Shivering thermogenesis during acute hypercapnia

1994 ◽  
Vol 72 (3) ◽  
pp. 238-242 ◽  
Author(s):  
Victor Lun ◽  
John C. L. Sun ◽  
Gordon G. Giesbrecht ◽  
Igor B. Mekjavić
Keyword(s):  
Carbon Dioxide ◽  
Cold Exposure ◽  
Cold Water ◽  
Minute Ventilation ◽  
Water Immersion ◽  
Emg Activity ◽  
Gas Mixture ◽  
Electromyographic Activity ◽  
Esophageal Temperature ◽  
Shivering Thermogenesis

The effects of acute hypercapnia on human thermoregulation during cold exposure were investigated by immersion of eight male subjects to the neck in a 15 °C water bath until their core temperatures dropped to 35 °C or until 1 h of immersion had elapsed. Air was inspired throughout each experiment, with the exception of a 15-min period commencing with the attainment of an esophageal temperature (Tes) of 36.5 °C, during which subjects inspired a gas mixture containing 4% CO2, 20% O2, and 76% N2. Oxygen uptake ([Formula: see text], L∙min−1), inspired minute ventilation ([Formula: see text], L∙min−1), esophageal temperature (Tes, °C), rectal temperature (Tre, °C), mean unweighted skin temperature (Tsk, °C), mean heat flux (Q, W∙m−2), and electromyographic activity (EMG, mV) of the trapezius and masseter muscles were recorded continuously. [Formula: see text] and integrated EMG activity (IEMG) were used as the primary indicators of shivering thermogenesis. Shivering EMG was attenuated immediately following the switch of the inhaled gas mixture from air to 4% CO2. For both the massetter and trapezius muscles the IEMG was significantly suppressed (p < 0.05) during the hypercapnic period. The IEMG values preceding the switch to the hypercapnic mixture were 15% greater than those during the CO2 period. Similarly, IEMG values in the post-CO2 period were 55% greater than during the CO2 period. It is concluded that acute periods of hypercapnia during cold exposure may result in transient suppression of shivering tremor, but this does not appear to affect thermal balance, as reflected in the absence of any significant effect on Tes.Key words: temperature regulation, carbon dioxide, hypothermia, diving, cooling, cold water immersion, carbon dioxide retention.

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.

Effect of occluded venous return on core temperature during cold water immersion

1988 ◽  
Vol 65 (6) ◽  
pp. 2709-2713 ◽  
Author(s):  
K. D. Mittleman ◽  
I. B. Mekjavic
Keyword(s):  
Blood Flow ◽  
Cold Water ◽  
Water Immersion ◽  
Peripheral Circulation ◽  
Cold Water Immersion ◽  
Esophageal Temperature ◽  
Complete Neglect ◽  
Rate Of Cooling ◽  
Physical Laws ◽  
Male Subjects

Recent studies using inanimate and animal models suggest that the afterdrop observed upon rewarming from hypothermia is based entirely on physical laws of heat flow without involvement of the returning cooled blood from the limbs. During the investigation of thermoregulatory responses to cold water immersion (15 degrees C), blood flow to the limbs (minimized by the effects of hydrostatic pressure and vasoconstriction) was occluded in 17 male subjects (age, 29.0 +/- 3.3 yr). Comparisons of rectal (Tre) and esophageal temperature (Tes) responses were made during the 5 min before occlusion, during the 10-min occlusion period, and for 5 min immediately after the release of the cuffs (postocclusion). In the preocclusion phase, Tre and Tes showed similar cooling rates. The occlusion of blood flow to the extremities significantly arrested the cooling of Tes (P less than 0.05) with little effect on Tre. Upon release of the pressure cuffs, the returning extremity blood flow resulted in an increased rate of cooling, that was three times greater at the esophageal site (-0:149 +/- 0.052 vs. -0.050 +/- 0.026 degrees C.min-1). These results suggest that the cooled peripheral circulation, minimized during cold water immersion, may dramatically affect esophageal temperature and the complete neglect of the circulatory component to the afterdrop phenomenon is not warranted.

Effect of cold acclimation on neuromuscular function of the hand

2006 ◽  
Vol 31 (4) ◽  
pp. 480-481
Author(s):  
Carla L.M. Geurts
Keyword(s):  
Cold Stress ◽  
Cold Acclimation ◽  
Cold Exposure ◽  
Force Control ◽  
Cold Water ◽  
Water Immersion ◽  
Temperature Response ◽  
Neuromuscular Function ◽  
Cold Water Immersion ◽  
Hand Temperature

The research in this thesis investigated the effects of cold stress on neuromuscular function with the main focus on cold acclimation. In total, 6 studies, 1 field study and 5 experiments, were conducted. The field study showed that during manual work in cold weather, finger and hand temperature can drop to levels that may impair manual function. The first 2 experiments were conducted to investigate the effect of acute local cold stress on force control and to investigate the effect of cold-induced vasodilatation (CIVD) on neuromuscular function. In experiment 1, it was found that cooling of the hand in 10 °C cold water for 10 min did not improve force control, although neuromuscular function was significantly impaired after cooling. In experiment 2, cold-induced vasodilatation, occurring after 20 min of 8 °C cold-water immersion of the hand, was confined to the finger tip and had no effect on the temperature of the first dorsal interosseus (FDI) muscle or its neuromuscular function. A series of cold acclimation studies was conducted to investigate the effect of repeated cold-water hand immersions on neuromuscular function. In these experiments, neuromuscular function was tested before and after 2–3 weeks of daily hand immersion in 8 °C cold water for 30 min. In experiment 3, it was found that 3 weeks of cold-water immersion resulted in a decrease in minimum and mean index finger temperature and CIVD was attenuated. Neuromuscular function was not affected by this change in temperature response. In experiment 4, one hand was exposed daily to cold water and compared with the opposite control hand. Blood plasma catecholamine concentrations were increased after 2 weeks in the cold-exposed hand, but no changes in temperature response or neuromuscular function were found after repeated cold exposure. Thermal comfort after 30 min of cold-water immersion significantly improved after repeated cold exposure causing a discrepancy between actual and perceived temperature and it was suggested that this may impose a greater risk of cold injury owing to a change in behavioural thermoregulation. In the last experiment, core temperature was elevated by bicycling at a submaximal level during the cold hand immersion. Exercise had a direct effect on the temperature response during cold-water immersion, decreasing the minimum FDI temperature and slowing down the deteriorating effect of cold on neuromuscular function; however, exercise showed was no effect on local cold acclimation. It is concluded that local repeated cold exposures may improve finger and hand temperature and subjective thermal ratings, but that these changes are too small to improve neuromuscular function. The best remedy to maintain manual function is to limit or avoid cold stress as much as possible. If sufficient protection of the hands is impossible, core heating through exercise or passive heating may be a solution.

Free fatty acid availability and temperature regulation in cold water

1989 ◽  
Vol 67 (6) ◽  
pp. 2466-2472 ◽  
Author(s):  
L. Martineau ◽  
I. Jacobs
Keyword(s):  
Cold Exposure ◽  
Temperature Regulation ◽  
Cold Water ◽  
Vastus Lateralis ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
Glucose Levels ◽  
Plasma Ffa ◽  
Glycogen Utilization ◽  
Male Subjects

The purpose of this study was to investigate whether a reduced availability of plasma free fatty acids (FFA) would impair human temperature regulation during cold exposure. Seven seminude male subjects were immersed on two occasions in 18 degrees C water for 90 min or until their rectal temperature (Tre) decreased to 35.5 degrees C. The immersion occurred after 2 h of intermittent oral ingestion of either nicotinic acid (NIC) or a placebo (PLAC). Plasma FFA levels immediately before the immersion were significantly lower in NIC (87 +/- 15 mumol/l) than in PLAC (655 +/- 116 mumol/l, P less than 0.05). Although FFA levels increased by 73% in NIC during the immersion (P less than 0.05), they remained significantly lower than in PLAC (151 +/- 19 vs. 716 +/- 74 mumol/l, P less than 0.05) throughout the immersion. Muscle glycogen concentrations in the vastus lateralis decreased after cold water immersion in both trials (P less than 0.05), but the rate of glycogen utilization was similar, averaging 1.00 +/- 0.27 mmol glucose unit.kg dry muscle-1.min-1). Plasma glucose levels were significantly reduced after immersion in both trials (P less than 0.05), this decrease being greater in NIC (1.3 +/- 0.2 mmol/l) than in PLAC (0.7 +/- 0.1 mmol/l, P less than 0.05). O2 uptake increased to 3.8 +/- 0.3 times preimmersion values in both trials (P less than 0.05). Mean respiratory exchange ratio (RER) immediately before the immersion was greater in NIC (0.87 +/- 0.02) than in PLAC (0.77 +/- 0.01, P less than 0.05). Cold exposure increased RER in PLAC but not in NIC.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle glycogen utilization during shivering thermogenesis in humans

1988 ◽  
Vol 65 (5) ◽  
pp. 2046-2050 ◽  
Author(s):  
L. Martineau ◽  
I. Jacobs
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Cold Water ◽  
Vastus Lateralis ◽  
Water Immersion ◽  
Venous Blood ◽  
Cold Water Immersion ◽  
Vastus Lateralis Muscle ◽  
Glucose Levels ◽  
Shivering Thermogenesis

The purpose of the present study was to clarify the importance of skeletal muscle glycogen as a fuel for shivering thermogenesis in humans during cold-water immersion. Fourteen seminude subjects were immersed to the shoulders in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Biopsies from the vastus lateralis muscle and venous blood samples were obtained before and immediately after the immersion. Metabolic rate increased during the immersion to 3.5 +/- 0.3 (SE) times resting values, whereas Tre decreased by 0.9 degrees C to approximately 35.8 degrees C at the end of the immersion. Intramuscular glycogen concentration in the vastus lateralis decreased from 410 +/- 15 to 332 +/- 18 mmol glucose/kg dry muscle, with each subject showing a decrease (P less than 0.001). Plasma volume decreased (P less than 0.001) markedly during the immersion (-24 +/- 1%). After correcting for this decrease, blood lactate and plasma glycerol levels increased by 60 (P less than 0.05) and 38% (P less than 0.01), respectively, whereas plasma glucose levels were reduced by 20% after the immersion (P less than 0.001). The mean expiratory exchange ratio showed a biphasic pattern, increasing initially during the first 30 min of the immersion from 0.80 +/- 0.06 to 0.85 +/- 0.05 (P less than 0.01) and decreasing thereafter toward basal values. The results demonstrate clearly that intramuscular glycogen reserves are used as a metabolic substrate to fuel intensive thermogenic shivering activity of human skeletal muscle.

scholarly journals Application of carbon dioxide to the skin and muscle oxygenation of human lower-limb muscle sites during cold water immersion

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9785
Author(s):  
Miho Yoshimura ◽  
Tatsuya Hojo ◽  
Hayato Yamamoto ◽  
Misato Tachibana ◽  
Masatoshi Nakamura ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Skin Temperature ◽  
Cold Water ◽  
Tap Water ◽  
Water Immersion ◽  
Recovery Period ◽  
Cold Water Immersion ◽  
Hot Water ◽  
Muscle Oxygenation ◽  
Concentration Changes

Background Cold therapy has the disadvantage of inducing vasoconstriction in arterial and venous capillaries. The effects of carbon dioxide (CO2) hot water depend mainly on not only cutaneous vasodilation but also muscle vasodilation. We examined the effects of artificial CO2 cold water immersion (CCWI) on skin oxygenation and muscle oxygenation and the immersed skin temperature. Subjects and Methods Fifteen healthy young males participated. CO2-rich water containing CO2 >1,150 ppm was prepared using a micro-bubble device. Each subject’s single leg was immersed up to the knee in the CO2-rich water (20 °C) for 15 min, followed by a 20-min recovery period. As a control study, a leg of the subject was immersed in cold tap-water at 20 °C (CWI). The skin temperature at the lower leg under water immersion (Tsk-WI) and the subject’s thermal sensation at the immersed and non-immersed lower legs were measured throughout the experiment. We simultaneously measured the relative changes of local muscle oxygenation/deoxygenation compared to the basal values (Δoxy[Hb+Mb], Δdeoxy[Hb+Mb], and Δtotal[Hb+Mb]) at rest, which reflected the blood flow in the muscle, and we measured the tissue O2 saturation (StO2) by near-infrared spectroscopy on two regions of the tibialis anterior (TA) and gastrocnemius (GAS) muscles. Results Compared to the CWI results, the Δoxy[Hb+Mb] and Δtotal[Hb+Mb] in the TA muscle at CCWI were increased and continued at a steady state during the recovery period. In GAS muscle, the Δtotal[Hb+Mb] and Δdeoxy[Hb+Mb] were increased during CCWI compared to CWI. Notably, StO2values in both TA and GAS muscles were significantly increased during CCWI compared to CWI. In addition, compared to the CWI, a significant decrease in Tsk at the immersed leg after the CCWI was maintained until the end of the 20-min recovery, and the significant reduction continued. Discussion The combination of CO2 and cold water can induce both more increased blood inflow into muscles and volume-related (total heme concentration) changes in deoxy[Hb+Mb] during the recovery period. The Tsk-WI stayed lower with the CCWI compared to the CWI, as it is associated with vasodilation by CO2.

scholarly journals Seven days of cold acclimation substantially reduces shivering intensity and increases nonshivering thermogenesis in adult humans

2019 ◽  
Vol 126 (6) ◽  
pp. 1598-1606 ◽  
Author(s):  
Kyle Gordon ◽  
Denis P. Blondin ◽  
Brian J. Friesen ◽  
Hans Christian Tingelstad ◽  
Glen P. Kenny ◽  
...  
Keyword(s):  
Cold Acclimation ◽  
Core Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
Metabolic Changes ◽  
Whole Body ◽  
Nonshivering Thermogenesis

Daily compensable cold exposure in humans reduces shivering by ~20% without changing total heat production, partly by increasing brown adipose tissue thermogenic capacity and activity. Although acclimation and acclimatization studies have long suggested that daily reductions in core temperature are essential to elicit significant metabolic changes in response to repeated cold exposure, this has never directly been demonstrated. The aim of the present study is to determine whether daily cold-water immersion, resulting in a significant fall in core temperature, can further reduce shivering intensity during mild acute cold exposure. Seven men underwent 1 h of daily cold-water immersion (14°C) for seven consecutive days. Immediately before and following the acclimation protocol, participants underwent a mild cold exposure using a novel skin temperature clamping cold exposure protocol to elicit the same thermogenic rate between trials. Metabolic heat production, shivering intensity, muscle recruitment pattern, and thermal sensation were measured throughout these experimental sessions. Uncompensable cold acclimation reduced total shivering intensity by 36% ( P = 0.003), without affecting whole body heat production, double what was previously shown from a 4-wk mild acclimation. This implies that nonshivering thermogenesis increased to supplement the reduction in the thermogenic contribution of shivering. As fuel selection did not change following the 7-day cold acclimation, we suggest that the nonshivering mechanism recruited must rely on a similar fuel mixture to produce this heat. The more significant reductions in shivering intensity compared with a longer mild cold acclimation suggest important differential metabolic responses, resulting from an uncompensable compared with compensable cold acclimation. NEW & NOTEWORTHY Several decades of research have been dedicated to reducing the presence of shivering during cold exposure. The present study aims to determine whether as little as seven consecutive days of cold-water immersion is sufficient to reduce shivering and increase nonshivering thermogenesis. We provide evidence that whole body nonshivering thermogenesis can be increased to offset a reduction in shivering activity to maintain endogenous heat production. This demonstrates that short, but intense cold stimulation can elicit rapid metabolic changes in humans, thereby improving our comfort and ability to perform various motor tasks in the cold. Further research is required to determine the nonshivering processes that are upregulated within this short time period.

Human thermoregulatory responses during cold water immersion after artificially induced sunburn

1992 ◽  
Vol 262 (4) ◽  
pp. R617-R623 ◽  
Author(s):  
K. B. Pandolf ◽  
R. W. Gange ◽  
W. A. Latzka ◽  
I. H. Blank ◽  
A. J. Young ◽  
...  
Keyword(s):  
Skin Temperature ◽  
Rectal Temperature ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
The Body ◽  
Esophageal Temperature ◽  
Mean Skin Temperature ◽  
Thermoregulatory Responses ◽  
The Mean

Thermoregulatory responses during cold-water immersion (water temperature 22 degrees C) were compared in 10 young men before as well as 24 h and 1 wk after twice the minimal erythemal dose of ultraviolet-B radiation that covered approximately 85% of the body surface area. After 10 min of seated rest in cold water, the mean exercised for 50 min on a cycle ergometer (approximately 51% of maximal aerobic power). Rectal temperature, regional and mean heat flow (hc), mean skin temperature from five sites, and hearrt rate were measured continuously for all volunteers while esophageal temperature was measured for six subjects. Venous blood samples were collected before and after cold water immersion. The mean skin temperature was higher (P less than 0.05) throughout the 60-min cold water exposure both 24 h and 1 wk after sunburn compared with before sunburn. Mean hc was higher (P less than 0.05) after 10 min resting immersion and during the first 10 min of exercise when 24 h postsunburn was compared with presunburn, with the difference attributed primarily to higher hc from the back and chest. While rectal temperature and heart rate did not differ between conditions, esophageal temperature before immersion and throughout the 60 min of cold water immersion was higher (P less than 0.05) when 24 h postsunburn was compared with presunburn. Plasma volume increased (P less than 0.05) after 1 wk postsunburn compared with presunburn, whereas plasma protein concentration was reduced (P less than 0.05). After exercise cortisol was greater (P less than 0.05) 24 h postsunburn compared with either presunburn or 1 wk postsunburn.(ABSTRACT TRUNCATED AT 250 WORDS)

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