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No Performance or Affective Advantage of Drinking versus Rinsing with Water during a 15-km Running Session in Female Runners

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Abstract

The advantage of ingesting fluids during endurance exercise lasting < 90 min has recently been challenged, but literature confirming or disputing this case is limited, particularly for female athletes. This study examined the effects of consuming water versus mouth rinsing with water during a running time trial. Recreationally active female runners (n = 19) completed two, 15-km time trials on an outdoor course in temperate environment (~20ºC; 87% RH) separated by at least one week in a randomized cross-over study design. Participants consumed 355 ml of water (DW) during their run or mouth rinsed (MR) with water from a handheld water bottle every 3 km for 5 s with physiological, perceptual, and affective variables assessed. DW or MR did not affect completion time (79.8 ± 8.1 min and 79.2 ± 8.2 min, p = 0.23), HR (p = 0.35), or RPE (p = 0.73), respectively. Sweat losses were greater (p = 0.03) for DW: 1.47 ± 0.34 L compared to MR: 1.28 ± 0.27 L; however, thirst sensation was not significantly different for MR: 6.7 ± 1.4 compared to DW: 6.2 ± 1.6. A significant effect was exhibited for time (p < 0.01) but not condition for Feeling Scale and Felt Arousal Scale or Energetic and Tense Arousal. Carrying only one smaller fluid container for MR versus a larger or multiple water bottles/backpack systems used for water consumption can reduce fluid load carried during extended duration runs without altering performance or affect for runs of 1.0-1.5 h. MR may also be beneficial to decrease thirst without ingesting fluid for runners that limit exercise fluid consumption because of gastrointestinal discomfort concerns.
Original Research
No Performance or Affective Advantage of Drinking versus Rinsing with Water
during a 15-km Running Session in Female Runners
LAUREN N. SHAVER*1, ERIC. K. O’NEAL2, ERIC E. HALL‡1, and SVETLANA
NEPOCATYCH‡1
1Department of Exercise Science, Elon University, Elon, NC, USA; 2Department of Health,
Physical Education and Recreation, University of North Alabama, Florence, AL, USA
*Denotes undergraduate student author, Denotes professional author
ABSTRACT
International Journal of Exercise Science 11(2): 910-920, 2018. The advantage of ingesting fluids during
endurance exercise lasting < 90 min has recently been challenged, but literature confirming or disputing this case
is limited, particularly for female athletes. This study examined the effects of consuming water versus mouth
rinsing with water during a running time trial. Recreationally active female runners (n = 19) completed two, 15-km
time trials on an outdoor course in temperate environment (~20ºC; 87% RH) separated by at least one week in a
randomized cross-over study design. Participants consumed 355 ml of water (DW) during their run or mouth rinsed
(MR) with water from a handheld water bottle every 3 km for 5 s with physiological, perceptual, and affective
variables assessed. DW or MR did not affect completion time (79.8 ± 8.1 min and 79.2 ± 8.2 min, p = 0.23), HR (p =
0.35), or RPE (p = 0.73), respectively. Sweat losses were greater (p = 0.03) for DW: 1.47 ± 0.34 L compared to MR:
1.28 ± 0.27 L; however, thirst sensation was not significantly different for MR: 6.7 ± 1.4 compared to DW: 6.2 ± 1.6.
A significant effect was exhibited for time (p < 0.01) but not condition for Feeling Scale and Felt Arousal Scale or
Energetic and Tense Arousal. Carrying only one smaller fluid container for MR versus a larger or multiple water
bottles/backpack systems used for water consumption can reduce fluid load carried during extended duration runs
without altering performance or affect for runs of 1.0-1.5 h. MR may also be beneficial to decrease thirst without
ingesting fluid for runners that limit exercise fluid consumption because of gastrointestinal discomfort concerns.
KEY WORDS: Hydration, endurance performance, affect, perceived exertion
INTRODUCTION
There is considerable debate over the most appropriate fluid intake strategies for endurance
athletes (2, 25). The American College of Sports Medicine (ACSM) guidelines recommend
individuals drink to avoid losing more than 2% of body mass during endurance exercise (25).
However, the results of a meta-analysis by Goulet et al. (15) contends that a loss in up to 4%
body mass does not mitigate cycling time trial performance in ecologically valid conditions (15).
In temperate, and even hot environmental settings, most runners attain sweat losses
significantly exceeding 2% body mass (20, 21), but are unlikely to surpass 4% loss in body mass
for events of half-marathon distance (19). Training or competition scenarios in this 2-4% body
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mass loss range create the most confusion in giving appropriate advice to runners to optimize
performance.
Dion et al. (12) demonstrated that although consuming water to maintain < 2% body mass loss
provides cardiovascular and thermoregulatory advantages, this strategy does not improve half-
marathon treadmill running performance in the heat (30 °C) compared to drinking ad libitum.
The volume of water ingested when limiting body mass loss to < 2% was 3.5 times greater than
consumed when runners drank ad libitum (12). Carrying the volume of fluid required by Dion
et al. (12) to meet suggested ACSM guidelines would require a considerable number of water
bottles to be carried or a backpack style hydration vest for an unassisted run. Likewise, ingesting
close to 2 L of fluid from standard 237 mL race aid stations style cups during competition would
be untenable for most runners without pace mitigation. Both strategies would likely inhibit
optimal running economy and performance, however a handheld water bottle could be a
practical alternative.
When less than optimal fluid intake is incurred between training bouts, thirst sensation increases
and performance decreases during runs in warm environments (9, 10). It is unknown if mouth
rinsing alone would alleviate thirst/mouth dryness and curtail performance decrement under
these conditions. However, if runners begin training bouts or competition expected to elicit 2-
4% body mass loss euhydrated, simply using carried fluid to rinse in the mouth to reduce thirst
sensation might be sufficient to maintain optimal performance and easy to carry. There appears
to be only one investigation that has examined the effects of rinsing versus ingesting water
during endurance exercise. Arnaoutis et al. (3) found that consuming 100 mL of water improved
cycling time to exhaustion performance when compared to mouth rinsing or a control treatment,
despite no physiological or perceptual benefit. On the other hand, Backhouse et al. (4) found
that consuming water before and every 20 minutes during a 90 min run at 70% VO2 max resulted
in a trend of increasing perceived pleasure from pre-run versus a pattern of increasing
displeasure when no water was consumed. Like Arnaoutis et al. (3), heart rate and RPE were
not different between sessions despite the prolonged duration of exercise, but thirst rating
increased at 40 min of exercise for the no consumption group versus ingestion trial (4).
The effects of rinsing versus ingesting water are not well understood, therefore, the purpose of
the study was to examine 15-km time trial performance and physiological and affective domain
outcomes when consuming versus mouth rinsing with water in female runners in which
environmental conditions and run duration were expected to elicit sweat losses between 2-4%
of body mass. An additional aim of this study was to further examine the accuracy in which
female runners estimate their sweat losses.
METHODS
Participants
Recreationally trained female runners (n = 23) between the ages of 18 and 45 (26 ± 6.5 y) who
completed 34 ± 11 km of running per week with an average best time of 116 ± 9 min (n = 17) for
half marathon (21.1 km) were recruited for this study. However, data from 4 participants were
excluded from further analysis due to significant environmental and sweat loss differences
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between outdoor running trials. Each participant read and signed an informed consent form
prior to participation. All procedures were approved by the local Institutional Review Board
prior to participants signing informed consent. During the screening session height (165 ± 5 cm)
and weight (60.3 ± 7.1 kg) were measured (Seca 700, Chion, CA). Body fat % (22 ± 4%) was
estimated using bioelectrical impedance analysis (BF 306, OMRON, Bannockburn, IL).
Protocol
A randomized cross-over study design was used for this study. Two treatment sessions that
included a 15-km outdoor time trial separated by 9 ± 3 days were completed. Water was chilled
(5-6° C) before the trials and warmed with the environment during the run with no intervention
to keep the water chilled once running began. During the time trials, participants either
consumed water (DW) or mouth rinsed with water (MR). Participants were instructed to drink
~ 90 ml of water at 3, 6, 9, and 12 kilometers for a total of 355 ml or rinse for 5 s every 3 kilometers
from a hand-held water bottle (Amphipod, Inc., Seattle, WA) without stopping. Before
beginning the run, participants were informed of where they were to drink or rinse using a map.
They were reminded of the specific location after each lap. To help approximate the volume of
water to be consumed, the bottle was demarcated with a marker into 5 even portions.
Participants were allowed to maintain their normal physical activity throughout the study but
were asked to avoid any strenuous exercise that would cause soreness or severe tiredness 24
hours prior each session and refrain from alcohol, and coffee consumption. They were also asked
to consume a similar dinner the night before each trial and 1000 ml of water to ensure similar
euhydration levels the following morning.
All trials commenced between 6:30-9:00 am depending on each individual’s schedule,
approximately 45-60 minutes after the participants consumed a standardized breakfast
consisting of a granola bar, banana, and 500 ml of water at home. After, reporting to the lab
participants provided a urine sample to determine urine specific gravity (USG) and urine color.
Urine color was recorded using an 8-point scale (1) and USG was measured with a manual
refractometer (ATA-2771, ATAGO U.S.A. Inc., Bellevue, WA). After subjects provided a urine
sample, nude body mass was measured to the nearest 0.1 kg (BF-679W/BF-680W, TANITA,
Arlington Heights, IL). Participants were then fitted with a heart rate (HR) monitor (Polar
Team2, Polar Electro, Kempele, Finland) before walking to the start/finish line of the running
course located outside the laboratory. HR was monitored throughout the time trial and session
HR was recorded as participants finished 15-km using the Polar Team2 software system. The 15-
km time trial was performed on a well-marked, mainly flat outdoor 5-km course (3 laps). All of
the run was performed on either concrete walkways or asphalt roads. Temperature and relative
humidity were recorded at the start of each trial using a mobile weather application (The
Weather Chanel App, Atlanta, GA). Time to complete each lap and overall time were assessed
with a standard stopwatch. Participants had five minutes to recover after 15-km time trial before
completing body mass measurement to determine sweat loss. During recovery, participants
walked back to the laboratory and were allowed to stretch keeping it consistent between trials.
Participants completed the Feeling Scale (FS) and Felt Arousal Scale (FAS) before, at the 5-km
and 10-km mark, immediately after finishing, and 15 minutes post-trial. A large FS and FAS was
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visually presented to the participants at the beginning/end of each lap. Participants were
instructed to verbally rate their FS and FAS to investigators as they passed without stopping.
The FS (16) was used to assess the affective valence of participants during exercise on an 11-
point scale (+5 very good to -5 very bad and 0 neutral). The FAS (26) measures arousal on
a 6-point scale (1 low arousal to 6 high arousal). The Activation-Deactivation Adjective
Checklist (AD ACL) (27) was administered before and immediately after each trial to assess
levels of activation and arousal using a self-rated test with 20 adjectives on a four point scale (1
not at all and 4 very much so). The AD ACL determines two bipolar dimensions: energetic
and tense arousal. The FS and FAS as well as the energetic and tense arousal were used to
measure the circumplex model of affects (24).
Stomach fullness and thirst sensation were collected before and after each trial. Stomach fullness
was measured on a scale 0-10 (0 empty/extremely hungry and 10 extremely full) and the
thirst sensation was measured on a scale 0-9 (0 not thirsty at all and 9 very, very thirsty) (13).
Session rate of perceived exertion (RPE) was measured immediately after the run was completed
on a 6-20 scale (6).
After each trial, participants were asked to verbally estimate how much sweat they thought they
lost during the run rounded to the nearest 30 mL. Participants were presented with an empty
experimental water bottle and informed that the water bottle used during the run held 360 mL
of water for a visual reference.
Statistical Analysis
Repeated measures ANOVA (time to complete each 5-km loop, thirst sensation, stomach
fullness, FS and FAS) and paired-samples t-test were used to analyze differences in dependent
variables (USG, urine color, body weight, total running time, HR, session RPE, sweat rate and
sweat loss) between DW or MR. All statistical analyses were performed using SPSS Version 22.0
(SPSS Inc., Chicago, IL, USA). Mauchlys’s Test of Sphericity was used to test the assumption of
sphericity. Data are presented as mean ± standard deviation, with the significance level set at p
< 0.05.
RESULTS
Runners reported to the laboratory equally euhydrated based on USG (DW = 1.010 ± 0.007; MR
=1.008 ± 0.006; p = 0.21 and urine color (DW = 2.8 ± 1.3; MR =2.5 ± 1.3; p = 0.13). Pre-run body
mass was lower for the DW session (DW = 59.7 ± 7.1; MR = 60.0 ± 7.1 kg; p = 0.03). There was no
significant difference in temperature (20.1 ± 3.0 ºC and 19.8 ± 2.6 ºC, p = 0.68), relative humidity
(85.3 ± 9.4% and 86.6 ± 10.4%, p = 0.68), session HR (180 ± 16 bpm and 178 ± 14 bpm, p = 0.35),
or session RPE (16.0 ± 2.0 and 16.4 ± 1.7, p = 0.73) between DW and MR conditions respectively.
Likewise, there were no differences in overall time trial performance (79.8 ± 8.1 and 79.2 ± 8.2
min, p = 0.23) for DW and MR conditions, respectively. Individual 15-km time trial results are
displayed in Figure 1. Individual data indicated that there were 4 runners that ran 2% faster
during drinking and 8 runners that ran 2% faster during rinsing. There was no significant
treatment effect (p = 0.23) for 5-km split times; however, the main effect for lap number
approached significance (p = 0.07) for individual 5-km split times at 1st 5-km (26.2 ± 2.6 and 26.1
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± 2.7), 2nd 5-km (26.4 ± 3.1 and 26.1 ± 2.9) or 3rd 5-km (27.1 ± 3.0 and 26.8 ± 2.9) for DW and MR
conditions, respectively.
Figure 1. 15-km Time trial individual data (n = 19). DW drinking water, MR mouth rinsing. Solid lines represent
<2% change in performance between trials. Long dash, solid fill marker represent >2% decrease in performance
during MR versus DW. Short dash, no fill markers represent >2% decrease in performance during DW versus MR.
Participants experienced significantly greater sweat loss (p = 0.03), sweat rate (p = 0.03) and %
body weight loss (p = 0.01) during DW (Table 1). There was no significant difference in
estimated absolute sweat loss (p = 0.34) or percent of actual sweat loss (p = 0.57) between DW
and MR conditions; however, participants significantly (p < 0.001) underestimated how much
sweat they actually lost in each treatment session (Table 1).
Table 1. Hydration and sweat loss estimate outcomes (n = 19; M ± SD).
Sweat Loss (L)
Sweat Rate (L/h)
Body mass loss (%)
Absolute (L)
% of Actual Sweat Loss
DW
1.44±0.34*
1.05±0.24*
2.4±0.6*
0.69±0.92†
47.8±56.0
MR
1.23±0.28
0.93±0.23
2.1±0.5
0.54±0.58†
42.8±44.1
DW drinking water, MR mouth rinsing. *Significantly different from MR p < 0.05. †Significantly different
within treatment versus actual sweat loss p < 0.05
60
65
70
75
80
85
90
95
100
DW MR
Finishing Time (min)
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There was a significant main effect for time (p < 0.001) but not for treatment (p = 0.10) or
interaction time by treatment (p = 0.70) observed for thirst sensation (Table 2). Thirst did not
differ between pre- or post-run between treatments, however, thirst ratings increased with time
as would be expected. There was a significant main effect for time (p < 0.001) but not for
treatment (p = 0.92) observed for stomach fullness (Table 2). Stomach fullness did not differ
between DW and MR treatment conditions, however, it decreased over time. In addition, a
significant time by treatment interaction was observed (p = 0.04) where greater decrease in
stomach fullness was observed in MR conditions compared to DW.
There were no significant differences in condition or condition by time effect for FS and FAS;
however, there was a significant time effect (p < 0.001). Univariate analyses revealed that this
was due to changes in both FS (p <0 .001) as well as FAS (p < 0.001). For the FS, compared to
baseline there was a non-significant trend towards an increase in negative valence at 10-km (p =
0.06) and 15-km (p = 0.08), but affect valence became more positive at 15 min post-run (p = 0.003).
FAS was found to increase at every time point following baseline (p < 0.001). See Figure 1 for a
graphical depiction of the results for FS and FAS. Energetic and tense arousal exhibited no
significant condition or condition by time interaction, but the main effect for time was significant
(p < 0.001). This was a result of significant changes in energetic arousal (p < 0.001) and tense
arousal (p = 0.01) over time. When plotted on the circumplex model there was a significant
increase in valence and arousal (see Figure 2).
Table 2. Thirst and stomach fullness responses (n = 19; M ± SD).
DW
MR
Pre
Post
Pre
Post
Thirst Sensation
3.6±1.9
6.2±1.6†
4.1±1.6
6.7±1.4†
Stomach Fullness
6.7±1.4
5.2±1.8†
7.2±1.4
4.6±1.3†
DW drinking water; MR mouth rinsing; Thirst Sensation Scale (0-7); Stomach Fullness Scale (0-10).
†Significantly different within treatment from pre-run p < 0.05
Figure 2. Feeling Scale (FS) and Felt Arousal
Scale (FAS) responses to drinking vs rinsing
over time. Solid and dashed line represents MR
- mouth rising and DW - water drinking,
respectively.
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DISCUSSION
It is unequivocal that regardless of environmental conditions during longer races (e.g. the
marathon), where sweat losses can easily exceed 4% body mass, that nearly all runners will
choose to and should drink during competition. This is also true during shorter distance races
such as a half-marathon that are conducted in the heat (7, 12, 19). However, during running
bouts that will elicit greater than 2% loss in body mass, but not more than 4% loss in body mass,
the efficacy for fluid ingestion to improve endurance performance is unclear. Thus, the purpose
of this study was to examine differences in physiological and affective responses and
performance under such training conditions for well-trained but recreational female runners
when drinking versus mouth rinsing with water. The main finding of the current study was that
ingestion of fluid was not advantageous compared to mouth rinsing during a 15-km outdoor
running time trial (Figure 1).
The current authors are aware of only one other investigation (3) in which water ingestion versus
mouth rinse has been examined. Arnaoutis et al. (3) found improved cycling performance in 10
trained, but non-elite men when consuming only 100 ml of water compared to rinsing with
water. Arnaoutis et al. (3) postulated the act of swallowing and ingestion of chilled fluids could
activate oral-pharyngeal receptors and in turn prolong exercise capacity. While the authors’
hypothesis was confirmed in contrast to the findings of the current investigation, it is critical to
examine methodological differences implemented. Arnaoutis et al. (3) study completed their
performance task following a 10-hour fast and a pre-performance test that consisted of 4 bouts
of low intensity running or cycling for 25 min followed by 5 min of passive rest to elicit 2%
dehydration prior to performance testing (3). In total, the dehydration protocol included 100
min of exercise and 20 minutes of passive rest in a hot environment (31 ˚C). The performance
task conducted was also a time trial to exhaustion which have been shown to have much higher
Figure 3. Energetic Arousal (EA) and Tense
Arousal (TA) responses to drinking vs rinsing
over time. Solid and dashed line represents MR
- mouth rising and DW - water drinking,
respectively.
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coefficient of variations than simple time trials (18). In contrast, the present study attempted to
replicate a more ecologically valid scenario in regards to training or competition conditions.
Sweat losses were induced during the simulated competition protocol only. Runners also began
exercise euhydrated and consumed a light breakfast 45-60 minutes before the run. Although
the time trial to exhaustion in (3) was not performed under hot conditions, it is plausible the 2 h
of thermoregulatory challenge prior to the performance task initiated an increased central drive
attributed to an oral-pharyngeal response of cold fluid ingestion. However, under such training
or race conditions it seems unlikely most runners would fail to ingest fluids if available, but
there is no evidence that this ergogenic effect exists during hard runs of 70-90 min in temperate
environmental conditions.
A concerted effort was made to create a drinking volume that would optimize the opportunity
for fluid ingestion to improve performance while limiting risk of stomach discomfort. The
volume of fluid selected was also chosen to minimize running economy and kinematic impact
from carrying a greater fluid mass. Dion et al. (12) found considerably greater abdominal
discomfort when participants consumed water ad libitum versus drinking to keep body mass
loss below 2% during a treadmill half-marathon in the heat (12). As would be expected,
participants felt less stomach fullness from the beginning to the end of the running session
regardless of treatment difference (Table 2). The faster pace of the male runners in (12) resulted
in similar duration of exercise to the current study. Despite drinking on average 225 mL and
1,705 mL more compared to the present study in the to-thirst and maintaining less than 2% body
weight loss, respectively, Dion et al. (12) did not find a significant difference in perceived thirst
until the 20-km mark of the half marathon. Likewise, simply rinsing fluids resulted in no
difference in thirst sensation difference (Table 2) in the current study. Akin to thirst sensation
and stomach discomfort, fluid ingestion failed to reduce cardiovascular drift or increase session
RPE in the present study. These results support previous investigations that suggest fluid intake
has little to no effect on cardiovascular responses or perceived exertion under similar exercise
tasks and conditions (3, 5, 8, 14, 23).
A study by de Araujo et al. (11) demonstrated that water activates both the primary and
secondary taste cortex. When individuals are thirsty, both consuming water and delivering
water into the mouth produced feelings of pleasantness and showed activation in the
orbitofrontal cortex (11). Thus, the reward of both drinking water and rinsing with water
activate the same part of the brain. This may help to explain why participants did not feel
different during the run, which may have a positive impact on performance as well. Similar to
Hall et al. (16), participants tended to feel worse and more aroused during exercise (16). After
exercise, participants felt better and levels of arousal decreased with ingestion resulting in no
improvement in affective domain responses (Figures 2 and 3).
Application of nearly all of the current guidelines for hydration strategies promoted by the
ACSM (25) require accurate estimation of sweat losses assessed by change in pre- to post-
exercise body mass, but this practice is not common in the running community (22). Previous
studies suggest that most, but not all runners will adequately rehydrate between training bouts
and that the majority of runners underestimate their sweat losses by ~50% (20,21). This
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phenomenon was further confirmed in the current study with nearly identical levels of
underestimation of sweat losses (Table 1) in a large group of trained but non-elite female runners
and highlights the need for greater promotion of the concept of implementing sweat loss
assessment techniques to optimize between bout fluid intake strategies and prevent over or
underestimation of fluids during long duration runs.
The major limitation of this study is that environmental conditions could not be standardized
between trials. However, the exclusion of data from participants that ran under significantly
different temperatures and humidity has hopefully mitigated this limitation. Specific dietary
and training habits may not have been similar between trials, as participants were not asked to
record to ensure compliance. Participants did not engage in formal 15-km training nor ran the
distance very often, which could have affected the results. In addition, some participants had
only 6-7 days to recover in between the trials, however, similar recovery time was previously
used for a half marathon distance by Dion et al. (12). Therefore, considering a shorter distance
in the present study the time in between the trials would be sufficient enough to recover for
most participants and would not have an effect on performance. Lastly, the inability to monitor
whether participant consumption of water during the rinsing trial may have influenced their
physiological and psychological responses.
In conclusion, ingestion of fluid during runs of 70-90 min that produce greater than 2 but less
than 4% loss in body mass from sweating did not improve run performance, alter heart rate,
stomach discomfort, and thirst sensation, or improve affective domain responses versus rinsing
when runners began exercise in a euhydrated state. Carrying fluid for rinsing versus
consumption can reduce the volume of fluid to be transported by the runner. Assessment of
change in body mass during runs can help runners identify their fluid consumption needs
between training bouts. All runners in this investigation began exercise euhydrated. Future
investigations examining the effects of mouth rinsing versus fluid ingestion when inadequate
between bout fluid replacement takes place is warranted.
ACKNOWLEDGEMENTS
The authors would like to thank all of the participants who kindly donated their time to
participate in the study. Elon University helped to make this study possible by providing
resources and opportunity.
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... No additional published articles were discovered. Data from nine published investigations [10][11][12][13][14][15][16][17][18] in which sweat loss was estimated were shared by current authors through personal communication. A new spreadsheet database was created for comprehensive analysis. ...
... Each investigation is summarized in Table 1. Two running studies [11,18] and one basketball study [12] incorporated designs in which sweat loss estimations were made twice by the same participants during separate training sessions. In these studies, participants were not informed of their actual sweat losses until after study completion. ...
... Both of these studies subcomponents are presented in separate rows in Table 1 due to the dramatic difference in testing conditions. The findings of Shaver et al. [11] are not presented in two rows due to the consistency in exercise modality, duration and environmental conditions. Muth et al. [16] also incorporated multiple sweat loss estimations within subjects, but participants were informed of their sweat loss volume after the first estimation session. ...
Article
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The main purposes of this review were to provide a qualitative description of nine investigations in which sweat losses were estimated by participants following exercise and to perform a quantitative analysis of the collective data. Unique estimations (n = 297) were made by 127 men and 116 women after a variety of exercise modalities in moderate to hot environmental conditions. Actual sweat loss exceeded estimated sweat loss (p < 0.001) for women (1.072 ± 0.473 vs. 0.481 ± 0.372 L), men (1.778 ± 0.907 vs. 0.908 ± 0.666 L) and when all data were combined (1.428 ± 0.806 vs. 0.697 ± 0.581 L), respectively. However, estimation accuracy did not differ between women (55.2 ± 51.5%) and men (62.4 ± 54.5%). Underestimation of 50% or more of sweat losses were exhibited in 168 (54%) of estimation scenarios with heavier sweaters displaying a higher prevalence and trend of greater underestimations in general. Most modern guidelines for fluid intake during and between training bouts are based on approximate sweat loss estimation knowledge. These guidelines will likely have minimal efficacy if greater awareness of how to determine sweat losses and accurate recognition of sweat losses is not increased by coaches and athletes.
... Other novel strategies include asking exercisers to alter their facial expressions (e.g., smiling or frowning; Brick et al., 2018;Philippen et al., 2012), to wear a transcranial direct current stimulation device (Baldari et al., 2018), and rinse their mouth with water rather than drink it (Shaver et al., 2018). However, the initial evidence on these strategies does not suggest they are particularly effective at improving how we feel during exercise. ...
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Abstract Current American College of Sports Medicine (ACSM) guidelines recommend replacing 150% of sweat losses between training bouts separated by ≤12 hours, but little evidence exists concerning the implications of this strategy for runners. Participants (n = 13) in this study replaced 75% (1637 ± 372 mL) or 150% (3099 ± 850 mL) of sweat losses following an outdoor evening run (∼75 minutes; Wet-bulb-globe temperature (WBGT) = ∼27°C) and consumed a standardised evening meal and breakfast before completing an outdoor (WBGT = ∼23°C) 10-km time-trial the following morning. Urine was collected between runs and urine specific gravity (USG) was assessed pre-run. Significant differences were found in pre-run body mass (75% = 69.6 ± 9.2; 150% = 70.1 ± 9.3 kg; P = 0.02) and USG (75% = 1.026 ± 0.005; 150% = 1.014 ± 0.007; P < 0.001). Heart rate during 10-km run (168 ± 14 versus 168 ± 12 beats min(-1)) and post-run intestinal temperature (39.08 ± 0.52 versus 39.00 ± 0.70 °C) did not differ for 75% and 150%, respectively, despite an ∼3% performance improvement (75% = 47.28 ± 6.64; 150% = 45.93 ± 6.04 minutes; P = 0.001) due to a faster pace in the second half of the run with 150% replacement. Session rate of perceived exertion (RPE) was lower (P = 0.02) during 150% (7.5 ± 1.3) versus 75% (8.4 ± 0.9). Reluctant drinkers potentially hinder training quality between evening and morning runs in the heat, but copious urine production and difficulty in consuming recommended fluid volumes suggest fluid replacement <150% may be more ideal.
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This study examined 24-h post-run hydration status and sweat loss estimation accuracy in college age runners (men = 12, women = 8) after completing a 1-h self-paced outdoor run (wet bulb globe temperature = 19.9 ± 3.0 °C). Sweat losses (1353 ± 422 mL; 1.9% ± 0.5% of body mass) were significantly greater (p < 0.001) than perceived losses (686 ± 586 mL). Cumulative fluid consumption equaled 3876 ± 1133 mL (218 ± 178 mL during) with 37% of fluid ingested lost through urine voids (1450 ± 678 mL). Fluid balance based on intake and urine production equaled +554 ± 669 mL at 12 h and +1186 ± 735 mL at 24 h. Most runners reported euhydrated (pre-run urine specific gravity (USG) = 1.018 ± 0.008) with no changes (p = 0.33) at hours 12 or 24 when both genders were included. However, USG was higher (p = 0.004) at 12 h post-run for men (1.025 ± 0.0070 vs. 1.014 ± 0.007), who consumed 171% ± 40% of sweat losses at 12 h vs. 268% ± 88% for women. Most runners do not need intervention concerning between bout hydration needs in temperate environments. However, repeated USG measurements were able to identify runners who greatly under or over consumed fluid during recovery. Practitioners can use multiple USG assessments as cheap method to detect runners who need to modify their hydration strategies and should promote assessment of sweat losses by change in body mass, as runners had poor perception of sweat losses.
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It has been demonstrated that exercise-induced dehydration (EID) does not impair, and ad libitum drinking optimizes, cycling time-trial (TT) performance. However, the idea that EID ≥ 2 % bodyweight (BW) impairs endurance performance is well ingrained. No study has tested the impact of EID upon running TT performance. We compared the effects of thirst-driven (TD) vs. programmed fluid intake (PFI) aimed at maintaining EID-associated BW loss <2 % on half-marathon performance. Ten trained distance runners underwent, in a randomized, crossover fashion, two, 21.1 km running TTs on a treadmill (30 °C, 42 % relative humidity) while facing a wind speed matching running speed and drinking water (1) according to thirst sensation (TD) or (2) to maintain BW loss <2 % of their pre-exercise BW (PFI), as recommended by the American College of Sports Medicine. Despite that PFI significantly reduced EID from 3.1 ± 0.6 (TD) to 1.3 ± 0.7 % BW (PFI), mean rectal temperature from 39.4 ± 0.4 to 39.1 ± 0.3 °C, mean body temperature from 38.1 ± 0.4 to 37.7 ± 0.2 °C and mean heart rate from 175 ± 9 to 171 ± 8 bpm, neither half-marathon time (TD 89.8 ± 7.7; PFI 89.6 ± 7.7 min) nor running pace (TD 4.3 ± 0.4; PFI 4.2 ± 0.4 min/km) differed significantly between trials. Albeit providing trivial cardiovascular and thermoregulatory advantages, in trained distance runners, PFI (1,380 ± 320 mL/h) offers no performance benefits over TD fluid intake (384 ± 180 mL/h) during a half-marathon raced under warm conditions.
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The purpose of this study was to determine how accurately runners estimate their sweat losses. Male (n = 19) and female (n = 20) runners (41 ± 10 yr, VO2max 57 ± 9 ml · kg-1 · min-1) from the southeastern U.S. completed an ~1-hr run during late summer on a challenging outdoor road course (wet bulb globe temperature 24.1 ± 1.5 °C). Runs began at ~6:45 a.m. or p.m. Before and after running, participants filled race-aid-station paper cups with a volume of fluid they felt would be equivalent to their sweat losses. Total sweat losses and losses by percent body weight differed (p < .01) between men (1,797 ± 449 ml, 2.3% ± 0.6%) and women (1,155 ± 258 ml, 1.9% ± 0.4%). Postrun estimates (738 ± 470 ml) were lower (p < .001) than sweat losses (1,468 ± 484 ml), equaling underestimations of 50% ± 23%, with no differences in estimation accuracy by percentage between genders. Runners who reported measuring changes in pre- and postrun weight to assess sweat losses within the previous month (n = 9, -54% ± 18%) were no more accurate (p = .55) than runners who had not (n = 30, -48% ± 24%). These results suggest that inadequate fluid intake during runs or between runs may stem from underestimations of sweat losses and that runners who do assess sweat-loss changes may be making sweat-loss calculation errors or do not accurately translate changes in body weight to physical volumes of water.
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Studies have reported that rinsing the mouth with a carbohydrate (CHO) solution improves cycling time-trial performance compared with rinsing with a placebo solution. However, no studies have compared the effect of mouth rinsing with a no-mouth-rinse control condition. The aim of this study was to compare the effects of a CHO mouth rinse with those of a placebo rinse and a no-rinse condition. Ten male cyclists completed three 1,000-kJ cycling time trials in a randomized, counterbalanced order. At every 12.5% of the time trial completed, participants were required to rinse their mouths for 5 s with either a 6.4% maltodextrin solution (CHO), water (WA), or no solution (CON). Heart rate and ratings of perceived exertion (RPE) were recorded every 25% of the time trial completed. Time to completion was faster in both CHO (65.7 ± 11.07 min) and CON (67.6 ± 12.68 min) than in WA (69.4 ± 13.81 min; p = .013 and p = .042, respectively). The difference between CHO and CON approached significance (p = .086). There were no differences in heart rate or RPE between any conditions. In summary, repeated mouth rinsing with water results in decreased performance relative to not rinsing at all. Adding CHO to the rinse solution appears to oppose this fall in performance, possibly providing additional benefits to performance compared with not rinsing the mouth at all. This brings into question the magnitude of the effect of CHO mouth rinsing reported in previous studies that did not include a no-rinse condition.
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Presents a description of the theory and research underlying the present author's (see record 1979-30156-001) Activation–Deactivation Adjective Check List (AD ACL) and describes a study involving 453 undergraduates that investigated the stability of factor structure of this test as a function of different rating-scale formats. The 2 core dimensions, energetic arousal (including tiredness) and tense arousal (including calmness), are believed associated with a variety of arousal-related characteristics, including physiological changes, sleep–wake cycles, exercise effects, various mood states, and various concomitants of stress. Analyses indicated that the factor structure of activation descriptors remained essentially the same with each scale. The importance of the underlying arousal model in relation to the activation descriptors is discussed. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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10 18–23 yr old telic-dominant and 10 20–22 yr old paratelic-dominant Ss performed a task that represented a video car-racing simulation. 12 of these Ss were interviewed on what they did the previous day, lifestyle, and planning orientation. Data obtained from a survey (110 undergraduates measured for telic or paratelic dominance), the task, and the interview support the construct validity of the telic (serious-minded, planning oriented, arousal avoiding) and paratelic (playful, here-and-now oriented, arousal seeking) constructs. Physiological measurements taken during task performance showed that telic Ss had steeper EMG gradients, higher tonic skin conductance, and greater thoracic respiratory amplitudes than did paratelic Ss. (28 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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232 undergraduates participated in 3 experiments that evaluated the feeling scale (FS) by W. J. Rejeski et al (1987) as a measure of affect during exercise. In Exp 1, Ss were instructed to check adjectives on the Multiple Affective Adjective Checklist—Revised that they would associate with either a "good" or a "bad" feeling during exercise. As predicted, discriminant function analysis indicated that the good/bad dimension of the FS appears to represent a core of emotional expression. In Exp 2, Ss rated how they felt during exercise at 3 rates of perceived exertion (RPE). Exp 3 involved 3 4-min bouts of exercise at 30, 60, and 90% of maximum oxygen consumption. RPE and the FS were moderately related, but only at easy and hard workloads. FS ratings evidenced greater variability as metabolic demands increased, and RPEs consistently had stronger ties to physiologic cues than responses to the FS. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
Studies have reported that rinsing the mouth with a carbohydrate solution improves cycling time trial performance compared to rinsing with a placebo solution. However, no studies have compared the effect of mouth rinsing to a no mouth rinse control condition. The aim of this study was to compare the effects of a carbohydrate mouth rinse to a placebo rinse and to a no-rinse condition. Ten male cyclists completed three 1000 kJ cycling time trials in a randomized, counterbalanced order. Every 12.5% of the time trial completed, participants were required to rinse their mouth for 5 s with either a 6.4% maltodextrin solution (CHO), water (WA) or no solution (CON). Heart rate and ratings of perceived exertion (RPE) were recorded every 25% of the time trial completed. Time to completion was faster in both CHO (65.7 ± 11.07 min) and CON (67.6 ± 12.68 min) compared to WA (69.4 ± 13.81 min; p = 0.013 and p = 0.042, respectively). The difference between CHO and CON approached significance (p = 0.086). There were no differences in heart rate or RPE between any conditions. In summary, repeated mouth rinsing with water results in decreased performance relative to not rinsing at all. Adding CHO to the rinse solution appears to oppose this fall in performance, possibly providing additional benefits to performance compared to not rinsing the mouth at all. This brings into question the magnitude of the effect of carbohydrate mouth rinsing reported in previous studies which did not include a no-rinse condition.