Effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during cold exposure

2011 ◽  
Vol 111 (4) ◽  
pp. 1014-1020 ◽  
Author(s):  
Denis P. Blondin ◽  
Anali Maneshi ◽  
Marie-Andrée Imbeault ◽  
François Haman
Keyword(s):  
Menstrual Cycle ◽  
Core Temperature ◽  
Heat Production ◽  
Total Heat ◽  
Whole Body ◽  
Large Contribution ◽  
Electromyographic Activity ◽  
Muscle Recruitment ◽  
Low Intensity ◽  
Fuel Selection

Differences in core temperature and body heat content, generally observed between the luteal and follicular phase of the menstrual cycle, have been reported to modulate the thermogenic activity of cold-exposed women. However, it is unclear how this change in whole body shivering activity will influence fuel selection. The goal of this study was to quantify the effects of the menstrual cycle on muscle recruitment and oxidative fuel selection during low-intensity shivering. Electromyographic activity of eight large muscles was monitored while carbohydrate, lipid, and protein utilization was simultaneously quantified in the follicular and luteal phases of the menstrual cycle in nonacclimatized women shivering at a low intensity. The onset (∼25 min), intensity (∼15% of maximal voluntary contraction), and pattern (∼6 shivering bursts/min) of the shivering response did not differ between menstrual cycle phases, regardless of differences in core temperature and hormone levels. This resulted in lipids remaining the predominant substrate, contributing 75% of total heat production, independent of menstrual phase. We conclude that hormone fluctuations inherent in the menstrual cycle do not affect mechanisms of substrate utilization in the cold. Whether the large contribution of lipids to total heat production in fuel selection confers a survival advantage remains to be established.

Human heat balance during postexercise recovery: separating metabolic and nonthermal effects

2008 ◽  
Vol 294 (5) ◽  
pp. R1586-R1592 ◽  
Author(s):  
Ollie Jay ◽  
Daniel Gagnon ◽  
Michel B. DuCharme ◽  
Paul Webb ◽  
Francis D. Reardon ◽  
...  
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Heat Production ◽  
Heat Balance ◽  
Heat Content ◽  
Total Heat ◽  
Whole Body ◽  
Active Recovery ◽  
Total Heat Loss ◽  
Body Heat

Previous studies report greater postexercise heat loss responses during active recovery relative to inactive recovery despite similar core temperatures between conditions. Differences have been ascribed to nonthermal factors influencing heat loss response control since elevations in metabolism during active recovery are assumed to be insufficient to change core temperature and modify heat loss responses. However, from a heat balance perspective, different rates of total heat loss with corresponding rates of metabolism are possible at any core temperature. Seven male volunteers cycled at 75% of V̇o2peak in the Snellen whole body air calorimeter regulated at 25.0°C, 30% relative humidity (RH), for 15 min followed by 30 min of active (AR) or inactive (IR) recovery. Relative to IR, a greater rate of metabolic heat production (Ṁ − Ẇ) during AR was paralleled by a greater rate of total heat loss (ḢL) and a greater local sweat rate, despite similar esophageal temperatures between conditions. At end-recovery, rate of body heat storage, that is, [(Ṁ − Ẇ) − ḢL] approached zero similarly in both conditions, with Ṁ − Ẇ and ḢL elevated during AR by 91 ± 26 W and 93 ± 25 W, respectively. Despite a higher Ṁ − Ẇ during AR, change in body heat content from calorimetry was similar between conditions due to a slower relative decrease in ḢL during AR, suggesting an influence of nonthermal factors. In conclusion, different levels of heat loss are possible at similar core temperatures during recovery modes of different metabolic rates. Evidence for nonthermal influences upon heat loss responses must therefore be sought after accounting for differences in heat production.

Effect of dietary protein and energy intakes on whole-body protein turnover and its contribution to heat production in chicks

1993 ◽  
Vol 69 (3) ◽  
pp. 681-688 ◽  
Author(s):  
K. Kita ◽  
T. Muramatsu ◽  
J. Okumura
Keyword(s):  
Protein Synthesis ◽  
Heat Production ◽  
Protein Turnover ◽  
Crude Protein ◽  
Total Heat ◽  
Interactive Effects ◽  
Whole Body ◽  
Small Range ◽  
Body Protein ◽  
Fractional Rate

A factorial 3 × 3 experiment was conducted with chicks to investigate the effect of manipulating crude protein (N × 6.25) intake (CPI) and metabolizable energyintake (MEI) simultaneously, in the range low to high (including adequate) levels with regard to the respective requirements, on whole-body protein turnover and its contribution to total heat production. The fractional rate of whole-body protein synthesis was increased curvilinearly by increasing MEI or CPI from low to high levels. In terms of absolute rates whole-body protein synthesis was enhanced by increasing MEI from low to adequate levels, the effect being greater at adequate and high CPI than at low CPI. The effect of varying CPI and MEI on whole-body protein degradation was similar, but less sensitive, to that on whole-body protein synthesis. Increasing MEI from low to high levels elevated totalheat production at all CPI levels. There were no interactive effects of varying CPI andMEI on the contribution of whole-body protein synthesis to total heat production, and in general the contribution increased with increasing CPI and decreased with increasing MEI.The contribution of whole-body protein synthesis to total heat production fell within a small range from 11.2 to 16.5%.

Large differences in peak oxygen uptake do not independently alter changes in core temperature and sweating during exercise

2011 ◽  
Vol 301 (3) ◽  
pp. R832-R841 ◽  
Author(s):  
Ollie Jay ◽  
Anthony R. Bain ◽  
Tomasz M. Deren ◽  
Matthew Sacheli ◽  
Matthew N. Cramer
Keyword(s):  
Oxygen Uptake ◽  
Body Mass ◽  
Core Temperature ◽  
Heat Production ◽  
Exercise Intensity ◽  
Peak Oxygen Uptake ◽  
Whole Body ◽  
Complex Interactions ◽  
Relative Exercise Intensity ◽  
Sudomotor Activity

The independent influence of peak oxygen uptake (V̇o2 peak) on changes in thermoregulatory responses during exercise in a neutral climate has not been previously isolated because of complex interactions between V̇o2 peak, metabolic heat production (Hprod), body mass, and body surface area (BSA). It was hypothesized that V̇o2 peak does not independently alter changes in core temperature and sweating during exercise. Fourteen males, 7 high (HI) V̇o2 peak: 60.1 ± 4.5 ml·kg−1·min−1; 7 low (LO) V̇o2 peak: 40.3 ± 2.9 ml·kg−1·min−1 matched for body mass (HI: 78.2 ± 6.1 kg; LO: 78.7 ± 7.1 kg) and BSA (HI: 1.97 ± 0.08 m2; LO: 1.94 ± 0.08 m2), cycled for 60-min at 1) a fixed heat production (FHP trial) and 2) a relative exercise intensity of 60% V̇o2 peak (REL trial) at 24.8 ± 0.6°C, 26 ± 10% RH. In the FHP trial, Hprod was similar between the HI (542 ± 38 W, 7.0 ± 0.6 W/kg or 275 ± 25 W/m2) and LO (535 ± 39 W, 6.9 ± 0.9 W/kg or 277 ± 29 W/m2) groups, while changes in rectal (Tre: HI: 0.87 ± 0.15°C, LO: 0.87 ± 0.18°C, P = 1.00) and aural canal (Tau: HI: 0.70 ± 0.12°C, LO: 0.74 ± 0.21°C, P = 0.65) temperature, whole-body sweat loss (WBSL) (HI: 434 ± 80 ml, LO: 440 ± 41 ml; P = 0.86), and steady-state local sweating (LSRback) ( P = 0.40) were all similar despite relative exercise intensity being different (HI: 39.7 ± 4.2%, LO: 57.6 ± 8.0% V̇o2 peak; P = 0.001). At 60% V̇o2 peak, Hprod was greater in the HI (834 ± 77 W, 10.7 ± 1.3 W/kg or 423 ± 44 W/m2) compared with LO (600 ± 90 W, 7.7 ± 1.4 W/kg or 310 ± 50 W/m2) group (all P < 0.001), as were changes in Tre (HI: 1.43 ± 0.28°C, LO: 0.89 ± 0.19°C; P = 0.001) and Tau (HI: 1.11 ± 0.21°C, LO: 0.66 ± 0.14°C; P < 0.001), and WBSL between 0 and 15, 15 and 30, 30 and 45, and 45 and 60 min (all P < 0.01), and LSRback ( P = 0.02). The absolute esophageal temperature (Tes) onset for sudomotor activity was ∼0.3°C lower ( P < 0.05) in the HI group, but the change in Tes from preexercise values before sweating onset was similar between groups. Sudomotor thermosensitivity during exercise were similar in both FHP ( P = 0.22) and REL ( P = 0.77) trials. In conclusion, changes in core temperature and sweating during exercise in a neutral climate are determined by Hprod, mass, and BSA, not V̇o2 peak.

scholarly journals Influence of mild cold on 24 h energy expenditure, resting metabolism and diet-induced thermogenesis

1981 ◽  
Vol 45 (2) ◽  
pp. 257-267 ◽  
Author(s):  
M. J. Dauncey
Keyword(s):  
Energy Expenditure ◽  
Heat Loss ◽  
Heat Production ◽  
Total Heat ◽  
Whole Body ◽  
Partial Replacement ◽  
Total Heat Loss ◽  
Resting Metabolism ◽  
Diet Induced Thermogenesis ◽  
Lower Temperature

1. It has been suggested previously that people in developed countries do not expose themselves to cold severe enough to induce a metabolic response. The energy expenditure, as both heat production and total heat loss, of nine women was therefore measured continuously while each lived for 30 h in a whole-body calorimeter on two occasions, one at 28° and the other at 22°. All subjects followed a predetermined pattern of activity and food intake. The environmental conditions were judged by the subjects to be within those encountered in everyday life. In the standard clothing worn, 28° was considered to be comfortably warm but not too hot, while 22° was judged to be cool but not too cold.2. Heat production for 24 h was significantly greater at the lower temperature, by (mean ± SE) 7.0 ± 1.1%. The range was between 2 and 12%. Total heat loss was also significantly greater, by 6%, and there was a large change in the partition of heat loss. At the lower temperature sensible heat loss increased by 29% while evaporative heat loss decreased by 39%.3. Resting metabolism measured in the morning 12–13 h after the last meal was significantly greater at 22° than at 28°, whereas there was no difference when the resting measurement was made for 2.5 h following a meal.4. In conclusion: (a)environmental temperature may play a more important role than was previously recognized in the energy balance of those living in this country, and (b) there is an indication of at least a partial replacement of cold-induced by diet-induced thermogenesis in man.

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.

scholarly journals Influence of dietary non-protein energy intake on whole-body protein turnover in chicks

1989 ◽  
Vol 61 (2) ◽  
pp. 235-244 ◽  
Author(s):  
K. Kita ◽  
T. Muramatsu ◽  
I. Tasaki ◽  
J. Okumura
Keyword(s):  
Energy Intake ◽  
Heat Production ◽  
Protein Turnover ◽  
Total Heat ◽  
Metabolizable Energy ◽  
Whole Body ◽  
Synthesis Rate ◽  
Dietary Energy ◽  
Body Protein ◽  
Dietary Energy Intake

1. Three experiments were conducted to investigate the influence of dietary energy intake on whole-body protein turnover in chicks.2. In Expt 1 a semi-purified diet with various dietary metabolizable energy (ME) concentrations, 10.9, 12.6, 14.2 and 15.9 kJ/g, was fed ad lib. to young chicks. Whole-body fractional synthesis rate (FSR) was increased with each increment in dietary ME level from 12.6 to 15.9 kJ/g, and whole-body fractional degradation rate (FDR) showed a similar, though less sensitive, trend to that of FSR.3. In Expts 2 and 3, chicks were given graded ME intakes of 84, 126, 167, 209 or 293 kJ/d with a fixed intake of dietary protein. FSR was increased when the energy intake was raised from 84 to 167 kJ/d, and above this level it was almost constant. Similar to the trend obtained with ad lib. feeding, the response of FDR to changes in dietary energy intake was less sensitive than that of FSR.4. Total heat production was increased when dietary energy intake was increased from 84 to 167 kJ/d, and there was no further increase at 209 kJ/d. In contrast, the contribution of protein synthesis to total heat production was not affected by varying the dietary energy intake.

scholarly journals Oxidative fuel selection and shivering thermogenesis during a 12- and 24-h cold-survival simulation

2016 ◽  
Vol 120 (6) ◽  
pp. 640-648 ◽  
Author(s):  
François Haman ◽  
Olivier L. Mantha ◽  
Stephen S. Cheung ◽  
Michel B. DuCharme ◽  
Michael Taber ◽  
...  
Keyword(s):  
Cold Exposure ◽  
Muscle Glycogen ◽  
Whole Body ◽  
Muscle Recruitment ◽  
Glycogen Depletion ◽  
Total Carbohydrate ◽  
Fuel Selection ◽  
Isotopic Methods ◽  
Shivering Thermogenesis

Because the majority of cold exposure studies are constrained to short-term durations of several hours, the long-term metabolic demands of cold exposure, such as during survival situations, remain largely unknown. The present study provides the first estimates of thermogenic rate, oxidative fuel selection, and muscle recruitment during a 24-h cold-survival simulation. Using combined indirect calorimetry and electrophysiological and isotopic methods, changes in muscle glycogen, total carbohydrate, lipid, protein oxidation, muscle recruitment, and whole body thermogenic rate were determined in underfed and noncold-acclimatized men during a simulated accidental exposure to 7.5°C for 12 to 24 h. In noncold-acclimatized healthy men, cold exposure induced a decrease of ∼0.8°C in core temperature and a decrease of ∼6.1°C in mean skin temperature (range, 5.4-6.9°C). Results showed that total heat production increased by approximately 1.3- to 1.5-fold in the cold and remained constant throughout cold exposure. Interestingly, this constant rise in Ḣprod and shivering intensity was accompanied by a large modification in fuel selection that occurred between 6 and 12 h; total carbohydrate oxidation decreased by 2.4-fold, and lipid oxidation doubled progressively from baseline to 24 h. Clearly, such changes in fuel selection dramatically reduces the utilization of limited muscle glycogen reserves, thus extending the predicted time to muscle glycogen depletion to as much as 15 days rather than the previous estimates of approximately 30–40 h. Further research is needed to determine whether this would also be the case under different nutritional and/or colder conditions.

Circadian rhythm changes in core temperature over the menstrual cycle: method for noninvasive monitoring

2000 ◽  
Vol 279 (4) ◽  
pp. R1316-R1320 ◽  
Author(s):  
Mary D. Coyne ◽  
Christina M. Kesick ◽  
Tammy J. Doherty ◽  
Margaret A. Kolka ◽  
Lou A. Stephenson
Keyword(s):  
Circadian Rhythm ◽  
Menstrual Cycle ◽  
Core Temperature ◽  
Temperature Sensor ◽  
Temperature Sensors ◽  
Cycle Phase ◽  
Noninvasive Method ◽  
Menstrual Cycle Phase ◽  
Cosinor Analysis ◽  
Temperature Amplitude

The purpose of this study was to determine whether core temperature (Tc) telemetry could be used in ambulatory women to track changes in the circadian Tc rhythm during different phases of the menstrual cycle and, more specifically, to detect impending ovulation. Tcwas measured in four women who ingested a series of disposable temperature sensors. Data were collected each minute for 2–7 days and analyzed in 36-h segments by automated cosinor analysis to determine the mesor (mean temperature), amplitude, period, acrophase (time of peak temperature), and predicted circadian minimum core temperature (Tc-min) for each cycle. The Tcmesor was higher ( P ≤ 0.001) in the luteal (L) phase (37.39 ±0.13°C) and lower in the preovulatory (P) phase (36.91 ±0.11°C) compared with the follicular (F) phase (37.08 ±0.13°C). The predicted Tc-min was also greater in L (37.06 ± 0.14°C) than in menses (M; 36.69 ± 0.13°C), F (36.6 ± 0.16°C), and P (36.38 ± 0.08°C) ( P ≤ 0.0001). During P, the predicted Tc-min was significantly decreased compared with M and F ( P ≤ 0.0001). The amplitude of the Tc rhythm was significantly reduced in L compared with all other phases ( P ≤ 0.005). Neither the period nor acrophase was affected by menstrual cycle phase in ambulatory subjects. The use of an ingestible temperature sensor in conjunction with fast and accurate cosinor analysis provides a noninvasive method to mark menstrual phases, including the critical preovulatory period.

Interaction of central and peripheral factors in physiological temperature regulation

1961 ◽  
Vol 200 (3) ◽  
pp. 572-580 ◽  
Author(s):  
M. M. Fusco ◽  
J. D. Hardy ◽  
H. T. Hammel
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Heat Production ◽  
Temperature Regulation ◽  
Physiological Temperature ◽  
Warm Environment ◽  
Quantitative Estimates ◽  
Cool Environment ◽  
Localized Heating ◽  
Environmental Temperatures

To evaluate the relative importance of central and peripheral factors in physiological temperature regulation, calorimetric measurements of thermal and metabolic responses in the unanesthetized dog to localized heating of the supraoptic and preoptic regions were made at various environmental temperatures. At all temperatures, heating the hypothalamus caused an imbalance in the over-all heat exchange, and lowered core temperature by 0.8°–1.0°C. In a neutral environment, this was effected by a 30–40% depression of the resting rate of heat production. In a cool environment, heating inhibited shivering so that heat production, relative to heat loss, was low. In a warm environment, vigorous panting and vasodilatation were elicited, thereby increasing heat loss. On cessation of heating, shivering occurred in response to the lowered core temperature, but differed in intensity depending upon the peripheral thermal drive. Reapplication of heating suppressed shivering in all cases. From these data some quantitative estimates were made of the sensitivity of the hypothalamic thermoregulatory ‘centers’, and of the interaction and relative contributions of central and peripheral control.

scholarly journals Development of a new militarily-relevant whole-body low-intensity blast model for mild and subconcussive traumatic brain injury: Examination of acute neurological and multi-organ pathological outcomes

2021 ◽  
Author(s):  
Sarah C Hellewell ◽  
Ibolja Cernak
Keyword(s):  
Shock Tube ◽  
Brain Injuries ◽  
Neuronal Damage ◽  
Clinical Findings ◽  
Neurological Dysfunction ◽  
Whole Body ◽  
Bipedal Stance ◽  
Low Intensity ◽  
Realistic Representation ◽  
Blast Induced Neurotrauma

This work describes a newly developed experimental mouse model reproducing features of blast-induced neurotrauma (BINT), induced in operationally relevant manner using a compressed air-driven shock tube. Mild BINT (smBINT) was induced by one exposure to a low-intensity blast (LIB), whereas subconcussive BINT (rscBINT) was caused by repeated exposures to LIB. To mimic an operational scenario when a soldier is standing when exposed to blast using a quadruped experimental animal (mouse), a whole-body holder was developed to position mice in a bipedal stance, face-on toward the pressure wave generated in a shock tube. This restraint avoids bobble head movement, thus prevents tertiary blast effects, and allows administration of fast-acting inhaled anesthetics via nose cone. Using this model, we established and validated paradigms for primary blast-induced mild and repetitive traumatic brain injuries Our results showed that a single exposure to 69 kPa (10 psi) was capable of inducing smBINT, whereas three-rounds of exposure to 41 kPa (6 psi) caused rscBINT. Mice recovered rapidly from both types of BINT without prolonged neurological dysfunction. Mild superficial pathology was found predominantly in the lungs 24h after injury, with equivalent pathology after smBINT or repetitive rscBINT. The Purkinje layer of the cerebellum exhibited neuronal damage persisting up to 7d. Similar to some other models as well as clinical findings, this model reproduces blast-induced cerebellar pathology. In conclusion, this model positioning mice in a bipedal stance and facing front-on toward the shockwave provides realistic representation of operational scenarios and reproduces militarily-relevant smBINT and rscBINT in the laboratory.

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