THE EFFECTS OF ICE SLURRY INGESTION ON REPEATED-SPRINT ABILITY IN
HEAT

Jenna Rose Bilancia, B.S.
East Stroudsburg University of Pennsylvania

A Thesis Submitted in Partial Fulfillment of
the Requirements for the Degree of Master of Science in Exercise Science
to the office of Graduate and Extended Studies of
East Stroudsburg University of Pennsylvania

January 10, 2020

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ABSTRACT
A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of
Master of Science in Exercise Science to the office of Graduate and Extended Studies of
East Stroudsburg University of Pennsylvania
Student’s Name: Jenna Rose Bilancia
Title: The Effects of Ice Slurry Ingestion on Repeated-Sprint Ability in Heat
Date of Graduation: January 10, 2020
Thesis Chair: Chad A. Witmer, Ph.D.
Thesis Member: Gavin Moir, Ph.D.
Thesis Member: Matthew Miltenberger, Ph.D.
Abstract
Introduction: Repeated-sprint ability is used to measure the physiological demands of
stop-and-go activities. Athletes have a high physiological demand and environmental stress
during high heat conditions. Precooling is where you preemptively lower core temperature
to increase heat storage capacity. Purpose: The aim of this study was to examine the effect
of ice slurry ingestion (0±1°C) vs. water (4°C) prior to the start of and during halftime of
a simulated athletic competition in the heat on repeated-sprint cycling in recreationally
active college-aged males. Methodology: The researchers used a precooling protocol of
7.5g/kg bodyweight of both water (control) and ice-slurry (experimental) over a 30-minute
period prior to the exercise protocol. The participants participated in two, 10 minute halves.
Including 5 second sprints, followed by 55 seconds of active recovery at 50 watts.
Following the first half of the exercise protocol, participants ingested 2.5 g/kg of ice slurry
in the 10 minute passive recovery period. Data collected: core temperature (degrees
Celsius), mean power output, peak power output, rating of perceived exertion, heart rate
(BPM). Results: There was no significant difference in core temperature, average mean
and peak power, and fatigue within condition. There was a statistically significant
difference in mean core temperature overall between groups (F=18.36, p=0.00) and fatigue
by half within condition (F=5.526, p=0.025). Conclusion: The ice slurry was effective in
lowering core temperature, there were no performance enhancements from precooling.
Further research needs to be done.

TABLE OF CONTENTS
SECTIONS

PAGES

List of Figures

List of Tables

vii

CHAPTER 1: INTRODUCTION

Purpose

Null Hypotheses

Delimitations

Limitations

Operational Definitions

CHAPTER 2: LITERATURE REVIEW

Repeated Sprints

Performance in the Heat

Cooling Methods

CHAPTER 3: METHODOLOGY

Participants

Procedures

Ice Slurry Ingestion

Urine Refractometry

Statistical Analysis

CHAPTER 4: RESULTS

CHAPTER 5: DISCUSSION & CONCLUSION

Discussion

Future Considerations

Conclusion

REFERENCES

APPENDICES

Appendix A

44
iv

Appendix B

Appendix C

Appendix D

LIST OF FIGURES
Figure 1. Core temperature baseline vs. pre-exercise by condition

Figure 2. Mean core temperature of all participants overall

Figure 3. Average core temperature by sprint

Figure 4. Average mean power output of all participants by condition

Figure 5. Average peak power output of all participants by condition

LIST OF TABLES
Table 1. Subject Characteristics

Table 2. Mean core temperature of all participants per half by condition

Table 3. Fatigue, calculated by percent decrement, of all participants per half by
condition

Table 4. Heart rate of all participants per half by condition

Table 5. Rating of perceived exertion (RPE) of all participants per half by condition

vii

CHAPTER 1: INTRODUCTION

The ability to produce a high sprint speed or power output and the ability to
maintain that sprint speed or power output during subsequent sprints is defined as
repeated-sprint ability (Glaister, 2008). Repeated-sprint ability is one assessment used to
measure the physiological demands of stop-and-go activity (Glaister, 2008). Many sports
such as soccer, field hockey, and lacrosse require that athletes perform repeated sprints
throughout competition. Repeated-sprint ability in sports has been researched heavily due
to the technology to track the distances covered throughout a match. (Dobson & Keogh,
2017). Many different repeated sprint protocols are available in literature. Most protocols
are designed to mimic the multiple short, maximal bouts of activity interspersed with rest
periods in a competition. This is in an effort to translate research to practical application.
The rest periods may be fixed or variable and active or passive. The sprint portion is
usually a 4-8 second sprint, while the typical rest period is 20-30 seconds active recovery
(Spencer et al., 2008). Although repeated-sprint athletes rely on anaerobic metabolic
pathways for ATP synthesis, there is research to show that they also rely heavily on the
aerobic system (Glaister, 2008). Relying heavily on the aerobic system is due to the
incomplete rest time after the maximal sprint protocols. While the PCr-ATP system is the
1

primary system to fuel athletes during the anaerobic portions of a game, the aerobic
system also plays an important role to assist with PCr replenishment (Sanders., 2017).
Due to the metabolic demands of repeated sprints these athletes endure high stress on the
body during practice and competition without taking into account external environmental
factors.
Although athletes in stop-and-go sports may be limited by metabolic factors,
environmental heat poses another potential challenge to performance for these athletes.
Many of these athletes have practice or competition for extended periods of time in the
heat due to when their sport is in season. For example, the beginning of soccer and field
hockey season during the fall or the end of lacrosse in the spring season. Thus, heat
stress has the potential to become another limiting factor to performance, and the ability
to mitigate heat stress presents an opportunity to enhance performance. The
hypothalamus is a major component of the responses in the body’s autonomic system to
heat stressors. The effector response to maintain thermal homeostasis is determined by
the relative amount of heat loss and gain within the body (Nagashima, K., 2015). In
situations where heat gain exceeds heat loss, the body will initiate heat dissipation
responses in order to protect core temperature. In most individuals their heart rate will
increase with exposure to the heat secondary to a decreased blood pressure due to a
reduction in plasma volume via sweating (Cheung, S. S., 2010). If these athletes continue
to perform in these high heat environments it can lead to decreased in performance. This
decrease in performance is due to the body protecting itself from the damage an increase
in core temperature can do to the body by limiting exercise (Cheung, S. S., 2010;
Cheung, S. S., & McLellan, T. M., 1998). When athletes train or compete in high heat

conditions for an extended period of time, the possibility of heat illness increases due to
the body’s inability to rid the excess heat produced. Impaired exercise performance in
heat has consistently been attributed to critically high core temperatures from the
environment and exercise-related metabolic heat production (Brade, et al, 2013).
Elevations in core temperature have been reported to affect metabolic, central nervous
system, cardiovascular, and physiological responses to exercise (Hayes et al, 2014).
These responses from the body are believed to occur once a certain core temperature set
point has been reached; at that temperature the body will begin to shut down unnecessary
energy expenditures and the individual fatigues (Cheung, S. S., 2010). This shut down
will lead to the inability to continue with performance or competition.
There are many heat management strategies that have been used in research to lower core
temperature prior to the start of and during exercise to cool the body to increase
performance. Strategies include ice slurry ingestion, cool water immersion, ice vest, or a
combination of these strategies. Cold water immersion is considered to be the gold
standard for cooling the body as it is most effective as a post-activity treatment (Casa, D.
J., 2007). However, cold water immersion for athletes is not practical for use prior to
competition or during. Cooling vests are a more recent modality and can be worn under
clothing for athletes. For this method it is important to try and cover as much skin surface
area as possible for the best result because it uses air as a convective way to cool the body
(Chinevere et al., 2008). This is also done as a pre or post exercise method (Faulkner,et
al, 2019). Researchers have found the cooling vests to be an effective method in lowering
core temperature (Chinevere et al., 2008, Faulkner., et al, 2019, Hadid et al., 2008). Many
cooling strategies have been researched for endurance based events. For example

researchers found that a cooling jacket and sleeves for 30 minutes prior to exercise
benefited the time trials of cyclists in ambient temperatures of 24°C, 27°C, and 35°C
(Faulkner,et al, 2019). One of the most recent precooling methods is ice ingestion as a
practical method of precooling that has resulted in improved endurance performance in
hot and humid conditions (Zimmerman et al, 2015). Ice ingestion is used a method prior
to exercise to preemptively lower the individual’s core temperature.
Precooling is done so that core temperature can be lowered in order to raise the
individual’s heat storage capacity (Siegel et al, 2010). Heat storage capacity is the
amount of thermal energy being stored in the body. There has been research that shows
how precooling is an effective way at lowering the individual’s core temperature prior to
exercise thereby effectively increasing their heat storage capacity and diminishing the
detrimental effects of heat to performance or the body (Jones et al, 2016; Walker et al,
2014; Siegel et al, 2010; Zimmerman et al, 2015). This allows the individual to exercise
or perform for a longer period of time before the body begins to limit movement to
protect itself at a set point temperature. For highly fit individuals the body’s temperature
marker appears to be approximately 39.2°C (Cheung, S. S. 2010). Research supports the
set point marker at which the body signals the system to shut down (Cheung, S. S., 2010).
The use of an ice-slurry is highly practical because it can be administered to many people
at a low cost.
There is limited research looking at the effects of precooling using only ice ingestion as
opposed to multiple precooling techniques combined on repeated sprint athletes. Precooling offers a cost-effective method at reducing core temperature. Utilizing precooling
with repeated sprints may offer a possible solution to improve exercise performance in
4

hot conditions and limit the added challenges of the environment on these athletes. This
study looks to fill this gap in the literature for precooling in stop-and-go sports.
Purpose
The purpose of this study is to examine the effect of ice slurry ingestion vs. placebo prior
to the start of and during halftime of a simulated athletic competition in the heat on
repeated-sprint cycling in recreationally active college-aged males.
Null Hypotheses
There will be no difference in core temperature between ingestion of ice slurry and a
placebo post precooling protocol.
There will be no difference in core temperature between ingestion of ice slurry and a
placebo during exercise protocol.
There will be no difference in average mean power output between ingestion of ice slurry
and a placebo during exercise protocol.
There will be no difference in average peak power output between ingestion of ice slurry
and a placebo during exercise protocol.
There will be no difference in fatigue between the ingestion of ice slurry and a placebo
during exercise protocol.
There will be no difference in heart rate between ingestion of ice slurry and a placebo
during exercise protocol.
There will be no difference in rating of perceived exertion between ingestion of ice slurry
and a placebo during exercise protocol.
5

Delimitations
1)

Participants were recreationally active individuals from a university in

northeastern Pennsylvania.
2)

Participants were males aged from 18-35 years.

Participants were physically active at least three times per week following ACSM

guidelines, 20-60 minutes of activity, 3-5 times per week (Garber et al., 2011).
4)

Participants were apparently healthy with no prior history of heat illness.

Participants were apparently healthy with no lower extremity injuries in the past

year.
Limitations
1)

Participant dropout due to illness or injury.

Participants giving maximal effort each sprint.

Participants’ adherences to pre-conditions.

Participants’ level of heat acclimatization.

Operational Definitions
Average Mean Power Output – Average power output (in watts) per 5 second cycle
sprint, averaged across all sprints
Average Peak Power Output – Maximum power output (in Watts) per 5 second cycle
sprint, averaged across all sprints

Ice slurry – 7.5 g/kg of ice slurry (-1 or 0°c) for precooling, equal amounts for every 5
minutes in a 30 minute precooling, 10 minute half time with slurry ingestion of 2.5g/kg
(Siegel et al, 2010).
Control condition – Water kept at 4 degrees Celsius (Siegel et al., 2010).
Heat conditions – A tent heated to 33 degrees Celsius with electric heaters (Zimmerman
et al., 2015)
Termination criteria – Core temperature greater than or equal to 39.5ºC, HR greater than
10 bpm over age predicted max heart rate using the formula “220-Age” (Physical
Activity Basics – CDC, 2018) or the participant requests to end the test (Hailes et al,
2016).
Recreationally active – Physically active at least three times per week following ACSM
guidelines, 20-60 minutes of activity, 3-5 times per week (Garber et al., 2011).
Fatigue – Percent Decrement Method is fatigue = 100 – [(total power output/ideal power
output) x 100] where total power output is the sum of all mean power values from all
sprints. Ideal power output is the number of sprints multiplied by the maximum mean
power (Glaister, 2008).
Repeated-sprint protocol – 5 second, maximal sprint each minute, followed by 55
seconds of active recovery at 50 watts on the cycle. The 5 second sprint was performed at
a resistance of 0.07 Nm/kg bodyweight of each participant (Duffield, et al,. 2003) on an
electromagnetically braked cycle ergometer (Lode Excalibur Sport, Groningen, The
Netherlands). The protocol ended with the participant completing a final 55 second active
recovery.
7

CHAPTER 2: LITERATURE REVIEW

Repeated Sprints
The ability to produce a high sprint speed or power output and the ability to
maintain that sprint speed or power output during subsequent sprints is defined as
repeated-sprint ability (RSA) (Glaister, 2008). This ability is viewed as a key factor when
performing in field sports such as field hockey, soccer, or lacrosse. (Spencer et al., 2005).
The sprint portion is usually a 4-8 second sprint, while the rest period it typically 20-30
seconds (Spencer et al., 2005). Most protocols are designed to mimic multiple short,
maximal bouts of activity with fixed rest periods in a competition.
Analyzing repeated sprints has progressed greatly with modern technology. The most
current technique is using GPS to track an individual’s movement throughout a match or
a game, which allows for the researcher to track velocities and distances covered by the
athlete (Dobson & Keogh, 2007; Spencer et al., 2005). GPS tracking and time-motion
analysis have shown that sprinting accounts for 1-10% of the total distance covered by an
athlete and 1-3% of total playing time (Buchheit, Mendez-Villanueva, Simpson &
Bourdon, 2010; Spencer et al., 2004). Although technology can provide a great amount of
8

information, the movements performed can vary. These movements can be categorized
into sprinting and striding or a combination of the two (Spencer et al., 2004). It has been
demonstrated that the combination of striding and sprinting as one category resulted in a
3.7 – 4.4 seconds of sprinting with 40 – 56 seconds of recovery in between the high
intensity bouts for soccer athletes (Withers et al., 1982). When sprinting was placed in its
own category research showed the sprint duration as 2 – 3 seconds (Barros et al., 1999).
There is a wide range of sprints performed throughout the game/match of these field
sports. The average number of sprints performed are 19-62 per match in soccer (Mohr et
al., 2003; Yamanaka et al., 1988), field hockey (Spencer et al., 2004), and rugby (Duthie,
Pyne, & Hooper, 2005). This wide range in sprints could be due to the different positions
of the athletes and the different sports being played. It was reported that strikers in field
hockey performed about twice as many sprints as fullbacks did throughout a single match
(Lothian & Farrally, 1994).
When evaluating repeated-sprint performance, the most likely contributors to fatigue in
the individual is the buildup of inorganic phosphate or lactate (Girard et al., 2011).
Looking at a protocol including ten, six second sprints, at the beginning of the exercise
the participants use approximately 92% of ATP from the immediate energy system, or by
anaerobic glycolysis (Girard et al., 2011). For example on sprint ten in the protocol, 60%
of the ATP is still being supplied through the anaerobic metabolism (Girard et al., 2011).
This reliance on anaerobic pathways due to the intensity of the exercise will increase the
concentration of both inorganic phosphate and lactate in the muscle cell (Girard et al.,
2011). As the competition goes on and the sprints progress, the reliance on the aerobic
metabolism and subsequent manifestation of fatigue increase (Girard et al., 2011).

Research showed that by sprint ten in a repeated-sprint protocol of a 6 second sprint with
30 second passive recovery about 40% of ATP is being produced aerobically (Girard et
al., 2011). This study has shown that by the 10th sprint with the same protocol the PCr
stores have dropped about 51% from resting (Girard et al., 2011). This is important to
keep in mind for the present study because of the added detrimental effect the
environment can have on an athlete in addition to the already existing fatigue.
Performance of the athlete would unlikely compromised if the rest time between the
sprints were two minutes. This is due to the almost full recovery between these sprints
(Spencer et al., 2005). However, it is important to keep in mind that rest periods between
sprints in competition are usually an active recovery. This may affect the recovery of the
athlete as the competition continues. Sprinting is a key aspect to many of these stop and
go sports, however there are other movements or factors throughout the competition that
may cause fatigue. Elements such as jogging, jumping, changing direction and
environmental factors can cause added fatigue on the athletes in competition.
Performance in the Heat
The hypothalamus (specifically the preoptic area) plays a major role in the autonomic
responses to heat stressors. Once the body drifts from its core temperature set point,
research has shown the body begins to show symptoms (Cheung, S. S. 2010; Nagashima,
K., 2015). It was theorized that this occurs to protect the body’s system integrity. When
the body experiences a high heat environment the autonomic response will cause a few
things to happen. There are three ways the body will try to lower its core temperature and
release heat; convection, conduction and evaporation (Nagashima, K., 2015). The body’s
superficial vessels will dilate causing blood to flow from the core body parts to the skin.
10

This movement is the body’s way to try and release heat by convection or conduction
from the core to the environment. In some situations, especially athletic competitions the
body will sweat to lose heat via evaporation from the skin (Nagashima, K., 2015). These
autonomic responses depend on the amount of heat gained vs. the amount of heat loss
within a system. Heat gain can be from basal metabolic rate, muscular activity, or the
environment in which the activity is performed; while heat loss is mainly influenced by
the individuals’ perspiration and evaporation (Cheung, S. S., 2010; Nagashima, K.,
2015). If too much heat is gained or not enough heat is lost, exertional heat illness can
occur.
There are three classifications of exertional heat illnesses; heat cramps, heat exhaustion,
and heat stroke. Once the hypothalamus has been damaged from either heat exhaustion or
heat stroke, it will not work at the same capacity it once did (Cheung, S. S., 2010;
Nagashima, K., 2015). The body’s thermoregulatory system becomes compromised due
to excessive heated conditions or because of too much physical exertion; or from a
combination of the both (Phinney et al., 2001). Heat illnesses are more prevalent in
certain populations (children, elderly, overweight individuals), in certain environments
(hot/humid environments), while exercising for extended periods of time, and as a result
of impairment to sweating. Therefore, it seems that athletes, specifically stop and go
athletes competing in the summer or high heat environments, should be concerned with
keeping their body temperature normal or lower. Exertional heat illness poses a serious
threat to athletes who is participate in high intensity sports in hot environment. Athletes
with a higher amount of gear worn such as football are at an even further likelihood of
having an exertional heat illness (Phinney et al., 2001).

Impaired exercise performance in heat has consistently been attributed to critically high
core temperatures from the environment and exercise related metabolic heat production
(Brade, et al., 2013). Elevations in core temperature have been reported to affect
metabolic, central nervous system, cardiovascular and physiological responses to exercise
(Hayes et al., 2014). Fatigue during repeated-sprint activity seems likely to be
exacerbated with the addition of heat stress onto the significant metabolic demands that
are placed on participants. It stands to reason that the ability to mitigate the physiological
impact of the heat stress may confer benefits both to performance and in reduction of the
risk of exertional heat illness.
Cooling Methods
There are three methods of cooling the body shown in the research investigated.
These methods include ice slurries, cold water immersions, and convective cooling vests.
Some protocols used a combination of these methods.
Walker et al. (2014) investigated the effects of cold water immersion and ice
slurry ingestion on 74 participants. There were three groups including a cold water
immersion, control, and ice slurry ingestion group. This study was based on the
occupation of firefighters, simulating a search and rescue in a heat chamber. The
participants performed 2x20 minute searches/halves in a 40.5°C heat chamber During the
half time the participants would exit the chamber, take off their jackets, and change
breathing apparatus. Unlike the ice slurries which were used as a precooling method, cold
water immersion is mostly seen as a post exercise protocol to assist in bringing core
temperature back to normal. After the entire exercise protocol the participants would
enter the cold water immersion tank which was 15°C for up to 15 minutes (Walker et al.,
12

2014). Cold water immersion is known as the gold standard to lower core temperature or
return core temperature to normal post exercise. However, there are some limitations.
Cold water immersion is not practical for prior to an athletic event. There is also a
concern that if the individual remains immersed too long they could be at risk for
hypothermia.
Cooling vests/sleeves are used to cover as much as the body surface as possible. It
is also the newest method to enter the research field. This form of cooling can be worn
under uniforms/clothing. One study looked at twelve male team sport players. The
participants completed four experimental conditions, initially involving a 30-min
precooling period consisting of either a cooling jacket, ingestion of an ice slushy,
combination of cooling jacket and ice ingestion, or control group. This was followed by
70 minutes of repeat sprint cycling in 35ºC, 60% relative humidity (Brade et al., 2014).
The exercise protocol consisted of 2x30-min halves, separated by a 10-min half-time
period where the same cooling method was used. Each half was comprised of 30x4
second maximal sprints. The researchers concluded, a combination of cooling jacket and
ice ingestion (external and internal) body cooling techniques may enhance repeated sprint
performance in the heat compared to individual cooling methods (Brade et al., 2014).
Ice slurries have been found to be a practical and low cost method in cooling the body
prior to exercise. There has been research done to support the claims that precooling with
a slurry has preemptively lowered core temperature and in turn increased an individual’s
heat storage capacity (Siegel et al., 2010). However, there is also research that
demonstrates the ice-slurry ingestion influenced heat storage capacity but did not

improve physical performance (Zimmerman et al., 2015). It is still being used and
researched as a method of precooling to try and lower core body temperature.
The precooling protocol employed in the present study was based on that of Siegel et al.
(2011) who found that the ingestion of 7.5 g/kg of ice slurry (1°C), ingested at 1.25 g/kg
every five minutes, reduced rectal temperature significantly by 0.66 ± 0.14°C. There were
10 male participants who either ingested a control cold water 4°C or an experimental 0°C
ice slurry before running a ventilatory threshold test in a heat chamber (34°C) (Siegel et
al., 2010). These results were associated with prolonged run time to exhaustion by 19 ±
6%, compared to cold fluid (4°C) ingestion. Ice slurry ingestion has been compared to the
other methods listed earlier.
In another study that researched ice slurries, 9 moderately trained females
performed 2, 36 minute halves on a cycle ergometer (Zimmerman et al., 2015). The
cycling protocol mimicked stop and go sports such as soccer and field hockey similar to
the present study. There was a control group where water was used as the precooling
protocol and an experimental group where precooling included crushed ice ingestion. The
crushed ice ingestion protocol did lower core body temperature significantly before
exercise, compared to the control water protocol, and it also lowered the perception of
thermal stress (Zimmerman et al., 2015). However, there was no improvement in
performance (Zimmerman et al., 2015). Ishan et al. (2010) found 40 km cycling time
trail performances to be improved by 6.5% in endurance trained males. These males
regularly competed in triathlons and cycling while ingesting 6.8 g/kg (1.4 ± 1.1°C) of
crushed ice. This reduced GI temperature by 1.1 ± 0.6 °C compared to tap water (26.8 ±

1.3°C). These athletes did the precooling thirty minutes prior to the event (Ishan et al.,
2010).
A study suggested that an ice slurry has been used based on the law of enthalpy of
fusion. This says that ice requires increased heat absorption to change from a solid to a
liquid, enabling ice to absorb more heat than water of a similar temperature (Merrick et
al., 2003). Performance benefits of precooling with an ice slurry ingestion may be due to
the proximity to the brain’s blood supply, potentially leading to the increase of brain
cooling as opposed to the core. The brain cooling may be due to the proximity of the
mouth and esophagus to the carotid arteries, potentially resulting in the cooling of the
blood flowing to the brain (Mariak et al., 1999). This would increase the time required for
the brain to reach a critically high temperature. Thus, ice slurry ingestion would
potentially increase exercise time to exhaustion and allow for greater metabolic heat
production/storage (Siegel & Laursen, 2011).
Precooling by ice-slurry ingestion seems to be a reliable method to lower core
temperature prior to exercise, however, it is not clear if it will uniformly improve
performance in sports and occupational fields such as firefighting. Ice slurries may be a
practical application to combat heat related illnesses and mitigate the detrimental effects
of heat on performance in repeated-sprint athletes.

CHAPTER 3: METHODOLOGY

Participants
The participants consisted of recreationally active males aged 18-30 years. Participant
participation was voluntary, and each participant had no history of heat illness or heat
injury. Participants were apparently healthy and recreationally active at least three times
per week for a minimum of thirty days following ACSM guidelines (Garber et. al, 2011).
Before the start of the experiment the participants completed an informed consent
(Appendix A), heat illnesses and injuries questionnaire (Appendix B), and a PAR-Q
(Appendix C). The design of the study was a randomized, counter-balanced crossover
experiment. Approval from the East Stroudsburg University Institutional Review Board
(IRB) was obtained for this study (Appendix D).

Demographic Data

Note. Table 1 describes all subject demographics which include height (cm), weight (kg),
and age (years).

Procedures
Participants were asked to visit the laboratory a total of three times consisting of
orientation / familiarization, and two experimental visits: precooling and control. Each
session was separated by a minimum of seven days for a washout period (Duffield, et al.,
2003).
Session one included an introduction to the experiment and explanation of the protocol
where participants were free to ask any questions regarding the study, followed by
completion of the informed consent. Participants were then asked to complete the forms
discussed earlier (Informed consent, heat illness questionnaire, and PAR-Q). It was
explained that prior to arriving at the laboratory for testing, the participants needed to
refrain from any vigorous exercise for 24 hours, and to avoid food, drink, cigarettes, or
17

caffeinated products two hours prior to the testing session (Duffield, et al,. 2003).
Demographic data were then collected including height (m), mass (kg), and body mass
index (BMI) (kg/m2). Each participant’s bike seat height was obtained and remained
constant throughout the all sessions. The final part of the orientation session was the
familiarization protocol. Participants completed one half of the repeated-sprint protocol
(see below) and were able to ingest water ad libitum.
Sessions two and three included the full repeated-sprint protocol, one with the
experimental trial and the other with the placebo. Visits began with pre-exercise urine
refractometry to determine the hydration status of the participant. The protocol for urine
refractometry is described in detail below. Following confirmation of euhydration status,
the participant entered the heat chamber 30 minutes prior to the warm-up and remained in
the heat chamber for the remainder of the protocol. The heat chamber was maintained at
33 degrees Celsius. During the 30 minute pre-exercise period instructions were provided,
including informing the participant as to the experimental or control protocol to be
followed (protocols are described in detail below). At the end of the 30 minutes the
participant began the warm-up protocol. This included a 5 minute warm-up, with 3
minutes of cycling at 75 watts and then increasing to 100 watts for two minutes (Duffield,
et al,. 2003). There was a 5 minute passive recovery period following the warm-up, with
the subject seated on the cycle, before continuing on to the exercise protocol.
The exercise bout was a repeated-sprint cycling protocol, consisting of two 10 minute
halves. This exercise protocol was designed to mimic a full contest of a stop and go sport.
Each half was separated by a 10 minute break which included a passive recovery with the
participant seated on the cycle. Participants ingested either ice slurry (experimental) or
18

cool water (control) both prior to the exercise and again at half time, as described in
detail below. The exercise protocol consisted of one 5 second, maximal sprint each
minute, followed by 55 seconds of active recovery at 50 watts on the cycle. The 5 second
sprint was performed at a resistance of 0.07 Nm/kg bodyweight of each participant
(Duffield, et al,. 2003) on an electromagnetically braked cycle ergometer (Lode Excalibur
Sport, Groningen, The Netherlands). The protocol ended with the participant completing
a final 55 second active recovery. Following the active recovery, each participant got off
of the cycle and remained in the heat chamber until their heart rate returned to within ten
beats per minute of the resting measurement of that testing session. The last step of the
experiment was to do a post exercise urine refractometry and core temperature to insure
that participants were adequately hydrated prior to leaving the laboratory.
Each of the following measurements was recorded after every five second sprint
throughout the protocol. The data collected from each sprint was core temperature
(degrees Celsius), rating of perceived exertion (RPE) was taken using the Borg’s six to
twenty scale (RPE, Borg, 1998) (Appendix E), mean power output (W), peak power
output (W), heart rate (BPM), and work (KJ). Mean power output, peak power output,
and work were collected by a computer running LEM software directly interfaced with
the electromagnetically braked cycle ergometer. Core temperature was collected using
the rectal thermistor (Measurement Specialties, Andover, Minnesota). Heart rate was
monitored throughout the testing sessions using a Polar Heart Rate Monitor (Polar
Accurex Plus; Polar Electro Oy, Kempele, Finland). Fatigue was calculated using the
percent decrement score, which has been reported to be valid and reliable in determining
fatigue (Glaister, 2008):

Fatigue = 100 – [(Total power output ÷ Ideal power output) X 100]
Where total power output is the sum of all mean power values from all sprints. Ideal
power output is the number of sprints multiplied by the maximum mean power (Glaister,
2008).
Ice Slurry Ingestion
The same exercise protocol was followed for both experimental and control sessions.
During the 30 minutes prior to the warm-up while the participant was in the heat
conditions, they ingested 7.5 g/kg bodyweight of ice slurry in equal amounts every 5
minutes over the 30 minute time period. The ice slurry was plain ice. After the precooling
protocol, the individual continued to their 5 minute warm-up period as discussed earlier.
Following the first 10 minute half of the exercise protocol, the participant ingested 2.5
g/kg bodyweight of ice slurry in the 10 minute recovery half time period. Following the
recovery time there was the final 10 minute half of repeated-sprints (Siegel et al., 2010),
which replicated the first half of the exercise. The control condition consisted of the
ingestion of water in an amount equivalent to the ice slurry condition (Brade, et al,.
2013). The water was 4 degrees Celsius due to the typical temperature of drinks found in
a conventional refrigeration unit (Siegel et al., 2010). All exercise protocols were
followed exactly in both conditions.

Urine Refractometry
Hydration status was assessed using urine refractometry (Atago Hand-held
Refractometer, Japan). The procedures for urine refractometry remained constant for pre
and post exercise in both conditions. Participants were instructed in the procedures to
secure a clean catch urine sample and then provide the sample in a double sealed cup.
The sealed container was opened while maintaining hand placement on the container
throughout the entire test. Using a pipette the researcher placed a small drop onto the
refractometer. Using the same pipette the sample was returned to the sample cup. Taking
clean water with that pipette the researcher discarded the water into a different waste cup
to clean the pipette. This was repeated two more times to ensure cleaning. The sample
was viewed, looking on the left side of the reader, the blue line will determine the value.
The participants could continue with the protocol if they had a specific urine gravity of
1.020 or below which was an indication of euhydration (How to Maximize Performance
Hydration, NCAA., 2013). However, if the sample measurement was 1.021 or greater the
participant was dehydrated and the researchers gave the participant 16 ounces of water to
drink within 30 minutes on site of the experiment. A second urine refractometry test was
then administered after an additional 30 minutes (How to Maximize Performance
Hydration, NCAA, 2013). To ensure hydration, participants were told to drink 16 ounces
2-3 hours before the session, they were advised to drink another 8 ounces of water 15
minutes before the session (How to Maximize Performance Hydration, NCAA., 2013).

Statistical analysis
Statistical analysis was performed using SPSS 20.0 (IBM Corporation) (SSPS., Chicago,
IL). Descriptive data (means, standard deviations) were calculated for all demographic
(age, height, weight, BMI) data. In addition, descriptive data was calculated for all
dependent variables (percent decrement, average mean power output, average peak power
output, core temperature, RPE, and heart rate). A one way ANOVA was used to
establish significant difference between groups (control, experimental) for baseline core
temperature (pre slurry ingestion) and for pre exercise temperature (post ice
slurry/placebo ingestion). A two-way ANOVA (groups [2-levels]; time [2-levels]) was
used to establish significant differences in all other dependent variables across
supplement and placebo conditions. The study had two levels (halves) by two conditions
(control and experimental). If significant F values were observed, post hoc analysis of the
data was performed by application of a pairwise comparisons with Bonferroni correction.
An alpha of 0.05 was used for all analyses.

CHAPTER 4: RESULTS

The purpose of this study was to examine the effect of ice slurry ingestion prior to the
start of and during halftime of a simulated athletic competition in the heat utilizing
repeated-sprint cycling protocol in recreationally active college-aged males.

Figure 1. Core temperature baseline vs. pre-exercise by condition

Figure 1 depicts there was no significant difference between control group and
experimental group for core temperature at baseline⁺ (Control = 36.96 ± 0.09°C,
experimental = 37.0 ± 0.07°C, F = 1.39, p = 0.255). There was a significant difference
between control group and experimental group for core temperature pre-exercise*
(Control = 37.06 ± 0.11°C, experimental = 36.06 ± 0.69°C, F = 18.16, p = 0.00).

Table 2. Mean core temperature of all participants per half by condition

Core Temperature

Group

(ºC) Half 1

(ºC) Half 2

(ºC) Overall

Control Group

37.14 ± 0.14

37.24 ± 0.33

37.19 ± 0.25

Experimental Group

36.31 ± 0.70

36.44 ± 0.82

36.38 ± 0.75

Mean

36.72 ± 0.65

36.84 ± 0.73

36.78 ± 0.69

Note. Values are mean ± standard deviation.
Table 2 depicts there was no main effect of core temperature for group by half (F =
0.003, p = 0.954) nor was there a main effect revealed from the ANOVA for half (F =
0.378, p = 0.543). Furthermore, there was not a significant difference through interaction.

Figure 2. Mean core temperature of all participants overall
Figure 2 depicts there was a main effect for group (F=18.365, p <0.01) The control group
overall mean core temperature was 37.19 ± 0.25ºC and the experimental group overall
mean core temperature was 36.38 ± 0.75 ºC. Demonstrating the ice slurry is effective
throughout the exercise protocol.

Half time ice slurry
ingestion.

Figure 3. Average core temperature by sprint
Figure 3 depicts average core temperature by sprint, clearly demonstrates the effect of the
ice slurry on core temperature at both pre exercise and at half time.

Figure 4. Average mean power output of all participants by condition

There was no significant difference in average mean power output by group
(Control = 956.60 ± 159.68 watts, experimental = 973.88 ± 149.23 watts, F=0.067,
p=0.798). There was no significant difference in average mean power output by half
(Half 1 = 976.58 ± 156.27 watts, half 2 = 953.90 ± 153.44 watts, F = 0.352, p = 0.557).
The average mean power output for the control group, first half was 950.8 ± 162.6 watts.
The average mean power output for the experimental group, first half was 991.8 ± 148.9
watts. The average mean power output for the control group, second half was 951.8 ±
157.4 watts. The average mean power output for the experimental group, second half was
956.0 ± 148.1 watts.

Figure 5. Average peak power output of all participants by condition

There was no significant difference in average peak power by group (Control =
1381.47 ± 215.36 watts, experimental = 1399.46 ± 208.20 watts, F=0.027, p = 0.871).
There was no significant difference between average peak power output by half (Half 1 =
1400.75 ± 215.97 watts, half 2 = 1380.18 ± 207.45 watts, F = 0.172, p = 0.681). The
average peak power output for the control group, first half was 1392.53 ± 27.55 watts.
The average peak power output for the experimental group, first half was 1408.92 ±
20.95 watts. The average peak power output for the control group, second half was
1370.36 ± 82.61 watts. The average peak power output for the experimental group,
second half was 1390.00 ± 66.49 watts.

Table 3. Fatigue, calculated by percent decrement, of all participants per half by condition

Group

Fatigue (%) Half 1

Fatigue (%) Half 2

Fatigue (%) Overall

Control Group

54.51 ± 1.24

56.81 ± 2.20

55.66 ± 2.09*

Experimental Group

54.63 ± 1.65

56.45 ± 4.30ⸯ

55.54 ± 3.30

Mean

54.57 ± 1.42⁺

56.63 ± 3.32

55.60 ± 2.72

Note. Values are mean ± standard deviation for fatigue.
As can be seen in table 3 there was no significant difference for fatigue by group* (F =
0.019, p = 0.891) nor a main effect for group by half⁺ (F = 0.71, p = 0.79). However,
there was a significant difference for fatigue by halfⸯ (F = 5.526, p = 0.025).

Table 4. Heart rate of all participants per half by condition

Heart rate (BPM)

Half 1

Half 2

Overall

Group
Control Group

150.06 ± 16.68

158.26 ± 17.39

154.16 ± 12.91

Experimental Group

140.93 ± 19.70

150.99 ± 17.35

145.96 ± 12.91

Mean

145.49 ± 12.88

154.62 ± 13.04

150.06 ± 13.59

Note. Values are mean ± standard deviation for heart rate.
As can be seen in table 4 there was no significant difference between heart rate by group
(F = 3.792, p = 0.060), heart rate by half (F = 4.705, p = 0.038), nor heart rate group by
half (F = 0.049, p = 0.827).

Table 5. Rating of Perceived Exertion (RPE) of all participants per half by condition

Group

RPE Half 1

RPE Half 2

RPE Overall

Control Group

13.84 ± 1.70

14.87 ± 1.39

14.36 ± 2.48

Experimental Group

13.33 ± 1.69

14.23 ± 1.63

13.75 ± 2.47

Mean

13.59 ± 1.67

14.55 ± 1.50

14.07 ± 1.64

Note. Values are mean ± standard deviation for RPE.
As can be seen in table 5 there was no significant difference in RPE by group (F = 1.143,
p = 0.293). There was no significant difference in RPE by half (F = 3.224, p = 0.082), nor
was there a main effect for RPE for group by half (F = 0.13, p =0.910).

CHAPTER 5: DISCUSSION & CONCLUSION

The purpose of this study is to examine the effect of ice slurry ingestion prior to
the start of and during halftime of a simulated athletic competition in the heat utilizing a
repeated-sprint cycling protocol with recreationally active college-aged males. The
results of this study indicated that there were no significant differences in average mean
power output, average peak power output, and fatigue. However, there was a significant
finding in core temperature by conditions.
The current investigation found no significant difference (p > 0.05) between
conditions for average mean power output and average peak power output. In a similar
study, Brade et al., (2012) looked at 12 male team sport players completing four different
conditions, including a combination of a cooling jacket and ice ingestion, control group,
cooling jacket alone, and ice ingestion alone. The precooling was administered 30
minutes prior to exercise with an ice jacket and ice slushy. The exercise was repeatedsprints on the cycle including 2 x 30 minute halves, separated by a 10 minute half-time
period. Each half was comprised of 30 × 4 second maximal sprints on 60 second marks,
interspersed with 56 seconds of sub-maximal exercise at varying intensities for an active

recovery. The data suggested that there was a better performance in the cooling jacket
alone and the combination groups compared to ice slushy by itself for all performance
variables at every stage, except for peak power. The data suggested better performance in
the cooling jacket group compared to ice slushy alone for peak power.
Similar to the results of the present study, Brade et al. (2012) found no
statistically significant difference in the ice slushy alone precooling group for RPE, mean
and peak power outputs. It was found that repeated sprint performance in the heat may be
enhanced using a combination of precooling methods involving internal and external, not
a singular precooling method such as an ice slushy (Brade et al., 2012). It is suggested by
Brade et al. (2012) that using a cooling jacket may have had an insulating effect, by
impairing heat flow along a temperature gradient from body core to skin, perhaps
accounting for the difference in core temperature returning to baseline throughout the
exercise of the current study. Therefore, potentially due to the lack of insulation of the
individuals as the exercise protocol continued, their core temperature began to rise.
Minetts et al. (2011) looked at precooling, with ten male team-sport athletes.
These athletes performed 85-minutes of free-paced intermittent-sprint running after 20
minutes of precooling via cooling jacket. Researchers looked at distances covered, heart
rate, perceptual exertion, and thermal stress. The results of this study showed that
exercise heart rate was reduced with whole body precooling prior to the exercise (Minetts
et al., 2011). Heart rate had shown to be lower in the experimental trials for all subjects in
both halves (Minetts et al., 2011). Whereas, in the present study we would expect to see a
change in heart rate due to precooling, vasodilation of the vessels. We did not see this
response potentially due to not lowering the core temperature low enough or the
34

participants not elevating their core temperature close to the critical value. Their blood
pressure was not threatened enough through the environment or the ice slurry to observe
a change in heart rate.
In contrast to Minetts et al. (2011), the present study demonstrated that there was
no statistical significant difference for fatigue by conditions (p = 0.891). However, there
was a an expected statistical significant difference for fatigue by half, demonstrating
increase in culamative fatigue as participants progressed through the sprint protocol (p =
0.025). Fatigue was not significantly different between the groups. Although fatigue was
not different between groups, the core temperature of the participants was significantly
lower in the experimental group. This shows the ice slurry was effective at lowering core
temperature and increasing heat storage capacity. Although the critical value is 39.2°C
for core temperature, the increase in the participants’ core temperature may not have been
of a significant magnitude to elicit additional increases in fatigue (Brade et al., 2012).
The results from the current study demonstrated a statistically significant
difference in the core temperature between the participants’ baseline core temperature
and post precooling protocol (pre-exercise) (p < 0.05). This indicates that the precooling
protocol used was effective in lowering the participant’s core temperature prior to
exercise. It’s been speculated by Siegel et al. (2010) a decrease in core temperature may
enable more blood to be directed to working muscles to aid in waste removal and
delivery of oxygen and nutrients, both of which would aid performance. This finding is
similar to the results Siegel et al. (2010) found when investigating the effects of
precooling with an ice slurry on running performance in the heat. The researcher found
that the precooling protocol with an ice slurry was an effective means to decrease the
35

core temperature. As demonstrated in the present study, one of the potential theories was
that the precooling protocol could increase heat storage capacity for the individual.
However, in the present study the precooling may not have had an effect on participants
due to the fact that their core temperature did not approach the critical value (39.2°C) in
the placebo condition. Siegel et al. (2010) mentioned by lowering core temperature
before exercise, rectal temperature could increase over a longer period of time allowing
the participant to terminate exercise at a similar temperature, thereby potentially
improving performance by increasing heat storage capacity.
In another study (Zimmerman et al., 2015), it was shown that the ingestion of ice
effectively lowered the core temperature of women cycling in same temperature as the
present study. Although the results did not improve performance measures, the
researchers suggest there was not improvement due to the physiological differences in the
participants’ gender (Zimmerman et al., 2015). Zimmerman argued that Ice ingestion
alone may not be an effective way to maintain a lower core temperature throughout
exercise. Although the methodology demonstrated the ability to lower core temperature
directly after ice ingestion, this lowered core temperature was not maintained throughout
exercise. Notably, the female participants in Zimmerman’s study did not reach the critical
value of core temperature similar to the present study.
The lack in difference in RPE by half hints that pacing may have been an issue for
some participants. While this cannot be definitively determined, it is worth noting as a
potential contributor to the lack of effect of the precool protocol.

Future Considerations
Some things to consider for future works would to try and use a combination of
precooling methods to maintain the lowered core temperature throughout the exercise
protocol. While participant numbers in this study (n = 9) were similar to other studies that
have researched precooling methods (Castle et al., 2008 & Duffield & Marino., 2012) a
larger group of participants may have provided more conclusive results. Another area to
keep in mind for future considerations is inducing more heat stress to increase the
participants’ core temperature to induce fatigue greater capacity.
Conclusion
The results suggest that ice ingestion does not provide more of a performance
benefit than ingesting water prior to repeated-sprint exercise bouts in the heat (33°C). Ice
ingestion did however, improve heat storage capacity by lowering core temperature after
ingestion. There needs to be further research done to explore the potential avenues to
increase heat storage capacity in repeated-sprint athletes and the effects on performance.

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Appendices
Appendix A

Appendix B
Informed Consent
Title of Investigation: THE EFFECTS OF AN ICE SLURRY FOR PRECOOLING
AND COOLING DURING EXERCISE ON REPEATED SPRINTS IN HEAT
CONDITIONS

Principal Investigator:

Jenna Rose Bilancia

Overview of the study
Repeated sprints are one assessment used to measure the physiological demands of stopand-go activity (Glaister et al, 2004). The sprint portion is usually a 4-8 second sprint,
while the rest period usually is about 20-30 seconds (Spencer et al, 2008). There are
detrimental effects to the athletes when performing in high heat environments (Hayes et
al, 2014). There are many heat management strategies that have been used in research to
lower core temperature prior to the start of the exercise and in a short break to also cool
the body to increase performance. The task at hand was to identify a cost-effective
method which can lower core temperature in hot conditions as to ascertain a way to delay
detrimental effects on performance.
Testing Sessions
Visit one will consist of orientation, written informed consent, par-q, and heat illness
questionnaire. Demographic data will be collected, along with a 10-minute
familiarization trial. The trial will orient the subjects with the equipment being used and
45

the exercise protocol. Session two and three will be the experimental protocol. Subject
will begin with 30 minutes in the heat conditions (34 ˚C) where they will either ingest
7.5g/kg of body weight of water (4 ˚C) or ice-slurry (0 or 1˚C). Following the precooling
part, subjects will have a 5 minute warm-up, following the warm-up there will be a 10
minute half. This will include 10, 5 second sprints at 0.07N/kg and a 55 second active
recovery at 50 watts. There will then be a 10 minute recovery phase, where the subject
will ingest 2.5 g/kg of ice slurry or water depending on the session. Followed by a second
10 minute half following the same protocol. Heart rate, core temperature, RPE, percent
decrement average mean and peak power outputs will be collected following each 5
second sprint. . Heart rate and core temperature will be monitored continuously for safety
purposes. Urine refractometry will be used to ensure hydration status pre and posttesting; if hydration was not achieved before the trial, the researchers would hydrate the
subjects on site.
Although be it slight, there are still some risks involved. Any individual information
obtained from this study will remain confidential. Non-identifiable data will be used for
scientific presentations. You may withdraw from the study at any time. If you have any
questions you may contact the principal investigator at jbilancia@live.esu.edu; or by
telephone at 973-876-3784. If you feel you were put at risk, or have any further concerns,
you can contact Dr. Chad Witmer.
cwitmer@po-box.esu.edu

Tel: (570)-422-3362

YOU ARE MAKING A DECISION WHETHER OR NOT TO PARTICIPATE.
YOUR SIGNATURE INDICATES THAT YOU HAVE READ THE
INFORMATION PROVIDED AND YOU HAVE DECIDED TO PARTICPIATE
IN THE STUDY.
I have read and understood the above explanation of the purpose and procedures for this
study and agree to participate. I also understand that I am free to withdraw my consent at
any time.
Participant

Print Name

Signature

Date

Signature

Date

Principal Investigator

Print Name

Witness Signature

Appendix C
Heat Illness Questionnaire
Title of Investigation: THE EFFECTS OF AN ICE SLURRY FOR PRECOOLING
AND COOLING DURING EXERCISE ON REPEATED SPRINTS IN HEAT
CONDITIONS

Principal Investigator:

Jenna Rose Bilancia

Please circle if you have ever experienced any of the following problems in the past:
Heat cramps

Heat exhaustion

Heat stroke

Heat rash

Please circle if you have ever experienced any of the following problems in a hot
environment in the past:
Confusion
Fainting
Seizures
Very high body temperature

I have not experienced any illness, symptoms, or health problems related to heat in the
past. I understand the purpose and procedures for this study. I also understand that I am
free to withdraw my consent at any time.
Participant

Print Name

Signature

Date

Signature

Date

Principal Investigator

Print Name

Witness Signature

Appendix D

Physical Activity Readiness Questionnaire (PAR-Q) and
You
Regular physical activity is fun and healthy, and increasingly more people are starting to
become more active every day. Being more active is very safe for most people. However, some
people should check with their doctor before they start becoming much more physically active.
If you are planning to become much more physically active than you are now, start by
answering the seven questions in the box below. If you are between the ages of 15 and 69, the
PAR-Q will tell you if you should check with your doctor before you start. If you are over 69
years of age, and you are not used to being very active, check with your doctor.
Common sense is your best guide when you answer these questions. Please read the
questions carefully and answer each one honestly:
YES
NO

□ □ 1.

Has your doctor ever said that you have a heart condition and that you should only do
physical activity recommended by a doctor?

□ □ 2.

Do you feel pain in your chest when you do physical activity?

□ □ 3.

In the past month, have you had chest pain when you were not doing physical activity?

□ □ 4.

Do you lose your balance because of dizziness or do you ever lose consciousness?

□ □ 5.

Do you have a bone or joint problem that could be made worse by a change in your physical
activity?

□ □ 6.

Is your doctor currently prescribing drugs (for example, water pills) for your blood pressure
or heart condition?

□ □ 7.

Do you know of any other reason why you should not do physical activity?

□ □ 8.

Have you ever suffered a heat illness/injury? If yes, please list below.

Talk to your doctor by phone or in person BEFORE you start becoming much more physically active

or BEFORE you have a fitness appraisal. Tell your doctor about the PAR-Q and
which questions you answered YES.

you

You may be able to do any activity you want – as long as you start slowly and build up
gradually. Or, you may need to restrict your activities to those which are safe for you. Talk

answered:
•

with your doctor about the kinds of activities you wish to participate in
and follow his/her advice.
Find out which community programs are safe and helpful for you.

NO to all questions

Delay becoming much more active:

• If you are not feeling well because of a temporary If you answered NO honestly to
all PAR-Q illness such as a cold or a fever – wait until you feel questions, you can be
reasonably sure that you can: better; or