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Physiologia Plantarum Nov 2022
Topics: Climate Change; Adaptation, Physiological; Agriculture; Acclimatization; Epigenesis, Genetic
PubMed: 36572663
DOI: 10.1111/ppl.13835 -
American Journal of Physiology.... Nov 2022Acclima(tiza)tion to heat or hypoxia enhances work capacity in hot and hypoxic environmental conditions, respectively; an acclimation response is considered to be... (Review)
Review
Acclima(tiza)tion to heat or hypoxia enhances work capacity in hot and hypoxic environmental conditions, respectively; an acclimation response is considered to be mediated by stimuli-specific molecular/systemic adaptations and potentially facilitated by the addition of exercise sessions. Promising findings at the cellular level provided the impetus for recent studies investigating whether acclimation to one stressor will ultimately facilitate whole body performance when exercise is undertaken in a different environmental condition. The present critical Mini-Review examines the theory of cross-adaptation between heat and hypoxia with particular reference to the determinants of aerobic performance. Indeed, early functional adaptations (improved exercise economy and enhanced oxyhemoglobin saturation) succeeded by later morphological adaptations (increased hemoglobin mass) might aid acclimatized humans perform aerobic work in an alternative environmental setting. Longer-term acclimation protocols that focus on the specific adaptation kinetics (and further allow for the adaptation reversal) will elucidate the exact physiological mechanisms that might mediate gains in aerobic performance or explain the lack thereof.
Topics: Humans; Hot Temperature; Oxyhemoglobins; Acclimatization; Exercise; Hypoxia
PubMed: 36094448
DOI: 10.1152/ajpregu.00339.2021 -
High Altitude Medicine & Biology Jun 2024Ramchandani, Rashi, Ioana Tereza Florica, Zier Zhou, Aziz Alemi, and Adrian Baranchuk. Review of athletic guidelines for high-altitude training and acclimatization.... (Review)
Review
Ramchandani, Rashi, Ioana Tereza Florica, Zier Zhou, Aziz Alemi, and Adrian Baranchuk. Review of athletic guidelines for high-altitude training and acclimatization. 00:000-000, 2024. Exposure to high altitude results in hypobaric hypoxia with physiological acclimatization changes that are thought to influence athletic performance. This review summarizes existing literature regarding implications of high-altitude training and altitude-related guidelines from major governing bodies of sports. A nonsystematic review was performed using PubMed and OVID Medline to identify articles regarding altitude training and guidelines from international governing bodies of various sports. Sports inherently involving training or competing at high altitude were excluded. Important physiological compensatory mechanisms to high-altitude environments include elevations in blood pressure, heart rate, red blood cell mass, tidal volume, and respiratory rate. These responses can have varying effects on athletic performance. Governing sport bodies have limited and differing regulations for training and competition at high altitudes with recommended acclimatization periods ranging from 3 days to 3 weeks. Physiological changes in response to high terrestrial altitude exposure can have substantial impacts on athletic performance. Major sport governing bodies have limited regulations and recommendations regarding altitude training and competition. Existing guidelines are variable and lack substantial evidence to support recommendations. Additional studies are needed to clarify the implications of high-altitude exposure on athletic ability to optimize training and competition.
Topics: Humans; Acclimatization; Altitude; Athletic Performance; Sports; Guidelines as Topic; Hypoxia; Blood Pressure
PubMed: 38207236
DOI: 10.1089/ham.2023.0042 -
International Journal of Sports... Jul 2022To survey elite athletes and practitioners to identify (1) knowledge and application of heat acclimation/acclimatization (HA) interventions, (2) barriers to HA...
PURPOSE
To survey elite athletes and practitioners to identify (1) knowledge and application of heat acclimation/acclimatization (HA) interventions, (2) barriers to HA application, and (3) nutritional practices supporting HA.
METHODS
Elite athletes (n = 55) and practitioners (n = 99) completed an online survey. Mann-Whitney U tests (effect size [ES; r]) assessed differences between ROLE (athletes vs practitioners) and CLIMATE (hot vs temperate). Logistic regression and Pearson chi-square (ES Phi [ϕ]) assessed relationships.
RESULTS
Practitioners were more likely to report measuring athletes' core temperature (training: practitioners 40% [athletes 15%]; P = .001, odds ratio = 4.0, 95% CI, 2%-9%; competition: practitioners 25% [athletes 9%]; P = .020, odds ratio = 3.4, 95% CI, 1%-10%). Practitioners (55% [15% athletes]) were more likely to perceive rectal as the gold standard core temperature measurement site (P = .013, ϕ = .49, medium ES). Temperate (57% [22% hot]) CLIMATE dwellers ranked active HA effectiveness higher (P < .001, r = .30, medium ES). Practitioners commonly identified athletes' preference (48%), accessibility, and cost (both 47%) as barriers to HA. Increasing carbohydrate intake when training in the heat was more likely recommended by practitioners (49%) than adopted by athletes (26%; P = .006, 95% CI, 0.1%-1%). Practitioners (56% [28% athletes]) were more likely to plan athletes' daily fluid strategies, adopting a preplanned approach (P = .001; 95% CI, 0.1%-1%).
CONCLUSIONS
Practitioners, and to a greater extent athletes, lacked self-reported key HA knowledge (eg, core temperature assessment/monitoring methods) yet demonstrated comparatively more appropriate nutritional practices (eg, hydration).
Topics: Acclimatization; Athletes; Body Temperature; Hot Temperature; Humans; Thermotolerance
PubMed: 35338104
DOI: 10.1123/ijspp.2021-0462 -
Journal of Science and Medicine in Sport Feb 2018
Topics: Acclimatization; Athletic Injuries; Exercise; Female; Humans; Steam Bath; Thermotolerance
PubMed: 29275863
DOI: 10.1016/j.jsams.2017.12.003 -
International Journal of Sports... Jun 2023Altitude training is often regarded as an indispensable tool for the success of elite endurance athletes. Historically, altitude training emerged as a key strategy to... (Review)
Review
BACKGROUND
Altitude training is often regarded as an indispensable tool for the success of elite endurance athletes. Historically, altitude training emerged as a key strategy to prepare for the 1968 Olympics, held at 2300 m in Mexico City, and was limited to the "Live High-Train High" method for endurance athletes aiming for performance gains through improved oxygen transport. This "classical" intervention was modified in 1997 by the "Live High-Train Low" (LHTL) model wherein athletes supplemented acclimatization to chronic hypoxia with high-intensity training at low altitude.
PURPOSE
This review discusses important considerations for successful implementation of LHTL camps in elite athletes based on experiences, both published and unpublished, of the authors.
APPROACH
The originality of our approach is to discuss 10 key "lessons learned," since the seminal work by Levine and Stray-Gundersen was published in 1997, and focusing on (1) optimal dose, (2) individual responses, (3) iron status, (4) training-load monitoring, (5) wellness and well-being monitoring, (6) timing of the intervention, (7) use of natural versus simulated hypoxia, (8) robustness of adaptative mechanisms versus performance benefits, (9) application for a broad range of athletes, and (10) combination of methods. Successful LHTL strategies implemented by Team USA athletes for podium performance at Olympic Games and/or World Championships are presented.
CONCLUSIONS
The evolution of the LHTL model represents an essential framework for sport science, in which field-driven questions about performance led to critical scientific investigation and subsequent practical implementation of a unique approach to altitude training.
Topics: Humans; Sports; Hypoxia; Altitude; Acclimatization; Awards and Prizes; Oxygen Consumption
PubMed: 37116895
DOI: 10.1123/ijspp.2022-0501 -
Journal of Comparative Physiology. B,... Jan 2017Several species undergo substantial physiological and biochemical changes to confront the harsh conditions associated with winter. Small mammalian hibernators and... (Review)
Review
Several species undergo substantial physiological and biochemical changes to confront the harsh conditions associated with winter. Small mammalian hibernators and cold-hardy insects are examples of natural models of cold adaptation that have been amply explored. While the molecular picture associated with cold adaptation has started to become clearer in recent years, notably through the use of high-throughput experimental approaches, the underlying cold-associated functions attributed to several non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), remain to be better characterized. Nevertheless, key pioneering work has provided clues on the likely relevance of these molecules in cold adaptation. With an emphasis on mammalian hibernation and insect cold hardiness, this work first reviews various molecular changes documented so far in these processes. The cascades leading to miRNA and lncRNA production as well as the mechanisms of action of these non-coding RNAs are subsequently described. Finally, we present examples of differentially expressed non-coding RNAs in models of cold adaptation and elaborate on the potential significance of this modulation with respect to low-temperature adaptation.
Topics: Acclimatization; Animals; Cold Temperature; Humans; RNA, Untranslated
PubMed: 27866230
DOI: 10.1007/s00360-016-1049-2 -
Trends in Ecology & Evolution Oct 2020Studies suggest that many species are already living close to their upper physiological thermal limits. Phenotypic plasticity is thought to be an important mechanism for... (Review)
Review
Studies suggest that many species are already living close to their upper physiological thermal limits. Phenotypic plasticity is thought to be an important mechanism for species to counter rapid environmental change, yet the extent to which plastic responses may buffer projected climate change - and what limits the evolution of plasticity - is still unclear. The tolerance-plasticity trade-off hypothesis predicts that the evolution of plasticity may be constrained by a species' thermal tolerance. Empirical evidence is equivocal, but we argue that inconsistent patterns likely reflect problems in experimental design/analysis, limiting our ability to detect and interpret trade-off patterns. Here, we address why we may, or may not see tolerance-plasticity trade-offs and outline a framework addressing current limitations, focusing on understanding the underlying mechanisms.
Topics: Acclimatization; Adaptation, Physiological; Climate Change; Thermotolerance
PubMed: 32513551
DOI: 10.1016/j.tree.2020.05.006 -
Journal of Physiological Anthropology Jul 2022This review mainly aimed to introduce the findings of research projects comparing the responses of tropical and temperate indigenes to heat. From a questionnaire survey... (Review)
Review
This review mainly aimed to introduce the findings of research projects comparing the responses of tropical and temperate indigenes to heat. From a questionnaire survey on thermal sensation and comfort of Indonesians and Japanese, we found that the thermal descriptor "cool" in tropical indigenes connotes a thermally comfortable feeling, suggesting that linguistic heat acclimatization exists on a cognitive level. Ten male students born and raised in Malaysia were invited to Fukuoka, Japan, and compared their responses with 10 Japanese male students with matched physical fitness and morphological characteristics. Cutaneous thermal sensitivity: The sensitivities were measured at 28 °C. The forehead warm sensitivity was significantly blunted in Malaysians. The less sensitivity to the warmth of tropical indigenes is advantageous in respect to withstanding heat stress with less discomfort and a greater ability to work in hot climates. Passive heat stress: Thermoregulatory responses, especially sweating, were investigated, during the lower leg hot bathing (42 °C for 60 min). The rectal temperature at rest was higher in Malaysians and increased smaller during immersion. There was no significant difference in the total amount of sweating between the two groups, while the local sweating on the forehead and thighs was lesser in Malaysians, suggesting distribution of sweating was different from Japanese. Exercise: Malaysian showed a significantly smaller increase in their rectal temperature during 55% maximal exercise for 60 min in heat (32 °C 70% relative humidity), even with a similar sweating and skin blood flow response in Japanese. The better heat tolerance in Malaysians could be explained by the greater convective heat transfer from the body core to the skin due to the greater core-to-skin temperature gradient. In addition, when they were hydrated, Malaysian participants showed better body fluid regulation with smaller reduction in plasma volume at the end of the exercise compared to the non-hydrated condition, whereas Japanese showed no difference between hydration conditions. We further investigated the de-acclimatization of heat adaptation by longitudinal observation on the heat tolerance of international students who had moved from tropical areas to Fukuoka for several years.
Topics: Acclimatization; Body Temperature; Body Temperature Regulation; Climate; Hot Temperature; Humans; Male; Sweating
PubMed: 35836266
DOI: 10.1186/s40101-022-00302-3 -
Giornale Italiano Di Medicina Del... Sep 2022Background. Aim of our study was to measure the first responses to hypobaric hypoxia: changes in ventilation minute, heart rate, and hemoglobin saturation which are...
Background. Aim of our study was to measure the first responses to hypobaric hypoxia: changes in ventilation minute, heart rate, and hemoglobin saturation which are important parameters involved in the health of mine-workers at high-altitude. Material and Methods. We develop a study of parameters mentioned on Chilean miners working in an underground mine at high altitude, between 3.070 and 3.656 masl, in an unusual shift system consisting of 12-hour daily work during 4 days, and consecutive 4 resting days. The results obtained at high altitude are contrasted with the corresponding for clerks working at 800 masl. Results. Either miners who has work less than 6 months at HA as those who are exposed at their workplace to contaminants, as diesel and others, show Hemoglobin Saturation below 90%. Heart Rate increases in response to exposure to acute and/or chronic hypoxia at high altitude. Miners during their resting period at 800 masl or less show an average heart rate lower than clerks no exposed to high altitude. Average Minute Volume of miners at high altitude, on each and every day of the shift, is higher than the mean volume of clerks at 800 masl. Conclusions. The most of studied miners present acclimatization responses at high altitude in all the studied parameters. The increase in Minute Volume implies a risky condition due to the increase of inhaled toxic inherent to the production process. It appears as an urgency to study the combined effects of hypobaric at high altitude and toxics present at the underground mine.
Topics: Humans; Altitude; Hypoxia; Mining; Acclimatization; Hemoglobins
PubMed: 36622823
DOI: No ID Found