scholarly journals Thermoregulatory and Metabolic Demands of Naval Special Warfare Divers During a 6-h Cold-Water Training Dive

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrea C. Chapin ◽  
Laura J. Arrington ◽  
Jake R. Bernards ◽  
Karen R. Kelly
Keyword(s):  
Metabolic Rate ◽  
Skin Temperature ◽  
Core Temperature ◽  
Cold Water ◽  
Substrate Utilization ◽  
Individual Variability ◽  
Fat Percentage ◽  
Special Operations ◽  
Exposure Patterns ◽  
Not At Risk

Introduction: Extreme environmental conditions induce changes in metabolic rate and substrate use due to thermoregulation. Cold-water full-body submersion for extended periods of time is inevitable for training and missions carried out by Naval Special Warfare divers. Anthropometric, physiologic, and metabolic data have been reported from partial immersion in cold water in non-thermally protected men; data is limited in thermally protected divers in extremely cold water. Thermoregulatory and metabolic demands during prolonged cold-water submersion in Naval Special Warfare divers are unknown.Objective: Assess thermoregulatory and metabolic demands of Naval Special Warfare divers surrounding prolonged cold-water submersion.Materials and Methods: Sixteen active-duty U.S. Navy Sea Air and Land (SEAL) operators tasked with cold-water dive training participated. Divers donned standard military special operations diving equipment and fully submerged to a depth of ∼ 6 m in a pool chilled to 5°C for a 6-h live training exercise. Metabolic measurements were obtained via indirect calorimetry for 10-min pre-dive and 5-min post dive. Heart rate, skin temperature, and core temperature were measured throughout the dive.Results: Core temperature was maintained at the end of the 6-h dive, 36.8 ± 0.4°C and was not correlated to body composition (body fat percentage, lean body mass) or metabolic rate. SEALs were not at risk for non-freezing cold injuries as mean skin temperature was 28.5 ± 1.6°C at end of the 6-h dive. Metabolic rate (kcal/min) was different pre- to post-dive, increasing from 1.9 ± 0.2 kcal/min to 2.8 ± 0.2 kcal/min, p < 0.001, 95% CI [0.8, 1.3], Cohen’s d effect size 2.3. Post-dive substrate utilization was 57.5% carbohydrate, 0.40 ± 0.16 g/min, and 42.5% fat, 0.13 ± 0.04 g/min.Conclusion: Wetsuits supported effective thermoprotection in conjunction with increase in thermogenesis during a 6-h full submersion dive in 5°C. Core temperature was preserved with an expected decrease in skin temperature. Sustained cold-water diving resulted in a 53% increase in energy expenditure. While all participants increased thermogenesis, there was high inter-individual variability in metabolic rate and substrate utilization. Variability in metabolic demands may be attributable to individual physiologic adjustments due to prior cold exposure patterns of divers. This suggests that variations in metabolic adjustments and habituation to the cold were likely. More work is needed to fully understand inter-individual metabolic variability to prolonged cold-water submersion.

scholarly journals Core Temperature in Triathletes during Swimming with Wetsuit in 10 °C Cold Water

Sports ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 130 ◽  
Author(s):  
Jørgen Melau ◽  
Maria Mathiassen ◽  
Trine Stensrud ◽  
Mike Tipton ◽  
Jonny Hisdal
Keyword(s):  
Water Temperature ◽  
Skin Temperature ◽  
Core Temperature ◽  
Rectal Temperature ◽  
Physiological Response ◽  
Cold Water ◽  
Temperature Response ◽  
Open Water ◽  
Open Water Swimming ◽  
Ironman Distance

Low water temperature (<15 °C) has been faced by many organizers of triathlons and swim-runs in the northern part of Europe during recent years. More knowledge about how cold water affects athletes swimming in wetsuits in cold water is warranted. The aim of the present study was therefore to investigate the physiological response when swimming a full Ironman distance (3800 m) in a wetsuit in 10 °C water. Twenty triathletes, 37.6 ± 9 years (12 males and 8 females) were recruited to perform open water swimming in 10 °C seawater; while rectal temperature (Tre) and skin temperature (Tskin) were recorded. The results showed that for all participants, Tre was maintained for the first 10–15 min of the swim; and no participants dropped more than 2 °C in Tre during the first 30 min of swimming in 10 °C water. However; according to extrapolations of the results, during a swim time above 135 min; 47% (8/17) of the participants in the present study would fall more than 2 °C in Tre during the swim. The results show that the temperature response to swimming in a wetsuit in 10 °C water is highly individual. However, no participant in the present study dropped more than 2 °C in Tre during the first 30 min of the swim in 10 °C water.

Thermoregulation of juvenile grey seals, Halichoerus grypus, in air

1996 ◽  
Vol 74 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Patrice Boily ◽  
David M. Lavigne
Keyword(s):  
Metabolic Rate ◽  
Core Temperature ◽  
Low Temperatures ◽  
Heat Load ◽  
Cold Water ◽  
Internal Heat ◽  
Ambient Air ◽  
Halichoerus Grypus ◽  
Metabolic Depression ◽  
Air Temperatures

Metabolic rate, core temperature, and duration of sleep-related apnea events were monitored in three juvenile grey seals (Halichoerus grypus) aged 7–19 months (49–78 kg), at ambient air temperatures ranging from −18 °C to 35 °C. At low temperatures, only one seal increased its metabolic rate (at −18 °C), whereas at high temperatures (up to 35 °C) none of the three animals increased its metabolic rate. Nonetheless, seals usually became hyperthermic when they were subjected to air temperatures of 30 °C or higher. There was no indication that the duration of sleep-related apnea was greater at higher temperatures. The sleeping metabolic rate was significantly lower (20%) than the resting level. A metabolic depression associated with sleep may be advantageous at higher temperatures, reducing the internal heat load of the animal. These results suggest that cold-water adaptations of juvenile grey seals do not interfere with their ability to cope with higher air temperatures. Also, such animals should not be directly limited in their distribution by either high or low ambient air temperatures.

Comparison of thermal responses between rest and leg exercise in water

1985 ◽  
Vol 59 (1) ◽  
pp. 248-253 ◽  
Author(s):  
M. M. Toner ◽  
M. N. Sawka ◽  
W. L. Holden ◽  
K. B. Pandolf
Keyword(s):  
Metabolic Rate ◽  
Skin Temperature ◽  
Cold Water ◽  
Metabolic Responses ◽  
Mean Skin Temperature ◽  
Cool Water ◽  
Heat Flows ◽  
Male Volunteers ◽  
Leg Exercise ◽  
Over Time

This study examined both the thermal and metabolic responses of individuals in cool (30 degrees C, n = 9) and cold (18 degrees C, n = 7; 20 degrees C, n = 2) water. Male volunteers were immersed up to the neck for 1 h during both seated rest (R) and leg exercise (LE). In 30 degrees C water, metabolic rate (M) remained unchanged over time during both R (115 W, 60 min) and LE (528 W, 60 min). Mean skin temperature (Tsk) declined (P less than 0.05) over 1 h during R, while Tsk was unchanged during LE. Rectal (Tre) and esophageal (Tes) temperatures decreased (P less than 0.05) during R (delta Tre, -0.5 degrees C; delta Tes, -0.3 degrees C) and increased (P less than 0.05) during LE (delta Tre, 0.4 degrees C; Tsk, 0.4 degrees C). M, Tsk, Tre, and Tes were higher (P less than 0.05) during LE compared with R. In cool water, all regional heat flows (leg, chest, and arm) were generally greater (P less than 0.05) during LE than R. In cold water, M increased (P less than 0.05) over 1 h during R but remained unchanged during LE. Tre decreased (P less than 0.05) during R (delta Tre, -0.8 degrees C) but was unchanged during LE. Tes declined (P less than 0.05) during R (delta Tes, -0.4 degrees C) but increased (P less than 0.05) during LE (delta Tes, 0.2 degrees C). M, Tre, and Tes were higher (P less than 0.05), whereas Tsk was not different during LE compared with R at 60 min.

Comparison of core threshold temperatures for forehead sweating based on esophageal and rectal temperatures

1993 ◽  
Vol 71 (8) ◽  
pp. 597-603 ◽  
Author(s):  
Matthew D. White ◽  
Igor B. Mekjavić
Keyword(s):  
Skin Temperature ◽  
Core Temperature ◽  
Cold Water ◽  
Water Immersion ◽  
Phase 1 ◽  
Rate Of Change ◽  
The Body ◽  
Continuous Assessment ◽  
The Core ◽  
Threshold Temperatures

A protocol incorporating successive hot and cold water immersions, causing respective warming and cooling of the body, has been used to determine the core threshold for sweating. Disparate results have been reported for the core threshold of sweating, and these have been attributed to the possible existence of core temperature gradients during such a protocol. Spatial and temporal core temperature (Tc, °C) gradients during dynamic changes in body temperature may give rise to different values of core temperature thresholds for sweating, depending on the Tc measurement site. In addition, during such an immersion protocol skin temperature transients may influence expression of thresholds using esophageal temperature (Tes). With these considerations, the effects of Tc gradients and skin temperature on Tc thresholds for sweating were examined. Subjects (n = 22) were immersed to the neck in 40 °C water until Tes reached 38.5 °C (phase 1), followed immediately by cooling in 30.6 °C water until extinction of sweating was observed (phase 2). Cooling was continued in the latter bath after the sweating extinction until total immersed time reached 50 min or until shivering was initiated (phase 3). During the trials continuous assessment was made of rectal temperature (Tre) and Tes, mean unweighted skin temperature (Tsk, °C), forehead sweating rate ([Formula: see text], g∙m−2∙min−1) oxygen consumption ([Formula: see text], L∙min−1), and surface heat flux ([Formula: see text], W∙min−2). With the current protocol it appeared inappropriate to determine the Tc thresholds for onset of sweating, as sweating was initiated prior to any significant displacement of Tc, but was most likely influenced by Tsk and its rate of change. During the transfer to the 30.6 °C bath Tes followed a similar profile and rate of response as Tsk, suggesting it was affected by transient Tsk changes, whereas the rate of Tre response was significantly different than rates of skin and esophageal temperatures. Significantly different rates of Tes and Tre gave Tc gradients during such a protocol and it is concluded that this may confound determination of Tc thresholds using such a protocol.Key words: temperature regulation, hypothermia, hyperthermia, water immersion.

568. The rate of secretion of milk and fat

1955 ◽  
Vol 22 (1) ◽  
pp. 22-36 ◽  
Author(s):  
G. L. Bailey ◽  
P. A. Clough ◽  
F. H. Dodd
Keyword(s):  
Metabolic Rate ◽  
Fat Percentage ◽  
Preceding Interval ◽  
Rate Of Decline ◽  
Carry Over

1. The effects of variations in the length of the milking interval and of the preceding milking interval were measured for five cows.2. The yield of milk increased with the lengths and decreased with the square of the lengths of the milking interval and of the previous milking interval.3. The yield of fat increased with the length of the milking interval and the length of the preceding milking interval and decreased with the square of the length of the milking interval.4. The biological implications of each of the mathematical terms are discussed.5. The effect of the preceding interval was through a direct carry-over of residual milk and also by an effect on the metabolic rate of the alveoli throughout the following interval.6. The rate of secretion of both milk and fat declined with increasing milking interval; there was evidence that the rate of decline for the milk was greater than that for the fat, for the fat percentage of the milk tended to increase.

A second postcooling afterdrop: more evidence for a convective mechanism

1992 ◽  
Vol 73 (4) ◽  
pp. 1253-1258 ◽  
Author(s):  
G. G. Giesbrecht ◽  
G. K. Bristow
Keyword(s):  
Core Temperature ◽  
Initial Rate ◽  
Treadmill Exercise ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
Probable Mechanism ◽  
Warm Bath ◽  
Male Subjects ◽  
Shivering Thermogenesis

An attempt was made to demonstrate the importance of increased perfusion of cold tissue in core temperature afterdrop. Five male subjects were cooled twice in water (8 degrees C) for 53–80 min. They were then rewarmed by one of two methods (shivering thermogenesis or treadmill exercise) for another 40–65 min, after which they entered a warm bath (40 degrees C). Esophageal temperature (Tes) as well as thigh and calf muscle temperatures at three depths (1.5, 3.0, and 4.5 cm) were measured. Cold water immersion was terminated at Tes varying between 33.0 and 34.5 degrees C. For each subject this temperature was similar in both trials. The initial core temperature afterdrop was 58% greater during exercise (mean +/- SE, 0.65 +/- 0.10 degrees C) than shivering (0.41 +/- 0.06 degrees C) (P < 0.005). Within the first 5 min after subjects entered the warm bath the initial rate of rewarming (previously established during shivering or exercise, approximately 0.07 degrees C/min) decreased. The attenuation was 0.088 +/- 0.03 degrees C/min (P < 0.025) after shivering and 0.062 +/- 0.022 degrees C/min (P < 0.025) after exercise. In 4 of 10 trials (2 after shivering and 2 after exercise) a second afterdrop occurred during this period. We suggest that increased perfusion of cold tissue is one probable mechanism responsible for attenuation or reversal of the initial rewarming rate. These results have important implications for treatment of hypothermia victims, even when treatment commences long after removal from cold water.

scholarly journals Introduction of a Portable and Non-invasive Technology for Hand and Foot Cooling: A Preclinical Feasibility Study

2021 ◽  
Author(s):  
Shirin Davarpanah Jazi ◽  
Johan Ralf ◽  
Mohammad FazelBakhsheshi
Keyword(s):  
Skin Temperature ◽  
Healthy Subjects ◽  
Cold Water ◽  
Healthy Individuals ◽  
Cooling Performance ◽  
Non Invasive ◽  
Reduced Dose ◽  
Before And After ◽  
Hands And Feet ◽  
Near Future

Abstract Purpose: Chemotherapy-induced peripheral neuropathy (CIPN) is caused by damage to neural structures in distal limbs. CIPN can lead to reduced dose or cessation of chemotherapy. Cooling the hands/feet has shown to be effective in reducing or preventing CIPN. However, when using ice bath or ice gloves/socks is no way to maintain the targeted temperature and prevent ice from melting. Also, patients have difficulty tolerating the freezing temperatures over long periods of chemotherapy. The aim of this study was to test the cooling performance of a recently developed non-invasive system that can ultimately replace current cooling methods.Methods: COOLPREVENT circulates cold water at tolerable temperatures into malleable gloves/socks. As well, COOLPREVENT does not require replacing of melted ice. We administered a cooling protocol via COOLPREVENT on three healthy subjects for 60 minutes. Immediately before and after cooling, skin temperature in the hands and feet were measured. Level of discomfort was also recorded during the cooling process.Results: Results showed that COOLPREVENT reduce skin temperature by 14.5±3.8°C and 10.7±1.7°C in the hands and feet, respectively within 60 minutes without significant discomfort.Conclusion: Although our study is limited by the small number of subjects and participation of healthy individuals, but we can conclude that COOLPREVENT can be a safe and appropriate method for hand and foot cooling. We hope that these preliminary findings can pave the way to designing clinical trials we plan to conduct in the near future.

scholarly journals Effect of food intake on the ventilatory response to increasing core temperature during exercise

2019 ◽  
Vol 44 (1) ◽  
pp. 22-30 ◽  
Author(s):  
Keiji Hayashi ◽  
Nozomi Ito ◽  
Yoko Ichikawa ◽  
Yuichi Suzuki
Keyword(s):  
Food Intake ◽  
Body Temperature ◽  
Skin Temperature ◽  
Core Temperature ◽  
Mean Skin Temperature ◽  
Carbon Dioxide Elimination ◽  
Transient Effect ◽  
Mean Body Temperature ◽  
Ventilatory Parameters ◽  
Effect Of Food

Food intake increases metabolism and body temperature, which may in turn influence ventilatory responses. Our aim was to assess the effect of food intake on ventilatory sensitivity to rising core temperature during exercise. Nine healthy male subjects exercised on a cycle ergometer at 50% of peak oxygen uptake in sessions with and without prior food intake. Ventilatory sensitivity to rising core temperature was defined by the slopes of regression lines relating ventilatory parameters to core temperature. Mean skin temperature, mean body temperature (calculated from esophageal temperature and mean skin temperature), oxygen uptake, carbon dioxide elimination, minute ventilation, alveolar ventilation, and tidal volume (VT) were all significantly higher at baseline in sessions with food intake than without food intake. During exercise, esophageal temperature, mean skin temperature, mean body temperature, carbon dioxide elimination, and end-tidal CO2 pressure were all significantly higher in sessions with food intake than without it. By contrast, ventilatory parameters did not differ between sessions with and without food intake, with the exception of VT during the first 5 min of exercise. The ventilatory sensitivities to rising core temperature also did not differ, with the exception of an early transient effect on VT. Food intake increases body temperature before and during exercise. Other than during the first 5 min of exercise, food intake does not affect ventilatory parameters during exercise, despite elevation of both body temperature and metabolism. Thus, with the exception of an early transient effect on VT, ventilatory sensitivity to rising core temperature is not affected by food intake.

Peripheral blood flow during rewarming from mild hypothermia in humans

1985 ◽  
Vol 58 (1) ◽  
pp. 4-13 ◽  
Author(s):  
G. K. Savard ◽  
K. E. Cooper ◽  
W. L. Veale ◽  
T. J. Malkinson
Keyword(s):  
Blood Flow ◽  
Core Temperature ◽  
Skin Blood Flow ◽  
Cold Water ◽  
Mild Hypothermia ◽  
Muscle Blood Flow ◽  
Venous Occlusion ◽  
Warm Bath ◽  
Peripheral Blood Flow ◽  
Deep Body Temperature

During the initial stages of rewarming from hypothermia, there is a continued cooling of the core, or after-drop in temperature, that has been attributed to the return of cold blood due to peripheral vasodilatation, thus causing a further decrease of deep body temperature. To examine this possibility more carefully, subjects were immersed in cold water (17 degrees C), and then rewarmed from a mildly hypothermic state in a warm bath (40 degrees C). Measurements of hand blood flow were made by calorimetry and of forearm, calf, and foot blood flows by straingauge venous occlusion plethysmography at rest (Ta = 22 degrees C) and during rewarming. There was a small increase in skin blood flow during the falling phase of core temperature upon rewarming in the warm bath, but none in foot blood flow upon rewarming at room air, suggesting that skin blood flow seems to contribute to the after-drop, but only minimally. Limb blood flow changes during this phase suggest that a small muscle blood flow could also have contributed to the after-drop. It was concluded that the after-drop of core temperature during rewarming from mild hypothermia does not result from a large vasodilatation in the superficial parts of the periphery, as postulated. The possible contribution of mechanisms of heat conduction, heat convection, and cessation of shivering thermogenesis were discussed.

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