2,467 research outputs found

    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

    Human acclimation and acclimatization to heat: A compendium of research, 1968-1978

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    Abstracts and annotations of the majority of scientific works that elucidate the mechanisms of short-term acclimation to heat in men and women are presented. The compendium includes material from 1968 through 1977. Subject and author indexes are provided and additional references of preliminary research findings or work of a peripheral nature are included in a bibliography

    Human acclimation and acclimatization to heat A compendium of research

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    Annotated bibliography on human acclimation and acclimatization to hea

    Assessment of Heat Stress for Outdoor Work Conditions in Saudi Arabia

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    Outdoor workers have an increased risk of heat stress in Saudi Arabia since it is one of the hottest places in the Middle East. Recently, the government decided to limit outdoor work hours during the months of June, July, and August every year, and banned working under the direct sunlight from 12:00 to 03:00 p.m., although outdoor workers in the petroleum, natural gas, or emergency maintenance work industries are exempt from this prohibition. Traditionally, the efforts by safety and health professionals to mitigate work-related heat injury has been directed toward the assessment of environmental heat stress (e.g., wet-bulb globe temperature), rather than toward the associated physiological strain responses (e.g., heart rate and core temperatures). However, because a worker’s physiological response to given heat stress is modified independently by individual factors of each worker (e.g., age, sex, chronic disease, others), it becomes challenging to protect workers on an individual basis from heat-related injury without assessing those physiological responses. The primary objective of this study was to examine whether limiting work hours will reduce the risk of heat stress among outdoor workers or not. That can be achieved by (1) examining if the ban on three-month midday outdoor work needs to be extended to cover the period from June 1st to September 30th (2) examining if the midday break between 12:00 pm and 03:00 pm need to be extended by a few more hours. A field study was carried out in Dammam City on Saudi Arabia’s eastern coast where the humidity reaches 95% and temperature can reach 47°C (116.6°F) during summer months. The core temperature of 20 subjects matched for age, gender, and experience subjects was monitored while they performed their normal duties in the outdoor environment of Dammam City. The core temperature of these outdoor workers was measured using a novel non-invasive measurement method. The obtained results showed that subjects were under the risk of heat stress over a large part of the workday and their body temperature exceeds the allowable core temperature (38.5°C; 101.3°F) which the ACGIH has proposed to protect workers from experiencing heat stress. The intensity of exposure was high from (10:00-12:00 a.m.) that is not included in the midday break. A control group (non-policy) which did not experience the mid-day break showed essentially the same core body temperature as the experimental (policy) group. Among chief findings was that complying with a midday break work ban (12:00–3:00 p.m.) was not effective in reducing heat stress risk under the conditions and limitations of the design. The policymakers should be informed that this particular policy is not helpful and does not significantly lower core body temperatures. Some policy modifications are suggested which might better impact core body temperatures under these extreme conditions

    Wearable sensor technology to predict core body temperature : a systematic review

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    Heat-related illnesses, which range from heat exhaustion to heatstroke, affect thousands of individuals worldwide every year and are characterized by extreme hyperthermia with the core body temperature (CBT) usually > 40 °C, decline in physical and athletic performance, CNS dysfunction, and, eventually, multiorgan failure. The measurement of CBT has been shown to predict heat-related illness and its severity, but the current measurement methods are not practical for use in high acuity and high motion settings due to their invasive and obstructive nature or excessive costs. Noninvasive predictions of CBT using wearable technology and predictive algorithms offer the potential for continuous CBT monitoring and early intervention to prevent HRI in athletic, military, and intense work environments. Thus far, there has been a lack of peer-reviewed literature assessing the efficacy of wearable devices and predictive analytics to predict CBT to mitigate heat-related illness. This systematic review identified 20 studies representing a total of 25 distinct algorithms to predict the core body temperature using wearable technology. While a high accuracy in prediction was noted, with 17 out of 18 algorithms meeting the clinical validity standards. few algorithms incorporated individual and environmental data into their core body temperature prediction algorithms, despite the known impact of individual health and situational and environmental factors on CBT. Robust machine learning methods offer the ability to develop more accurate, reliable, and personalized CBT prediction algorithms using wearable devices by including additional data on user characteristics, workout intensity, and the surrounding environment. The integration and interoperability of CBT prediction algorithms with existing heat-related illness prevention and treatment tools, including heat indices such as the WBGT, athlete management systems, and electronic medical records, will further prevent HRI and increase the availability and speed of data access during critical heat events, improving the clinical decision-making process for athletic trainers and physicians, sports scientists, employers, and military officers. © 2022 by the authors

    Criteria for a Recommended Standard: Occupational Exposure to Hot Environments (Revised Criteria 1986)

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    "This document contains the recommendations of the National Institute for Occupational Safety and Health (NIOSH) for worker exposure to heat stress. Heat-induced occupational illnesses, injuries, and reduced productivity occur in situations in which the total heat load exceeds the capacities of the body to maintain normal body functions without excessive strain. The total heat load represents the sum of the heat gained from the environment plus the heat generated in the body. Total heat stress is the heat load minus the heat lost from the body to the environment. This document presents how the reduction of adverse health effects can be accomplished by the proper application of engineering and work practice controls, worker raining and acclimatization, measurements and assessment of heat stress, medical supervision, and proper use of heat protective clothing and equipment." - NIOSHTIC-2CurrentPrevention and ControlEnvironmental Healt

    The physiological strain index does not reliably identify individuals at risk of reaching a thermal tolerance limit

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    Purpose The physiological strain index (PSI) was developed to assess individuals' heat strain, yet evidence supporting its use to identify individuals at potential risk of reaching a thermal tolerance limit (TTL) is limited. The aim of this study was to assess whether PSI can identify individuals at risk of reaching a TTL. Methods Fifteen females and 21 males undertook a total of 136 trials, each consisting of two 40-60 minute periods of treadmill walking separated by ~ 15 minutes rest, wearing permeable or impermeable clothing, in a range of climatic conditions. Heart rate (HR), skin temperature (T sk), rectal temperature (T re), temperature sensation (TS) and thermal comfort (TC) were measured throughout. Various forms of the PSI-index were assessed including the original PSI, PSI fixed , adaptive-PSI (aPSI) and a version comprised of a measure of heat storage (PSI HS). Final physiological and PSI values and their rate of change (ROC) over a trial and in the last 10 minutes of a trial were compared between trials completed (C, 101 trials) and those terminated prematurely (TTL, 35 trials). Results Final PSI original , PSI fixed , aPSI, PSI HS did not differ between TTL and C (p > 0.05). However, differences between TTL and C occurred in final T sk , T re-T sk , TS, TC and ROC in PSI fixed , T re , T sk and HR (p < 0.05). Conclusion These results suggest the PSI, in the various forms, does not reliably identify individuals at imminent risk of reaching their TTL and its validity as a physiological safety index is therefore questionable. However, a physiological-perceptual strain index may provide a more valid measure

    Heat tolerance and acclimation in female athletes

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    This thesis aimed to develop a running heat tolerance test (RHTT) to assess changes in heat tolerance and to investigate the mechanism and optimisation of heat acclimation (HA) for female athletes. The first study introduced a RHTT and assessed its repeatability. Results demonstrate good agreement, strong correlations and small differences between repeated trials. The typical error of measure values suggested low within-participant variability. Furthermore, the RHTT was effective in differentiating between individuals’ physiological responses, demonstrating that heat tolerance lies along a continuum. The second study examined the sensitivity of the RHTT to changes in heat tolerance and to evaluate individual responses to HA. Results demonstrate that the RHTT is sensitive to changes in heat tolerance and that the magnitude of adaptation is highly individual; supporting the use of the RHTT in future investigations. Reducing thermal strain through HA in not fully understood for a female population. The third study compared males’ and females’ temporal patterning to short-term HA (STHA; 5-d) and long-term HA (LTHA; 10-d). The RHTT was used to quantify changes in heat tolerance. The results confirm that whilst STHA may be effective in achieving partial adaptation in males and females, females require LTHA to establish reductions in thermoregulatory and cardiovascular strain. Improved thermotolerance following HA, reduces disruptions to cellular homeostasis principally, but not exclusively, by increasing basal heat shock protein 72 following transcription of its gene (Hsp 72 mRNA) as part of the heat shock response (HSR). The fourth study compared males’ and females’ Hsp72 mRNA response during STHA and LTHA. The similar transcription of Hsp72 mRNA observed in all participants suggests that there are no differences in the endogenous criteria to elicit the HSR between sexes. The fifth study assessed the effectiveness of preceding STHA with a passive heat exposure (HAsauna) in females. HAsauna resulted in reductions in thermoregulatory, cardiovascular and perceptual strain. The adaptation pathway was likely mediated in part, by plasma volume expansion and an improved thermoeffector and thermosensitivity response of the sudomotor function. Together, evidence in this thesis supports the notion that special considerations need to be taken when using HA to attenuate thermoregulatory strain in female athletes prior to training and competing in the heat
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