishing Switzerland 2013

Abstract Although expert groups have developed

guidelines for fluid intake during sports, there is debate

about their real-world application. We reviewed the liter-

ature on self-selected hydration strategies during sporting

competitions to determine what is apparently practical and

valued by athletes. We found few studies of drinking

practices involving elite or highly competitive athletes,

even in popular sports. The available literature revealed

wide variability in fluid intake and sweat losses across and

within different events with varied strategies to allow fluid

intake. Typical drinking practices appear to limit body

mass (BM) losses to *2 % in non-elite competitors. There

are events, however, in which mean losses are greater,

particularly among elite competitors and in hot weather,

and evidence that individual participants fail to meet cur-

rent guidelines by gaining BM or losing[2 % BM over the

competition activity. Substantial ([5 %) BM loss is noted

in the few studies of elite competitors in endurance and

ultra-endurance events; while this may be consistent with

winning outcomes, such observations cannot judge whether

performance was optimal for that individual. A complex

array of factors influence opportunities to drink during

continuous competitive activities, many of which are out-

side the athlete’s control: these include event rules and

tactics, regulated availability of fluid, need to maintain

optimal technique or speed, and gastrointestinal comfort.

Therefore, it is questionable, particularly for top competi-

tors, whether drinking can be truly ad libitum (defined as

‘‘whenever and in whatever volumes chosen by the ath-

lete’’). While there are variable relationships between fluid

intake, fluid balance across races, and finishing times, in

many situations it appears that top athletes take calculated

risks in emphasizing the costs of drinking against the

benefits. However, some non-elite competitors may need to

be mindful of the disadvantages of drinking beyond

requirements during long events. Across the sparse litera-

ture on competition hydration practices in other sports,

there are examples of planned and/or ad hoc opportunities

to consume fluid, where enhanced access to drinks may

allow situations at least close to ad libitum drinking.

However, this situation is not universal and, again, the

complex array of factors that influence the opportunity to

drink during an event is also often beyond the athletes’

control. Additionally, some competition formats result in

athletes commencing the event with a body fluid deficit

because of their failure to rehydrate from a previous bout of

training/competition or weight-making strategies. Finally,

since fluids consumed during exercise may also be a source

of other ingredients (e.g., carbohydrate, electrolytes, or

caffeine) or characteristics (e.g., temperature) that can

increase palatability or performance, there may be both

desirable volumes and patterns of intake that are indepen-

dent of hydration concerns or thirst, as well as benefits

from undertaking a ‘‘paced’’ fluid plan. Further studies of

real-life hydration practices in sports including information

on motives for drinking or not, along with intervention

studies that simulate the actual nature of real-life sport, are

needed before conclusions can be made about ideal

drinking strategies for sports. Different interpretations

may be needed for elite competitors and recreational

participants.

A. K. Garth (&) � L. M. Burke

Sports Nutrition, Australian Institute of Sport, Belconnen,

ACT 2617, Australia

e-mail: [email protected]

L. M. Burke

e-mail: [email protected]

Sports Med (2013) 43:539–564

DOI 10.1007/s40279-013-0028-y

1 Introduction

The major reason for drinking during sporting events is to

reduce the fluid deficit incurred through the loss of sweat.

Other considerations for consuming fluids during sporting

events lasting longer than *45 min includes the ingestion

of common drink ingredients known to enhance perfor-

mance such as carbohydrate [1], electrolytes [2] and caf-

feine [3], as well as the contribution of cool [4] or icy [5]

fluids to comfort and thermoregulation during exercise.

Guidelines for hydration practices in sport have evolved

from prescriptive recommendations to consume a certain

fluid volume during exercise [6] to the adoption of a

practiced and individualized plan that can partially replace

sweat losses as well as provide other ingredients or char-

acteristics previously mentioned [2, 7–9]. This advice is

not universally embraced, however; alternative views are

that ad libitum drinking is sufficient to address fluid needs

during sports or that thirst should dictate the need for, and

volume of, fluid replacement during exercise [10]. This

debate has led to dissention between scientists [10, 11] and

confusion among athletes.

It is beyond the scope of this review to discuss optimal

hydration strategies for sports or the effects of dehydration

on sports performance. However, to aid in the development

of a consensus of guidelines for fluid intake in sports, it

would be useful to have an up-to-date appreciation of the

self-selected fluid practices of athletes during competition.

Such data would provide information on what is apparently

practical and valued by athletes under real-life competition

conditions. When or if further investigation from other

sources leads to the development of new hydration guide-

lines that are theoretically optimal for sports performance,

knowledge of current strategies may help to identify groups

that could most benefit from a change in their practices and

an appreciation of the challenges that would need to be

addressed for change to occur.

Accordingly, the aim of this review was to summarize

the available data on fluid intake by competitive athletes

across different types of field-based sporting competition.

We divided sporting events into a series of categories based

on shared characteristics such as duration and intensity of

exercise, the environment of play, individual versus group

participation and cultural factors. Information of interest

from descriptive studies of competition behavior included

the pre-exercise hydration status of athletes, the type and

volume of fluid consumed during the competition, and

estimations of sweat rates and net fluid balance over the

session. We were interested to identify the factors influ-

encing fluid intake and sweat losses across a range of sports

with shared features. We limited our investigations to

competition situations since different factors influence fluid

balance considerations in training scenarios. A specific

interest was the degree to which fluids could be consumed

ad libitum, which is defined by the dictionary as

‘‘according to pleasure or desire’’ and operationally by us

as ‘‘whenever and in whatever volumes chosen by the

athlete.’’ We note that although the term ad libitum is often

used interchangeably with the phrase ‘‘drink to thirst,’’ the

difference between these behaviors is significant and merits

its own discussion [12].

2 Literature Search Methodology

We undertook a comprehensive literature search of studies

investigating voluntary fluid intake and sweat losses of

athletes during competition in field settings. We searched

the databases PubMed and GoogleScholar, using the search

fields ‘‘hydration,’’ ‘‘sport,’’ ‘‘sweat rates,’’ ‘‘competition,’’

‘‘fluid loss,’’ ‘‘fluid intake,’’ ‘‘fluid balance,’’ ‘‘dehydra-

tion,’’ ‘‘hyponatremia,’’ and ‘‘athletes.’’ We limited our

search to studies published since 1980 because of differ-

ences in culture, rules, and opportunities for fluid intake

during events prior to this time. Studies needed to at least

include information on fluid intake, body mass changes,

and/or sweat rates during the event using appropriate

methodologies to be accepted in our review. Data were

extracted from the fully reported studies in peer-reviewed

literature identified by our search, with additional studies

being located by cross-referencing from this literature.

Abstracts, single case studies, and unpublished data were

not included among the final information sources. The last

day of the search was 31 May 2012.

3 Summary of Fluid Balance During Sports Activities

We undertook a narrative examination of the literature

located by our search to identify the characteristics of

sweat loss and fluid intake during the different categories

of sporting events. By looking at the available data we

aimed to (1) summarize the number of studies that have

been conducted across sports within each category, with

the type and caliber of athletes involved; (2) note the

typical mean and range of values for sweat loss and vol-

untary fluid intake of athletes involved in these sporting

events; (3) identify where there is consistent evidence that

the match between fluid intake and sweat losses falls out-

side current guidelines [i.e., intakes that are excessive in

comparison to sweat losses leading to a gain in body mass

(BM) over the session or intakes that are less than sweat

losses so that the loss of BM is[2 %]; (4) identify specific

factors that impede or assist hydration practices in com-

petition activities with particular interest in opportunities to

drink and access to fluids; (5) note other influences on fluid

540 A.K. Garth, L.M. Burke

intake other than to address hydration needs, and finally (6)

identify the areas in which further data on fluid intake

during sporting events are needed. We divided sports into

groups that shared some key characteristics with regard to

nutritional needs and event logistics.

3.1 Single-Day Endurance Events

We defined endurance events as continuous sporting

activities of *45–180 min for the top competitors, typified

by the half marathon and marathon, Olympic distance tri-

athlon, road cycling time trial, 20 km race walking. An

unusual characteristic of these events is that elite and

recreational athletes often compete in the same race,

meaning that the event will include participants with a

large range of finishing times. Indeed, the increased num-

bers of recreational participants have skewed event com-

pletion times. For example, the 1978 New York City

Marathon had 8,588 participants with 80 % finishing the

course in\4.5 h (9.4 %\3 h) [8]. In comparison, the same

event in 2001 had 23,651 competitors with only 2.4 %

finishing in \3 h and the majority (78 %) finishing

between 3.5–5.5 h [8]. Nevertheless, we will consider all

competitors in such sports to have competed in an endur-

ance event.

As in all sports, the rates and total volume of sweat loss

vary with the intensity and duration of the event, with

potential for large differences between athletes, even those

in the same race. The outdoor setting increases the poten-

tial for large differences in sweat losses between events of

the same type, according to specific characteristics such as

the event terrain and environmental conditions (heat,

humidity, altitude, wind, etc.). In some cases, these aspects

can change markedly over the duration of the same event.

In addition to addressing hydration issues, fluids consumed

during endurance races may be a major source of carbo-

hydrate and caffeine, both of which can enhance perfor-

mance of sporting activities of this type [3, 13].

A key characteristic of the hydration opportunities in

endurance events is that athletes must drink while ‘‘on the

move.’’ Access to fluids during the majority of events is

typically governed by a network of drink stations/feed

zones, although this can be supplemented or replaced in

other endurance sports by the transport of fluids by the

individual athlete. Elite athletes are often able to provide

their own specific race supplies at aid stations, while in

mass participation events, the provisions at feed stations

available to general competitors are governed by the race

organizer. Opportunities to drink must consider the time

lost in obtaining and consuming fluid and the potential for

gut discomfort due to drinking while exercising at rela-

tively high intensities. Practicing drinking during event-

simulating training sessions may facilitate the development

of appropriate skills and gut tolerance in some athletes.

Devices such as fluid-containing backpacks and spill-proof

bottles may also enhance access to fluid and opportunities

to drink during some endurance sports. However, in other

sports, technique requirements such as bike handling dur-

ing downhill mountain bike riding or maintaining an

aerodynamic position during road cycling time trials may

interfere with opportunities to obtain or consume fluids.

Similarly, pacing strategies and race tactics may interfere

with the athlete’s opportunities to drink. Some endurance

athletes may deliberately or subconsciously restrict fluid

intake during events in the belief that accrual of a fluid

deficit may enhance performance, particularly in hilly ter-

rain, because of the effect of a lower BM in increasing the

economy of movement and improving the power-to-weight

ratio [14]. Finally, fluid intake by some endurance athletes

may be driven by their desire to consume other ingredients

found in everyday drinks or specialized sports beverages

such as carbohydrate, caffeine, and electrolytes, or by the

desire to regulate body temperature via the intake of cool

drinks.

Despite the range and popularity of endurance sports in

both elite and mass participation formats, our literature

search located only nine studies providing information on

fluid intake during competition in these events [15–23].

Each involved distance running (eight studies of the mar-

athon and one of the half marathon) and typically included

competitors of mixed and sub-elite caliber. The data from

these studies are presented in Table 1, although in the case

of studies where the ‘‘pre-race’’ BM value was collected at

registration 1–3 days prior to the race, we excluded

information on BM change over the race from this sum-

mary. Such a methodology provides a spurious estimate of

the acute change across the event itself, although it has

been suggested as a means to control for BM gain asso-

ciated with carbohydrate loading and thus provide a more

accurate reflection of body fluid changes [24].

We note that the only available information on fluid

intake by elite marathon runners were gathered by an

innovative but largely unvalidated technique of retrospec-

tively examining television footage of the behavior of the

leading runner(s) at the race drinking stations at the 2004

Athens Olympics [23] and at 13 Olympic or big city

marathons [22]. Video analysis of the duration of time in

which a bottle or cup was held to the mouth, together with

a calculation of flow rate from drink bottles derived from

laboratory simulations, was used to estimate fluid intake at

the drinking stations that were included in the footage;

these results were then extrapolated to the ‘‘missing’’

drinking stations to estimate fluid consumption over the

whole race. Since these data were collected from world

class marathon runners, they are important to consider, but

must be treated with appropriate caution. Indeed, all fluid

Fluid Balance During Competitive Sporting Activities 541

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balance data collected in field conditions are likely to

involve some inaccuracies since even simple measure-

ments such as weighing individuals and weighing or

recording the volume of fluids consumed from known

containers can be compromised because of the conditions

or requirements of competition.

Our analysis of the summarized data in Table 1 shows

that observations of endurance events involving mixed-

caliber fields have been limited to events conducted in mild

to warm conditions (9–24 �C). Studies in which data were

collected immediately pre- and post-race showed that the

typical change in BM across the event was a deficit of

*1–2 %. However, where information on the spread of

BM changes within the subject population was provided

[16, 17, 19–21], it showed that the experiences of indi-

vidual runners spanned a deficit of [2 % BM to a gain in

mass. Indeed, in the study that involved the largest number

([600) of participants, individual BM changes over the

marathon ranged from -8 to ?5 % [17]. The authors of

this study commented that the chief drivers of hydration

practices were biological and behavioral influences since

all participants received the same race day advice to con-

sume 250 ml fluid every 20 min. However, as the aid

stations were placed 5 km apart, the variation in race times

means that some competitors would have been unable to

adhere to this recommendation; therefore, it is not possible

to draw this conclusion. The authors also noted a rela-

tionship between finishing time and BM losses with the

faster runners incurring a greater fluid deficit. However,

since BM change only accounted for 4.7 % of the variance

in race time, its relationship is clearly complex.

A focus of five of the studies in this category was the

monitoring of changes in blood sodium concentrations over

the event; this relates to interest in the development of

hyponatremia during sporting activities. The incidence of

biochemical hyponatremia, defined as a blood sodium

concentration \135 mmol/l, ranged between 0–28 % in

these papers; however, no cases were reported to be clin-

ically symptomatic [15, 16, 18–20]. Several studies noted

differences in drinking behavior between the group that

was characterized as normotremic and those who devel-

oped asymptomatic hyponatremia [15, 20]. In one case,

mean fluid intakes of 400 and 800 ml/h and a mean loss

and gain of BM differentiated the normotremic and hyp-

onatremic runners respectively [15], while differences in

the other study were lower fluid intakes (19 vs. 32 ‘‘cups’’)

and greater overall BM losses from pre-race registration to

post-race (1.6 vs. 0.14 kg) [20]. Both studies failed to find

a relationship between fluid intake and finishing time,

although it is noted that the finish times of participants

indicated that all were recreational runners.

It is important to briefly acknowledge limitations in the

common methodologies of field-based fluid balanceTa

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studies; these prevent a direct translation of BM changes

during competition into absolute measures of hydration

status or even changes in hydration status over an event,

particularly during longer endurance sports and ultra-

endurance events. First, studies typically fail to measure or

account for pre-race hydration status of subjects. In prac-

tice, many athletes increase fluid intake in the day(s) lead-

ing up to the race to ensure euhydration or in some cases

achieve hyperhydration [25, 26]; this can subsequently

increase pre-race BM and may overestimate the level of

true dehydration from BM change alone (i.e., the hyper-

hydrated individual may incur sweat losses greater than

fluid intake during exercise before reaching a ‘‘baseline’’

BM or hydration status). During longer exercise, the uti-

lization of substantial amounts of body fat and carbohy-

drate also contributes to body mass change during exercise,

and during prolonged exercise production of metabolic

water and the liberation of water bound to glycogen may

also affect fluid balance [27]. Indeed, some researchers

have tried to identify the change in body mass equivalent of

‘‘no net fluid loss’’ during endurance and ultra-endurance

activities as the point at which there is no change in serum

sodium concentrations [20, 28]. However, this is also likely

to oversimplify the situation since such an observation is

also influenced by electrolyte losses in sweat and urine, as

well as fluid/electrolyte shifts between body compartments.

Analysis of the hydration practices of top marathon

runners from extrapolations of their videotaped behavior at

drinking stations requires careful interpretation because of

the unconventional methodologies, but nevertheless pro-

vides some interesting information. The footage revealed

that they spent a total of 2–51 s [22, 23], representing less

than 1 % of race time, engaged in drinking activities. The

estimated (maximum) intake of fluid by male marathon

winners, the majority of which are likely to be East African

athletes, was claimed to be an average of 550 ± 340 ml/h

with a range of 30–1,090 ml/h [22]. There were no corre-

lations between fluid intake and either ambient conditions

or running speed among these observations. Indeed, in

similar environmental conditions, runners can behave dif-

ferently in different races as illustrated by the athlete who

ran the Berlin marathon in 2006 (12 �C) and 2008 (16 �C)

with an estimated fluid intake of 1,839 ml for the first year

(2:03:59 finishing time) and 1,098 ml for the second

(2:06:08). Specific investigation of this runner during the

2009 Dubai marathon has gained attention: the authors of

the study estimated that in moderate conditions (16 �C,

54 % humidity) he consumed 1,735 ml of fluid (830 ml/h)

of a 16 % carbohydrate drink (carbohydrate intake of

133 g/h) and recorded a BM change of 5.7 kg over the

race; this suggested a sweat rate of 3.6 l/h and an incurred

fluid deficit of 9.8 % BM [22]. Indeed, significant loss of

BM was likely to have occurred in the case of all winners

of the observed marathons in this study. However, caveats

over the magnitude and the necessity of such fluid losses

are necessary: possibly erroneous fluid intakes were esti-

mated at only 63 % of drink stations; hence, extrapolated

fluid intake combined with limitations in the use of body

mass changes to measure fluid changes during prolonged

exercise mean that the results cited in this study may not

reflect true levels of dehydration or sweat loss. Further-

more, observational studies are unable to make judgements

about whether practices are harmful or helpful to the

individual.

In summary, the current literature on fluid balance in

real-life endurance sports is sparse and not reflective of the

range of sporting events in which there is large participa-

tion or even scientific interest (e.g., hyponatremia in mar-

athons). Clearly, there is a public health need to continue to

collect data on recreational athletes who may be at risk of

hyponatremia from over-hydrating before and during

events. However, to comprehensively understand fluid

intake during competition, it would be useful to further

examine elite athletes who are influenced by different

conditions and considerations. Such factors include greater

rewards for performance, potentially greater opportunities

for individual race support, and higher racing speeds,

which may further limit opportunities for drinking or risks

of gut discomfort. Tactical considerations in which runners

may use the feed zone as a time for a surge or breakaway

may also influence fluid intake. There is also interest in

cultural differences in drinking practices since observations

on the East African runners suggest a background of low

habitual drinking during exercise [29]. Finally, information

on the type and temperature of drinks chosen during

endurance events is topical in view of the impacts of these

on palatability and voluntary intake; in addition a desire by

athletes to consume carbohydrates and caffeine during such

sports may contribute to the pattern and volume of fluid

intake.

3.2 Single-Day Ultra-Endurance Events

We classified ultra-endurance events as those in which the

top competitors finish in [3 h; this includes ultra-mara-

thons, 50-km race walking, many cycling road races, and

half Ironman and Ironman triathlons. Many of these events

also involve mass participation with a mixture of elite to

recreational competitors and share the characteristics of

endurance sports with regard to opportunities for fluid

intake during the event. Again, the outdoor environment

creates large variability in factors influencing sweat rates,

even within the same individual in the same race, since the

greater duration and distance covered in the event allow for

greater variability in factors such as terrain and tempera-

ture. Since the intensity of the event is reduced compared


with endurance events, sweat rates are theoretically lower

and there may be increased opportunity for fluid intake.

However, the extended duration of the race may also

increase the absolute fluid deficit or gain if there is a

mismatch between sweating and fluid intake. Guidelines

for race nutrition during ultra-endurance events [13], which

promote high rates of carbohydrate intake (up to 80–90 g/h),

may also contribute to the timing and volume of fluid

intake since carbohydrate-containing fluids can contribute

substantially to meeting these goals. For example, Speedy

et al. reported that * 2/3 of the fluid consumed by Ironman

triathletes contained carbohydrate (sports drink, cola

drinks) [30] and can contribute *50 % of the carbohydrate

consumed during the race [31].

Our literature search located 25 studies of ultra-endur-

ance events involving running [16, 32–41], cycling [42–

44], and multisport combinations conducted over a single

day [24, 27, 28, 30, 45–51] (Table 2). All involved a mixed

caliber of male and female competitors. Events spanned

5–24 h and a range of environmental conditions from cool

(8 �C) to hot (38 �C), although most races involved tem-

perate conditions. Again, many investigations were focused

on the incidence of hyponatremia, which occurred in

0–51 % of the study participants and occurred mostly in

asymptomatic forms. Overall, mean weight loss over the

race ranged from 1.5–5.2 % BM; information on standard

deviations within subject populations suggest that indi-

vidual outcomes spanned a loss of [7 % to a gain of 5 %

BM. Correlations between sweat loss and finishing time

were unclear, with faster athletes recording a greater total

loss of BM over the race in some studies [32, 33] while the

slowest athletes reported greatest losses in others [47]. As

in the endurance events, weight gain was associated with

hyponatremia [30, 47] particularly in the case of severe

decreases in serum sodium concentrations. However,

hyponatremia was also reported in individuals who main-

tained [50] or even lost BM [30, 47] including substantial

changes of a 9 % BM loss [30]. Thus, the etiology of

hyponatremia is complex.

Observations of fluid intake during ultra-endurance

events noted mean intakes ranging from 300–1,000 ml/h

with large individual variations in these rates. Factors

contributing to differences in fluid intake include the mode

of activity: greater rates of intake were typically observed

during cycling activities (400–900 ml/h) than running

events (300–700 ml/h). Although this finding may also

reflect individual behaviors as well as differences in other

conditions or requirements between events, evidence from

multisport events also supports differences in drinking

practices between different types of exercise. For example,

observations from an Ironman triathlon showed a mean BM

loss in the swim and run legs; however, greater fluid

intakes were seen during the bike segment relative to both

fluid intake during the other legs and concurrent sweat

losses, leading to net BM gain while cycling [30]. This

finding has been attributed to both greater access to fluid

(provided at drink stations and also carried on the bike) and

greater opportunities (ease) of drinking while riding.

However, it is also explained by the cumulative effects of

the race and the athlete’s total nutrition plan; the observed

‘‘over-drinking’’ on the bike may be beneficial in restoring

the fluid deficit or addressing thirst incurred during the

swim or ‘‘protecting’’ the athlete from a subsequent fluid

deficit on the run, as well as providing high rates of car-

bohydrate intake for a substantial portion of the total race.

Another factor that appears to contribute to fluid intake

is the frequency of access to drinks. This may be influenced

by the number or spacing of drink stations during an event.

Compared to the previous year’s race, an increased spacing

of drink stations in an Ironman triathlon held in temperate

conditions (from 12 km to every 20 km on the cycle course

and from 1.8 to 2.5 km on the marathon) was associated

with a reduced incidence of hyponatremia in those seeking

medical care from 22 to 3 % of race entrants and the

abolition of weight gains [1 % BM [52]. This may be

useful in controlling the issue of over-hydration in slower,

recreational level athletes or during events in cool weather.

In the case of more serious athletes, however, it reduces the

flexibility to choose how often and when they will drink

during a race (i.e., true ad libitum drinking) and neglects

the influence of race tactics on determining when the ath-

lete is able to make use of drink stations. Another factor

that may influence access to fluids in some races is the

opportunity for athletes to carry their own supplies or to

have access to a support crew. One study noted that the

faster athletes in a race consumed more from personal

supplies compared to the slower competitors in the race

[34]. In summary, although there are more studies on fluid

balance in ultra-endurance sports, across a greater range of

events, than in endurance sports, the scarcity of investi-

gations of elite athletes is again noted.

3.3 Fluid Balance in Multi-Day Ultra-Endurance

Events

Sports such as cycling, mountain biking, running, and

single or multisport adventure racing include multiday

competition formats with events lasting from 2 days to

3 weeks. Events can be further divided into those in which

competitors are required to complete the course in a con-

tinuous manner of their own choosing, where the periods

taken to sleep or eat are included in the finishing time, and

those in which competitors complete a number of stages

each day with these individual performances accumulating

to produce the final results. Access to nutritional support

may come from a variety and combination of sources


Ta

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2F

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bal

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)

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139.8

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)

139.8

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)

139.6

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[59]

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]

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including self-sufficiency, official feed zones, sporadic

checkpoints for supplies and assistance from the team

support crew. The determinants of sweat losses and fluid

intake vary as discussed in the previous section on single-

day endurance and ultra-endurance sports, with the addi-

tional challenges that intake during the event may need to

contribute to substantial requirements for fluid, carbohy-

drates, and energy over the duration of the whole event and

that deficits from 1 day may carry over to the next. With

such variability between the conditions and requirements

of such events, we might expect some difficulty in finding

universal themes.

Our literature search yielded seven studies [53–60]

providing observations from ten separate multiday events,

including four involving elite cyclists of international

caliber (Table 3). One event involved a continuous road

cycling format, while the others involved road cycling,

mountain biking, or ultra-running activities with one or

more stages each day. Environmental conditions ranged

from cold (4 �C) to hot (32 �C), sometimes within the

same event. Studies reported mean BM changes across a

competitive stage ranging from 0.2–3 % BM, with the

likelihood that elite athletes recorded a fluid deficit

exceeding 3 % BM in hot weather races [54]. Mean fluid

intakes across stages varied between studies from

300–1,000 ml/h. Indicators of day-to-day hydration status,

such as observations of on waking urine samples or

maintenance of early morning BM, suggested mild dehy-

dration to general fluid restoration [56, 57, 60].

Several of these studies provided insights into the

determinants of fluid intake during the competitive activ-

ity. First, the format of a cycling race was seen to influence

fluid intake, with road cyclists drinking less during crite-

rium and individual time-trial formats than road races [60].

This observation was explained by the briefer length of the

race as well as reduced access to fluids (lack of feed zones)

and opportunity to drink (the conflict between taking time

to drink and the need to ride aggressively or in a stream-

lined position). However, it was also noted that the rules

and culture of road cycling have evolved to promote

greater opportunities for fluid and energy intake during the

road race format. In addition to feed zones in which all

cyclists can obtain food and fluid supplies from their

support crews, designated riders within a cycling team

(‘‘domestiques’’) assume a role of ferrying food and drinks

supplies from the team car throughout the race to the

cyclists who are in contention to win [60]. Despite activ-

ities designed to increase access to fluid during road races,

several papers noted obstacles to opportunities for drink-

ing. These included the need to keep hands on the han-

dlebars during steep ascents and descents in road cycling

[54, 60] or difficult terrain in mountain biking [57], as well

as aggressive riding tactics and the ‘‘breakaway’’ wherebyTa

ble

2co

nti

nu

ed

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)aE

nvir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s

(%)a

Flu

idin

take

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

Knec

htl

eet

al.

[44]

37

M

Tra

ined

mix

ed

cali

bre

Sw

iss

MT

B

bik

em

aste

rs

120

km

540

±80

Air

:11

(at

star

t)

Hum

idit

y:

NR

NR

-1.9

±1.6

c0.7

±0.2

1.0

10

±0.0

07

1.0

14

±0.0

07

138.3

±2.1

137.3

±1.5

NR

USG

uri

ne

spec

ific

gra

vit

y,

PR

Epre

-exer

cise

,P

OST

post

-exer

cise

,[N

a?

]blo

od

sodiu

mco

nce

ntr

atio

n(m

mol/

l),

EA

Hex

erci

se-a

ssoci

ated

hyponat

rem

ia,

Mm

ale,

Ffe

mal

e,N

/Adat

aex

cluded

from

the

table

bec

ause

of

use

of

inap

pro

pri

ate

met

hodolo

gy,

NR

not

report

ed,

CR

cram

p,

NC

no

cram

p,

Nor

norm

otr

emic

,R

xre

ceiv

edm

edic

altr

eatm

ent

for

any

condit

ion,

NR

xno

med

ical

trea

tmen

tre

ceiv

ed,

2d

2day

spri

or

tora

ceday

,0d

race

day

aD

ata

are

report

edas

mea

n±

SD

(if

pro

vid

ed)

unle

ssoth

erw

ise

stat

ed

bIn

ciden

ce(%

)of

exer

cise

-ass

oci

ated

hyponat

rem

ia.

Val

ue

inbra

cket

sre

fers

toth

enum

ber

of

case

sth

atw

ere

sym

pto

mat

ic

cS

pec

ific

pre

-rac

eti

me

not

spec

ified

but

pre

sum

edto

be

wit

hin

2h

of

race

star

t


Ta

ble

3F

luid

bal

ance

char

acte

rist

ics

of

mu

ltid

ayst

age

even

ts

Stu

dy

Su

bje

cts

Ev

ent

Du

rati

on

(min

)aE

nv

iro

nm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)aD

Bo

dy

mas

s

(%)a

Flu

idin

tak

e(l

/

h)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)aE

AH

case

sb

Ro

ad

cycl

ing

Ro

ss etal

.

[60

]

5M

Eli

teA

ust

rali

an

Nat

ion

alR

oad

Ser

ies

(NR

S)

team

To

ur

of

Gip

psl

and

(NR

Sst

age

race

)

9st

ages

ov

er

5d

ays

Air

:

15

.8±

1.4

Hu

mid

ity

:

54

±1

2

1.1

±0

.3-

1.5

±0

.3

(ro

ad)

-1

.1±

0.2

(cri

t)

0.4

1±

0.1

9

(ro

ad)

0.2

4±

0.1

9

(cri

t)

1.0

23

±0

.00

6

(dai

ly)

NR

NR

NR

NR

Ro

ss etal

.

[60

]

5M

Eli

teA

ust

rali

an

Nat

ion

alR

oad

Ser

ies

team

To

ur

of

Gee

lon

g

(NR

Sst

age

race

)

6st

ages

ov

er

5d

ays

Air

:

13

.2±

2.1

Hu

mid

ity

:

80

±8

0.5

6±

0.1

4

(ro

ad)

0.2

7±

0.2

1

(cri

t)

1.0

17

±0

.00

5

(dai

ly)

NR

NR

NR

NR

Ru

st etal

.

[53

]

65

M

Tra

ined

mix

ed

cali

bre

Sw

iss

cycl

ing

mar

ath

on

72

0k

min

*3

day

s

1,7

73

±2

61

Air

:9

–2

5

Hu

mid

ity

:

NR

NR

-1

.5±

1.7

c,d

0.6

7±

0.2

31

.01

3±

0.0

01

(day

1)

1.0

19

±0

.00

1

(day

3)

13

7.4

(day

1)

13

7.6

(day

3)

0

Eb

ert

etal

.

[54

]

8M

Eli

tep

rofe

ssio

nal

team

To

ur

do

wn

un

der

71

9k

min

6d

ays

NR

Air

:

20

.2–

32

.9

Hu

mid

ity

:

14

–6

9

1.6

0±

0.1

0-

2.8

c1

.00

±0

.10

NR

NR

NR

NR

NR

Eb

ert

etal

.

[54

]

6F

Eli

te Au

stra

lian

nat

ion

alsq

uad

To

ur

De

L’A

ud

e

78

8k

min

10

day

s

NR

Air

:7

.7–

27

.8

Hu

mid

ity

:

29

–7

6

0.9

0-

2.6

c0

.40

±0

.06

NR

NR

NR

NR

NR

Gar

cia-

Ro

ves

etal

.

[55

]

10

M

Eli

tep

rofe

ssio

nal

team

39

24

hp

erio

ds

du

rin

gth

e

3-w

eek

tou

ro

f

Sp

ain

NR

NR

NR

NR

1.2

6±

0.5

5ld

=1

.03

l/h

W=

0.2

3l/

h

SD

NR

NR

NR

NR

NR

Mo

un

tain

bik

ing

(MT

B)

Ro

se etal

.

[56

]

18

M

Tra

ined

mix

ed

cali

bre

San

i2C

MT

Bra

ce

24

8k

mo

ver

3

stag

es

42

6 (sta

ge

1)

36

6 (sta

ge

2)

25

8 (sta

ge

3)

Air

:9

–2

2

Hu

mid

ity

:

43

–1

00

Rai

nst

age

1

NR

-1

.4

(sta

ge

1)

-2

.0

(sta

ge

2)

-1

.0

(sta

ge

3)

0.3

4(s

tag

e1

)

0.4

1(s

tag

e2

)

0.5

5(s

tag

e3

)

1.0

18

(sta

ge

1)

1.0

25

(sta

ge

3)

14

1 (sta

ge

1)

14

0 (sta

ge

3)

0

Sch

enk

etal

.

[57

]

25

M

Tra

ined

mix

ed

cali

bre

Tra

nsa

lpM

TB

66

5k

min

8

stag

es

38

3±

55

cA

ir:

4–

32

Hu

mid

ity

:

NR

Rai

nst

age

2,

3,

8

NR

-0

.17

to

-1

.44

c0

.49

to0

.75

d

(ran

ge)

NR

NR

NR

NR

0


the lead rider is distant from the support of the domestiques

[54, 60].

Fluid intake has been correlated to both the temperature

at the start of the stage [57] and the duration of the stage

[60], while there are reports of both a negative correlation

between the finishing time within a stage and fluid intake

or level of deficit [54] as well as a lack of association or

even positive correlation between success in a race and

fluid intake/body mass maintenance [60]. It is intuitive at

one level that the fastest athletes in a race might incur the

greatest fluid deficit [54, 61] as a result of a higher sweat

rate, less opportunity to obtain or drink fluids at high speed,

and less inclination to lose time or risk gastrointestinal

upset due to drinking during high intensity exercise.

However, a complex range of factors differentiates the

faster and slower competitors in an event, and other factors

that are peculiar to a sport may change this relationship.

For example, in one cycling study, the fastest competitors

within each stage were shown to have incurred the smallest

losses of BM [60]. This was explained by the team tactic in

road cycling whereby cyclists who are deemed to have the

best chance of winning spend much of the race riding

within the slipstream of the peloton or their team mates,

thus reducing their power outputs (and sweat rates) while

allowing them to achieve greater intakes of fluid and

energy. Further studies on such events, including those

involving elite competitors, may provide further insights

into cultural, behavioral, and logistical determinants of

fluid intake.

3.4 Outdoor Team Sports

Team sports enjoy the highest participation rates of any

sporting activities in the world as well as lucrative rewards

for success in professional codes. Popular outdoor sports

include the various codes of football (soccer, rugby union,

rugby league, American, Australian), field hockey,

lacrosse, cricket, baseball, and softball. Sweat rates are

underpinned by intermittent high-intensity work patterns,

which are variable and unpredictable between and within

sports. Even from match to match, the same player can

experience different workloads (and sweat losses) due to

different game demands, changing playing times due to

substitutions, and substantial differences in total match

duration due to periods of overtime that compensate for

times when the ball is out of play or decide the outcome of

tied matches. Fluid losses are also affected by the wide

variety of climates and altitude of outdoor environments in

which team sports are played and in some sports the

requirement to wear heavy and impermeable protective

clothing. Depending on the competition format (weekly

fixtures, road trips of multiple games or tournament for-

mats), there may sometimes be less than 24 h betweenTa

ble

3co

nti

nu

ed

Stu

dy

Su

bje

cts

Ev

ent

Du

rati

on

(min

)aE

nv

iro

nm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)aD

Bo

dy

mas

s

(%)a

Flu

idin

tak

e(l

/

h)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)aE

AH

case

sb

Ult

ra-r

un

nin

g

Sin

gh

etal

.

[58

]

5M

,7

F

Tra

ined

mix

ed

cali

bre

Th

ree

cran

es

chal

len

ge

95

km

trai

lru

n

ov

er3

stag

es

25

8±

66

cA

ir:

11

.5–

22

.8

Hu

mid

ity

:

54

–9

7

NR

-3

.1d

(-2

.06

±

0.5

7k

g)

NR

NR

NR

NR

NR

NR

Kn

ech

tle

etal

.

[59

]

25

M

Tra

ined

mix

ed

cali

bre

Sw

iss

Jura

Mar

ath

on

35

0k

min

7

stag

es

37

3±

50

Air

:n

ot

stat

ed

Hu

mid

ity

:

NR

NR

-1

.4±

2.0

c,e

0.5

4–

0.7

5e

(ran

ge)

1.0

16

(day

1)

1.0

24

(day

7)

13

7.6

±1

.41

37

.7±

2.2

0

US

Gu

rin

esp

ecifi

cg

rav

ity

,P

RE

pre

-ex

erci

se,P

OS

Tp

ost

-ex

erci

se,[N

a?

]b

loo

dso

diu

mco

nce

ntr

atio

n(m

mo

l/l)

,E

AH

exer

cise

-ass

oci

ated

hy

po

nat

rem

ia,M

mal

e,F

fem

ale,

NR

no

tre

po

rted

,ro

ad

road

race

stag

e,

crit

crit

eriu

mra

cest

age,

Ww

ater

,S

Dca

rbo

hy

dra

te–

elec

tro

lyte

spo

rts

dri

nk

aD

ata

are

rep

ort

edas

mea

n±

SD

(if

pro

vid

ed)

un

less

oth

erw

ise

stat

edb

Inci

den

ce(%

)o

fex

erci

se-a

sso

ciat

edh

yp

on

atre

mia

.V

alu

ein

bra

cket

sre

fers

toth

en

um

ber

of

case

sth

atw

ere

sym

pto

mat

icc

Sp

ecifi

cp

re-r

ace

tim

en

ot

spec

ified

bu

tp

resu

med

tob

ew

ith

in2

ho

fra

cest

art

dP

erst

age

eT

ota

lev

ent


matches, with players carrying a fluid deficit (and/or fuel

depletion) from one match to the next.

Opportunities to drink during team sports include breaks

in the game that are both predetermined (e.g., between

official periods) or impromptu (e.g., timeouts, substitu-

tions), with team infrastructure organizing access to fluids

at such occasions. Although rules vary between sports,

opportunities to drink are increased when officials are

permitted to take drinks on-field or to the side of the field to

players who are not directly involved in play. When official

rules dictate that drinks are limited to the warm-up and

half-time break (e.g., between the 45-min periods of play in

soccer), there is little opportunity for ad libitum drinking.

Heat policies also exist for some team sports whereby

options such as increasing fluid carriers to run fluids to

players, additional breaks in play or extending breaks

between periods of play can improve opportunities to

consume fluids in extreme conditions [62, 63]. The provi-

sion of individual drink bottles for each player supports

better hygiene practices and may enhance access to fluid as

well as increase awareness of total fluid intake. Interest in

consuming carbohydrates [1] or caffeine [3] during the

warm-up and match by drinking fluids providing a source

of these substances may also influence hydration practices.

While there was an old culture in some team sports to

deliberately withhold fluids to ‘‘toughen a player’’ [64], a

newer belief, at present only underpinned by anecdotal

support rather than rigorous evidence, is that intake of

sodium-containing fluids may address the problem of

whole body cramps in some susceptible individuals [65]. In

some team sports, there is also a culture of intravenous

rehydration immediately before or between periods of play

within a game [66], although this may not be permitted

under anti-doping codes that govern other sports [67].

The current literature, summarized in Table 4, includes

match data from soccer; eight data sets, ranging from the

elite junior level to the highest level professional league

matches [68–73], rugby league; data from two professional

teams over a competition season [74], rugby union; one

data set from a junior elite level match [75], cricket; one

data set from sub-elite grade play [76] and beach volley-

ball; one data set from a 3-day tournament of mixed level

players [77]. Of these, only one study involved female

players (junior elite soccer players) [72]. Environmental

conditions that have been studied range from cool (6–8 �C)

to hot (31–35 �C) weather. Several studies that included a

test of pre-game hydration status in conjunction with fluid

testing found that a subset of players reported on match day

with urine samples consistent with dehydration [69, 70].

Studies of male team sports typically found mean sweat

rates [500 ml/h across all weather conditions, with cases

of sweat rates [1,500 ml/h during matches played in hot

conditions [69, 73, 77]. Mean fluid intakes ranged from

300–800 ml/h across sports, although in games where the

highest mean sweat rates were recorded, and mean fluid

intakes were *1,000 ml/h. Overall, mean BM changes

over a match ranged from *1–1.5 % in cool to warm

conditions to [2 % BM in cases of soccer and cricket

played in hot conditions. Where studies reported ranges in

BM changes over a match, there were instances where this

exceeded 4 % BM in individual players [69, 70, 76]. There

were few data on the choice of fluid intake during matches,

although one study reported that the total volume of fluid

consumed by players was not different when they were

provided with sports drink and water compared with water

alone [69].

In summary, the existing data on fluid balance during

team competitions are few in number but include several

observations from matches played by elite and professional

players from several sports. However, more data are nee-

ded before a clear pattern can be established for any sport,

with observations modified by caliber, age, and sex. Future

studies should include a greater range of sports and their

various permutations of conditions and participants. It

would also be useful to note the types of drinks (or other

products) contributing to match intake and to note the

conditions under which fluids were available. This would

help to determine the importance of scheduled versus ad

hoc opportunities for fluid intake on total hydration

practices.

3.5 Indoor Team Sports

Popular team sports played in indoor arenas include bas-

ketball, volleyball, netball, and futsal. These sports share

the characteristics of outdoor team sports in relation to the

high intensity intermittent work patterns, unpredictable

game characteristics from one match to the next, and both

predetermined and impromptu breaks in play. These breaks

typically provide good opportunities to drink, with players

having rapid access to drinks that are kept court-side. There

are several features of indoor team sports, however, that

merit special attention. The first is that the smaller court

size changes the work-to-rest ratios of intermittent indoor

sports compared to field-based sports, and there is a con-

siderable energy cost associated with acceleration, decel-

eration, and changes in direction. Therefore, seemingly

small game demands can be quite energy-demanding and

associated with high sweat rates. Secondly, the air-condi-

tioned or controlled environment of the arena can provide

temperature conditions that are different to the outside

weather; this means that there is less difference between

sweat losses and hydration demands of sports played in

summer seasons versus winter seasons than in field sports.

There are few studies of the hydration characteristics of

competitive matches in indoor team sports (Table 4), with


Ta

ble

4F

luid

bal

ance

char

acte

rist

ics

of

oth

ersp

ort

s:te

am,

rack

et,

aqu

atic

,‘‘

on

wat

er,’’

win

ter,

and

mo

tor

spo

rts

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)a

Envir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s(%

)a

Flu

id

inta

ke

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

Ou

tdoor

team

sport

s

Footb

all

(socc

er)

Da

Sil

va

etal

.[6

8]

10

M

Eli

teyouth

(Bra

zil)

Mat

ch110

cA

ir:

31.2

±2.0

Hum

idit

y:

48

*1.2

2-

1.6

±0.8

*0.6

11.0

21

±0.0

04

NR

NR

NR

NR

Mohr

etal

.

[73]

20

M

Pro

fess

ional

(Spai

n)

Mat

ch110

cA

ir:

31.2

–31.6

Hum

idit

y:

NR

1.7

5-

2.0

0.9

81.0

24

NR

NR

NR

NR

Kurd

ak

etal

.[6

9]

22

M

Clu

ble

vel

(Turk

ey)—

team

sA

and

B

Mat

ch1

A(W

)

B(W

)

90

Air

:34.3

±0.6

Hum

idit

y:

64

2.1

0(A

)

2.1

0(B

)

-1.9

±0.9

(A)

-2.5

±0.9

(B)

1.2

2(A

)

0.9

8(B

)

1.0

12

±0.0

06

(A)

1.0

12

±0.0

08

(A)

NR

NR

NR

Mat

ch2

A(W

)

B(W

?S

D)

90

Air

:34.4

±0.6

Hum

idit

y:

65

2.1

0(A

)

2.0

0(B

)

-2.2

±0.9

(A)

-2.6

±0.9

(B)

1.0

0(A

)

0.8

9(B

)

1.0

10

±0.0

06

(B)

1.0

06

±0.0

03

(B)

Ara

gon-

Var

gus

etal

.[7

0]

17

M

Cost

aR

ica

Pre

mie

rD

iv.

Mat

ch180

cA

ir:

34.9

±1.2

Hum

idit

y:

35

1.4

8±

0.3

6-

3.4

±1.1

0.6

51.0

18

±0.0

08

NR

NR

NR

NR

Mau

ghan

etal

.[7

1]

29

M

Engli

shP

rem

ier

Lea

gue

Tea

mA

(A);

n=

9

Tea

mB

(B);

n=

11

Subst

itute

s(S

u);

n=

9

Mat

ch96

dA

ir:

6–8

Hum

idit

y:

50–60

1.0

9(A

)

1.0

1(B

)

0.2

6(S

u)

-0.9

±0.7

(A)

-1.3

±0.6

(B)

-0.1

±0.5

(Su)

0.6

8(A

)

0.4

3(B

)

0.4

9(S

u)

NR

NR

NR

NR

NR

Bro

adet

al.

[72]

32

M

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch93

±23

Air

:9.6

Hum

idit

y:

56

1.0

3±

0.2

7-

1.4

±0.7

0.3

6±

0.1

9N

RN

RN

RN

RN

R

Bro

adet

al.

[72]

32

M

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch99

±24

Air

:24.6

±2.1

Hum

idit

y:

41

1.2

1±

0.3

3-

1.4

±0.9

0.5

2±

0.3

8N

RN

RN

RN

RN

R

Bro

adet

al.

[72]

17

F

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch119

±4

Air

:25.5

±0.4

Hum

idit

y:

78

0.7

6±

0.2

2-

1.2

±0.9

0.4

1±

0.1

5N

RN

RN

RN

RN

R

Rugby

unio

nand

rugby

league


Ta

ble

4co

nti

nu

ed

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)a

Envir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s(%

)a

Flu

id

inta

ke

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

O’H

ara

etal

.[7

4]

14

M

UK

Super

Lea

gue—

team

s

Aan

dB

Rugby

Lea

gue

seas

on

eN

Rc

Air

:12.1

±5.3

Hum

idit

y:

70

NR

-1.2

±0.6

(A)

-1.4

±0.7

(B)

1.1

2l

(A)f

1.5

6l

(B)g

0.6

4l

(B)h

NR

NR

NR

NR

NR

Mei

ret

al.

[75

]

28

M

Eli

tedev

elopm

ent

squad

(Engla

nd)

\21

Rugby

Unio

n

Cham

pio

nsh

ip(4

gam

es;

G1–4)

NR

Air

:18.5

±1.6

Hum

idit

y:

40

0.5

4±

0.5

5

(G1)

0.4

9±

0.6

5

(G2)

0.8

9±

0.6

5

(G3)

0.9

2±

0.8

8

(G4)

-0.8

±0.8

(G1)

-0.7

±0.9

(G2)

-1.3

±0.9

(G3)

-1.3

±1.2

(G4)

NR

NR

NR

NR

NR

NR

Cri

cket

Gore

etal

.

[76

]

3M

Fir

stgra

de

bow

lers

Mat

ch360

cA

ir:

32.8

±0.5

Hum

idit

y:

29

1.3

7±

0.0

6-

4.3

±0.7

0.4

6N

RN

RN

RN

RN

R

Bea

chvo

lley

ball

Zet

ou

etal

.

[77

]

47

M

Tra

ined

mix

ed

cali

bre

3day

tourn

amen

t42.2

(per

mat

ch)

Air

:33.6

±2.8

Hum

idit

y:

56

1.9

9±

1.1

2

(per

mat

ch)

-0.8

±0.7

(per

mat

ch)

1.0

4±

0.6

9

(per

mat

ch)

NR

NR

NR

NR

NR

Ind

oor

team

sport

s

Bask

etball

Ost

erber

g

etal

.[7

8]

29

M

Pro

fess

ional

NB

A

NB

Am

atch

40

(pla

yin

g

tim

e

21

±8)

Air

:20–22

�C

Hum

idit

y:

18–22

3.3

0-

1.4

±0.6

1.5

0N

RN

RN

RN

RN

R

Bro

adet

al.

[72

]

19

M

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(W

inte

r)85

±24

Air

:18.9

±0.9

Hum

idit

y:

36

±6

1.5

9±

0.3

6-

1.0

±0.6

0.9

2±

0.4

6N

RN

RN

RN

RN

R

Bro

adet

al.

[72

]

19

M

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(S

um

mer

)89

±21

Air

:23.3

±2.6

Hum

idit

y:

41

±11

1.6

0±

0.3

7-

0.9

±0.7

1.0

8±

0.6

1N

RN

RN

RN

RN

R

Bro

adet

al.

[72

]

12

F

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(W

inte

r)81

±7

Air

:17.0

±1.3

Hum

idit

y:

58

±16

0.9

8±

0.2

5-

0.7

±0.5

0.6

0±

0.1

7N

RN

RN

RN

RN

R

Bro

adet

al.

[72

]

12

F

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(S

um

mer

)93

±2

Air

:25.6

±1.5

Hum

idit

y:

60

±8

0.9

2±

0.2

5-

0.7

±0.5

0.6

0±

0.1

7N

RN

RN

RN

RN

R

Net

ball


Ta

ble

4co

nti

nu

ed

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)a

Envir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s(%

)a

Flu

id

inta

ke

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

Bro

adet

al.

[72

]

22

F

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(W

inte

r)74

±13

Air

:16.5

±2.6

Hum

idit

y

43

±3

0.8

8±

0.1

8-

0.3

±0.6

0.6

6±

0.2

5N

RN

RN

RN

RN

R

Bro

adet

al.

[72

]

22

F

Eli

teju

nio

r

(Aust

rali

a)

Mat

ch(S

um

mer

)79

±15

Air

:22.1

±0.1

Hum

idit

y:

66

±2

0.9

8±

0.2

6-

0.9

±0.6

0.5

2±

0.1

9N

RN

RN

RN

RN

R

Rack

etsp

ort

s

Ten

nis

Tip

pet

etal

.

[79

]

7F

Pro

fess

ional

(WT

A)

WT

Am

atch

Har

dco

urt

119.9

±40.1

Air

:30.3

±2.3

Hum

idit

y:

NR

2.0

0±

0.5

0-

1.2

±1.0

1.5

±0.5

01.0

25

NR

NR

NR

NR

Lott

etal

.

[80

]

16

M

Univ

ersi

tysq

uad

3se

tm

atch

Indoor

har

dco

urt

68.1

±12.8

Air

:17

±2

Hum

idit

y:

42

±9

1.1

0±

0.4

0-

0.2

±0.7

0.9

6±

0.6

2N

RN

RN

RN

RN

R

Ber

ger

on

etal

.[8

1]

8M

Eli

teju

nio

r

(US

A)

Junio

rC

ham

pio

nsh

ips

Har

dC

ourt

78.8

±10.9

(S)

106.6

±11.2

(D)

S:

Air

:

29.6

±0.4

Hum

idit

y:

NR

D:

Air

:

31.3

±0.5

Hum

idit

y:

NR

1.1

5(S

)

1.0

7(D

)

-0.9

±0.2

(S)

-0.5

±0.3

(D)

0.8

5(S

)

0.9

6(D

)

1.0

17

(S)

1.0

25

(D)

NR

NR

NR

NR

Horn

ery

etal

.[8

2]

14

M

Pro

fess

ional

(aver

age

rankin

g512)

Aust

rali

anci

rcuit

Har

dco

urt

119

±36

Air

:32.0

±4.5

Hum

idit

y:

38

±14

2.0

4±

0.4

4-

1.1

±0.5

NR

1.0

23

NR

NR

NR

NR

Horn

ery

etal

.[8

2]

14

M

Pro

fess

ional

(aver

age

rankin

g512)

Aust

rali

anci

rcuit

Cla

yco

urt

79

±13

Air

:25.4

±3.8

Hum

idit

y:

32

±5

1.5

1±

0.3

2-

0.3

±0.6

NR

1.0

21

NR

NR

NR

NR

Mora

nte

etal

.[8

3]

19

M

Tra

ined

mix

ed

cali

bre

Mat

ch

Har

dco

urt

NR

Air

:25

Hum

idit

y:

NR

1.2

±0.2

0

(E)

0.8

±0.3

0

(Rec

)

NR

NR

NR

NR

NR

NR

NR

Mora

nte

etal

.[8

3]

6F

Tra

ined

mix

ed

cali

bre

Mat

ch

Har

dco

urt

NR

Air

:23.3

–26.9

Hum

idit

y:

NR

1.0

±0.2

0

(E)

0.6

±0.4

0

(Rec

)

NR

NR

NR

NR

NR

NR

NR


Ta

ble

4co

nti

nu

ed

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)a

Envir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s(%

)a

Flu

id

inta

ke

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

Ber

ger

on

etal

.[8

4]

12

M,

8F

Sub-e

lite

(US

A

Univ

ersi

ty

Div

isio

n1)

Mid

day

mat

chof

3day

(D1–3)

tourn

amen

t

Har

dco

urt

90

Air

:32.2

±1.5

Hum

idit

y:

54

±2

1.8

(M)

1.1

(F)

-1.3

±0.8

(M)

-0.7

±0.8

(F)

1.1

3(M

)

0.8

7(F

)

NR

NR

145.4

±2.3

(D1)

145.0

±2.8

(D2)

143.8

±1.6

(D3)

145.6

±2.1

(D1)

144.6

±3.4

(D2)

144.8

±2.2

(D3)

NR

Aq

uati

csp

ort

s

Wate

rpolo

Cox

etal

.

[85

]

23

M

Eli

teA

ust

rali

an

squad

Tourn

amen

t47

Air

:24.1

Wat

er:

27.3

Hum

idit

y:

54

0.7

9-

0.4

0.3

8N

RN

RN

RN

RN

R

Ult

ra-s

wim

min

g

Wag

ner

etal

.[8

6]

25

M,

11

F

Tra

ined

mix

ed

cali

bre

26.4

km

swim

Sw

itze

rlan

d

528

(M)

599

(F)

Air

:18.5

–28.1

Hum

idit

y:

42–93

Wat

er:

22.9

–24.1

NR

-0.5

±1.1

(M)

-0.1

±1.6

(F)

0.5

6±

0.2

2(M

)

0.4

4±

0.1

7

(F)

1.0

14

(M)

1.0

14

(F)

1.0

11

(M)

1.0

12

(F)

NR

NR

17

(0)

‘‘O

n-w

ate

r’’

sport

s

Sail

ing

Nev

ille

etal

.[8

8]

32

M

Pro

fess

ional

crew

Lea

dup

race

to

Am

eric

a’s

Cup

150

Air

:32

±1

Hum

idit

y:

52

±5

0.9

6±

0.3

8-

0.7

±0.8

0.6

41.0

19

1.0

22

NR

NR

NR

Sla

ter

etal

.

[87

]

26

M,

9F

Clu

ble

vel

din

ghy

crew

Clu

bre

gat

ta

Sin

gap

ore

300

Air

:29–33

Hum

idit

y:

62–81

0.4

7(M

)

0.2

3(F

)

-2.1

(M)

-0.9

(F)

0.2

4(M

)

0.1

6(F

)

NR

NR

NR

NR

NR

Win

ter

sport

s

Ice

hock

ey

Logan

-

Spre

nger

etal

.[8

9]

24

M

Eli

teju

nio

r

Onta

rio

Hock

eyL

eague

210

cA

ir:

10.8

±0.2

Hum

idit

y:

30

±2

0.9

0(A

ll)

0.9

0(F

o)

1.0

5(D

ef)

-1.3

±0.3

(All

)

0.6

8(A

ll)

1.0

16

NR

NR

NR

NR

Pal

mer

etal

.

[90

]

14–18

M

Eli

teju

nio

r

Onta

rio

Hock

eyL

eague

95

Air

:11.4

±0.8

Hum

idit

y:

52

±3

1.5

0±

0.1

0

(W)

1.5

0±

0.1

0

(SD

)

-0.9

±0.2

(W)

-1.0

±0.2

(SD

)

0.8

2±

0.0

8

(W)

0.7

2±

0.0

7

(SD

)

1.0

23

NR

NR

NR

NR

Alp

ine

mult

isport

Stu

empfl

e

etal

.[9

1]

17

M,

3F

Tra

ined

mix

ed

cali

bre

Susi

tna

100

mil

e(r

un,

cycl

eor

ski)

Ala

ska

2,2

92

Air

:-

14

to-

2

Hum

idit

y:

NR

snow

NR

-1.6

0.3

0N

RN

R104.8

±1.2

138.4

±2.2

0

Moto

rsp

ort

s


data being limited to one study of professional male bas-

ketball players [78] and a series of data sets of elite junior

male and female basketball players [72] and female netball

players [72]. Professional basketball was associated with

high sweat rates (3.3 l/h) despite small amounts of active

game time [78]. This was matched with high rates of fluid

intake (1,500 ml/h), which typically kept the net fluid

deficit\2 % BM. The data set from the junior elite players

compared fluid balance in the same players during games

played in a winter season and summer competition [72].

Similar rates of sweat loss and fluid intake were observed

across seasons (sweat rates of *1,000 ml/h for females

and 1,600 ml/h for males, matched by fluid intakes of

500–600 and 900–1,100 ml/h, respectively). In some of

these sports, the frequency of breaks and access to fluids

mean that there are good opportunities for fluid intake to

match sweat losses; in some cases, perhaps, this access

almost matches our working definition of ad libitum

drinking. Nevertheless, further studies would be of value,

particularly of matches in elite or professional competi-

tions. Whether the desire to consume carbohydrates or

caffeine via the ingestion of sports drinks or energy drinks

influences fluid intake in these sports also warrants further

consideration and research since guidelines for these

nutrients/ingredients now reach across these shorter events

[1, 3].

3.6 Racket Sports

The most common racket sports played throughout the

world are badminton, table tennis, tennis, and squash.

Activity, as in the case of team sports, is of a variable and

intermittent high-intensity nature, with games being played

indoor (badminton, squash, table tennis), outdoor (tennis),

or in both environments even within the same competition

(e.g., tennis in stadia with a closing roof). Again, each

racket sport has its own unique set of rules that dictates the

opportunities to consume fluids; in general, players can

drink at breaks in play that are predetermined (e.g.,

between games or sets) but variable in the time elapsing

between opportunities. Some sports (e.g., tennis) have

developed ‘extreme heat’ policies that permit additional

breaks in play and opportunities to drink when weather

conditions are likely to cause a high thermoregulatory

strain on the body. Players can generally access fluids kept

at the side of the court or in close proximity. Due to

variations in rules and skill levels of the competitors,

matches can span from brief (*15 min) to long ([6 h).

Competition is usually conducted over a series of rounds,

either on the same day or over a number of days, causing a

potential carryover of fluid deficits between matches. An

interest to consume carbohydrates [1] and caffeine [3] may

promote the intake of fluids containing such ingredients,Ta

ble

4co

nti

nu

ed

Stu

dy

Subje

cts

Even

tD

ura

tion

(min

)a

Envir

onm

ent

(�C

,%

)

Sw

eat

rate

(l/h

)a

DB

ody

mas

s(%

)a

Flu

id

inta

ke

(l/h

)a

US

G(P

RE

)aU

SG

(PO

ST

)a[N

a?]

(PR

E)a

[Na?

]

(PO

ST

)a

EA

H

case

sb

Bre

arle

y

etal

.[9

2]

4M

Pro

fess

ional

(Aust

rali

a)

V8

Super

car

Cham

pio

nsh

ipR

ace

31

±7

Air

:28.9

Cab

in:

48.6

Hum

idit

y:

NR

1.0

6±

0.1

2-

0.6

±0.6

NR

NR

NR

1.0

13

NR

NR

NR

not

report

ed,

USG

uri

ne

spec

ific

gra

vit

y,

[Na

?]

blo

od

sodiu

mco

nce

ntr

atio

n,

EA

Hex

erci

se-a

ssoci

ated

hyponat

rem

ia,

PR

Epre

-exer

cise

,P

OST

post

-exer

cise

,M

mal

e,F

fem

ale,

Ww

ater

,SD

carb

ohydra

te–el

ectr

oly

tesp

ort

sdri

nk,

NB

AN

atio

nal

Bas

ket

bal

lA

ssoci

atio

n,

WT

AW

om

en’s

Ten

nis

Ass

oci

atio

n,

Ssi

ngle

s,D

double

s,E

elit

e,R

ecre

crea

tional

,F

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especially in the longer events or those commencing

without opportunity for full recovery from the previous

match.

To date, the published literature on fluid balance during

competition is isolated to studies of tennis [79–84]. The

eight data sets observe junior elite, recreational, and pro-

fessional players as well as matches on hard, clay, or

indoor courts (Table 4). Conditions ranged from temperate

to hot, with the majority of outdoor matches being played

in temperatures [25 �C. Sweat rates appear to differ

according to the caliber of the athlete with elite and sub-

elite players losing *1,000–2,000 ml/h compared with

*600–800 ml/h for recreational players [83]. Ambient

playing temperature also influenced sweat rates with

players competing in conditions \25 �C tending to have

lower sweat rates (600–1,000 ml/h) than those competing

in conditions[25 �C (800–2,000 ml/h). Mean BM changes

over a match were 0–1 % BM; however, standard devia-

tions indicate that individual players experienced changes

ranging from losses[2 % BM to a gain in BM. Mean fluid

intakes of *800–1,500 ml/h were reported, with some

individuals, including professional women players, con-

suming [2,000 ml/h. Three studies that investigated the

pre-game hydration status using urine specific gravity

(USG) found that many players started a match with mild

dehydration (mean USG [1.020) [79, 82]; this outcome

was more pronounced when they were required to play two

matches in a day [81].

In summary, information on fluid balance is limited to

tennis and, due to the heterogeneity of sports, this infor-

mation cannot be extrapolated to other racket sports. It is

also important to note that the current literature does not

include matches played under the extreme circumstances

that are typical in many Grand Slam tournaments (men’s

five-set matches of [3 h duration, court temperatures

[40 �C); further studies are needed to support anecdotal

reports of substantial fluid losses in some players in these

situations particularly during tournaments when incomplete

recovery from the previous match may have occurred. As

in team sports, it is of interest to gather information about

the type of fluids that are consumed during matches to

ascertain whether the intention to consume other ingredi-

ents found in drink influences hydration practices.

3.7 Aquatic Sports

A number of competitive sports involve exercising while

submerged in water; these include pool swimming, open

water swimming, synchronized swimming, and water polo.

While some of these events are conducted in pools in which

the international governing body (FINA) mandates a small

range in water temperature (25–28 �C), open water events

can be carried out in lakes, rivers, and oceans with a much

larger temperature range. Cool water provides greater

convective heat losses and reduces sweat losses compared

to land-based activities [85]. Sweat losses are increased,

however, in warmer water or during high-intensity exercise;

the external environment such as humid indoor settings or

hot weather for outside pools and open water may also

contribute to greater sweat losses since the athlete’s body is

not fully submerged. There is no need to hydrate during

pool-based swimming races (maximum race length

*15–20 min) or synchronized swimming (2–4 min rou-

tine). However, for open water swimmers (5–25 km races,

ultra-endurance races, and escorted channel crossings), the

opportunity to consume fluid and carbohydrate during races

requires a temporary stop to their activity. Access to fluids

and foods is provided from feeding pontoons or individual

feed boats, although some swimmers may carry small

supplies tucked into their swimming costumes. Meanwhile,

the opportunity to drink in water polo is limited to substi-

tutions, time-outs, and between quarters, with access to

fluids being enhanced by the availability of drink bottles on

the pool deck. Of course, there is a potential for accidental

ingestion of water from the pool or open water environment.

Indeed, the aquatic environment creates several unique

issues related to sweat losses and fluid intake in these sports.

It also creates errors and limitations to the serial measure-

ments of body mass used to measure fluid balance during an

exercise session [85].

The data on fluid balance in competitive water events

(Table 4) are limited to one study of elite male water polo

players who were estimated to consume *400 ml/h in

meeting sweat losses of *800 ml/h, with all players

recording a slight loss of body mass over the match [85]. A

study of an ultra-endurance open water race involving

swimmers of mixed caliber and sex reported mean fluid

intakes of 440–560 ml/h over a *10 h period, leading to a

range in BM changes from modest deficits to gains [86].

Asymptomatic hyponatremia was reported in 8 % of males,

with a greater incidence of hyponatremia in females

(36 %), including one symptomatic case. Clearly, more

investigation of these sports is warranted and may need to

include warnings against overhydration. Whether the type

and temperature of fluids influence fluid intakes in endur-

ance events or extreme conditions is of interest; hot fluids

may offer palatability and thermoregulatory incentives in

cold water events, cold fluids may be pleasurable when

swimming in warm water, and swimmers may seek to

consume carbohydrates or caffeine containing fluids in

longer races.

3.8 ‘‘On-Water’’ Sports

Competitive sports can also take place on equipment that

traverses rivers, lakes, and oceans; these include the


Olympic events of rowing, kayaking, canoeing, sailing, and

windsurfing as well as non-Olympic sports such as water-

skiing, wakeboarding, surfing, kite surfing, and stand-up

paddle boarding. Athletes in these ‘‘on-water’’ sports can

compete as individuals (e.g., surfing, water-skiing, rowing,

kayaking, sailing) or as teams (e.g., rowing, kayaking,

sailing), with events lasting from minutes (kayaking,

rowing) to months (off-shore sailing). While there is no

need for fluid intake during brief events, opportunities to

consume fluids during longer races that can feature large

sweat losses (e.g., sailing, endurance rowing, and paddling

events) can be limited by the practical challenge that many

activities (e.g., winching, stroking, paddling) involve the

use of both hands. Drinking in most ‘‘on-water’’ sports is

challenged, ironically, by the limited access to a suitable

fluid supply that must be carried on the craft. Indeed, in

events such as sailing, fluid supplies need to be considered

within the weight and boat space limits [87].

There is a lack of information on fluid balance in the

large number of sporting activities within this category; the

only published data come from sailing events (Table 4).

Sweat rates in sailing sports vary markedly between and

within races, according to factors such as wind speed and

direction, sea spray, race tactics, and crew position [88].

Typically, however, single-day sailing regattas are held in

the afternoon (during the heat of the day) and can result in

high fluid losses, especially when convective heat loss is

restricted by waterproof clothing and/or lifejackets [87,

88]. Slater et al. studied dinghy sailors during a club regatta

(multiple races within the same session), while Neville

et al. investigated a professional America’s Cup ‘big-boat

yacht’ crew. While these events were of comparable race

duration (90–100 min), the total ‘‘on-water’’ time differed

(*5 and 2.5 h, respectively) because of the time taken to

reach and leave the course or recover between races.

Estimated sweat rates for race time in these sailing events

were *1,500 and *800 ml/h for males and females,

respectively. BM loss for the total ‘‘on-water’’ time aver-

aged *2 and 1 %, respectively, but included individuals

who ranged in BM changes from -2.5 to ?2.5 %. Crew

positions with the most continuous and physically

demanding roles, such as bowmen and grinders, were

found to have the highest sweat rates and less ability to

replace these [88].

As is the case for most categories of sports, further

research of ‘‘on-water’’ sports is needed to document

present patterns of fluid intake and to ascertain the effect of

different types of drinks on hydration practices.

3.9 Winter Sports

Winter sports are those that take part on snow or ice and

span a wide range of activities including skiing, ice-

skating, snowboarding, ice-hockey, sledding, and, more

recently, multisport events. Each of these broad categories

also includes a number of permutations, each with unique

physiological and logistical characteristics. For example,

within the skiing category, sports range from brief and

largely skill-based activities (e.g., aerial skiing) to pro-

longed or sustained high-intensity races (e.g., Nordic ski-

ing). Other sports include team games such as ice hockey

with intermittent high-intensity work patterns.

Additional factors influencing sweat rates include the

environmental conditions such as temperature, humidity,

altitude, and, in the case of outdoor sports, solar radiation

and wind. The diverse array of uniform requirements also

affects sweat rates. Many sports require heavy padding (ice

hockey) or extensive waterproof and insulating clothing

(e.g., snowboarding), which can restrict evaporation of

sweat and convective heat loss, while others have uniforms

intended to maximize aerodynamics (e.g., short-track speed

skating, luge) or to meet aesthetic requirements (e.g.,

costumes in figure skating).

There are also several factors that influence opportuni-

ties to drink and have access to fluids. The logistics

involved with transporting fluids around remote environ-

ments and preventing drinks from freezing in low-tem-

perature environments can restrict access to fluids.

However, such challenges can be addressed via the use of

portable hydration backpacks, well-insulated containers, or

containers that can be carried next to the body for warmth.

Fluid intake may also be reduced in cold environments

either intentionally (to minimize the need to urinate when

there are no facilities and/or changing out of clothing is

difficult and time-consuming) or unintentionally (reduced

thirst drive in cold environments). By contrast, access to

warm/hot fluids may both increase voluntary intake in cold

conditions as well as provide a role in thermoregulation. In

aerial sports where a higher power-to-weight ratio may be

advantageous, functional dehydration may be a cultural

determination of fluid intake.

Despite the breadth of winter sports, research into fluid

balance shifts in these sports is scarce. The three published

studies summarized in Table 4 on athletes competing in

winter sports involve elite junior ice-hockey players [89, 90]

and mixed-caliber athletes in a multisport event [91]. The

ice-hockey events were conducted in cool (10–11 �C) indoor

arenas, while the multisport event was conducted in a much

colder (-14 to -2 �C) snow-covered terrain. Both activities

required athletes to wear insulating clothing or padded uni-

forms restricting convective heat losses. Sweat losses in the

ice-hockey matches ranged from 900–1,500 ml/h with sig-

nificant differences between playing positions (forwards and

defense [ goalie). However, high rates of fluid intake

(700–800 ml/h) kept mean BM changes to *1 % BM. In

one study, provision of sports drinks was not shown to have


any effect on drinking behavior [90]. Measurement of USG

on pre-match samples showed variability in hydration status

at the start of the game [89, 90].

Data from the multisport study [91] showed a mean BM

loss of 1.6 % with fluid intakes of 300 ml/h and the

absence of cases of hyponatremia. Overall, it is difficult to

make summary statements regarding typical fluid intakes

and losses in winter sports athletes, because of the limited

number of studies. Given the unique nature of winter sports

with regards to both sweat losses and access to fluids, it

would be beneficial to explore this area further.

3.10 Motor Sports

Motor sports include racing cars (e.g., V8 Supercar, NA-

SCAR, Formula 1), motorbikes (Grand Prix racing, su-

perbikes, motocross), and airplanes (e.g., Air Race World

Championship). The combination of often unrecognized

physical activity, the wearing of heat-retardant and padded

clothing and helmets, high cabin temperatures, and high

heat radiation from the race track can exacerbate sweat

losses. Access to fluid is limited to supplies carried by the

driver/pilot, although more recent technologies such as

motorized fluid delivery and cooling systems can assist by

reducing the thermal load and providing an accessible fluid

source. Of course, opportunities to drink may be dictated

by the technical nature of the course; some drivers in car-

and motorbike-based sports restrict fluid intake to straight

sections of the track to counter the challenge of high intra-

abdominal pressures during cornering [92]. In addition, in

competitions that have a ‘round’ format, driver/pilots may

carry a fluid deficit from one race into the next.

There has only been one published investigation

(Table 4) of fluid balance characteristics during motor

sports [92]. This study, conducted on a small sample of V8

Supercar Championship drivers, showed that over a short

(*30 min) race in a hot environment (cabin temperature

*48 �C), drivers incurred a BM loss of 0.6 % with a sweat

rate of *1,000 ml/h. Fluid intake was not recorded during

this race. Since many motorsport races are conducted over

a longer period of time, it is possible that drivers could lose

a substantial volume of fluid, which may be difficult to

replace during a race. Given the apparent risk of fluid

imbalance caused by the potential for high fluid losses and

low fluid intakes during motor sports, it would seem per-

tinent to investigate this area further.

3.11 Aesthetic and Skill Sports

There are no published studies on fluid balance during

competition for aesthetic (e.g., gymnastics) and skill-based

sports (e.g., diving, archery, shooting, golf). Given that

competitions for aesthetic sports such as gymnastics are

generally held in a climate-controlled indoor arena and

involve short-duration events, low sweat losses are antici-

pated. Skill-based sports generally involve low-intensity

exercise, although golfers may walk some distance over a

round if not using motorized equipment to commute

between holes. Nevertheless, they may have long periods

in hot conditions. The major opportunity to drink during

aesthetic and skill-based sports occurs between rounds;

however, athletes who participate in sports with a high

number of twists, turns, or flips may choose to restrict fluid

intake to minimize gastrointestinal discomfort or BM.

Access to fluids is reduced when sessions are undertaken in

remote environments but can be increased by the provision

of fluid stations or the portage of fluid by caddies. In

summary, very little is known about the fluid balance

behaviors of athletes competing in aesthetic and skill-based

sports.

3.12 Weight-Making Sports

Numerous reports have described the acute weight loss

strategies employed by athletes in boxing, wrestling, judo,

weightlifting, and horse racing in order to meet the weigh-

in requirements of their sport [93]. However, little is

known about the fluid deficits incurred during competition

bouts or days. Pre-competition fluid deficits, achieved on

the days before, and morning of, the weigh-in can be high

as athletes typically reduce BM by deliberately dehydrating

themselves via exposure to heat and/or exercise in warm

conditions wearing impermeable clothing as well as

restricting fluid intake prior to weigh-in [94, 95].

Depending on the interval between weigh-in and the event,

and the athlete’s own preferences, there may not be suffi-

cient opportunity to rehydrate before the match or race. In

some cases, intake of substantial amounts of fluid prior to

the event is prevented by the placement of the weigh-in

after the race (e.g., horse racing). Weight-making sports

typically involve events of a brief nature with opportunities

for fluid intake being restricted to periods between bouts,

heats, or races in the same session or day. Nevertheless,

athletes in combat sports may deliberately restrict fluid

intake within competition to avoid gastrointestinal dis-

comfort associated with physical contact to the abdomen.

In summary, given the likelihood of a fluid deficit prior to

competition, further information on the fluid behaviors of

athletes during competition would be beneficial.

4 Discussion

This review has summarized our current knowledge about

the self-chosen hydration practices of athletes across a

variety of competitive situations, attempting to understand


what athletes drink and the factors that underpin these

practices. Unfortunately, there is a scarcity of data on most

sports, particularly involving the top competitors. Fur-

thermore, much of the available data on fluid balance in

athletes in competition settings relies on estimates of

observed and self-reported fluid intakes rather than accu-

rate measurement. Therefore, we acknowledge the limita-

tions of our following observations and our inability to

provide in-depth analysis in such a broadly based article.

Across the diverse nature of sports, there is a complex

number of factors that influence fluid intake during com-

petitive events. Environmental conditions appear to be one

consistent factor affecting fluid intake, with higher rates of

intake in warmer environments. However, in many events

the athlete’s ability to drink at a rate that tracks their sweat

losses is often dictated by factors out of their control such

as event rules, race tactics, regulated access to fluid, the

priority of maintaining optimal technique or speed, and

gastrointestinal comfort. This is especially true in endur-

ance and ultra-endurance events involving continuous

activity, where the time taken to obtain or consume drink is

included in the race time and where intake while moving at

high speeds is both difficult and a risk factor for gut dis-

turbances. The lack of self-determination of fluid intake

and/or the observation of lengthy periods without oppor-

tunity to consume fluids may invalidate the concept that

athletes can drink ad libitum (defined by us as ‘‘whenever

and in whatever volumes chosen by the athlete’’). Unfor-

tunately, there are relatively few data on drinking practices

in most continuous sports, particularly involving elite or

highly competitive athletes, and almost no information on

the athletes’ rationale for their drinking behaviors. One of

the few specific studies of the factors affecting fluid intake

in sports competition [96] found that the most important

influences on hydration practices reported by recreational

runners were thirst (56 %) and a pre-set schedule (36 %).

The majority (87 %) reported little or no influence from

sports drink companies but were influenced (57 %) by trial

and error or personal history. The authors also noted that

the cohort that drank to a set schedule was significantly

older, more experienced, and faster than those who only

drank when thirsty.

The diversity of the strategies used by athletes to drink

during endurance/ultra-endurance events means that the

relationships between fluid intake or loss of body mass

across a race and the competitor’s finishing time (i.e.

success) vary between sports and specific events. However,

the available data and knowledge of the characteristics of

sports suggest that, particularly for elite athletes, there are

many events that fail to provide the athlete with opportu-

nities to truly drink according to thirst or desire. Rather, in

many situations it appears that top athletes take calculated

risks in emphasizing the costs of drinking against the

benefits; this may be consistent with winning performances

although such observations cannot judge whether the per-

formance was optimal for that individual. Finally, some

non-elite participants may need to be mindful of the dis-

advantages of drinking beyond requirements during long

events.

Similarly, a large range of factors influences drinking

behaviors during team and racket sports, events under-

taken in or on water, winter sports, and other events.

Team and racket sports offer a combination of planned

and ad hoc opportunities to consume fluid and associated

nutrients during the game or match, which vary from

frequent (e.g., basketball) to limited (e.g., soccer).

Enhanced access to fluids is often made possible by

strategies or resources provided by the team infrastructure.

Other sports involve unique challenges to drinking during

competition, including poor access to fluid, the priority of

maintaining optimal technique or speed, and gastrointes-

tinal comfort. It is likely, therefore, that some athletes in

some of these sports could be considered to have at least

close to ad libitum access to fluids. However, this situation

is probably not widespread. Furthermore, in some of these

sports, there is evidence that athletes commence compe-

tition with some degree of body fluid deficit due to their

failure to restore fluid balance from prior dehydrating

events (a previous bout of training or competition, or

weight-making strategies involving fluid restriction or

encouraged sweating).

Published studies on fluid intake during the large array

of these sports events are too few in number, particularly

involving elite competitors, to make specific judgments

on real life practices. Nevertheless, the available litera-

ture suggests that voluntary fluid intakes of competitors

vary greatly between and within events. While the typi-

cal match between sweat losses and fluid intakes by most

athletes results in a mild to moderate loss of BM over

the event (\2 % BM), in some situations individual

participants fail to meet current sports nutrition guide-

lines by gaining BM or losing [2 % BM over the event.

Players participating in team sports such as cricket and

soccer, and perhaps tennis, when played in hot conditions

at the elite level, appear to be particularly at risk of

substantial fluid losses that are unable to be matched

with adequate fluid intake, and fluid deficits [4 % BM

have been observed in some individuals in these sports.

Further research should target observations of fluid bal-

ance in elite competitors and collect information on fluid

choices and the rationale for drinking across all sports

and events.

Finally, in many sports athletes may use fluids with

ingredients (e.g., carbohydrates, electrolytes or caffeine) or

characteristics(e.g., temperature) that improve palatability

or performance.


5 Conclusions

Further studies of real-life hydration practices during

competitive events including information on motives for

drinking or not, along with intervention studies that sim-

ulate the actual nature of real-life sport, are needed before

conclusions can be made about ideal drinking strategies for

sports. In any case, it is likely that a range of drinking

strategies may be appropriate and that athletes need to have

an individualized and flexible approach to their hydration

practices. It should be remembered that fluids consumed

during exercise may also be a source of other ingredients

(e.g., caffeine, carbohydrates, electrolytes) or have charac-

teristics (e.g., temperature) known to enhance palatability,

voluntary consumption, thermoregulation, or performance,

which may dictate a desirable volume and pattern of intake

that is independent of thirst. There may be benefits associ-

ated with a ‘‘paced’’ approach to drinking during sports, in

which the athletes plan to spread their intake of these

nutrients as well as a reasonable replacement of their sweat

losses across the opportunities that their event provides to

consume fluids.

Acknowledgments Alison Garth was the recipient of a Gatorade

Fellowship in Sports Nutrition during the preparation of this manu-

script. Louise Burke has been employed by various organizations and

sporting teams that receive sponsorship from companies that manu-

facture sports drinks. She has received research funding and under-

taken education activities supported by such companies while in

various laboratories: Australian Institute of Sport: 1990–2012 (Iso-

sport-Berrivale Orchards, Gatorade, Powerbar) and Sports Science

Institute of South Africa: 1997 (Energade-Bromor Foods). Louise was

a member of the panel that prepared the 2007 American College of

Sports Medicine Position stand on Exercise and Fluid Replacement.

She has not been a member of the Gatorade Sports Science Institute’s

Advisory Board.

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