| 1. |
- Blakeson, Magdalene C., et al.
(författare)
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Illness Incidence, Psychological Characteristics, and Sleep in Dogsled Drivers During the Iditarod Trail Sled Dog Race
- 2022
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier BV. - 1080-6032 .- 1545-1534. ; 33:1, s. 92-96
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Every March, dogsled drivers (mushers) compete in a 1569-km race across Alaska, involving physical exertion, mental exertion, and sleep deprivation for up to 2 wk. These factors may increase mushers’ vulnerability to illness, making them a relevant study population for acute infection risk factors. Specifically, the influence of psychological factors on illness risk during prolonged physical exertion has rarely been investigated. The aim of this study was to examine the relationship between psychological characteristics, sleep deprivation, and illness incidence in Iditarod mushers. Methods: Fourteen mushers completed 4 psychological instruments to assess state and trait anxiety, resilience and perceived stress, and self-reported upper respiratory symptoms (URS) in the month before the race. Mushers self-reported sleep duration and URS during the race. Results: State and trait anxiety, resilience, and perceived stress did not differ between mushers with and without pre- and in-race URS (P>0.05). However, all mushers who reported in-race URS had reported URS ≤9 d before the race, and the onset of symptoms during the race typically occurred shortly after a rest period. Sleep duration was higher in mushers who reported in-race URS, both before (4.9±0.3 h, P=0.016) and during illness (5.9±1.3 h, P=0.006), vs mushers without in-race URS (3.4±0.8 h). Conclusions: This study highlights recent illness, rest periods, and greater sleep requirements as potential risk factors for URS onset during a multiday endurance challenge, whereas psychological factors were not associated with URS.
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| 2. |
- Henriksson, Otto, 1976-, et al.
(författare)
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Protection against cold in prehospital care : wet clothing removal or addition of a vapor barrier
- 2015
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier. - 1080-6032 .- 1545-1534. ; 26:1, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The purpose of this study was to evaluate the effect of wet clothing removal or the addition of a vapor barrier in shivering subjects exposed to a cold environment with only limited insulation available.METHODS: Volunteer subjects (n = 8) wearing wet clothing were positioned on a spineboard in a climatic chamber (-18.5°C) and subjected to an initial 20 minutes of cooling followed by 30 minutes of 4 different insulation interventions in a crossover design: 1) 1 woolen blanket; 2) vapor barrier plus 1 woolen blanket; 3) wet clothing removal plus 1 woolen blanket; or 4) 2 woolen blankets. Metabolic rate, core body temperature, skin temperature, and heart rate were continuously monitored, and cold discomfort was evaluated at 5-minute intervals.RESULTS: Wet clothing removal or the addition of a vapor barrier significantly reduced metabolic rate (mean difference ± SE; 14 ± 4.7 W/m(2)) and increased skin temperature rewarming (1.0° ± 0.2°C). Increasing the insulation rendered a similar effect. There were, however, no significant differences in core body temperature or heart rate among any of the conditions. Cold discomfort (median; interquartile range) was significantly lower with the addition of a vapor barrier (4; 2-4.75) and with 2 woolen blankets (3.5; 1.5-4) compared with 1 woolen blanket alone (5; 3.25-6).CONCLUSIONS: In protracted rescue scenarios in cold environments with only limited insulation available, wet clothing removal or the use of a vapor barrier is advocated to limit the need for shivering thermogenesis and improve the patient's condition on admission to the emergency department.
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| 3. |
- Mei-Dan, O, et al.
(författare)
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Fatalities in wingsuit BASE jumping
- 2013
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Ingår i: Wilderness & environmental medicine. - : Elsevier BV. - 1545-1534 .- 1080-6032. ; 24:4, s. 321-327
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Morrison, Shawnda A, et al.
(författare)
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Finger and Toe Temperature Responses to Cold After Freezing Cold Injury in Elite Alpinists.
- 2015
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Ingår i: Wilderness & environmental medicine. - : Elsevier BV. - 1545-1534 .- 1080-6032. ; 26:3
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To assess whether previous freezing cold injuries (FCI) would affect digit skin temperatures and rewarming rates during a follow-up cold stress test protocol.; DESIGN: Nonrandomized control trial.; METHODS: Twenty elite alpinists participated; alpinists with previous FCI requiring digit amputations (injured, INJ: n = 10 total, n = 8 male) were compared with ability-matched, uninjured alpinists (control, CON: n = 10, all male). Digit skin temperature was measured using infrared thermography as an index of peripheral digit perfusion after a cold stress test, which consisted of 30 minutes of immersion in 8°C water.; RESULTS: The INJ alpinists' injured toes were warmer (approximately 6%) than their uninjured toes immediately after cold immersion (95% CI, 0.01°C to 1.00°C; P = .05); there were no differences between the rates of rewarming of injured and uninjured toes (INJ, 0.5° ± 0.1°C/min; CON, 0.7° ± 0.3°C/min; P = .16). Although the INJ alpinists had colder injured fingers immediately after the 35°C warm bath compared with their own uninjured fingers (32.2° ± 2.0°C vs 34.5° ± 0.5°C; P = .02), there were no differences observed between the rates of rewarming of injured and uninjured fingers after cold exposure (INJ, 1.1° ± 0.2°C/min; CON, 1.3° ± 0.5°C/min; P = .22).; CONCLUSIONS: Even after FCI that requires digit amputation, there is no evidence of different tissue rates of rewarming between the injured and uninjured fingers or toes of elite alpinists.
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| 5. |
- Sperlich, Billy, et al.
(författare)
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Exercising in a Hot Environment : Which T-shirt to Wear?
- 2013
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier BV. - 1080-6032 .- 1545-1534. ; 24:3, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The aim of this study was to investigate thermoregulatory, cardiorespiratory, metabolic, and perceptual responses while running in a hot environment (31.7 degrees +/- 1.0 degrees C; 42% +/- 3% relative humidity) and wearing T-shirts made from different fiber types. Methods.-Eight well-trained men performed 4 tests wearing either a T-shirt made of 100% polyester with 4, 6, or 8 channels, or one made of 100% cotton. Each test consisted of 30 minutes running at 70% of peak oxygen uptake, followed by a ramp test to exhaustion and 15 minutes of recovery. Results.-There were no differences in skin, core, and body temperatures between fiber types during submaximal and high-intensity running (best P = .08). During recovery, body temperature and shivering/sweating sensations were lower when wearing 4- and 6-channel fibers (P <= .04) compared with cotton. The relative humidity at the chest and back were lower for all polyester T-shirts compared with cotton during and after submaximal and maximal running (P <= .007). Heart rate (best P = .10), oxygen uptake (P = .95), respiratory exchange ratio (best P = .93), ventilation (best P = .99), and blood lactate concentration (best P = .97) did not differ between the fiber types. Nor were any differences in time to exhaustion (best P = .76), ratings of perceived exertion (best P = .09), thermal sensation (best P = .07), or sensation of clothing wetness (best P = .36) discovered. Conclusions.-Although statistical analysis revealed lower shivering/sweating sensations while wearing 4- and 6-channel fiber shirts during recovery, with an improved chest and back microenvironment for all polyester T-shirts, the question remains whether these differences are of any practical relevance because the performance of the well-trained men was unaffected.
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| 6. |
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| 7. |
- Ståhle, Lars, et al.
(författare)
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Effects of Food or Sleep Deprivation During Civilian Survival Training on Clinical Chemistry Variables
- 2013
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Ingår i: Wilderness & environmental medicine (Print). - : Elsevier BV. - 1080-6032 .- 1545-1534. ; 24:2, s. 146-152
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Tidskriftsartikel (refereegranskat)abstract
- Objective.-To describe clinical chemistry and weight changes after short-term food or sleep deprivation or multiple deprivations during civilian survival training. Methods.-Data from one baseline-controlled two-period crossover study designed to compare sleep deprivation for up to 50 hours with food deprivation for up to 66 hours (n = 12) and data from regular multiple-deprivations survival training comparing participants (n =-33) with nondeprived instructors (n = 10). Results.-Food deprivation was associated with decreased body weight, blood glucose, serum triglycerides, sodium, chloride, and urine pH, and there were increases in blood and urine ketones and. serum free fatty acids. Sleep deprivation was associated with a minor decrease in hemoglobin and erythrocyte particle count and volume fraction and an increase in leukocytes. Conclusions.-The clinical chemistry and body weight changes associated with food deprivation were qualitatively similar to those observed in fasting obese patients but developed quicker in the survival training setting. Sleep deprivation had few effects on the clinical chemistry profile except for hematological variables. Physicians evaluating clinical chemistry data from patients subjected to short-term food or sleep deprivation should take the physiological state into account in their assessment.
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| 8. |
- Ståhle, Lars, et al.
(författare)
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Effects of Sleep or Food Deprivation During Civilian Survival Training on Cognition, Blood Glucose and 3-OH-butyrate
- 2011
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Ingår i: Wilderness & environmental medicine (Print). - 1080-6032 .- 1545-1534. ; 22:3, s. 202-210
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Tidskriftsartikel (refereegranskat)abstract
- Objectives.-The study was designed to compare effects of food deprivation (FD) and sleep deprivation (SD) on cognition during survival training. Methods.-In a cross-over design (n = 12), the effects of FD (up to 66 hours followed by 500 kcal intake over 24 hours) and SD (up to 50 hours) on cognitive variables, blood glucose, and 3-OH-butyrate were studied. Results.-Food deprivation and SD impaired attention-dependent tasks. The FD impairment of simple reaction time was independent of blood glucose levels, which were normalized by a 500 kcal intake over 24 hours while the reaction time was not. Sleep deprivation and FD impaired maze-solving performance on all variables except rule breaks, which were significantly occurring after 50 hours of SD. Delayed word recall was impaired by SD for 50 hours. On the Balloon Analogue Risk Task, SD was associated with reduced risk-taking. In a gambling task, both SD for 50 hours and FD for 66 hours were associated with a tendency to make early choices when presented with consecutive choices, but the risk-taking was not affected. Conclusions.-Sleep deprivation has multiple cognitive effects, including attention, memory, visual-spatial ability, and risk-taking. Food deprivation had no affect on risk-taking, while the other tasks were affected in a way similar to SD but were less pronounced. The FD effects on cognition did not appear to depend on blood sugar levels. The need to sleep should be prioritized in survival situations to avoid cognitive impairment.
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| 9. |
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