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Sports Phys Essay Sample

Introduction

Exercising in hear environments has been shown to increase body core temperature, in particular in prolonged exercise (Armstrong et al., 1985). It has been recommended to consume fluids to maintain performance and reduce thermoregulatory straining (Sawka et al., 2007). Research has shown that fluid consumption before exercise improves hydration with colder drinks preferable in hot environments (Boulze et al., 1983). Cold drinks can be shown as beneficial by a reduction in body core temperature and heat storage, which in turn could explain the performance benefit when consuming cold or iced drinks (Kay & Marino, 2000). https://www.buy-cheapessay.com/

Research shows that consuming cold drinks prior to exercise in hot environments has seen reduction in core body temperature (Lee et al., 2008). Relative studies show that body core temperature has reduced with cold drink consumption prior to exercise in the heat (Szlyk et al., 1989). This can be shown to a possibility of influencing cardiovascular strain, due to the redirections of blood flow from the skin to muscles. Cardiovascular strain, can be explained by a reduction in heart rate (Mündel et al., 2006). Whilst exercising in the heat, under the influence of a pre-cooling drink, studies have shown an increase of activation to the central nervous system (CNS) and improvement of performance (Morrison et al., 2004) Additional feedback has been shown to be provided by thermo receptors in the mouth and gastrointestinal tract, which may partly alter feedback when it comes to perception of body core temperature.

The purpose of this study was to examine whether there is an ergogenic benefit of cold beverage ingestion in an endurance event in the heat when comparable to lower temperature environments as well. We hypothesized that when compared to room temperature water (thermo neutral), the consumption of an iced slushy would improve endurance performance, with attenuation of thermoregulatory and cardiovascular strain. In the absence of heat environments it was further hypothesized that the strain of heat would be made more prevalent.

Methods and Materials

Participants

1 male university student, age 20, body weight (89.4kg) and height (176.6cm) was selected to take part in this study. Participant was of healthy population and identified as recreationally active at the time of study (VO2peak: 45.1 ml/kg/min). The protocol was detailed along with possible risks and discomfort, and an ESSA pre-exercise screen was completed.

Prior to the commencement of this study, a baseline V02MAX test was undertaken. This was done for the purpose of obtaining an initial view of the participant, as well as provides Vo2 speed data to be used within the study. Trials were conducted at the same time of day, with a time of seven days separating each trial. Participants were asked to refrain from heavy exercise the day before, no alcohol consumption, and to keep their last meal and hydration consistent prior to starting each trial.

A total of three trials were undertaken. A ‘thermo neutral’ control’ trial at 22 degrees Celsius, then two in a hot temperature of 35 Degrees. All trials were conducted in 50% humidity. Each trial had the subject performing a modified version of the Loughborough Intermittent Shuttle Test. This involved a circuit of 60m walking, 20m maximal sprint, 4 seconds rest, 60m 55% vo2max, and 60m 95% vo2max. This circuit was repeated for duration of 15 minutes, followed by a 3-minute passive recovery, followed by another 15-minute circuit. Taking the participant’s baseline vo2max data into account, the 55% speed was set at 7.5km/hr and the 95% speed was 15.5km/hr.

All trials were conducted in the same temperature chamber using a Woodway WWCURVE non-motorized treadmill. 600ml of fluid was consumed 5 min prior to commencement. The normal and first hot temperature trial used room temperature water, whereas the third hot trail used an ice slushy formula, to investigate the effects of pre-cooling on performance.

Measurements

A number of measurements were taken throughout each trial. Heart rate (HR), Rate of perceived exertion (RPE) and thermic effect was measured at every minute interval. Skin and core body temperatures were also recorded using a Visio Focus Technimad Thermo scan core body scanner, recording temperature every 5 minutes. Additionally, three skin temperature sensors were used, located on the right scapula, left calf, and forehead. This data was extrapolated from computer software post trial.

Results

From the laboratory testing, the participants’ RPE across given exercise intensities during the intermittent shuttle test were gathered and used to see the differences between the Pre-Cooling and No Pre-Cooling Effects and the effect of Temperature in different environments.

Figure 1. The effect of pre-cooling on Rated Perceived Exertion (RPE)

Figure 1 showed the difference in RPE between all three-laboratory tests. When referring to Figure 1, this shows the relationship between RPE and time in the environment at the intermittent intensities, this shows a clear difference between Pre-Cooling in the environment and no Pre-Cooling in the hot environment, evidently in the final half of the test. The control displays a steadier RPE, with the variance of these totals being much less than the hotter environment. RPE on average is recorded 0.44 lower in the pre-cooling test when compared to the non-cooling effect test. In comparison, the pre-cooling test only recorded a 0.06 increase when compared with the control test, completed at 10 degrees cooler than the Pre-Cooling test.

Figure 2. The effect of pre-cooling on Heart Rate (HR)

Referring to figure 2, it is displayed that Heart Rate is much lower in the initial stages of first and second half of the test in relation to the Pre-Cooling intervention, when compared to the non-cooling intervention. This shows that during the immediate phases of the test, that the cooling effect has had a response in relation to heart rate. Heart Rate on average is 5.2% lower in the data collected from the Pre-Cooling trial, in comparison to the Non-Cooling trial.

Figure 3. The effect of temperature on core body temperature.When drawing on Figure 3, it can be clearly seen the effect of cooling on core body temperature when compared to the trial without cooling effect. This can be reinforced by the first 23 minutes of the test having a lower core body temperature than the test without cooling effect. On average the core body temperature is 0.41 degrees lower in the cooling effect test. This can be clearly shown in Figure 4, below.

Figure 4. The effect of heat on average core body temperature over a number of tests.When reporting Sensational temperature it is displayed that the lowest of all values where displayed in the cooling effect trial. Sensation of Temperature was on average 0.47 lower when the participant ingested iced slushy, compared to when they did not.

Figure 5. Sensation Temperature Scale in different environments. Shows that although the sensation of temperature at times was equal at time periods, when comparing pre-cooling and non-cooling effect, that pre-cooling almost always recorded a lower sensation of temperature response from the participant.

Discussion

This study was designed to find the effect that heat has on individual’s perception during intermittent training protocols, under varied pre hydration protocol. The present study found that iced slushies lowered perception of effort, lowered heart rate, lowered sensation of temperature and lowered core body temperature during intermittent exercise, leading to an increase in exercise performance.

Recent studies have looked into the relationship between heat and the pre-cooling effect through many exercise protocols. Although recent studies have a variation of ages, gender, dose size, exercise modality and intensity/duration of exercise, it is clear that the pre-cooling effect does influence a number of subjective and objective measures. Selected results from this study showed that on average there was a 5.1% reduction in RPE when slushy was ingested before the test, when compared to the heat test without the slushy. However, the biggest variation in the RPE was shown when the participant re-entered the chamber after the allotted break period, with a variation of 36.1% in RPE scores, suggesting that the slushy had an effect of the participant after the break period. This suggests that the pre-cooling effect is not only effective before exercise, but also in break periods. This finding is reinforced by Zimmerman et al (2017) who set out a similar study, where males, of similar weight and height this studies participant, undertook a steady state cycling test, with a pre-cooling drink 30 minutes prior to the commencement of the test. This test found that the participants when ingesting pre-cooling drinks before exercise exhibited a RPE of 0.3 on average lower than without the pre-cooling drinks. Although this is encouraging, it must be stated that the control group of participants was much larger allowing for more depth in research. Further limitations can be found into the structure of the protocol, displaying as a steady state test, in comparison to an intermittent test. This is reinforced by Stevens et al. (2013) who justify the research as being reflective in steady state efforts.

Current research has also looked into the relationship between pre-cooling and heart rate, with evidence showing that pre-cooling before exercise may reduce heart rate. Results from this study show that there was on average a 5.2% reduction in heart rate over the tests duration when the participant ingested the pre-cooling drink. Burdon et al. (2013) reinforce this with there study of a similar procedure, with participants ingesting ice prior to exercise, stating that the majority of participants (7 out of 10) saw a reduction in heart rate over the duration of the experiment, with a reduction of between 6 – 11 beats per minute. However, a number of limitations faced this study, with participants cycling for 90 minutes and being administered a cold drink every 15 minutes throughout the experiment. Temperatures were also a limitation in this study, with participants performing in a chamber set to 32 degress and 40% humidity, a number of degrees and per cent lower than the experiment just conducted.
A number of studies have looked into the association between pre-cooling and sensation of temperature, in relation to heat. Outcomes from the study show that perceived sensation of temperature was on average a score of 0.47 lower when the participant ingested the slushy compared to when he did not. This is reinforced by Siegel et al (2012) who’s research found that there was an observed decrease in thermal comfort when iced slushy was ingested. This is justified by Schlader et al. (2011) who states that this sensation is influenced generally by skin temperature. Limitations in the above mentioned research, is also found, but not limited to the environmental surroundings of being in the Netherlands, which can be exposed to freezing temperatures, as apposed to Brisbane with a minimum of 6 – 8 degrees.

A number of recent studies have also considered the relationship between pre-cooling and core body temperature. Findings from this study have exposed multiple findings in relation to core body temperature. The findings included, but were not limited to a mean core body temperature of 0.41 Degrees Celsius lower in the pre-cooling test, when compared to the heat test, without any pre-cooling drink. The slushy ingestion test also showed that until the twenty third minute of the test, the core body temperature was lower than in the room temperature water test, displaying that the slushy had an effect immediately on core body temperature. Siegel et al. (2010) found that core body temperature was significantly lower after the consumption of ice slurry when compared to water (p=0.017). This reinforces the relation between pre-cooling and exercise in the heat however there are some limitations with this research. This research was conducted under maximal testing, were participants decided to stop through volitional fatigue. Similarities do run between the experiments, as this testing was completed on a treadmill and involved higher speed efforts.

One common limiting factor that seemed to be apparent, in comparison to these other studies was the number of participants involved, with all of the studies having more than 10 participants, in turn providing a greater data set. In addition to this the timing around the ingestion of the slushy varied from immediately before the exercise to 30 minutes prior to exercise. This in turn provided a varied results set with studies that ingested 10 minutes or more before exercise, showing the greatest variance in results, when compared to control and non-cooling experiments.

Conclusion & Practical Application

Pre-exercise cooling has shown a reduction in RPE, HR, Core Body Temperature and Sensation of Temperature. When compared to exercise in the heat with no pre-cooling drinks, a reduction in RPE, HR, Core Body Temperature and Sensation of Temperature was shown. The main results were shown in the intitial stages of the test, so it is important that for the cooling effect to be implemented into endurance based exercise, that cooling drinks must be consumed on a frequent basis throughout performance. These benefits could mean that pre-cooling drinks could be used (in acceptable doses) when provided to athletes prior to training or games in order to improve performance when faced with hot climates.

References

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