Determination of body heat storage in clothing: calorimetry versus thermometry

Two methods of estimating body heat storage were compared under differing conditions of clothing, training, and acclimation to heat. Six male subjects underwent 8 weeks of physical training [60–80% of maximal aerobic power ( ) for 30–45 min · day–, 3–4 days · week^–1 at < 25 °C dry bulb (db)] followed by 6 consecutive days of heat acclimation (45–55% for 60 min · day^–1 at 40°C db, 30% relative humidity)]. Nine other male subjects underwent corresponding periods of control observation followed by heat acclimation. Before and after each treatment, subjects walked continuously on a treadmill (1.34 m · s^–1, 2% grade) in a climatic chamber (40°C db, 30% relative humidity) for an average of 118 min (range 92–120 min) when wearing normal light combat clothing and for an average of 50 min (range 32–68 min) when wearing protective clothing resistant to nuclear, biological, and chemical agents. The heat storage was determined calorimetrically (by the balance of heat gains and losses) and thermometrically [by the conventional equations, using one or two set(s) of relative weightings for the rectal temperature (T _re) to mean skin temperature _sk of 4:1 and 4:1, 2:1 and 4:1, or 2:1 and 9:1 in thermoneutral and hot environments, respectively]. _sk was calculated from 12-site measurements, weighted according to the regional distribution of body surface area and the first eigenvectors of principal component analysis. There were only minor differences (< 5%) between the heat storage values calculated by given weighting factors forT _re and _sk, whether the individual coefficients were derived from estimates of regional surface area or principal component methodologies. When wearing normal clothing, no significant differences were found between the two estimates of heat storage (calorimetry vs thermometry with an invariant relative weighting of 4:1) in any experimental condition, with one specific exception: when wearing protective clothing, thermometry underestimated the heat storage by 24–31%. This underestimation was attenuated by using two sets of relative weightings of 2: 1 and 4: 1 or 2: 1 and 9: 1. The results suggest that when subjects wearing protective clothing are transferred from thermoneutral to hot environments, the accuracy of thermometric estimates of heat storage can be improved by using two sets of weighting factors forT _re and _sk     

Heat emission and body temperature of albino rats exposed to hyperbaric oxygen

In model experiments in which bodies simulating an animal were heated under steady-state conditions the effect of hyperbaric oxygen (1.2–4 atm) on the level of heat flow (HF) from the bodies and their temperature was studied. Under hyperbaric conditions an increased level of HF was recorded, followed by a decrease as the exposure continued. At the same time the temperature of these bodies fell, evidence of increased heat loss. Periods of compression and decompression were accompanied by a marked rise and fall of HF respectively. In experiments on albino rats fluctuations in the HF level during compression and decompression were smaller, the HF level during exposure to a constant high pressure remained virtually constant, and the rectal and subcutaneous temperature did not differ statistically significantly from their initial level. It is suggested that this effect may be the result of increased heat production.Department of Hypoxic States, A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. (Presented by Academician of the Academy of Medical Sciences of the USSR, N. N. Sirotinin.) Translated from Byulleten' Éxperimental'noi Biologii i Meditsiny, Vol. 86, No. 10, pp. 410–414, October, 1978.     

Human body temperature is inversely correlated with body mass

Summary Forty-two women and 18 men of mean age 54 years had their sub-lingual oral temperature measured hourly from 0700 h to 2300 h. Mean oral temperature (averaged over the 17 readings) was inversely correlated with body mass in the group as a whole (r=−0.44,df=58,p=0.0003). The women had significantly higher mean oral temperatures than the men, but the inverse relationship between mean oral temperature and body mass was still significant when the data from the women were analyzed separately (r=−0.37,df=40,p=0.013). The results suggest that in humans, mean body temperature is inversely related to body mass, irrespective of gender.     

Body temperature and heart rate relationships during submaximal bicycle ergometer exercises

Summary Twenty-three male subjects performed submaximal exercise at approximately 80% max on a bicycle ergometer. Rectal temperature, skin temperatures, and heart rate measurements were taken during the exercise and during the corresponding recovery periods. The lag in body temperature (rectal temperature and mean body temperature) responses at the onset of exercise or recovery from exercise was shown in comparison with heart rate. Certain differences existed in the relationship between body temperature and heart rate during the exercise and the recovery period. The correlation coefficient of body temperature with heart rate was high from the 24th min of exercise until the 21st min of the recovery period. The regression equation of post-work rectal temperature on heart rate at moderate work loads (approximately 80% max) in the present study was similar to the equation at light work loads (25∼35% max) for data reported from different laboratories. However, at the termination of exercise the regression equation of rectal temperature on heart rate at light work loads from different laboratories does not agree with the equation of rectal temperature on heart rate at moderate exercise, in the present study. There is good agreement with the equation from the maximum state at a moderate exercise (times of maximum heart rate against maximum body temperature). The correlation coefficients for rectal temperature on heart rate at the maximum state were high. The relationship between body temperature and heart rate at the termination of light exercise is similar to that between these two parameters at the maximum state for moderate exercise.     

Residual analysis in the determination of factors affecting the estimates of body heat storage in clothed subjects

Body heat storage can be estimated by calorimetry (from heat gains and losses) or by thermometry [from changes (Δ) in mean body temperature (T _b) calculated as a weighted combination of rectal (T _re) and mean skin temperatures (T _sk)]. If an invariant weighting factor ofT _re andT _sk were to be used (for instance, ΔT _b = 0.8 · ΔT _re + 0.2 · ΔT _sk under hot conditions), body heat storage could be over- or underestimated substantially relative to calorimetry, depending on whether the subject was wearing light or protective clothing. This study investigated whether discrepancies between calorimetry and thermometry arise from methodological errors in the calorimetric estimate of heat storage, from inappropriate weightings in the thermometric estimate, or from both. Residuals of calorimetry versus thermometric estimates were plotted against individual variables in the standard heat balance equation, applying various weighting factors toT _re andT _sk. Whether light or protective clothing was worn, the calorimetric approach generally gave appropriate estimates of heat exchange components and thus heat storage. One exception was in estimating latent heat loss from sweat evaporation. If sweat evaporation exceeded 650 g·h⁻¹ when wearing normal clothing, evaporative heat loss was overestimated and thus body heat storage was underestimated. Nevertheless, if data beyond this ceiling were excluded from the analyses, the standard 4:1 weighting matched calorimetric heat storage estimates quite well. When wearing protective clothing, the same 4:1 weighting approximated calorimetric heat storage with errors of less than approximately 10%, but only if environmental conditions allowed a subject to exercise for more than 90 min. The best thermometric estimates of heat storage were provided by using two sets of relative weightings, based upon the individual's metabolic heat production ( in kilojoules per metre squared per hour): {4 − [( )· ] 2}:1 for an initial, thermoneutral environment and {4 + [( ) · ] · 5}: 1 for a final, hot environment; the optimal value of lay between 450 and 500 kJ m⁻² · h⁻¹. We concluded that the accuracy of thermometric estimates of heat storage can be improved by modifying weighting factors ofT _re andT _sk according to the environment, type of clothing, and metabolic rate.     

Daily activity and body temperature

Summary Body temperature varies between 36 and 39° C in states ranging from sleep to high levels of sustained exercise, but it is not known whether this continuum of body temperature is related to a continuum of activity. Calorimetric studies of sedentary days were undertaken with four levels of food intake, men doing mild sustained exercise, and men and women walking and cycling vigorously. Steady states of metabolism were followed by slow exponential changes to steady states of heat loss (Q), followed in turn by changes in rectal temperature (T _re). Regression analysis showed a continuous, curvilinear relationship between Q andT _re from the low end of the activity spectrum (50 W) to progressively higher levels of exercise (600 W). These related continua of activity and body temperature appear to be the result of heat regulation.     

Heat regulation during exercise with controlled cooling

Summary During heavy sustained exercise, when sweating is usually needed to dissipate the extra metabolic heat, controlled cooling caused heat loss to match total heat production with little sweating. The total heat produced and metabolic rate were varied independently by having subjects walk uphill and down. Heat loss was measured directly with a suit calorimeter; other measurements included metabolic energy from respiratory gas exchange and body temperatures. Thermoregulatory sweating was minimized by adjusting cooling in the calorimeter suit. Heat loss rose to match total heat, not metabolic rate, and there was a slow rise in rectal temperature. In the absence of major thermoregulatory response rectal temperature correlated most closely with total heat; it also correlated with the relative oxygen cost of exercise. Heat flow or heat content appeared to be the controlled variable and body temperature rise a secondary event resulting from thermal transport lag.     

丙基硫氧嘧啶对冷环境中大鼠体温的影响

目的:研究冷暴露对大鼠体温调节功能的影响。方法:给大鼠服用抗甲状腺素药物丙基硫氧嘧啶(PTU)复制甲状腺功能低下模型。用数字体温计测量大鼠的结肠温度,放射免疫方法测量血浆中的T₃和T₄浓度。在连续给PTU两周后,观察大鼠暴露到冷环境中时体温的变化。结果:给大鼠PTU两周后,血浆中T₃和T₄浓度显著低于对照组(P<0.01),同时体温也明显降低(P<0.01);但将大鼠置于6℃冷环境中时,体温的升高反应与对照组比较无明显差异。结论:甲状腺功能低下的大鼠短时间暴露于冷环境中,仍具有足够的生热反应。     

Effects of partial humid heat exposure during different segments of sleep on human sleep stages and body temperature

The effects of partial humid heat exposure applied at different segments of sleep on sleep stages and body temperature were examined. In the first experiment, eight male subjects slept under 26 degrees C 50% (26) and 26 degrees C for the first 3 h and 45 min followed by a 30-min transition to the conditions of 32 degrees C 80%, which was maintained for the final 3 h and 45 min (26-32). Wakefulness increased significantly over the last 4 h under 26-32 compared to 26. Mean skin temperature and clothing microclimate temperature (Tcm) were significantly higher during the last 3 h and 45 min, while rectal temperature (Tre) was higher during the last 3 h under 26-32 than in 26. In the second experiment, eight male subjects slept under 26 degrees C 50% (26) and 32 degrees C 80% for the first 3 h and 45 min followed by a 30-min transition to 26, which was then maintained for the last 3 h and 45 min (32-26). Wakefulness increased both in first and during the last 4 h, and slow wave sleep (SWS) decreased in the first 4 h under 32-26 compared to 26. Mean Tsk was significantly higher during the first 4:15 h. Tcm decreased in 32-26 compared to 26 just after the 30-min transition due to cooling effects. Tre was higher during the first 5 h under 32-26 compared to 26. These results suggest that humid heat exposure during the initial segment of sleep may be more disruptive to sleep stage distribution, Tre decline, and maintenance of Tcm than the same exposure during the later sleep segments.     

Effects of anesthetic injected into brainstem sites on body temperature and behavioral thermoregulation

The preoptic/anterior hypothalamic region (PO/AH), the posterior (PH) and lateral hypothalamic (LH) regions, the mesencephalic reticular formation (MRF) and the medulla oblongata (MED) have all been implicated in the control of body temperature. The purpose of the present research was to learn whether differential effects upon physiological and behavioral thermoregulation are produced by temporarily depressing the activity of these regions with anesthetic. The rectal temperature (T_re) of rats with central cannulae was recorded after sodium pentobarbital injections while the animals rested in 23°, 10° and 34°C environments. In other experiments the effects of central anesthetic injections on behavioral regulation against heat were measured. Anesthetic injected into the PO/AH region caused changes in T_re and behavior that are consistent with a coordinated rise in the set point of body temperature control. Injections into the MED produced transient and rapid decreases in T_re without affecting behavioral thermoregulation. Bilateral injections into the LH caused hyperthermia in the 10° and 34°C environments, hypothermia in the 23°C environment and had no effect on behavioral temperature regulation. No changes in thermoregulatory responses were observed after PH and MRF injections. These results indicate that there are differences among the 5 brain regions in relative importance to overall temperature control and specific differences in the significance of certain regions to the two forms of temperature control; physiological and behavioral temperature regulation.     

Effect of massage therapy on preterm neonate's body temperature

BackgroundLow-cost care strategies can be implemented to avert the morbidity and mortality associated with hypothermia in preterm neonates.ObjectiveTo determine the effect of massage therapy on body temperature of preterm neonates.MethodsA quasi-experimental design was conducted among 72 preterm neonates at a level II special care nursery in Western Kenya. Neonates were recruited on the third day of life and followed up for 10 days. Neonates in the intervention group were massaged three times a day for 15 minutes. Body temperature was monitored and recorded before, during and after each therapy session. Neonates in the control group received routine care: temperature monitoring three times a day, feeding and diaper change.ResultsNeonates who received massage had higher mean body temperature than the control group during therapy on day 6 (p = .019) and after therapy on day 6 (p = .017) and day 8 (p = .005). A comparison within massage group (before/during, during/after, before/after) showed an increase in mean body temperature during therapy compared to before therapy (p <.001) and after therapy compared to before therapy (p <.001).ConclusionMassage therapy increases body temperature in preterm neonates.     

Analysis of the cold-water restraint procedure in gastric ulceration and body temperature

Gastric mucosal injury induced by body restraint can be enhanced when combined with cold-water immersion. Based on this fact, the present study had two main purposes: (i) to examine the contribution of each of these two forms of stress on the development of gastric ulceration and regulation of body temperature and (ii) to investigate the importance of the animal's consciousness on gastric ulceration induced by the cold-water restraint. Independent groups of animals were exposed for 3 h to one of the following stressful treatments: body restraint plus cold-water (20+1 degrees C) immersion, body restraint alone or cold-water immersion alone. Control animals were not exposed to any form of stress. Half of the animals submitted to each of the four treatments were anesthetized with thionembutal (35 mg/kg), whereas the other half was injected with saline. Results indicated that body restraint alone was not sufficient to induce gastric ulceration or changes in body temperature. On the other hand, cold-water exposure, either alone or in conjunction with body restraint, induced the same amount of stomach erosions and hypothermia. Therefore, it appears that body restraint does not play an important role on gastric ulceration induced by the cold-water restraint procedure. Present results also indicated that conscious and anesthetized animals immersed in cold water presented robust gastric ulceration and a marked drop in body temperature. However, conscious animals developed more severe gastric damage in comparison to anesthetized animals although both groups presented the same degree of hypothermia. These findings suggest that hypothermia resulting from cold-water exposure has a deleterious effect on gastric ulceration but the animal's conscious activity during the cold-water immersion increases the severity of gastric mucosal damage. It is concluded that cold-water restraint is a useful procedure for the study of the underlying mechanisms involved in stress-induced ulceration.     

Postmortem time estimation using body temperature and a finite-element computer model

In the Netherlands most murder victims are found 2–24 h after the crime. During this period, body temperature decrease is the most reliable method to estimate the postmortem time (PMT). Recently, two murder cases were analysed in which currently available methods did not provide a sufficiently reliable estimate of the PMT. In both cases a study was performed to verify the statements of suspects. For this purpose a finite-element computer model was developed that simulates a human torso and its clothing. With this model, changes to the body and the environment can also be modelled; this was very relevant in one of the cases, as the body had been in the presence of a small fire. In both cases it was possible to falsify the statements of the suspects by improving the accuracy of the PMT estimate. The estimated PMT in both cases was within the range of Henssges model. The standard deviation of the PMT estimate was 35 min in the first case and 45 min in the second case, compared to 168 min (2.8 h) in Henssges model. In conclusion, the model as presented here can have additional value for improving the accuracy of the PMT estimate. In contrast to the simple model of Henssge, the current model allows for increased accuracy when more detailed information is available. Moreover, the sensitivity of the predicted PMT for uncertainty in the circumstances can be studied, which is crucial to the confidence of the judge in the results.This work is based on the confidential reports TNO-TM-98-M57 and TNO-TM-00-C032 (in Dutch) to the specific forensic forces of the Dutch police     

Effect of posture on body temperature of young men in cold air

We studied eight young adult men to see whether a supine posture caused a fall in body core temperature in the cold, as it does in thermoneutral conditions. In air at 31°C (thermoneutral), a supine posture for 3 h reduced mean aural, gastric, oesophageal and rectal temperatures by 0.2–0.4°C, compared to upright and increased femoral artery blood flow from 278 (SEM 42) ml · min⁻¹ whilst upright to 437 (SEM 42) ml·min⁻¹ whilst supine. In cold air (8°C) the supine posture failed to reduce these temperature differences significantly, or to increase femoral blood flow; it reduced heart rate, and increased arterial systolic and pulse pressures adjusted to carotid sinus level, less than in thermoneutral conditions. However, the behaviour of core temperature at the four sites was significantly nonuniform between the two postures in the cold, mainly because the supine posture tended to reduce rectal temperature. It may have done so by reducing heat production in the muscles of the pelvis, since it reduced overall metabolic rate from 105 (SEM 8) to 87 (SEM 4) W · m⁻² in the cold. In other respects the results indicated that posture ceased to have an important effect on body core temperatures during cold stress.     

A thermographic study of the effect of body composition and ambient temperature on the accuracy of mean skin temperature calculations

Summary The problem associated with using measurements from a small number of sites to determine mean skin temperature was investigated by studying variations in distributions of skin temperatures of the bare torsos of humans exposed to ambient temperatures of 18, 23, and 28° C. Following a 60 minute equilibration period the temperatures of four regions (chest, abdomen, upper back, and lower back) were measured using both thermistors and an infra-red thermographic system. Regions of the torso usually represented by a single temperature exhibited significant point-to-point temperature variations especially in chilled subjects. Also an earlier finding was confirmed: in that larger variations in skin temperature distributions occur as body fat content increases. Caution must therefore be used in applying the concept of a mean skin temperature derived from a few select sites, especially with nude subjects who are chilled or have a high body fat content.     

Effects of local and core body temperature on grip force modulation during movement-induced load force fluctuations

Impaired manual functioning often occurs when the hands are exposed to cold temperatures, but the underlying mechanism is not clearly understood. Tactile feedback is thought to provide important information during object manipulations in order to scale and regulate grip forces; however, topical anaesthetic-induced tactile sensation impairments may not realistically simulate the systemic neuromuscular impairment of the whole hand that could occur during cold temperature exposure. In two experiments, we studied the impact of (1) local hand cooling [thermoneutral finger skin temperature, cold (<8°C)] and (2) core body temperature (thermoneutral core body temperature, pre-heated by 0.5°C, pre-cooled by 0.5°C) with cold hands on manual dexterity and the ability to control and co-ordinate grip forces during a cyclical load-lifting task. In Experiment 1 (n = 10), hand cooling significantly decreased Purdue Pegboard performance (P = 0.002), while increasing grip force by ∼5 N during the cyclical load-lifting task compared to thermoneutral (P = 0.037). The temporal co-ordination of grip and load forces was unaffected by hand cooling. In Experiment 2 (n = 11), pegboard performance was impaired following hand cooling (P < 0.001), and to a greater extent when the body was pre-cooled (p < 0.001). However, neither grip force (P = 0.99) nor the temporal co-ordination of grasping and lifting forces (P = 0.85) were affected by core body temperature. These data support the existence of a robust centrally controlled feedforward system able to anticipate the dynamics of manual manipulations and accordingly regulate the temporal co-ordination of fingertip forces during object manipulation. This centrally controlled mechanism appears to differ from the mechanisms governing other aspects of manual dexterity.     

Restoration of vital activity of cooled animals without rewarming the body

The fatality of deep hypothermia in non-hibernating mammals follows the cessation of respiration and heart beat, and a massive influx of calcium (Ca⁺⁺) into cells. This review presents evidence relating to restoration of key physiological functions during hypothermia in several animal preparations. For example, in anaesthetized hypothermic rats (body temperature 16–17°C), a pharmacologically induced reduction in intracellular [Ca⁺⁺] [via intravenous administration of an ethylenediaminetatraacetate (EDTA) solution (0.15–0.16 mmole)] has been shown to restore cold shivering and respiration after several minutes. Also, activity in an isolated rat heart preparation has been shown to be halted when temperature is reduced in the range 14–12°C. However, decreasing the perfusate [potassium] by a factor of 2–3 relative to normal blood levels restored contractile activity. In conclusion, it is possible to restore the activity of key physiological systems involved in the thermoregulatory responses to sustained hypothermia without the need to rewarm the organism.     

Two aspects of body in psychoanalytic treatment

ABSTRACT

The article will describe two ways of using the body as an integral part of psychoanalytic psychotherapy, in order to find additional possibilities of healing in the therapeutic work.

We will present two case studies that combine the psychoanalytic perspective with that of body psychotherapy and with the practice of yoga in the spirit of non-duality.     

Circadian rhythm of core body temperature in two laboratory mouse lines

The circadian rhythm of core body temperature (Tb) was examined in two mouse lines bidirectionally selected for nest-building behavior (small (SNB) and big nest-builders (BNB)). This selection also resulted in more robust circadian organization of wheel-running activity in the SNB compared to the BNB mice. Tb was measured by an e-mitter implanted in the abdominal cavity. The circadian Tb rhythm of the SNB was more robust compared to the BNB regardless of whether the animals had access to a running wheel or not and regardless of the lighting conditions, i.e., 12 h:12 h light:dark (LD) cycle or constant dark (DD). Wheel-running activity rhythms of SNB were more robust in LD and DD compared to BNB. The amplitude of the circadian Tb rhythm increased significantly in response to wheel access in both mouse lines, but was not significantly different between the BNB and SNB. However, BNB tended to have lower amplitudes of circadian Tb rhythm in the absence of running wheels and a larger increase in the amplitude upon access to a running wheel compared to SNB. No differences were found in LD and DD between the lines in mean Tb and wheel-running activity levels. In addition, no differences between the two mouse lines were found in the free-running period of the Tb or wheel-running activity rhythms in DD. Overall, our findings reveal a more robust circadian phenotype of the SNB compared to the BNB.