Смартгодинник для прогнозування стану людини за екстремальних умов середовища

Nine well-trained, unacclimatized female hockey players performed the Loughborough Intermittent Shuttle Test (LIST) interspersed with three field hockey skill tests in hot (30°C, 38% relative humidity) and moderate (19°C, 51% relative humidity) environmental conditions. Field hockey skill performance declined in both the hot and moderate conditions following 30 and 60 min of the LIST compared with pre-LIST values (P < 0.01). This decrement in performance was compounded in the hot environment with a 6% poorer performance in the heat recorded for the second skill test at 30 min (P < 0.05, hot 101.7 ± 3.6 vs moderate 95.7 ± 2.9 s; mean ± s x). However, no difference was found in the decision-making element of the skill test. Fifteen-metre sprint times were slower in the hot condition (P < 0.01). In the hot environment, rectal temperature (P < 0.01), perceived exertion (P < 0.05), perceived thirst (P < 0.01), blood glucose concentration (P < 0.05) and serum aldosterone concentration (P < 0.01) were higher. Estimated mean ( ± s x) sweat rate was higher in the hot trial (1.27 ± 0.10 l · h−1) than in the moderate trial (1.05 ± 0.12 l · h−1) (P < 0.05). Body mass was well maintained in both trials. No differences in serum cortisol, blood lactate, plasma volume or plasma ammonia concentrations were found. These results demonstrate that field hockey skill performance is decreased following intermittent high-intensity shuttle running and that this decrease is greater in hot environmental conditions. The exact mechanism for this decrement in performance remains to be elucidated, but is unlikely to be due to low glycogen concentration or dehydration.

It is unknown whether a passive warm-up or an active warm-up performed at an intensity based on lactate thresholds could improve prolonged intermittent-sprint performance either in thermoneutral or hot environmental conditions. To investigate this issue, 11 male athletes performed three trials that consisted of 80 min of intermittent-sprinting performed on a cycle ergometer, preceded by either an active or a passive warm-up. Active warm-up and intermittent-sprint performance were performed in both hot and thermoneutral environmental conditions, while passive warm-up and intermittent-sprint performance were performed in hot conditions only. First sprint performance was also assessed. Results showed no significant interaction effects between any of the trials for total work (J · kg–1), work decrement, and power decrement (P = 0.10, P = 0.42, P = 0.10, respectively). While there were no significant differences between trials for work done for first sprint performance (P = 0.22), peak power was significantly higher after passive warm-up compared with active warm-up performed in either thermoneutral (P = 0.03) or in hot conditions (P = 0.02). Results suggest that the main benefits of warm-up for first sprint performance are derived from temperature-related effects. Active warm-up did not impair prolonged intermittent-sprint performance in the heat compared with thermoneutral conditions.

Iron homeostasis is modulated by many factors (biological sex, diet, contraceptive use, etc.), but a key regulator is the hormone hepcidin. Hepcidin blocks the only known cellular iron exporting channel leading to reduced iron availability in the circulation. Reduced iron availability can negatively impact the development of new red blood cells, a process that is critical to adaptations during training to enhance performance. While previous literature shows that the interleukin-6 (IL-6) cytokine response to exercise results in elevated hepcidin production, there is no current literature quantifying circulating endotoxins effect on augmenting hepcidin production during exercise in hot environmental conditions. Endotoxins permeate through the gut into the circulation during sustained endurance exercise or when body core temperature is greatly elevated. The purpose of this study is to examine the time course and magnitude of the inflammatory and hepcidin responses to circulatory endotoxins evoked by exercise under hot environmental conditions in female athletes. We hypothesize that endotoxins in the circulation may contribute additional inflammatory insult on exercising athletes, leading to increased inflammatory signaling (such as IL-6) and therefore increased hepcidin production. These results will inform how hot environmental exercise may impact iron balance and provide insight into the impact of endotoxin-associated gut permeability as a new aspect of maintaining proper iron status in athletes. In a randomized cross-over study design, fourteen endurance trained female athletes (age 28.2 (range: 36) years; body mass index 23.2 (21.8, 24.6) kg·m-2; VO2max 56.2 (51.1, 61.4) ml·kg-1·min-1) completed two exercise sessions on a treadmill at 70% VO2max in hot (35°C and 40% relative humidity) and cool (11°C and 40% relative humidity) environmental conditions. Body core temperature was measured throughout the duration of exercise. Blood samples were collected pre-exercise, post-exercise, and serially every hour for 3-h after exercise for analysis of lipopolysaccharide (LPS), tumor necrosis factor alpha (TNFa), interleukin-6 (IL-6), and hepcidin. Results were compared using a mixed model; values are presented mean±95% CI. End-exercise body core temperature was significantly elevated in the hot exercise condition compared to the cool (hot: D1.87°C; cool: D0.93 °C, p = 0.012). There were no changes in LPS concentrations at any time point. TNFa was similarly elevated in both hot and cold exercise conditions. IL-6 concentrations were elevated in both conditions immediately post-exercise, but the hot condition had a greater rise in IL-6 concentration (hot: D1.15 (1.4, 0.90; cool: D0.73 (0.90, 0.56), p = 0.01). Hepcidin concentrations were similarly elevated in both conditions after exercise, except at 3-h post-exercise, where the rise in hepcidin was greater in the hot exercise condition (hot: D7.74 ng/mL (11.78, 3.71); cool: D3.14 ng/mL (5.40, 0.88); p = 0.004). These data suggest that exercise in a hot environment evokes elevated IL-6 production, and elevated peak hepcidin concentration 3-h post-exercise compared to a cool exercise condition. Additionally, these data indicate that LPS did not change with exercise and likely does not contribute to the elevated inflammation seen post-exercise in the hot condition. Funded by the Wu Tsai Human Performance Alliance and the Joe and Clara Tsai Foundation. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

PurposeComponents of immune function are affected by physical activity in an adverse environment. The purpose of this study was to compare plasma differences in inflammatory cytokines including tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), in addition to the stress hormone cortisol, during prolonged cycling under normal and hot environmental conditions in elite cyclists.Methods and designSix trained elite male cyclists (27 ± 8 years; 75.5 ± 4 kg; maximum oxygen uptake [VO2max] = 66 ± 6 mL/kg/min, mean ± SD). The cyclists biked for 2.5 h at their prescribed 60% maximum exercise workload (Wmax) or 75% VO2max either in an environmental chamber set at 15°C and 40% relative humidity (NEUTRAL) or at 35°C and 40% relative humidity (HOT). The cyclists were given 4 mL of water/kg body weight every 15 min under both conditions.ResultsTotal cortisol concentrations were elevated (P < 0.05) immediately postexercise and 12 h postexercise in both the NEUTRAL and HOT conditions. TNF-α concentrations were only significantly (P = 0.045) elevated postexercise in HOT conditions. During the HOT conditions, a significant (P = 0.006 and 0.007, respectively) difference in IL-6 was seen immediately after and 12 h postexercise. During the NEUTRAL condition, IL-6 was only significantly elevated postexercise (P < 0.05).ConclusionsHeat exposure during a long bout of exercise is sufficient to elicit stress response in elite cyclists. However, the degree of release of anti-inflammatory and proinflammatory cytokines might be related to several factors that include the athlete’s fitness level, hydration status, exercise intensity, and length of exposure to hot environments.

This study compared performance parameters of two wheelchair basketball games under hot (30.3 °C, 52% relative humidity) and temperate (21.6 °C, 30% relative humidity) environmental conditions and described the characteristics of wheelchair basketball. Eight wheelchair basketball players from two teams were monitored during two games using an indoor position tracking system. Total distance, mean- and peak-speed, playing-time, number of sprints, sprints per minute, heart rate and rate of perceived exertion were recorded. Additionally, athletes with a lesion level above and below T6 were compared. No measured parameter differed between the games. Across quarters (Q) mean velocity (m/s) (Q1: 1.01; Q2: 1.10; Q3: 1.18; Q4: 1.06; p < 0.001) and sprints per minute (Q1: 16; Q2: 14; Q3: 23; Q4: 14; p = 0.033) differed significantly, independent of the conditions. Descriptive statistics did not reveal differences between the groups with a lesion level below or above T6. In the present study, hot environmental conditions seemed not to have an impact on activity parameters of wheelchair basketball players. It was speculated that the game intensity and therefore metabolic heat production was too low; consequently, the athletes had a sufficient heat loss to prevent a decrease in performance during the play in hot conditions.

Four influential models, capable of predicting human responses to hot and cold environments and potentially suitable for use in practical applications, were evaluated by comparing their predictions with human data published previously. The models were versions of the Pierce Lab 2-node and Stolwijk and Hardy 25-node models of human thermoregulation, the Givoni and Goldman model of rectal temperature response, and ISO/DIS 7933. Experimental data were available for a wide range of environmental conditions, with air temperatures ranging from -10 to 50 degrees C, and with different levels of air movement, humidity, clothing and work. The experimental data were grouped into environment categories to allow examination of the effects of variables, such as wind or clothing, on the accuracy of the models' predictions. This categorization also enables advice to be given regarding which model is likely to provide the most accurate predictions for a particular combination of environmental conditions. Usually at least one of the models was able to give predictions with an accuracy comparable with the degree of variation that occurred within the data from the human subjects. The evaluation suggests that it is possible to make useful predictions of deep-body and mean skin temperature responses to cool, neutral, warm and hot environmental conditions. The models' predictions of deep-body temperature in the cold were poor. Overall, the 25-node model provided the most consistently accurate predictions. The 2-node model was often accurate but could be poor for exercise conditions. The rectal-temperature model usually overestimated deep-body temperature, although its predictions for very hot or heavy exercise conditions could be useful. The ISO model's allowable exposure times would not have protected subjects for some exercise conditions.

Extreme environmental conditions present athletes with diverse challenges; however, not all sporting events are limited by thermoregulatory parameters. The purpose of this leading article is to identify specific instances where hot environmental conditions either compromise or augment performance and, where heat acclimation appears justified, evaluate the effectiveness of pre-event acclimation processes. To identify events likely to be receptive to pre-competition heat adaptation protocols, we clustered and quantified the magnitude of difference in performance of elite athletes competing in International Association of Athletics Federations (IAAF) World Championships (1999-2011) in hot environments (>25 °C) with those in cooler temperate conditions (<25 °C). Athletes in endurance events performed worse in hot conditions (~3 % reduction in performance, Cohen's d > 0.8; large impairment), while in contrast, performance in short-duration sprint events was augmented in the heat compared with temperate conditions (~1 % improvement, Cohen's d > 0.8; large performance gain). As endurance events were identified as compromised by the heat, we evaluated common short-term heat acclimation (≤7 days, STHA) and medium-term heat acclimation (8-14 days, MTHA) protocols. This process identified beneficial effects of heat acclimation on performance using both STHA (2.4 ± 3.5 %) and MTHA protocols (10.2 ± 14.0 %). These effects were differentially greater for MTHA, which also demonstrated larger reductions in both endpoint exercise heart rate (STHA: -3.5 ± 1.8 % vs MTHA: -7.0 ± 1.9 %) and endpoint core temperature (STHA: -0.7 ± 0.7 % vs -0.8 ± 0.3 %). It appears that worthwhile acclimation is achievable for endurance athletes via both short-and medium-length protocols but more is gained using MTHA. Conversely, it is also conceivable that heat acclimation may be counterproductive for sprinters. As high-performance athletes are often time-poor, shorter duration protocols may be of practical preference for endurance athletes where satisfactory outcomes can be achieved.

Mathematical simulation of the rheological behavior of MWCNT (20%)-ZnO (80%)/single-grade SAE50 hybrid nanofluid to introduce the most optimal correlation function and determining the optimal lubrication conditions in hot and cold environments

This study investigated the single and combined effects of environmental heat stress and physical exercise on executive function (EF) performance, prefrontal cortex oxygenation, thermoregulatory responses and subjective perceptions. Sixteen subjects participated in four experimental sessions: two under moderate environmental conditions (23°C), with and without physical exercise (R23, E23), and two under hot environmental conditions (35°C), with and without physical exercise (R35, E35). In each session, participants completed EF tasks before and after 1h of passive rest or 45min of moderate-intensity cycling followed by 15min of rest. We used Δresponse time (ΔRT) and Δaccuracy (ΔACC) of EF tasks to demonstrate changes from pre to post experiment. Additionally, changes in cerebral oxygenation during EF tasks were illustrated using the Δoxygenation difference. Heat stress alone increased core temperature (Tcore), mean skin temperature (Tskin), heart rate (HR), thermal sensation (TS), and rating of perceived exertion (RPE). Exercise in a hot environment further increased physiological indicators and RPE, but TS exhibited a different pattern, with lower TS in R35 compared to E35 during the second battery of executive function tests. Moreover, heat stress alone increased ΔRT for the More-Odd Shifting task and the Stroop task under incongruent conditions, while decreasing the Δoxygenation difference during the More-Odd Shifting task. ΔRT for the 2-back, More-Odd Shifting and Stroop tasks under incongruent conditions were lower in the E35 trial than in the R35 trial, whereas the Δoxygenation difference was higher in the E35 trial compared to the R35 trial. These findings indicate that environmental heat stress alone increases Tcore and Tskin, alters TS, and impairs EF performance by decreasing prefrontal cortex oxygenation. A 45-min moderate-intensity exercise combined with environmental heat stress enhances the increases in body temperatures but mitigates the detrimental effects of heat stress alone on EF performance by increasing prefrontal cortex oxygenation.

We coupled a cardiovascular model with a thermoregulation model to predict human blood pressure in unsteady environmental conditions. Our cardiovascular model is a lumped parameter model and consists of 42 segments, which include the entire artery and vein system, divided into 18 segments; the heart, divided into 4 segments; and the pulmonary artery and vein. The vessel parameters were adjusted on the basis of local body blood volume and flow of the thermoregulation model in a thermoneutral environment. Blood pressure under unsteady environmental conditions is predicted by changing the heart rate and vessel resistance of the cardiovascular model which is controlled by blood flow that the thermoregulation model predicts. It is possible to predict the increase in blood pressure under cold environmental conditions and the increase in cardiac output under hot environmental conditions and when bathing. The model was validated by simulating bathing experiments. As the result, the model predicted the peak blood pressure later than the experimental data in a cold environment. To improve the accuracy of the model, it is necessary to consider a method for controlling the heart rate, vessel resistance, and gravity effects after a change in posture.

The purpose of this observational study was to determine the circulating leukocyte subset response to completing the 2013 Hotter’N Hell Hundred recreational 164-km road cycle event in a hot and humid environmental condition. Twenty-eight men and four women were included in this study. Whole blood samples were obtained 1–2 hours before (PRE) and immediately after (POST) the event. Electronic sizing/sorting and cytometry were used to determine complete blood counts (CBC) including neutrophil, monocyte, and lymphocyte subsets. The concentration of circulating total leukocytes (103·μL−1) increased 134% from PRE to POST with the greatest increase in neutrophils (319%, p<0.0001). Circulating monocytes (including macrophages) increased 24% (p=0.004) and circulating lymphocytes including B and T cells increased 53% (p<0.0001). No association was observed between rolling time or relative intensity and leukocyte subset. Completing the Hotter n′ Hell Hundred (HHH), a 100 mile recreational cycling race in extreme (hot and humid) environmental conditions, induces a substantial increase in total leukocytes in circulation. The contribution of increases in specific immune cell subsets is not equal, with neutrophils increasing to greater than 4-fold starting values from PRE to POST race. It is likely that exercise in stressful environmental conditions affects the complement of circulating immune cells, although activational state and characterization of specific leukocyte subsets remains unclear. The observed increase in circulating cell sub-populations suggests that the circulating immune surveillance system may be acutely affected by exercise in hot and humid conditions.

Physical activity in the prevention and treatment of obesity and its comorbidities: evidence report of independent panel to assess the role of physical activity in the treatment of obesity and its comorbidities.

Physical activity and health

Eighty-four Bos taurus crossbred steers were used to investigate effects of level and duration of limit-feeding feedlot cattle in a hot environment. Pens (four/treatment) of steers (seven/pen) were fed feedlot finishing diets and randomly assigned to the following treatments: 1) restricted to approximately 75% of feed consumed when offered ad libitum for 21-d duration (RES21); 2) restricted to approximately 75% of ad libitum for 42-d duration (RES42); and 3) feed offered ad libitum (ADLIB). Tympanic temperatures (TT) were measured via thermistors placed in the ear canal and attached to data loggers. Restricting feed intake for both 21- and 42-d reduced tympanic temperature when compared with ADLIB treatment groups under hot environmental conditions. Temperature reductions exceeded 0.5 degrees C (P < 0.05) depending on time of day. The reduced tympanic temperature is likely due to a reduction in metabolic heat load and/or a concurrent reduction in metabolic rate. Within respective periods, no differences (P > 0.05) were found among treatments for panting or bunching score. However, different proportions of cattle were found to be bunching and panting with ADLIB cattle displaying a greater number of bunched steers that were panting when compared with the other groups. When averaged across diet treatments, dark-colored cattle had the greatest percentage of cattle showing moderate to excessive panting, while light-colored cattle displayed the least panting under thermoneutral climatic conditions. Under hot (mean daily temperature-humidity index >74) conditions, dark-colored cattle tended to bunch more (P = 0.073) and pant more (P < 0.01) than light-colored cattle. Mean TT were 0.2 to 0.6 degrees C (P < 0.05) greater for dark- vs light-colored cattle under hot conditions. Limit-feeding feedlot cattle during early summer is a successful tool for enhancing animal comfort by alleviating the combined effects of high climatic and metabolic heat load.

Aim: One of the most harmful agents in construction sites is heat exposure. The aim of this study was to evaluate the performance of new evaporative cooling vests in construction workers. Materials and Methods: This case–control study was implemented on 60 construction workers in hot conditions (air temperature 49.0°, relative humidity 5.5%) in the summer of 2019. In this study, 30 people with cooling vests (case group) and 30 people without cooling vests (control group) were working for 120 min in a hot environment. In both groups, heart rate oral temperature and wet bulb globe temperature (WBGT) index were measured. Moreover, the Perceptual Strain Index (PeSI) and Heat Strain Score Index (HSSI) questionnaires were completed by the workers. Data were analyzed after inter to SPSS16 software. Results: All of the WBGT values were higher than occupational exposure limit. The mean and standard deviation (SD) of the work heart rate in the case and control groups, was equal to 111.1 ± 7.6 beats per minute (bpm) and 114.3 ± 7.9 bpm respectively (P &lt; 0.05). Also the average and SD of the oral temperature in the case and control groups, respectively, was equal to 36.36 ± 0.41 and 36.37 ± 0.55. There was no statistically significant difference. Mean and SD of Physiological Strain Index (PSI), in case and control groups, were 2.53 ± 0.66 and 3.64 ± 0.81, respectively. The mean and SD of the PeSI and the HSSI in the case group were 4.64 ± 0.79 and 10.12 ± 1.71, respectively, and in the control group, 6.41 ± 0.85 and 15.88 ± 0.1.43. Statistically, the difference between PSI, PeSI, and HSSI means was significant. Conclusions: This study results showed that hot environmental conditions were stressful for construction workers and also Iranian evaporative cooling vests (Hifitcool brand) were able to reduce perceptual and physiological heat strain in construction workers in the hot conditions.