2,225 research outputs found

    Low-frequency electrical stimulation combined with a cooling vest improves recovery of elite kayakers following a simulated 1000-m race in a hot environment

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    This study compared the effects of a low-frequency electrical stimulation (LFES; Veinoplus® Sport, Ad Rem Technology, Paris, France), a low-frequency electrical stimulation combined with a cooling vest (LFESCR) and an active recovery combined with a cooling vest (ACTCR) as recovery strategies on performance (racing time and pacing strategies), physiologic and perceptual responses between two sprint kayak simulated races, in a hot environment (∼32 wet-bulb-globe temperature). Eight elite male kayakers performed two successive 1000-m kayak time trials (TT1 and TT2), separated by a short-term recovery period, including a 30-min of the respective recovery intervention protocol, in a randomized crossover design. Racing time, power output, and stroke rate were recorded for each time trial. Blood lactate concentration, pH, core, skin and body temperatures were measured before and after both TT1 and TT2 and at mid- and post-recovery intervention. Perceptual ratings of thermal sensation were also collected. LFESCR was associated with a very likely effect in performance restoration compared with ACTCR (99/0/1%) and LFES conditions (98/0/2%). LFESCR induced a significant decrease in body temperature and thermal sensation at post-recovery intervention, which is not observed in ACTCR condition. In conclusion, the combination of LFES and wearing a cooling vest (LFESCR) improves performance restoration between two 1000-m kayak time trials achieved by elite athletes, in the heat

    Thermoelectric cooling and heating of human body temperature

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    The cooling and/or heating of human body temperature is of critical importance and interest in a myriad of applications, however, the use of thermoelectric cooling has made little impact in this area. Current solutions focus on the use of wearable materials that assist the natural temperature regulation of the human body, or the use of liquid cooling techniques reliant on refrigerant fluid or large quantities of dry ice, often used in astronaut spacesuits, worn by surgeons during long surgical procedures, firefighters, military personnel, and motor racing drivers. The motivation for this work is to investigate the feasibility of using thermoelectricity to achieve the cooling process, replacing the existing use of refrigerant fluid and associated compressor and refrigeration components or the use of large quantities of dry ice to create chilled or cooled water. A thermoelectric cooling/heating prototype system has been designed and tested, and successfully demonstrates the temperature of circulating water within small tubes incorporated into a person’s vest undergarment can be used to regulate body temperature. The system briefly comprises: a small reservoir tank of water; a thermoelectric module, heatsink and electronic fan; a small electronic water pump; a proportional, integral, and derivative (PID) controller; interconnecting tubing to carry the circulating water; and a vest undergarment that is worn by the user to help regulate their body temperature. Results presented demonstrate the thermoelectric module successfully cools or heats the water circulating around the vest undergarment, which when worn by a user can be used to lower or increase their external body temperature and improve their temperature comfort levels. The thermoelectric cooling/heating system has several advantages over existing solutions including; a significant decrease in size and weight; system cost; accurate temperature control; ability to provide cooling or heating under user control; no moving parts within the thermoelectric module contributing to high reliability and reduced maintenance requirements; quiet in operation; the elimination of dry ice in the cooling process; and no use of refrigerate fluid or other harmful chemicals. Further work will optimize the design, scale the system to achieve specific cooling/heating targets, and demonstrate the effectiveness of the system in improving a user’s temperature comfort levels

    The Cooling Vest- Evaporative Cooling

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    The objective of this project was to investigate the cooling capability of an evaporative cooling vest; specifically, cooling of the torso region was studied. Modifying Natick Soldier Systems microclimate design, a microenvironment was created between the skin of the torso region and the outer layer of the cooling vest. A vest was designed, developed and tested using a mannequin with sweating capabilities. Through modeling and design test experimentation it was determined that this evaporative cooling system is indeed feasible

    Oral application of L-menthol in the heat: From pleasure to performance

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    When menthol is applied to the oral cavity it presents with a familiar refreshing sensation and cooling mint flavour. This may be deemed hedonic in some individuals, but may cause irritation in others. This variation in response is likely dependent upon trigeminal sensitivity toward cold stimuli, suggesting a need for a menthol solution that can be easily personalised. Menthol’s characteristics can also be enhanced by matching colour to qualitative outcomes; a factor which can easily be manipulated by practitioners working in athletic or occupational settings to potentially enhance intervention efficacy. This presentation will outline the efficacy of oral menthol application for improving time trial performance to date, either via swilling or via co-ingestion with other cooling strategies, with an emphasis upon how menthol can be applied in ecologically valid scenarios. Situations in which performance is not expected to be enhanced will also be discussed. An updated model by which menthol may prove hedonic, satiate thirst and affect ventilation will also be presented, with the potential performance implications of these findings discussed and modelled. Qualitative reflections from athletes that have implemented menthol mouth swilling in competition, training and maximal exercise will also be included

    Physiological and Perceived Psychological Responses of Collegiate Football Athletes to Ventilated Shoulder Pads During a Scrimmage

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    PURPOSE: The purpose of this study was to assess the effect of cold air ventilated shoulder pads on core temperature and perceived exertion in football athletes during a scrimmage. METHODS: Eight football athletes were randomly divided into two groups, one receiving cold air ventilation (v) and the other receiving no treatment (nv). Ratings of perceived exertion were taken and core temperatures were taken using a radio frequency device and swallowed CorTemp pills. RESULTS: Data were analyzed using paired and independent sample T-tests. There were no significant differences in core temperature or RPE between the ventilated and non-ventilated groups. No significant difference was found among ventilated subjects pre and post treatment. CONCLUSIONS: Although the RPE values were not significantly different between groups, there was a trend found among the data with post cooling RPE values, suggesting a psychological benefit for those receiving the cold-air treatment

    Self-Sustaining Cooling System

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    The rucksack loads that military, law enforcement, and hiking enthusiasts need for their tasks can be excessive and may lead to heat exhaustion. Cooling strategies have been proposed in the past, but there are significant constraints associated with these concepts. This MQP aimed to cool the body by pumping cooled water around the upper torso absorbing the body heat into the cooling water. The closed-system of cooled water flows to the back of the rucksack where heat is exchanged to an evaporative cooling system using a separate, non-potable water system. Field tests of the unit have documented significant quantitative cooling using this process

    Practical precooling strategies and cycling time trial performance

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    Whole-body precooling can improve endurance exercise performance, especially in the heat; however there are logistical considerations that restrict the use of various precooling strategies prior to actual competition. Precooling is proposed to collectively reduce deep skin and body temperature and in effect, increase the heat storage capacity of an athlete, thereby allowing a greater amount of work to be completed prior to attainment of a critical core temperature. While there is a sound theoretical basis for implementing precooling to improve cycling time trial performance in the heat, the practicalities of employing effective precooling strategies in the field warrant further investigation. The purpose of this thesis was to investigate the effectiveness of various practical precooling strategies for reducing core temperature and improving cycling time trial performance in hot (32-35ºC; 50-60% r.h.) and temperate (20-22 ºC; 50-60% r.h.) conditions. The first three studies of this thesis involved the manipulation of body temperature via a range of precooling strategies that were applied under hot and humid environmental conditions. In study 1, eight precooling strategies involving external application or internal ingestion of cold water and ice were evaluated for their effectiveness in lowering deep body temperature, with due consideration regarding their application in a practical setting. The novel strategy identified in this study, which involved the combined application of iced towels and ingestion of an ice-slurry (“slushie”) made from sports drink, was then compared with an established cooling strategy (Study 2). Both the new and established precooling strategies achieved noticeable cooling effects (moderate and very large, respectively) but only the new strategy enhanced mean power output (3%, 8W) during a 46.4 km laboratory-based cycling protocol, with performance improvements detected in the second half of the time trial. This strategy was also found to be practical to implement. In study 3, practical precooling and hyperhydration were evaluated to assess whether their combination offered further benefits to endurance cycling time trial performance, when assessed over the same laboroatory protocol. The main findings indicated that practical precooling and hyperhydration, with and without the co-ingestion of glycerol, failed to achieve a clear enhancement of cycling performance. However, when practical precooling and hyperhydration without glycerol was compared to the control condition (i.e., hyperhydration alone), there was a 2% (30 s) improvement in cycling performance time, which was detected in the second half (climb 2) of the time trial. These improvements may be partially explained by a lower percieved exertion, which was observed during the initial 10 km of the time trial. Study 4 was conducted to validate anecdotal reports and laboratory-based observations of thermoregulatory strain in elite cyclists during a real-life event performed in temperate environmental conditions. The rationale for this study was to determine whether the magnitude of hyperthermia achieved during real-life cycling performed in temperate conditions was high enough to possibly benefit from precooling. Although fluid losses during racing were mild (1.3%), cyclists experienced hyperthermia, at magnitudes typically associated with heat-stress induced fatigue (\u3e67% of observations). Therefore, in the final study of this thesis, the effects of practical precooling on 45.6 km cycling time trial performance was examined in both hot (32˚C) and temperate (21˚C) environmental conditions. The effectiveness of practical precooling was enhanced in temperate conditions, such that there was a greater magnitude of body cooling achieved. However, this strategy failed to provide a clear performance benefit in temperate conditions and instead, was likely to impair performance, particularly in the first (flat) section of the time trial course (-2.3%, 8 W). Collectively, the studies contained within this thesis have contributed to the development of a practical precooling strategy involving the combined application of iced towels and ingestion of a slushie made from sports drink. These studies confirm the effectiveness of this novel strategy in reducing skin and core temperature and enhancing heat storage capacity prior to the commencement of exercise. However, the associated reduction in thermoregulatory strain translates into a performance enhancement in hot, but not temperate conditions. This thesis has provided detailed information regarding the range of factors that may be involved in altering the efficacy of a precooling manoeuvre and offers a highly practical insight into the application of precooling strategies aimed at improving field-based sports performance specific to time trial cycling
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