Fluid Needs for Training, Competition, and Recovery
in Track-and-Field Athletes
Douglas J. Casa
University of Connecticut
Samuel N. Cheuvront
U.S. Army Research Institute of Environmental Medicine
Stuart D. Galloway
University of Stirling
Susan M. Shirreffs
University of St. Andrews
The 2019 International Amateur Athletics Federation Track-and-Field World Championships will take place in Qatar in the
Middle East. The 2020 Summer Olympics will take place in Tokyo, Japan. It is quite likely that these events may set the record for
hottest competitions in the recorded history of both the Track-and-Field World Championships and Olympic Games. Given the
extreme heat in which track-and-ﬁeld athletes will need to train and compete for these games, the importance of hydration is
ampliﬁed more than in previous years. The diverse nature of track-and-ﬁeld events, training programs, and individuality of
athletes taking part inevitably means that ﬂuid needs will be highly variable. Track-and-ﬁeld events can be classiﬁed as low,
moderate, or high risk for dehydration based on typical training and competition scenarios, ﬂuid availability, and anticipated
sweat losses. This paper reviews the risks of dehydration and potential consequences to performance in track-and-ﬁeld events.
The authors also discuss strategies for mitigating the risk of dehydration.
Keywords: athletics, dehydration, hydration, performance, rehydration, running
Seasonal environmental changes can create unique challenges for
year-long training among track-and-ﬁeld athletes. However, the
competitive track-and-ﬁeld season is held in the summer months
of the northern hemisphere and major international track-and-ﬁeld
competitions, such as the World Championships and the Olympic
Games culminate in the hottest months of the year. The 2019 IAAF
Track-and-Field World Championships will take place in Qatar in the
Middle East. The 2020 Summer Olympics will take place in Tokyo,
Japan. It is quite likely that these events may set the records for the
hottest Track-and-Field World Championships and Olympic Games
in recorded history. Serious caution is often warranted for hot-weather
Olympic track-and-ﬁeld events (Nielsen, 1996) and the safe preparation
and conduct of competitive hot-weather exercise is of great
international interest (Racinais et al., 2015). Given the extreme heat in
which training and competition are likely to take place in Qatar,
Tokyo, and other summer sporting venues of the future, the risks
associated with dehydration could be ampliﬁed more than in previous
years. This review focuses on the risks of dehydration and potential
consequences to performance in track-and-ﬁeld events. We also
discuss strategies for mitigating the risk of dehydration.
The 2003 International Olympic Committee consensus conference
concluded the following with regards to hydration in its
consensus statement, which was recently updated in 2011 (IOC
Consensus Statement, 2004; IOC Consensus Statement, 2011).
Dehydration impairs performance in most events, and athletes
should be well hydrated before exercise. Sufﬁcient ﬂuid
should be consumed during exercise to limit dehydration to
less than about 2% of body mass. . . . Sodium should be
included when sweat losses are high, especially if exercise
lasts more than about 2 h. Athletes should not drink so much
that they gain weight during exercise. During recovery from
exercise, rehydration should include replacement of both
water and salts lost in sweat.
Sports nutrition, and sports hydration in particular, is a widely
discussed and sometimes hotly debated topic (Cotter et al., 2014).
However, several recent and comprehensive treatments on the
topics of dehydration, rehydration, and sports performance buttress
existing IOC conclusions (Cheuvront & Keneﬁck, 2014; Evans et al.,
2017; McDermott et al., 2017; Savoie et al., 2015; Wittbrodt &
Millard-Stafford, 2018). In this review, up-to-date evidence for the
potential impact of dehydration on performance is described and
applied to circumstances and events in track and ﬁeld. Proposed
Casa is with Korey Stringer Institute, Department of Kinesiology, University of
Connecticut, Storrs, CT, USA. Cheuvront is with the U.S. Army Research Institute
of Environmental Medicine, Natick, MA, USA. Galloway is with the Faculty of
Health Sciences and Sport, University of Stirling, Scotland, UK. Shirreffs is with the
University of St Andrews, Scotland, United Kingdom. Casa (douglas.casa@uconn.
edu) is corresponding author.
175
International Journal of Sport Nutrition and Exercise Metabolism, 2019, 29, 175-180
https://doi.org/10.1123/ijsnem.2018-0374
© 2019 Human Kinetics, Inc. SCHOLARLY REVIEW
recommendations may be used by athletes and coaches to optimize
performance and health, and by governing organizations when considering
the rules and regulations of the sport or the timing of events.
Everyday Hydration Assessment
Optimal hydration reﬂects a physical state of having normal body
water and electrolytes, and it is an assumed starting point for most
of the strategies and recommendations reviewed in this paper.
The Venn diagram in Figure 1 is designed to simplify athlete selfassessment
of day-to-day hydration status and can help ensure an
optimal starting point for training and competition (Cheuvront &
Sawka, 2005). A daily loss of body weight (W) greater than 0.5 to
1.0 kg (1 to 2 lb), a small volume of dark colored urine (U; apple
juice or darker), and the noticeable sensation of thirst (T) are all
symptoms of dehydration. When two or more of these symptoms of
dehydration are present, dehydration is likely. If all three markers
are present, dehydration is very likely. When it is important to
account for hydration status, all three WUT symptoms should be
assessed upon waking each morning. If dehydration is likely or very
likely, greater attention should be given to 24-hr ﬂuid and electrolyte
intakes. The use of WUT helps to establish deviations from an
optimal hydration baseline and becomes increasingly important
when track-and-ﬁeld athletes travel to locations with warmer
weather or higher terrestrial elevations, both of which can increase
body water losses beyond normal. Travel to locations with limited
potable water availability also requires extra attention to water
planning and make WUT a useful tool for establishing the adequacy
of daily ﬂuid intakes. More advanced hydration assessment techniques
are unlikely to be implemented in competition but are
possible in advanced training venues. The interested reader can
also consult Maughan and Shirreffs (2008) for practical hydration
assessment guidance or Armstrong and Casa (2009) for the application
of more advanced assessment methods.
Basic Sweat Science
Physical activity requires the use of stored energy to perform work.
In the process, signiﬁcant body heat is generated. Were it not for
heat loss mechanisms, a 60-kg runner racing 10 km at 27-min
ﬁnishing pace would collapse from a lethal body temperature after
only 3.2 km (Dennis & Noakes, 1999; Nielsen, 1996). In weather
that is temperate or warmer, sweating accounts for more than 50%
of body heat removal and close to 100% in very hot environments
(Gagge & Gonzalez, 1996). Millions of sweat glands become
activated in response to exercise and the evaporation of sweat
from the skin carries away heat. In fact, the evaporation of 1 L of
sweat from the skin surface can carry away 83% of the heat
produced during a 27-min 10-km race (Wenger, 1972).
The primary factors that inﬂuence total sweat loss (L; Sweating
Rate × Time) include body size, exercise intensity, exercise
duration, the environment, and choice of clothing. These factors
explain more than 90% of the widely different sweat losses
expected among athletes (Gagnon et al., 2013). Widely different
factors among different track-and-ﬁeld athletes easily explain why
observed athlete sweating rates can range from 0.5 to 3.0 L/hr
(Baker et al., 2016). Typical ﬂuid needs for adults range from 2 to
4 L/day (Sawka et al., 2005) and function to replace obligatory
losses and dilute metabolic and dietary waste products (Cheuvront
& Keneﬁck, 2016). A typical 2-hr/day track-and-ﬁeld training
session could, therefore, increase daily ﬂuid needs by 1 to 6 L/day
due to the range of anticipated sweat losses. Electrolyte losses in
sweat (sodium and potassium) amount to about 1 g/L (assuming
50 mmol/L) (Baker et al., 2016), which at the low end is replaced
by habitual dietary practices, but at the upper end could require
special attention to food electrolyte intakes (Maughan & Shirreffs,
2008). At minimum, track-and-ﬁeld athletes must replace body
water and electrolyte losses daily. Failure to do so can lead to
dehydration, poor training, and competition outcomes.
Potential Body Water Balance Concerns for Trackand-Field
Athletes
Table 1 provides a composite picture of qualitative dehydration risk
by track-and-ﬁeld event categories using sweat losses and ﬂuid
availability in training and competition. The table also summarizes
the risk that dehydration, if present or accrued, would negatively
affect performance. The table is meant as a guide for a discussion of
event-speciﬁc risks only. Individual athletes are encouraged to
personalize their ﬂuid intake practices (see “Strategies to Optimize
Hydration” section).
Low-Risk Events
Track-and-Field events with a low-dehydration risk include jumping
(with exceptions), throwing, sprints, and multi-events. The
principle reasons for low risk are the types of training performed
(e.g., strength, power), the generally unlimited availability of
ﬂuids in both training and competitions, and the small effects that
dehydration has on these types of performance even when present.
Although there are no published data on sweating rates in low-risk
track-and-ﬁeld events, it is anticipated that losses would be lowest
in these events because explosive events like these generate
tremendous heat for only very short periods followed by signiﬁcant
rest breaks both in training (between sets) and competition
(between rounds). For example, Watson et al. (2005) monitored
sweat volume losses in simulated sprint sessions. In these sessions,
the subjects, who were experienced but not elite sprinters, warmed
up for 15 min then ran either a 50- and 200-m sprint separated by
40 min or undertook vertical jumps and a 400-m sprint. Each of
these sessions was undertaken twice. The body mass reductions
Figure 1 — The Venn diagram for athlete self-assessment of day-to-day
hydration status (Cheuvront & Sawka, 2005). If two or more of the signs
(W = reduced body weight, U = dark urine color, and T = feeling thirsty)
are present, then correction of ﬂuid balance is required.
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averaged 0.8 and 1.3 kg in the 50/200-m sessions over a 2-hr
period, and averaged 0.5 and 1.1 kg over 45 min in the 400 m and
vertical jump session. These reductions are equivalent to approximately
1–1.5% of the athletes’ body mass and easily replaceable
during the training session.
Jumping performance has frequently been investigated as a
means of assessing the inﬂuence of a body water loss on muscle
power: jump power and jump height have been most frequently
measured (Cheuvront et al., 2010; Gutiérrez et al., 2003; Hoffman
et al.,1995; Kraemer et al., 2001; Viitasalo at al., 1987; Watson et al.,
2005). In theory, intentional dehydration might be desired to try and
improve jumping performance by virtue of being “lighter.” In fact, if
dehydration did not impair muscle force production in any way, then
jump height improvements should reﬂect the level of dehydration
(i.e., 1% dehydration should improve jump height by 1%) (see
appendix in Cheuvront et al., 2010). The majority of studies
investigating the effects of dehydration on jump performance
have used between 1% and 4% dehydration (Cheuvront et al.,
2010; Gutiérrez et al., 2003; Hoffman et al., 1995; Watson et al.,
2005) although a 6% body mass loss has been investigated when
energy restriction has been combined with dehydration (Kraemer
et al., 2001; Viitasalo et al., 1987). Yet the majority of these studies
have found no signiﬁcant effect of the body mass reduction on
jumping power or height. When Cheuvront et al. (2010) replaced the
water lost as weight worn ergonomically as a vest, jump performance
decreased when dehydrated. This suggests that the beneﬁts of
being lighter when dehydrated are masked by the detrimental effects
of dehydration on muscle function. When the effects are combined,
there are no “measurable” effects on performance.
The conclusion that dehydration impairs some aspect(s) of
strength or power is cautionary for throwing events, which rely
heavily on strength and power. Indeed, two systematic reviews and
one meta-analysis summarizing the effects of dehydration on
muscle strength, power, and high-intensity anaerobic capacity
(Cheuvront & Keneﬁck, 2014; Judelson et al., 2007; Savoie
et al., 2015) determined that dehydration can impair strength
and power. However, it was concluded that a signiﬁcant loss of
body water (3–4% body mass) was required to produce small, but
signiﬁcant effects on performance. Although small effects remain
of utmost importance in elite sports (Hopkins et al., 1999), the risk
of achieving 3–4% dehydration in sprinting, jumping, and throwing
events is very low. Therefore, the risks to performance are also
low (Table 1). As a result, the main concern for hydration in lowrisk
track-and-ﬁeld events is to ensure that training and competition
are begun in a state of optimal hydration. This is especially true for
multi-event track-and-ﬁeld athletes who may be competing for
many hours, but with ample opportunities for rest and rehydration.
Moderate-Risk Events
The middle distances for running (800 m to 3 km) and some longdistance
running events (5–10 km) may be considered track-andﬁeld
events with moderate risk for dehydration. Although the risk
of dehydration is low in the events themselves due to their short
durations (< 2 to < 30 min), moderate risk for these events stems
from daily high and sustained sweat losses which could carry over
to negatively affect training and performance from day-to-day.
Fluid availability may also be high (e.g., track training) or low
(road training), depending on the training season or phase of
training. Moderate risk middle and long-distance running events
in track and ﬁeld are all contested entirely on a track. Therefore, as
for the sprints, the duration of the races are short enough to preclude
ﬂuid being taken during the events and too short for signiﬁcant
dehydration to develop during the race, even when sweating rates
are very high. As with low-risk events, the main concern for
hydration in low-risk track-and-ﬁeld events is to ensure that
training and competition are begun in a state of optimal hydration.
However, given the endurance and interval training frequently
undertaken by these athletes, the volumes of sweat that may be lost
and the likelihood that drinking during training may frequently be
limited for logistical or stomach comfort reasons, dehydration
during training for many middle and long distance runners may
be a common scenario. Deliberate rehydration strategies (see
“Basic Rehydration Science” section) may become necessary
when a signiﬁcant portion of the training has yet to take place,
particularly when the desire is to complete a high-quality training
session with a “performance” element to it. The negative effects of
dehydration on the energy system relied upon for competitive
middle and long-distance running is discussed below.
High-Risk Events
Long-distance running and walking events (20–50 km) may be
considered track-and-ﬁeld events with a high risk for dehydration.
In comparison to the other track-and-ﬁeld events, there has been a
considerable amount of both descriptive research into sweat losses
Table 1 Potential Body Water Balance Concerns for Track-and-Field athletes
Sweat lossesa
Availability of fluids Risk of dehydration Performance risk
Event Training Competition Training Competition Training Competition Training Competition
Jumping (high jump,
long jump, triple jump,
and pole vault)
Mod Low High High Low Lowb
Low Low
Throwing (shot put, javelin,
and discus)
Mod Low High High Low Low Low Low
Sprints (<800 m) Mod Low High High Low Low Low Low
Middle-distance running
(800 m to 10 km)
High Low Mod Low Mod Low Mod High
Long-distance
running/walking (>10 km)
High High Low Low High High High High
Multievents (decathlon) High Mod High High Low Low Low Low
Note. Mod = moderate.
a
Product of sweating rate and time. b
Assumes no purposeful dehydration.
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of runners during at least some of the long-distance events (in
particular, the marathon) and also intervention studies investigating
the effects of dehydration on endurance exercise performance.
Training involves many hours of running and walking where ﬂuid
availability/support must be planned in advance. During competitions,
ﬂuid availability is minimal and the intensity of exercise may
make it difﬁcult to prevent progressive dehydration from occurring,
particularly late in a competition when high levels of performance
are required. Indeed, dehydration to levels well beyond those
associated with impaired performance (>2% of body mass) has
been consistently reported at the ﬁnish of marathon races
(Cheuvront & Haymes, 2001).
The effects of dehydration on endurance running or walking
performance must be viewed through the lens of both laboratory and
ﬁeld studies of endurance “exercise.” The mode of test activity is often
not running or walking and the caliber of athlete tested is rarely elite.
However, research outcomes are interpreted using the same aerobic
energy system, and the knowledge that human performance responses
to stressors such as environmental heat vary only by degree when
comparing elite and recreational runners (Ely et al., 2008) or when
comparing laboratory outcomes to ﬁeld observations (Casa et al.,
2010), which permits reasonable extrapolation of results.
Cheuvront and Keneﬁck (2014) reviewed 34 studies conducted
between 1961 and 2012 investigating the effects of dehydration on
endurance exercise performance. Of the 60 total performance observations,
41 (68%) showed a statistically signiﬁcantly impairment
in performance when dehydrated and 12 more (88%) reported an
overall group decrement in performance that did not reach statistical
signiﬁcance. These ﬁndings are more impressive still when one
considers that most studies are undertaken with the minimal number
of test volunteers necessary to ﬁnd statistical signiﬁcance. Cheuvront
and Keneﬁck (2014) concluded that dehydration ≥2% of body mass
impairs endurance exercise performance as measured primarily by a
shortened time to exhaustion or reduction in sustainable exercise
intensity. Importantly, the effect is magniﬁed in warmer environmental
temperatures (Keneﬁck et al., 2010). In addition, partial
rehydration has been shown to dramatically enhance performance
and physiological function during running in the heat, and the effect
is exacerbated if the exercise is intense (Casa et al., 2010; Lopez et al.,
2016). Whether programmed or thirst-driven drinking strategies are
more successful depends highly on the circumstances of the training
and competition (Keneﬁck, 2018). A more detailed discussion of this
topic follows (see “Strategies for Optimizing Hydration” section). So
long as dehydration is limited to <2% of body mass, performance is
likely to be sustainable in all track-and-ﬁeld events.
Dehydration and Mental Readiness
The potential effects of dehydration on brain function could impact
track-and-ﬁeld athlete performance by interfering with one or more
aspects of concentration or motivation. It is widely and consistently
reported that dehydration has a negative effect on mood state
through one or more alterations in perceived tiredness, alertness,
confusion, fatigue, anger, or depression (Cheuvront & Keneﬁck,
2014). When dehydration is ≥2% body mass, it can also produce
unpleasant and distractive symptoms, such as dry mouth, thirst, and
headache (Cheuvront & Keneﬁck, 2014).
A meta-analysis by Wittbrodt and Millard-Stafford (2018)
examined the impact of dehydration on cognitive performance
from 33 studies that included more than 400 test subjects. Wide
variability was observed among studies, but the authors concluded
that dehydration ≥ 2% body mass produced a small, but statistically
signiﬁcant impairment in cognitive performance tasks involving
attention, executive function, and motor coordination (Wittbrodt &
Millard-Stafford, 2018). As ≥2% dehydration appears to describe
both physical and mental performance thresholds, it is likely that
the risks to attention, executive function, and motor coordination
are primarily for high-risk track-and-ﬁeld events that rely little on
the mental performance measures affected.
Basic Rehydration Science
Sweat is composed primarily of water (∼99.9%). Although sweat
electrolyte losses can require special attention to dietary replacement
(see “Basic Sweat Science” section), most ﬂuids are consumed
with meals and most meals generally provide ample
replacement of sweat electrolytes, particularly when energy consumption
matches energy utilization. However, when ﬂavor is
desired, timing between meals is uncertain or extended, or training/competition
is anticipated to be intense and prolonged, a typical
sports drink formulation can provide energy (4–6% carbohydrate),
contribute to the replacement of the electrolytes lost in sweat
(20 mmol/L sodium; 4 mmol/L potassium), and generally be
absorbed faster than water alone (Baker & Jeukendrup, 2014;
Leiper, 2015). For all track-and-ﬁeld athletes, optimal rehydration
may best be sustained between training days by behaviorallydriven
ingestion of solid food and water (Maughan et al., 1996).
However, between training sessions or events, beverages that
contain macronutrients or electrolytes are better retained than water
and should be considered (Maughan et al., 2016, 2018; Shirreffs
et al., 1996; Sollanek et al., 2018).
Strategies for Optimizing Hydration
It is clear that for all track-and-ﬁeld events, optimal day-to-day
hydration is most important for optimizing training and competition.
The concepts reviewed in Figure 1 are a simple but effective
starting point for success. Other simple (Maughan & Shirreffs,
2008) and more advanced techniques (Armstrong & Casa, 2009)
may also be adopted. For low- and moderate-risk track-and-ﬁeld
events, the daily use of Figure 1 and the use of thirst to guide
drinking behavior is probably sufﬁcient for optimizing hydration—
particularly when training and competing in familiar settings and
when there is no limit to food or ﬂuid access (Keneﬁck, 2018). But
when training or competing in high-risk events—particularly when
in unfamiliar settings or when access to food and ﬂuid may be
limited, then a more programmed approach centered around
knowledge of personal sweat losses is recommended (Cheuvront
& Keneﬁck, 2017; Keneﬁck, 2018).
Track-and-Field athletes train as they intend to compete; ﬂuid
replacement planning should be part of the strategy. For example, in a
marathon race, drink stations are positioned at regular intervals. The
absence of water stations during long training runs means implementing
a drinking strategy by other means, such as with wearable drink
systems. A simple strategy such as this can accustom gastric tolerance
and optimize hydration for the most difﬁcult training sessions. It
appears that while >90% of IAAF athletes have a ﬂuid intake plan
when competitions are forecasted to be hot, the volumes planned may
or may not reﬂect anticipated losses (Périard et al., 2017).
The ﬂip side of replacing sweat losses is to minimize sweat
losses so that less drinking is needed. Various kinds of thermal
management scenarios are possible, such as cold towels, ice vests,
indoor (air conditioned) exercise, and early morning- or lateevening
exercise. Ingestion of ice slurry before exercise is an
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178 Casa et al.
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alternative hydration strategy, but appears no more effective than
cold water and may produce untoward side effects (Jay & Morris,
2018). The practice of trying to delay dehydration by expanding total
body water using beverages with high salt concentrations or glycerol
is generally ineffective and carries its own risks (McDermott et al.,
2017). Approximately 50% of IAAF athletes practice some form of
thermal management before hot weather competitions (Périard et al.,
2017). Table 2 summarizes strategies for optimizing hydration.
Summary
The impact of dehydration on training and performance outcomes
in athletes remains a much-debated topic. Track-and-ﬁeld athletes
often train and compete in hot environmental conditions, where
ﬂuid balance and hydration become essential daily considerations.
Given the individual nature of sweating responses with training and
competition, each athlete should assess their own individual ﬂuid
requirements and determine if these are likely to be a cause for
concern (e.g., if >2% body mass loss observed). The risk of
impairment in training or performance with levels of dehydration
of <2% body mass loss is “low” and applies to many track-and-ﬁeld
events (particularly sprints, jumps, and throws). However, other
Track and Field events carry a “high” risk, typically in the longer
duration and continuous activities, such as endurance events. For
these events, careful attention should be placed on individualized
and planned hydration practices to optimize training and performance
outcomes.
Acknowledgments
The authors would like to offer our sincerest gratitude to Robert Carter,
who was an author on the original manuscript. In addition, they are grateful
for the assistance of Yasuki Sekiguchi, a doctoral student at the University
of Connecticut in the USA for his assistance with some technical aspects of
this publication. The opinions or assertions contained herein are the private
views of the authors and should not be construed as ofﬁcial or reﬂecting the
views of the Army or the Department of Defense. Approved for public
release: distribution unlimited.
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Table 2 Practical Strategies to Reduce Dehydration for Track-and-Field Athletes
Strategy Details
WUT First morning weight, urine color, and thirst sensation to guide day-to-day adequacy of water and electrolyte
consumption.
Incorporate electrolytes Rehydrate with meals and include sodium and potassium-rich foods.
Personalize ﬂuid needs Estimate personal sweat losses from changes in body weight pre- to postexercise.
Train as you compete Incorporate a competition drinking strategy into training (e.g., using wearable drinking systems as a
substitute for water stations).
Improve thermal management Train during the coolest times of daya
; consider indoor air-conditioned training in extreme heat; and consider use
of active cooling (e.g., cold towels, cold showers).
Note. W = reduced body weight; U = dark urine color; T = feeling thirsty. a
Except when deliberate heat acclimatization is desired.
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