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EFFECT OF COLD SHOWER ON RECOVERY FROM HIGH-
INTENSITY CYCLING IN THE HEAT
AMORNPAN AJJIMAPORN,
1
RUNGCHAI CHAUNCHAIYAKUL,
1
SIRIKUN PITSAMAI,
2
AND WAREE WIDJAJA
1
1
Department of Sports Physiology, College of Sports Science and Technology, Mahidol University, Salaya, Nakhonpathom,
Thailand; and
2
Faculty of Sports and Health Science, Institute of Physical Education Phetchabun, Muang District,
Phetchabun, Thailand
ABSTRACT
Ajjimaporn, A, Chaunchaiyakul, R, Pitsamai, S, and Widjaja, W.
Effect of cold shower on recovery from high-intensity cycling in
the heat. J Strength Cond Res 33(8): 2233–2240, 2019—
Post-exercise cooling, e.g., cold water immersion has shown
beneficial cardiovascular and hormonal effects during recovery
from exercise in a hot environment. However, not much is
known about the effects of a cold water shower (CWS) as
a recovery intervention. This study examined the effects of
a CWS on heart rate (HR), core temperature (Tc), salivary
cortisol, and thermal comfort sensation (TCS) after exercise
in the heat. Nine healthy male subjects (age, 21 61 year)
performed 45 minutes of cycling in a hot environment (358C,
40–60% relative humidity) at 65% of peak oxygen uptake.
Thereafter, subjects underwent the CWS condition (15 mi-
nutes, 158C water shower) or control (SIT25; 15 minutes
passive recovery in 258C room) in a randomized crossover
design. After each 15 minutes, subjects sat in a 258C room
for another 2-hour recovery. Heart rate, Tc, and TCS were
recorded before and immediately after exercise, immediately
after CWS or SIT25, and at 30 minutes, 1, and 2 hours during
additional recovery. Salivary cortisol was collected at the same
time points except at 30 minutes of the additional recovery
period. Thermal comfort sensation was higher immediately after
CWS (+4; very comfortable) than SIT25 (+1; just comfort-
able). The change of HR decreased faster with CWS (218.3
62.3%) than with SIT25 (27.0 64.6%) at the first 30-minute
recovery time point (p,0.01). No differences between recov-
ery conditions were observed for the Tcor salivary cortisol at
any time point during the 2-hour recovery period. The findings
demonstrate that a 15-minute, 158C CWS was not effective in
reducing Tcor salivary cortisol during recovery from exercise in
a hot environment. However, CWS can promote TCS by facil-
itating a faster HR recovery after 30-minute postintervention
compared with passive recovery. The cooling benefits of
a CWS could be only recommended to reduce cardiac stress
after routine workout in a hot environment.
KEY WORDS cooling recovery intervention, core temperature,
salivary cortisol levels, high-intensity performance, a hot
environment
INTRODUCTION
Exercise in a hot environment provides a stress that
leads to rapid physiological responses, as evi-
denced by a faster rise in heart rate (HR), higher
core temperature (Tc), enhanced skin blood flow,
and an increased release of neuroendocrine hormones (15).
Fatigue in endurance-trained subjects during exercise in the
heat has been related to a higher body temperature (10),
generally believed to be the principle contributing factor that
stimulates the secretion of cortisol (20). Hosick et al. (12)
reported that during exercise in a hot environment (388C),
at 65% of peak oxygen uptake (V
_
O
2
peak), cortisol was
increased when Tcwas elevated by approximately 18C
above resting Tc, with a gradual decrease within 24 hours
after exercise in well-trained subjects. Prolonged elevation of
cortisol after high-intensity exercise is believed to be detri-
mental to health. Previous studies reported that the cortisol
released in response to increased Tcmay influence inflam-
mation and regeneration of tissue damaged after acute stress
(12,19). Therefore, faster decreases in Tcand cortisol levels
after strenuous exercise are believed to benefit recovery in
athletes.
Cold-water immersion (CWI), ice massage, ice-vest, and
ice or cold gel pack application have been examined as post-
exercise cooling strategies to enhance recovery (25). Com-
pared with other cooling methods, CWI is the most efficient
recovery intervention after exercise in hot environments by
lowering Tc, HR, and cortisol levels (11,12,17,25). However,
the application of CWI requires ice, a large bathtub, and the
treatment space that may not be widely available. Hence, an
Address correspondence to Amornpan Ajjimaporn, amornpan.ajj@
mahidol.edu.
33(8)/2233–2240
Journal of Strength and Conditioning Research
Ó2019 National Strength and Conditioning Association
VOLUME 33 | NUMBER 8 | AUGUST 2019 | 2233
Copyright © 2019 National Strength and Conditioning Association. Unauthorized reproduction of this article is prohibited.
accessible alternative cooling recovery, which imparts simi-
lar physiological responses to the CWI method, may be
needed.
Taking a shower is an activity that millions of people
partake in as part of their routine after exercise. Eglin and
Tipton (7) showed that initially undertaking repeated cold
showering of the upper body (1–3 minutes at 108C) may
partly habituate subjects to subsequent head out CWI at the
same water temperature. The authors suggested that the
similar rates of decrease in skin temperatures between the
cooling methods were associated with a reduced respiratory
drive (breathing frequency) during the CWI. In addition, Juliff
et al. (14) observed that in elite netball players, contrast
showering (alternating 1 minute at 388C and 1 minute at 158
C for 14 minutes) after a netball-specific circuit session
decreased skin temperatures compared with a passive recov-
ery condition. However, despite the contrast showers having
a psychological impact (recovery perception scale), there was
no effect on Tcor performance measures (repeated agility).
Buijze et al. (2) reported that regular hot-to-cold showering
(30, 60, 90 seconds at 10–128C) for at least 30 days could
reduce self-reported sickness absence in healthy adults. Fur-
thermore, a recent study by Butts et al. (3) demonstrated that
a 15-minute 208C cold shower, applied to treat exertional
hyperthermia, resulted in a greater rate of decrease in Tc
and HR, and lower ratings of thermal sensation, compared
with passive rest. Although past studies have determined the
effects of cold showering on several physiological parameters,
to our knowledge, the cortisol response after a cold shower
intervention has not been examined. Therefore, the aim of this
study was to investigate the magnitude of change in the sal-
ivary cortisol response between a cold shower intervention
and passive rest, applied after exercise under hot conditions.
METHODS
Experimental Approach to the Problem
To determine the recovery benefits of a cold-water shower
(CWS) from high-intensity cycling in the heat, this study
examined the effects of 2 different interventions; a 15-minute
(158C, CWS) or passive recovery in 258C room (SIT25) on
HR, core temperature (Tc), salivary cortisol, and thermal
comfort sensation (TCS) after 45 minutes of cycling in
a hot environment (358C room temperature, 40–60% rela-
tive humidity) at 65% of peak oxygen uptake. This mode of
exercise and relative intensity has previously been shown to
significantly elevate Tc(.18C) and cortisol levels above
resting values under thermal stress (12). A similar cold
shower water temperature and duration of exposure (15 mi-
nutes at 208C) selected in our study has previously been
shown to reduce exercise-induced hypothermia through
greater rate of Tcreduction compared with passive rest (3).
The experimental design is shown in Figure 1. The study
used a randomized crossover design with the 2 recovery
interventions 7 days apart.
Subjects
Nine healthy male subjects aged between 20 and 25 years
(mean 6SD;age:20.961.0 years; body mass: 70.3 611.2 kg;
height: 175.6 68.4 cm; body mass index = 22.9 61.8 kg$m
22
,
% body fat = 16.6 66.1, V
_
O
2
peak = 32.6 64.1
ml$kg
21
$min
21
) participated in this study. Inclusion criteria
included being habitually active and typically engaged in at least
30 minutes of moderate exercise per day for a minimum of 3
days per week in the previous 3 months before the study. After
explanation of the testing procedures, and benefits and possible
risks of the study, informed consent forms were signed. Subjects
were instructed to refrain from additional exercise, alcohol and
caffeine intake for at least 48 hours before the testing sessions.
None of the participants were under pharmacological treatment
during the study. The experimental procedure was approved by
the Human Research Ethics Committee at Mahidol University
(MU-IRB 2014/12.2001).
Procedures
Initial Session. In the first visit, anthropometric data were
collected; height (cm), body mass (kg), body mass index
(kg$m
22
), and % body fat. Peak oxygen uptake (V
_
O
2
peak)
was then assessed using an incremental cycling test to estab-
lish the exercise intensity of 65% V
_
O
2
peak for the experimen-
tal trials. During the incremental cycling test on a Monark
cycle ergometer (Ergomedic 828 E; Monark Exercise AB,
Vansbro, Sweden), expired air was sampled with a mouth-
piece attached to an online gas collection system (Moxus
modular oxygen uptake system; AEI Technologies, Inc.,
Pittsburg, PA, USA). The incremental cycling protocol began
at 0.5 kp at 60 rpm for 2 minutes; thereafter, the intensity
increased by 0.5 kp every 2 minutes until volitional fatigue.
V
_
O
2
peak was recorded as the highest 30-second average.
Experimental Procedure. For each experimental condition,
participants arrived at the laboratory at 07:00 hours.
Breakfast consisted of a tuna sandwich, 250 ml of water
and 250 ml of orange juice, which was provided 90 minutes
before the experiment. The testing session was divided into 3
main periods: (a) 45 minutes of cycling; (b) 15 minutes of
a randomized intervention period (CWS or SIT25); and (c)
2-hour recovery period in a 258C room. Before starting the
experiment, urine specific gravity (USG) was measured using
a handheld refractometer (model Master-SUR/NM; Atago
Co Ltd., Tokyo, Japan) to ensure the subjects were not de-
hydrated (USG .1.020). Participants were provided with an
individual water bottle (500 ml; temperature range between
20 and 228C) and were encouraged to drink water ad libi-
tum throughout the experiment. Exercise was commenced
after 30-minute rest in a controlled room (temperature = 25
61.08C; relative humidity (rh) range between 40 and 60%).
The participants completed 45 minutes of cycling in a hot
room (temperature = 35.7 61.08C; rh range between 40
and 60%) at a constant load of the individual’s predeter-
mined kilopond of 65% of V
_
O
2
peak. After 45 minutes of
Recovery Effects of Cold Shower
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cycling, participants underwent either a 15-minute CWS or
SIT25. In CWS, participants took a 15 62.08C water
shower on 2 areas (back and chest), alternating between
each area every 3 minutes for 15 minutes. The flow rate of
the shower was 5 L$min
21
. The angle of the shower stream
was individually adjusted to allow the water from the base of
the neck downward, ensuring the head was not showered.
After 15 minutes, participants used bath towels to dry them-
selves before sitting in a room set at a temperature of 258C
for a period of 2 hours (recovery period). In SIT25, the
participants sat passively in a controlled room (temperature
=2561.08C; rh range between 40 and 60%) throughout
the intervention and recovery periods (Figure 1).
Measurements. Thermal comfort was measured using a 9-
point thermal comfort scale ranging from very uncomfort-
able (24) to very comfortable (4), with 0 representing the
transition from discomfort to comfort (26).
Heart rate was measured every 15 minutes until the end of the
experimental trial through telemetry from a chest strap and
a wrist watch receiver (FS1; PolarElectroOy,Kempele,Finland).
Salivary samples were collected for cortisol analysis imme-
diately postintervention (Post-Int), and at 1 and 2 hours during
the recovery period. Before the first saliva collection, contam-
ination with food debris was avoided by rinsing the mouth
with water. Salivary samples were collected using a cotton
swab and saliva-collecting tube (Salivette; Sarstedt, Newton,
NC, USA). After saliva collection, saliva-collecting tubes were
centrifuged at 3,000 rpm for 15 minutes at 48Candthen
stored at 2808C. Saliva samples were assayed for cortisol
in duplicate using a highly sensitive enzyme immunoassay
(Salimetrics, State College, PA, USA) (20). The test used 25
mL of saliva per determination, which has a lower limit of
sensitivity of ,0.19 nmol/L, and average intra-assay and
inter-assay coefficients of variation of 4.13 and 8.89%,
respectively.
Core temperature (Tc) was measured with an ingestible
temperature sensor with a radio transmitter to a data logger
(CoreTemp, HQ, Inc., Palmetto, FL, USA). Participants took
the capsule 5 hours before exercising (17).
Statistical Analyses
Statistical analysis was conducted using the Statistical
Package for Social Sciences (SPSS v17.0; SPSS Inc., Chicago,
IL, USA). As the data were normally distributed, all variables
were analyzed with repeated-measures analyses of variance
(condition 3time), where the between-group factor was
recovery condition (CWS vs. SIT25) and the within-
groups factor was time point for the exercise period (Pre-
Exercise vs. Post-Exercise), the intervention period (Post-
Exercise vs. Post-Int), and the recovery period (Post-Int, Post
30 min, Post 1 h, and Post 2 h). For cortisol, the 30-minute
time point during the recovery period was not presented
because we did not collect the samples at this time point.
To account for differences in the recovery period values
between conditions, HR, Tc, and cortisol values were ex-
pressed as percentage changes from the preceding recovery
time point value using the formula: [(recovery time point 2
preceding recovery time point)/recovery time point] 3100.
Significance was accepted at the p#0.05 level.
RESULTS
Pre-exercise to Post-exercise
Pre-exercise, there were no differences in HR, Tc,TCS,or
cortisol levels between conditions (p.0.05; Table 1). The
cycling exercise increased HR and Tcfrom pre-exercise val-
ues (p= 0.001) in both conditions to a similar extent (p.
0.05; Table 1). Thermal comfort sensation rating was signif-
icantly lower (p,0.001) at post-exercise (21; just
Figure 1. Experimental procedure and measurement.
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uncomfortable) compared with pre-exercise (+2; slightly
comfortable) in both conditions (p,0.001; Table 1). Cor-
tisol levels did not significantly change from pre-exercise in
either condition (p.0.05; Table 1).
Post-exercise to Postintervention
Heart rate, Tc, and cortisol values were not different
between CWS and SIT25 conditions immediately Post-Int
(p.0.05); however, CWS elicited a higher TCS rating (+4;
very comfortable) compared with SIT25 (+1; just comfort-
able; p= 0.04; Table 1). Within-group comparisons found
that HR was significantly decreased from post-exercise val-
ues immediately after both interventions, but no significant
effect for time was observed in Tcor cortisol levels in either
condition over the same period (p.0.05; Table 1). Thermal
comfort sensation rating was significantly rated higher at
Post-Int compared with post-exercise in both conditions
(p,0.05; Table 1).
Postintervention to Post 2 h Recovery
There was no difference in HR between conditions at any
time point during the recovery period (p.0.05). Heart rate
values were similar after the Post-Int period in both condi-
tions (CWS, 90 63b$min
21
and SIT25, 84 63b$min
21
)
(p= 0.10). In the CWS condition, HR values were reduced
over time, immediately decreasing after 30-minute Post-Int
(73 62b$min
21
,p,0.0001) until the end of the 2-hour
recovery period. Whereas, in the SIT25 condition, signifi-
cant decreases in HR values were observed only after 1-
hour Post-Int (73 63b$min
21
,p= 0.001) until the end
of the 2-hour recovery period (Table 1).
Intestinal temperature was observed to be similar between
conditions throughout the recovery period (p.0.05). At 30-
minute Post-Int, Tcwas significantly decreased in both con-
ditions (CWS, 37.09 60.178C and SIT25, 37.34 60.118C, p
.0.05) and remained below Post-Int Tcvalues until the end
of the 2-hour recovery period in SIT25 (37.15 60.088C, p,
0.001) and CWS (37.03 60.048C, p,0.001), respectively
(Table 1). Cooling rates were also calculated through the
difference in Tcfrom Post-Int at 30-minute, 1-, and 2-hour
recovery (Tcdivided by the recovery time). However, no
main effect for condition was observed (p.0.41; data not
shown).
There was no difference in salivary cortisol between
conditions during the recovery period (p.0.05). In the
CWS condition, cortisol was observed to decrease at 2
hours after recovery from Post-Int (p= 0.04). However,
there was no change in the SIT25 condition (p= 0.13)
(Table 1).
There was no difference in TCS ratings (p.0.05)
between conditions at any time point during the recovery
period. Thermal comfort sensation ratings were significantly
improved at 1 h (+3; comfortable, p= 0.03) and 2 h (+3;
comfortable, p= 0.03) (p= 0.02) compared with Post-Int
TABLE 1. Heart rate (HR), core temperature (Tc), salivary cortisol levels, and thermal comfort scores (units) measure at pre-exercise, post-exercise, and
postintervention in the passive recovery in 258C room temperature (SIT25) and 158C water showers (CWS) conditions (n= 9, mean 6SEM).*
Parameters Condition Pre-exercise Post-exercise Postintervention
Recovery period
30 min 1 h 2h
HR
(b$min
21
)
SIT25 79 64 156 62z84 63z77 637363§ 69 62§k
CWS 83 63 154 63z90 63z73 62§ 67 62§ 63 62§k
Tc(8C) SIT25 37.25 60.14 38.34 60.11z38.08 60.16 37.34 60.11§ 37.26 60.08§ 37.15 60.08§
CWS 37.14 60.11 38.10 60.23z38.02 60.20 37.09 60.17§ 37.16 60.08§ 37.03 60.04§
Cortisol
levels (mg/dl)
SIT25 0.084 60.011 0.150 60.043 0.324 60.109 — 0.100 60.008 0.084 60.011
CWS 0.082 60.008 0.186 60.050 0.408 60.138 — 0.132 60.021 0.112 60.018§
TCS SIT25 +2 602160z+1 60z+2 60+360§ +3 60§
CWS +2 602160z+4 60†z+3 60+360+360
*TCS = thermal comfort sensation.
†Significant difference between conditions at the same time point.
zSignificant difference from the preceding time point.
§Significant difference from the Post-Int.
kSignificant difference from the 30-minute recovery period (p,0.05).
Recovery Effects of Cold Shower
2236
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Figure 2. Percent change from postintervention (Post-Int) in (A) heart rate, (B) core temperature, and (C) salivary cortisol at 30-minute, 1-, and 2-hour recovery
period for passive recovery in 258C room temperature (SIT25, solid line) and the 158C water shower (CWS, broken line) conditions (n= 9, mean 6SEM).
a
Significant difference between conditions at the same time point; *significant difference from the Post-Int; #significant difference from the 30-minute recovery
period; and +significant difference from the 1-hour recovery period (p,0.05).
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(+1, just comfortable) in the SIT25 condition, but there was
no change in the CWS condition (p.0.99) (Table 1).
As shown in Figure 2A, %change in HR values for the CWS
condition demonstrated a faster decrease after 30-minute Post-
Int compared with those for the SIT25 condition (CWS, 18.34
62.35% and SIT25, 7.03 64.65%, p,0.01). Whereas, there
was no difference observed for %change in Tc
or salivary cortisol at any time point between conditions
(p.0.05) (Figure 2B, C). Within-group comparisons
found that % change in HR values were gradually
increased after 30 minutes until the end of 2-hour recovery
period in the CWS condition (p,0.02), but there was no
change at any time point in the SIT25 condition (p.0.05)
(Figure 2A). Percent change in Tcvalues were decreased at
30-minute Post-Int (p,0.01) and then increased until 2
hours after recovery for both conditions (p,0.05)
(Figure 2B). For % change in salivary cortisol, there was
a significant decrease after 1-hour Post-Int (p,0.01). Then,
the values were increased until the end of the 2-hour recovery
period (p,0.05) (Figure 2C).
DISCUSSION
This study investigated the effects of a CWS intervention on
recovery after cycling in a hot (;368C) environment. The
major findings were that taking a 158C CWS for 15 minutes
could promote a positive thermal comfort sensation imme-
diately at the end of the intervention period and facilitate
HR recovery within the first 30 minutes after showering.
However, the CWS protocol in our study had no effect on
Tcor salivary cortisol responses in healthy male subjects.
The TCS results demonstrated that CWS could induce
a comfortable rating sensation compared with SIT25 at the
end of the intervention period. Our findings may partly be
explained by the participants’ TWS rating improving
through return of their body temperature toward resting
values, upon removal from the cold exposure (9). Moreover,
the rating of temperature change, as pleasant or unpleasant,
is dependent on the preferable homeostatic state. For exam-
ple, a cold stimulus applied to the skin when the Tcis ele-
vated is likely to be identified as pleasant, whereas under
hypothermic conditions, the same stimulus may be judged
as unpleasant (4,18). Therefore, a reduced skin temperature
during the CWS intervention after exercise in the heat may
have resulted in a satisfied rating (3). Our findings are con-
sistent with previous studies that observed changes in TCS
after taking a cold shower, which suggested an associated
psychological impact (14,22). It is possible that CWS stim-
ulated the temperature-sensory receptors on the skin, send-
ing afferent thermal input signals to specific brain areas,
resulting in an improvement in the participants’ thermal
comfort sensation (8).
This study did not observe a difference in HR response
between CWS and SIT25 during the preintervention to
postintervention period (CWS = 64 b$min
21
and SIT25 =
72 b$min
21
). This outcome contrasts to that of Butts et al.
(3) whom reported lower HR values at 5 and 10 minutes
during a 20.88C CWS compared with passive rest in a heat
chamber (CWS = 45 b$min
21
and control = 27 b$min
21
). A
possible explanation for the discrepancy in our findings may
be that the passive control in Butts et al.’s (3) study was
undertaken in a heat chamber (33.4 62.18C), which was
at a temperature somewhat higher than the control used in
our study (25 61.08C). This may likely explain the con-
trasting HR responses between our studies (25).
Our study showed that the recovery effects of CWS were
present after the first 30 minutes during the recovery period,
with CWS eliciting faster recovery of HR than SIT25. The
present findings revealed that a CWS can lower HR by 18%
(;17 b$min
21
) compared with 7% (;7b$min
21
)(p,
0.013) for a SIT25 intervention. Our data compare favorably
with those of Buchheit et al. (1) who observed that CWI (148
C for 5 minutes) can decrease HR by 15% (;13 b$min
21
),
7 minutes after removal from CWI compared with being
seated in a heat chamber (33.4 62.18C). Therefore, our
results seem to indicate that CWS has a recovery cooling
effect by reducing cardiovascular strain after exercise in the
heat similar to that observed with CWI (6,25). We would
highlight that this effect was only observed at 30 minutes
after the CWS intervention and not beyond this time point.
It seems possible that these results are due to either one or
both of the following reasons. First, this study demonstrated
a comfortable sensation of CWS over SIT25 after 15 minutes
of the intervention period. This finding provides evidence
that the faster HR recovery may also be due to cold show-
ering causing the reduction of HR by a larger parasympa-
thetic activity to counteract exercise-induced sympathetic
dominance (14,22). Second, it is well known that cold water
temperatures can cause the vasoconstriction of cutaneous
blood vessels to maintain core temperature, which in turn
increases peripheral resistance and arterial blood pressure,
consequently enhancing venous return and increasing
venous pressure with a corresponding decrease in HR
(13,25).
In this study, the CWS was shown to have no recovery
effect on reducing Tcvalues after cycling in a hot environ-
ment. This finding supports previous research performed by
Juliff et al. (14), which also observed no differences in Tc
values between contrast showers and a passive recovery
intervention. A previous study by Butts et al. (3) also re-
ported no significant changes in rectal temperature (T
re
)
after cold showering compared with a passive recovery after
a 15-minute intervention. However, the authors reported
a significantly faster cooling rate over the first 5 minutes of
showering. In our study, we did not record Tcvalues over 5-
minute segments during the intervention period, but the
cooling rate values at the end of the 15-minute intervention
period were not different between conditions. Although we
also calculated cooling rate throughout the recovery period,
we did not observe a difference between the CWS and con-
trol conditions. Our findings contrast with Halson et al. (11),
Recovery Effects of Cold Shower
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who reported that CWI (11.5 60.38C for 60 seconds 33)
can decrease Tcvalues faster than sitting in a 24.28C room
temperature at 20 minutes after intervention. In line with
Halson et al.’s (11) findings, CWI (14.03 60.288C for 12 mi-
nutes) has been shown to be 38% more effective in Tccool-
ing after immersion than a passive recovery intervention (5).
Therefore, our results indicate that the CWS did not have
a recovery cooling effect on Tcvalues that is comparable
with CWI (5,10,11). A possible explanation for this may be
the different mechanisms of heat loss between showering
and immersion. During CWS, heat loss occurs through run-
ning water over the skin and is dependent on the water
temperature and water flow through a convection mecha-
nism (15). Alternatively, during CWI, conduction is the pri-
mary mechanism for heat loss when the skin or body parts
are immersed in cold water (16). Indeed, the conductive
cooling effect can cause a substantial reduction in Tcboth
during and after cold exposure, whereas convective heat loss
is relatively minimal in comparison (24). In addition, the
body surface area (BSA) of subjects exposed to the cold
stimulus during CWI is considerably larger than during
CWS (approximately 90% of the BSA in CWI vs. 34% of
the BSA in CWS) (7).
Cortisol, a stress hormone, is an indicator of the physical
stress and inflammatory response after strenuous exercise
(12,20). To the authors’ knowledge, this is the first study that
has reported on the effects of cold showers on the salivary
cortisol response after cycling in a hot environment. This
study did not identify any changes in measures of salivary
cortisol between 158C CWS and SIT25, indicating that
CWS was not effective in reducing cortisol during recovery
after exercising in the heat. A few studies have used CWI to
investigate the changes in cortisol levels on recovery after
body cooling (17,23). Minett et al. (17) showed that a 20-
minute exposure to 108C CWI decreased Tcvalues (1 h post
CWI ;1.78C) and cortisol levels at 1 hour after exercise
compared with sitting in a hot room (358C). However, in
contrast to these CWI findings, we observed no evidence
that cortisol secretion was affected by CWS. The contradic-
tory results may be due to the strong association between
reductions in cortisol levels with reductions in Tc(12). There-
fore, the lack of a cortisol response in our study is likely due to
the lack of a Tcchange (1 h post = ;0.948C) after CWS (21).
PRACTICAL APPLICATIONS
Our results indicate that a 158C cold shower for a duration
of 15 minutes is an adequate cooling intervention for pro-
moting a positive thermal comfort sensation by facilitating
HR recovery at 30 minutes after cold showering. However,
cold showering was not effective in reducing Tcor salivary
cortisol during post-exercise recovery as observed with
CWI. Consequently, the application of cold showering
may have limited benefits as a cooling treatment for patients
suffering from heat stress and as a recovery intervention for
elite athletes regaining sports performance from subsequent
exercise bouts. Because cold showering is energizing, easy to
use, hygienic, and has some perceptual beneficial effects, it
could be recommended as a post-exercise practice to refresh
the body and recover somewhat from the associated cardiac
stress, in healthy individuals.
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