The Impact of Pre-Cooling as an Intervention Strategy to Minimize Cardiovascular Strain and Augment 10,000 Meters Running Performance in the Heat

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The impact of pre-cooling as an intervention strategy to minimize cardiovascular strain and augment 10,000 meters running performance in the heat

Emma Iwikau

Abstract

The aim of this report was to investigate whether the utilization of pre-cooling (cooling vest) prior to a 10, 000m road-race run within a hot and humid environment, would result in improved performance. The report also aimed to examine any performance-related effects, and their underlying physiological mechanisms.

Fourteen (n=14) well-trained adult runners participated in two 10,000m-time trials, spaced 72 hours apart. Ambient conditions of both the control and experimental conditions were T= 32.5 °C, rel. humidity= 65% and T= 32.8’C, rel. humidity= 63% respectively. Procedure consisted of a 30 minute warm up (20 minutes steady state running at RPE 13, 10 minutes individualized stretching activity). During the warm up, the control condition required participants to wear a normal tee shirt, with the experimental condition requiring participants to wear a commercially available gel-based cooling vest. Conclusion of the 30 min warm up saw the tee shirt or ice- vest replaced with the race singlet, before commencing the 10, 000 m time trial. Time, pre and post body mass, heart rate, skin temperature and core temperature were all variables measured and recorded.

Participants were able to complete the 10,000m road-run in less time following the pre-cooling condition, suggesting that pre-cooling as an intervention strategy improved endurance performance. Results indicate this occurrence was due to significantly lower starting core and skin temperatures, reduced starting heart rate as well as an overall lower sweat rate. These factors allowed for a greater capacity of heat storage, minimizing thermoregulatory and cardiovascular strain and therefore allowing the body to operate at a higher level of performance before reaching critical limiting temperature.

Results
Figure 1 displays the difference between time trials obtained in both the control and pre-cooling conditions. The pre-cool time trial was significantly shorter than the control time trial (p<0.05).

The difference between baseline and post body mass (BM) were recorded to calculate sweat rate (L/hr.). Figure 2 displays the difference in sweat rate between the control and pre-cool conditions. Control sweat rate was significantly higher then sweat rate recorded for the pre-cool condition.

The above graph (Figure 3) depicts the mean heart rates and standard deviations for both control and pre-cool conditions. HR was recorded and displayed over three phases of the time trial (start, mid and end). Statistical analysis determined that there was a significant difference in HR between the three phases of the time trial (p<0.05). Statistical significance also occurred between control start HR and pre-cool start HR, with control start HR 5.10% greater than pre-cool start HR.

Skin temperature was also recorded and statistically analysed. Figure 4 displays the mean and standard deviations for skin temperature (Tsk) over three phases of the time trial for both the control and pre-cool conditions. Significant differences between both control and pre-cool conditions were found (p<0.05). Significant statistical differences were also discovered between each of the phases of the time trial (p<0.0167).

Figure 5 depicts mean and standard deviations for core temperature (Tc). Significant statistical difference occurred between the three different stages of the time trial (p<0.05). When compared separately, significant differences were found between all stages of the time trial (start vs. mid, start vs. end, mid vs. end) (p<0.0167).

Discussion

The purpose of this study was to investigate whether pre-cooling through the utilization of a cooling vest would augment endurance performance undertaken in the heat. Findings obtained from the study indicate that pre-cooling did...
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