Changes in gastrointestinal cell integrity after marathon running and exercise-associated collapse.

PURPOSE: Endurance exercise and hyperthermia are associated with compromised intestinal permeability and endotoxaemia. The presence of intestinal fatty acid-binding protein (I-FABP) in the systemic circulation suggests intestinal wall damage, but this marker has not previously been used to investigate intestinal integrity after marathon running. METHODS: Twenty-four runners were recruited as controls prior to completing a standard marathon and had sequential I-FABP measurements before and on completion of the marathon, then at four and 24 h later. Eight runners incapacitated with exercise-associated collapse (EAC) with hyperthermia had I-FABP measured at the time of collapse and 1 hour later. RESULTS: I-FABP was increased immediately on completing the marathon (T0; 2593 ± 1373 ng·l-1) compared with baseline (1129 ± 493 ng·l-1; p < 0.01) in the controls, but there was no significant difference between baseline and the levels at four hours (1419 ± 1124 ng·l-1; p = 0.7), or at 24 h (1086 ± 302 ng·l-1; p = 0.5). At T0, EAC cases had a significantly higher I-FABP concentration (15,389 ± 8547 ng.l-1) compared with controls at T0 (p < 0.01), and remained higher at 1 hour after collapse (13,951 ± 10,476 ng.l-1) than the pre-race control baseline (p < 0.05). CONCLUSION: I-FABP is a recently described biomarker whose presence in the circulation is associated with intestinal wall damage. I-FABP levels increase after marathon running and increase further if the endurance exercise is associated with EAC and hyperthermia. After EAC, I-FABP remains high in the circulation for an extended period, suggesting ongoing intestinal wall stress.

Heat-Related Illnesses.

Heat-related illnesses comprise a spectrum of syndromes resulting from disruption of thermoregulation in people exposed to high environmental heat. Symptoms range from heat edema and exercise-associated muscle cramps to exercise-associated collapse, heat exhaustion, and life-threatening heat stroke. Athletes, outdoor laborers, and military personnel are at greatest risk. Several intrinsic and extrinsic factors increase the risk of heat-related illness, including medical conditions, environmental factors, medication use, and inadequate acclimatization. Proper recognition and treatment are effective in preventing adverse outcomes. Management of the mildest forms of heat-related illness (e.g., heat edema, exercise-associated muscle cramps) is largely supportive, and sequelae are rare. Heat exhaustion is characterized by cardiovascular hypoperfusion and a rectal core temperature up to 104°F without central nervous dysfunction. Mild cooling, rest, and hydration are recommended. Heat stroke is a medical emergency in which patients present with rectal core temperature of 105°F or greater, multiorgan damage, and central nervous dysfunction. Ice water or cold water immersion is recommended. Patients adequately cooled within 30 minutes have excellent outcomes. Patients with heat stroke generally require hospitalization to monitor for medical complications despite rapid cooling. People diagnosed with heat stroke or severe heat-related illness should refrain from physical activity for at least seven days after release from medical care, then gradually begin activity over two to four weeks. Acclimatization, adequate hydration, and avoidance of activities during extreme heat are the most effective measures to reduce the incidence of heat-related illnesses.

High temperatures and nephrology: The climate change problem. / Altas temperaturas y nefrología: a propósito del cambio climático.

It is well known that climate change greatly affects human health, even though there are few studies on renal outcomes. Heat waves have been found to increase cardiovascular and respiratory morbidity and mortality, as well as the risk of acute renal failure and hospitalisation due to renal diseases, with related mortality. Recurrent dehydration in people regularly exposed to high temperatures seems to be resulting in an unrecognised cause of proteinuric chronic kidney disease, the underlying pathophysiological mechanism of which is becoming better understood. However, beyond heat waves and extreme temperatures, there is a seasonal variation in glomerular filtration rate that may contribute to the onset of renal failure and electrolyte disorders during extremely hot periods. Although there are few references in the literature, serum sodium disorders seem to increase. The most vulnerable population to heat-related disease are the elderly, children, chronic patients, bedridden people, disabled people, people living alone or with little social contact, and socioeconomically disadvantaged people.

International Classification of Disease Coding of Exertional Heat Illness in U.S. Army Soldiers.

INTRODUCTION: The severity of exertional heat illnesses (EHI) ranges from relatively minor heat exhaustion to potentially life-threatening heat stroke. Epidemiological surveillance of the types of and trends in EHI incidence depends on application of the appropriate International Classification of Disease, 9th Revision (ICD-9) diagnostic code. However, data examining whether the appropriate EHI ICD-9 code is selected are lacking. The purpose of this study was to determine whether the appropriate ICD-9 code is selected in a cohort of EHI casualties. MATERIALS AND METHODS: Chart reviews of 290 EHI casualties that occurred in U.S. Army soldiers from 2009 to 2012 were conducted. The ICD-9 diagnostic code was extracted, as were the initial and peak values for aspartate transaminase, alanine transaminase, creatine kinase, and creatinine. Diagnostic criteria for heat injury and heat stroke include evidence of organ and/or tissue damage; 2 out of 3 of the following must have been met to be considered heat injury (ICD-9 code 992.8) or heat stroke (ICD-9 code 992.0): aspartate transaminase/ alanine transaminase fold increase >3, creatine kinase fold increase >5, and/or creatinine ≥1.5mg/dL. Contingency tables were constructed from which sensitivity, specificity, and positive and negative predictive value were calculated. RESULTS: The 290 cases in this cohort represent ∼29% of all EHI at Fort Benning and ∼6% of all EHI Army-wide during the study period. There were 80 cases that met the laboratory diagnostic criteria for heat injury/stroke, however of those, 28 cases were diagnosed as an EHI other than heat injury/stroke (sensitivity = 0.65). 210 cases did not meet the laboratory diagnostic criteria, but 66 of those were incorrectly diagnosed as heat injury or heat stroke (specificity = 0.69). Positive and negative predictive values were 0.44 and 0.84, respectively. In total, the incorrect ICD-9 code was applied to 94 of 290 total cases. CONCLUSIONS: Our data suggest that caution is warranted when examining epidemiological surveillance data on EHI severity, as there was disagreement between the laboratory data and the selected ICD-9 code in ∼1/3 of all cases in this cohort. Of note is the lack of an ICD-9 or -10 code for heat injury; we recommend coding for heat exhaustion as the primary diagnosis and additional codes to capture the accompanying muscle, tissue, and/or organ damage.

Effects of caffeine on endurance capacity and psychological state in young females and males exercising in the heat.

Acute caffeine ingestion is considered effective in improving endurance capacity and psychological state. However, current knowledge is based on the findings of studies that have been conducted on male subjects mainly in temperate environmental conditions, but some physiological and psychological effects of caffeine differ between the sexes. The purpose of this study was to compare the physical performance and psychological effects of caffeine in young women and men exercising in the heat. Thirteen male and 10 female students completed 2 constant-load walks (60% of thermoneutral peak oxygen consumption on a treadmill until volitional exhaustion) in a hot-dry environment (air temperature, 42 °C; relative humidity, 20%) after caffeine (6 mg·kg-1) and placebo (wheat flour) ingestion in a double-blind, randomly assigned, crossover manner. Caffeine, compared with placebo, induced greater increases (p < 0.05) in heart rate (HR) and blood lactate concentrations in both males and females but had no impact on rectal or skin temperatures or on walking time to exhaustion in subjects of either gender. Caffeine decreased (p < 0.05) ratings of perceived exertion and fatigue in males, but not in females. In females, but not in males, a stronger belief that they had been administered caffeine was associated with a shorter time to exhaustion. In conclusion, acute caffeine ingestion increases HR and blood lactate levels during exercise in the heat, but it has no impact on thermoregulation or endurance capacity in either gender. Under exercise-heat stress, caffeine reduces ratings of perceived exertion and fatigue in males but not in females.

Complicated malaria symptoms associated with Plasmodium vivax among patients visiting health facilities in Mendi town, Northwest Ethiopia.

BACKGROUND: Malaria is still a major health problem in some parts of the world. Plasmodium falciparum is the common pathogenic parasite and is responsible for majority of malaria associated deaths. Recently the other benign parasite, P. vivax, is reported to cause life threatening severe malaria complications. Thus, this study was aimed to assess incidence of severe malaria symptoms caused by P. vivax parasite in some malaria endemic areas of Ethiopia. MATERIALS AND METHODS: Presumptive malaria patients (all age groups) seeking medication at the selected health facilities in Mendi town, Northwest Ethiopia, were recruited for the study. Socio-demographic, clinical and parasitological characteristics were assessed following standard procedures. Data was analyzed using descriptive statistics, chi-square test and relative risk. RESULTS: Of the 384 patients enrolled in the study for P. vivax mono-infection, 55 (14.3 %) of them were fulfilled at least one of the WHO criteria for severe malaria indicators. Some of these clinical manifestations were: prostration 14 (25.45 %), persistent vomiting 9 (16.36 %), respiratory distress 6 (10.9 %), hypoglycemia 5 (9.1 %), hyperpyrexia 8 (14.5 %), and severe anemia 13 (23.63 %). Differences in parasite load did not affect the frequency of some severe malaria symptoms. However, severe anemia, prostration, and persistent vomiting were significantly affected (P < 0.05) by relatively higher load of parasitemia, (OR = 3.8, 95 % CI, 1.1-13.7; OR = 4.4, 95 % CI, 1.4-13.9; and OR = 7, 95 % CI, 1.8-27.4) respectively. CONCLUSION: P.vivax associated severe malaria symptoms observed in this study is supportive evidence for the notion that P.vivax is no longer benign parasite but rather virulent. Thus, to meet international and regional targets of malaria eradication, a holistic prevention and control approaches should be designed.

A Spatial Framework to Map Heat Health Risks at Multiple Scales.

In the last few decades extreme heat events have led to substantial excess mortality, most dramatically in Central Europe in 2003, in Russia in 2010, and even in typically cool locations such as Vancouver, Canada, in 2009. Heat-related morbidity and mortality is expected to increase over the coming centuries as the result of climate-driven global increases in the severity and frequency of extreme heat events. Spatial information on heat exposure and population vulnerability may be combined to map the areas of highest risk and focus mitigation efforts there. However, a mismatch in spatial resolution between heat exposure and vulnerability data can cause spatial scale issues such as the Modifiable Areal Unit Problem (MAUP). We used a raster-based model to integrate heat exposure and vulnerability data in a multi-criteria decision analysis, and compared it to the traditional vector-based model. We then used the Getis-Ord G(i) index to generate spatially smoothed heat risk hotspot maps from fine to coarse spatial scales. The raster-based model allowed production of maps at spatial resolution, more description of local-scale heat risk variability, and identification of heat-risk areas not identified with the vector-based approach. Spatial smoothing with the Getis-Ord G(i) index produced heat risk hotspots from local to regional spatial scale. The approach is a framework for reducing spatial scale issues in future heat risk mapping, and for identifying heat risk hotspots at spatial scales ranging from the block-level to the municipality level.

Hydration status and fluid intake of urban, underprivileged South African male adolescent soccer players during training.

BACKGROUND: Poor hydration compromises performance and heightens the risk of heat stress which adolescents are particularly susceptible to as they produce comparatively larger amount of metabolic heat during exercise. This study determined the hydration status and fluid intake of socio-economically disadvantaged, male adolescent soccer players during training. METHODS: A pilot study was conducted among 79 soccer players (mean age 15.9 ± 0.8 years; mean BMI 20.2 ± 2.1 kg/m(2)). Hydration status was determined before and after two training sessions, using both urine specific gravity and percent loss of body weight. The type and amount of fluid consumed was assessed during training. A self-administered questionnaire was used to determine the players' knowledge regarding fluid and carbohydrate requirements for soccer training. RESULTS: Players were at risk of developing heat illness during six of the 14 training sessions (60 - 90 minutes in length). Although on average players were slightly dehydrated (1.023 ± 0.006 g/ml) before and after (1.024 ± 0.007 g/ml) training, some were extremely dehydrated before (24%) and after (27%) training. Conversely some were extremely hyperhydrated before (3%) and after training (6%). The mean percent loss of body weight was 0.7 ± 0.7%. The majority did not consume fluid during the first (57.0%) and second (70.9%) training sessions. An average of 216.0 ± 140.0 ml of fluid was consumed during both training sessions. The majority (41.8%) consumed water, while a few (5.1%) consumed pure fruit juice. More than 90% stated that water was the most appropriate fluid to consume before, during and after training. Very few (5.0%) correctly stated that carbohydrate should be consumed before, during and after training. CONCLUSIONS: Approximately a quarter were severely dehydrated. Many did not drink or drank insufficient amounts. The players' beliefs regarding the importance of fluid and carbohydrate consumption did not correspond with their practices. A nutrition education programme is needed to educate players on the importance of fluid and carbohydrate to prevent dehydration and ensure appropriate carbohydrate intake.

Circulatory endotoxin concentration and cytokine profile in response to exertional-heat stress during a multi-stage ultra-marathon competition.

Exertional-heat stress has the potential to disturb intestinal integrity, leading to enhanced permeability of enteric pathogenic micro-organisms and associated clinical manifestations. The study aimed to determine the circulatory endotoxin concentration and cytokine profile of ultra-endurance runners (UER, n=19) and a control group (CON, n=12) during a five stage 230km ultra-marathon (mean ± SD: 27h38min ± 3h55min) conducted in hot and dry environmental conditions (30ºC to 40ºC and 31% to 40% relative humidity). Body mass and tympanic temperature were measured, and venous blood samples were taken before (pre-stage) and immediately after (post-stage) each stage of the ultra-marathon for the analysis of gram-negative bacterial endotoxin, C-reactive protein, cytokine profile (IL-6, IL-1ß, TNF-α, IFN-γ, IL-10, and IL- 1ra), and plasma osmolality. Gastrointestinal symptoms and perceptive thermal tolerance rating were also monitored throughout competition. Mean exercise-induced body mass loss over the five stages ranged 1.0% to 2.5%. Pre- and poststage plasma osmolality in UER ranged277 to 282mOsmol/kg and 286 to 297 mOsmol/kg, respectively. Pre-stage concentrations of endotoxin (peak: 21% at Stage 5), C-reactive protein (889% at Stage 3), IL-6 (152% at Stage 2), IL-1ß (95% at Stage 5), TNF-α (168% at Stage 5), IFN-γ (102% at Stage 5),IL-10 (1271% at Stage 3), and IL-1ra (106% at Stage 5) increased as the ultra-marathon progressed in UER; while no changes in CON were observed (except for IL-1ß, 71% at Stage 5). Pre- to post-stage increases were observed for endotoxin (peak: 22% at Stage 3), C-reactive protein (25% at Stage 1), IL-6 (238% at Stage 1), IL-1ß (64% at Stage 1), TNF-α (101% at Stage 1), IFN-γ (39% at Stage 1), IL-10 (1100% at Stage 1), and IL-1ra(207% at Stage 1) concentrations in UER. Multi-stage ultra-marathon competition in the heat resulted in a modest circulatory endotoxaemia accompanied by a pronounced pro-inflammatory cytokinaemia by post-Stage 1, both of which were sustained throughout competition at rest (pre-stage) and after stage completion. Compensatory anti-inflammatory responses and other external factors (i.e., training status, cooling strategies, heat acclimatization, nutrition and hydration) may have contributed towards limiting the extent of pro-inflammatory responses in the current scenario.

High work output combined with high ambient temperatures caused heat exhaustion in a wildland firefighter despite high fluid intake.

The purpose of this case study is to examine the physiological/behavioral factors leading up to heat exhaustion in a male wildland firefighter during wildland fire suppression. The participant (24 years old, 173 cm, 70 kg, and 3 years firefighting experience) experienced heat exhaustion following 7 hours of high ambient temperatures and arduous work on the fire line during the month of August. At the time of the heat-related incident (HRI), core temperature was 40.1 °C (104.2 °F) and skin temperature was 34.4 °C (93.9 °F). His work output averaged 1067 counts·min(-1) (arbitrary units for measuring activity) for the 7 hours prior to the HRI, a very high rate of work over an extended time period during wildfire suppression. In the 2.5 hours leading up to the heat incident, he was exposed to a mean ambient temperature of 44.6 °C (112.3 °F), with a maximum temperature of 59.7 °C (139.5 °F). He consumed an average of 840 mL·h(-1) in the 7 hours leading up to the incident and took an average of 24 ± 11 drinks·h(-1) (total of 170 drinks). The combined effects of a high work rate and high ambient temperatures resulted in an elevated core temperature and a higher volume and frequency of drinking than typically seen in this population, ultimately ending in heat exhaustion and removal from the fire line. The data demonstrate that heat-related incidents can occur even with aggressive fluid intake during wildland fire suppression.

Heat-related illness.

Heat-related illness is a set of preventable conditions ranging from mild forms (e.g., heat exhaustion, heat cramps) to potentially fatal heat stroke. Hot and humid conditions challenge cardiovascular compensatory mechanisms. Once core temperature reaches 104°F (40°C), cellular damage occurs, initiating a cascade of events that may lead to organ failure and death. Early recognition of symptoms and accurate measurement of core temperature are crucial to rapid diagnosis. Milder forms of heat-related illness are manifested by symptoms such as headache, weakness, dizziness, and an inability to continue activity. These are managed by supportive measures including hydration and moving the patient to a cool place. Hyperthermia and central nervous system symptoms should prompt an evaluation for heat stroke. Initial treatments should focus on lowering core temperature through cold water immersion. Applying ice packs to the head, neck, axilla, and groin is an alternative. Additional measures include transporting the patient to a cool environment, removing excess clothing, and intravenous hydration. Delayed access to cooling is the leading cause of morbidity and mortality in persons with heat stroke. Identification of at-risk groups can help physicians and community health agencies provide preventive measures.

Validity of perceived skin wettedness mapping to evaluate heat strain.

The purpose of this study was to investigate the validity of a newly developed method for quantifying perceived skin wettedness (W (p)) as an index to evaluate heat strain. Eight male subjects underwent 12 experimental conditions: activities (rest and exercise) × clothing (Control, Tyvek and Vinyl condition) × air temperatures (25 and 32°C). To quantify the W (p), a full body map with 21 demarcated regions was presented to the subject. The results showed that (1) at rest in 25°C, W (p) finally reached 4.4, 8.3 and 51.6% of the whole body surface area for Control, Tyvek, and Vinyl conditions, respectively, while W (p) at rest in 32°C rose to 35.8, 61.4 and 89.8%; (2) W (p) has a distinguishable power to detect the most wetted and the first wetted regions. The most wetted body regions were the upper back, followed by the chest, front neck, and forehead. The first perceived regions in the skin wetted map were the chest, forehead, and upper back; (3) W (p) at rest showed a significant relationship with the calculated skin wettedness (w) (r = 0.645, p < 0.01) and (4) W (p) had a significant relationship with core temperature, skin temperature, heart rate, total sweat rate, thermal comfort, and humidity sensation (p < 0.05), but these relationships were dependent on the level of activities and clothing insulation. W (p) in hot environments was more valid as a heat strain index of workers wearing normal clothing in light works, rather than wearing impermeable protective clothing in strenuous works.

Heat stress and dehydration in kendo.

AIM: This study aimed to analyze sweat rate, water percentage alteration, and temperature variation during kendo practice in order to relate the thermal stress induced by such sports and draw recommendations for its secure practice. METHODS: Participants were 12 male individuals. The studied variables were: age, weight, stature, body mass index, fat percentage, water loss percentage, tympanic temperature, and sweat rate. Measures were obtained in one day of 120 min practice (T: 24.1 ± 2.5 °C; RH: 73 ± 8.5%) using obligatory training equipment. RESULTS: The age of participants was on average 26 ± 6.2 years, stature 1.8 ± 0.03 m, weight 78 ± 13.7 kg, BMI 24.12 ± 4.03 kg/m² and fat percentage 15.7 ± 5.1%. Weight and temperature final values were significantly different from the initial ones (P<0.01). Estimated sweat rate was 0.35 L.h-1 (95% CI = [0.299; 0.400]) and estimated percentage of water loss was 0.946% (95% CI = [0.694; 1.174]). CONCLUSION: Kendo practice using obligatory equipment significantly increases temperature, even when sweat rate and water loss percentage are low. The almost complete obstruction of the evaporative surface leads to heat accumulation, which may result in risks comparable to those of American football players. Thus, preventive measures must be established to minimize the risks of the combination among environment (tropical climate), equipment (bogu) and the high physiological demand of this sport in order to prevent greater damages to the health of practitioners.

The American football uniform: uncompensable heat stress and hyperthermic exhaustion.

CONTEXT: In hot environments, the American football uniform predisposes athletes to exertional heat exhaustion or exercise-induced hyperthermia at the threshold for heat stroke (rectal temperature [T(re)] > 39 degrees C). OBJECTIVE: To evaluate the differential effects of 2 American football uniform configurations on exercise, thermal, cardiovascular, hematologic, and perceptual responses in a hot, humid environment. DESIGN: Randomized controlled trial. SETTING: Human Performance Laboratory. PATIENTS OR OTHER PARTICIPANTS: Ten men with more than 3 years of competitive experience as football linemen (age = 23.8 +/- 4.3 years, height = 183.9 +/- 6.3 cm, mass = 117.41 +/- 12.59 kg, body fat = 30.1% +/- 5.5%). INTERVENTION(S): Participants completed 3 controlled exercise protocols consisting of repetitive box lifting (lifting, carrying, and depositing a 20.4-kg box at a rate of 10 lifts per minute for 10 minutes), seated recovery (10 minutes), and up to 60 minutes of treadmill walking. They wore one of the following: a partial uniform (PART) that included the National Football League (NFL) uniform without a helmet and shoulder pads; a full uniform (FULL) that included the full NFL uniform; or control clothing (CON) that included socks, sneakers, and shorts. Exercise, meals, and hydration status were controlled. MAIN OUTCOME MEASURE(S): We assessed sweat rate, T(re), heart rate, blood pressure, treadmill exercise time, perceptual measurements, plasma volume, plasma lactate, plasma glucose, plasma osmolality, body mass, and fat mass. RESULTS: During 19 of 30 experiments, participants halted exercise as a result of volitional exhaustion. Mean sweat rate, T(re), heart rate, and treadmill exercise time during the CON condition were different from those measures during the PART (P range, .04-.001; d range, 0.42-0.92) and FULL (P range, .04-.003; d range, 1.04-1.17) conditions; no differences were detected for perceptual measurements, plasma volume, plasma lactate, plasma glucose, or plasma osmolality. Exhaustion occurred during the FULL and PART conditions at the same T(re) (39.2 degrees C). Systolic and diastolic blood pressures (n = 9) indicated that hypotension developed throughout exercise (all treatments). Compared with the PART condition, the FULL condition resulted in a faster rate of T(re) increase (P < .001, d = 0.79), decreased treadmill exercise time (P = .005, d = 0.48), and fewer completed exercise bouts. Interestingly, T(re) increase was correlated with lean body mass during the FULL condition (R(2) = 0.71, P = .005), and treadmill exercise time was correlated with total fat mass during the CON (R(2) = 0.90, P < .001) and PART (R(2) = 0.69, P = .005) conditions. CONCLUSIONS: The FULL and PART conditions resulted in greater physiologic strain than the CON condition. These findings indicated that critical internal temperature and hypotension were concurrent with exhaustion during uncompensable (FULL) or nearly uncompensable (PART) heat stress and that anthropomorphic characteristics influenced heat storage and exercise time to exhaustion.

A practical cooling strategy for reducing the physiological strain associated with firefighting activity in the heat.

The aim of this study was to establish whether a practical cooling strategy reduces the physiological strain during simulated firefighting activity in the heat. On two separate occasions under high ambient temperatures (49.6 +/- 1.8 degrees C, relative humidity (RH) 13 +/- 2%), nine male firefighters wearing protective clothing completed two 20-min bouts of treadmill walking (5 km/h, 7.5% gradient) separated by a 15-min recovery period, during which firefighters were either cooled (cool) via application of an ice vest and hand and forearm water immersion ( approximately 19 degrees C) or remained seated without cooling (control). There was no significant difference between trials in any of the dependent variables during the first bout of exercise. Core body temperature (37.72 +/- 0.34 vs. 38.21 +/- 0.17 degrees C), heart rate (HR) (81 +/- 9 vs. 96 +/- 17 beats/min) and mean skin temperature (31.22 +/- 1.04 degrees C vs. 33.31 +/- 1 degrees C) were significantly lower following the recovery period in cool compared with control (p < 0.05). Core body temperature remained consistently lower (0.49 +/- 0.02 degrees C; p < 0.01) throughout the second bout of activity in cool compared to control. Mean skin temperature, HR and thermal sensation were significantly lower during bout 2 in cool compared with control (p < 0.05). It is concluded that this practical cooling strategy is effective at reducing the physiological strain associated with demanding firefighting activity under high ambient temperatures.