Thermoregulatory influence of a cooling vest on hyperthermic athletes

CONTEXT: Athletic trainers must have sound evidence for the best practices in treating and preventing heat-related emergencies and potentially catastrophic events. OBJECTIVE: To examine the effectiveness of a superficial cooling vest on core body temperature (T(c)) and skin temperature (T(sk)) in hypohydrated hyperthermic male participants. DESIGN: A randomized control design with 2 experimental groups. SETTING: Participants exercised by completing the heat-stress trial in a hot, humid environment (ambient temperature = 33.1 +/- 3.1 degrees C, relative humidity = 55.1 +/- 8.9%, wind speed = 2.1 +/- 1.1 km/hr) until a T(c) of 38.7 +/- 0.3 degrees C and a body mass loss of 3.27 +/- 0.1% were achieved. PATIENTS OR OTHER PARTICIPANTS: Ten healthy males (age = 25.6 +/- 1.6 years, mass = 80.3 +/- 13.7 kg). INTERVENTION(S): Recovery in a thermoneutral environment wearing a cooling vest or without wearing a cooling vest until T(c) returned to baseline. MAIN OUTCOME MEASURE(S): Rectal T(c), arm T(sk), time to return to baseline T(c), and cooling rate. RESULTS: During the heat-stress trial, T(c) significantly increased (3.6%) and, at 30 minutes of recovery, T(c) had decreased significantly (2.6%) for both groups. Although not significant, the time for return to baseline T(c) was 22.6% faster for the vest group (43.8 +/- 15.1 minutes) than for the no-vest group (56.6 +/- 18.0 minutes), and the cooling rate for the vest group (0.0298 +/- 0.0072 degrees C/min) was not significantly different from the cooling rate for the no-vest group (0.0280 +/- 0.0074 degrees C/min). The T(sk) during recovery was significantly higher (2.1%) in the vest group than in the no-vest group and was significantly lower (7.1%) at 30 minutes than at 0 minutes for both groups. CONCLUSIONS: We do not recommend using the cooling vest to rapidly reduce elevated T(c). Ice-water immersion should remain the standard of care for rapidly cooling severely hyperthermic individuals.     

Comparison of rectal and aural core body temperature thermometry in hyperthermic, exercising individuals: a meta-analysis

Objective:

To compare mean differences in core body temperature (T_core) as assessed via rectal thermometry (T_re) and aural thermometry (T_au) in hyperthermic exercising individuals.

Data Sources:

PubMed, Ovid MEDLINE, SPORTDiscus, CINAHL, and Cochrane Library in English from the earliest entry points to August 2009 using the search terms aural, core body temperature, core temperature, exercise, rectal, temperature, thermistor, thermometer, thermometry, and tympanic.

Study Selection:

Original research articles that met these criteria were included: (1) concurrent measurement of T_re and T_au in participants during exercise, (2) minimum mean temperature that reached 38°C by at least 1 technique during or after exercise, and (3) report of means, standard deviations, and sample sizes.

Data Extraction:

Nine articles were included, and 3 independent reviewers scored these articles using the Physiotherapy Evidence Database (PEDro) scale (mean  =  5.1 ± 0.4). Data were divided into time periods pre-exercise, during exercise (30 to 180 minutes), and postexercise, as well as T_re ranges <37.99°C, 38.00°C to 38.99°C, and >39.00°C. Means and standard deviations for both measurement techniques were provided at all time intervals reported. Meta-analysis was performed to determine pooled and weighted mean differences between T_re and T_au.

Data Synthesis:

The T_re was conclusively higher than the T_au pre-exercise (mean difference [MD]  =  0.27°C, 95% confidence interval [CI]  =  0.15°C, 0.39°C), during exercise (MD  =  0.96°C, 95% CI  =  0.84°C, 1.08°C), and postexercise (MD  =  0.71°C, 95% CI  =  0.65°C, 0.78°C). As T_re measures increased, the magnitude of difference between the techniques also increased with an MD of 0.59°C (95% CI  =  0.53°C, 0.65°C) when T_re was <38°C; 0.79°C (95% CI  =  0.72°C, 0.86°C) when T_re was between 38.0°C and 38.99°C; and 1.72°C (95% CI  =  1.54°, 1.91°C) when T_re was >39.0°C.

Conclusions:

The T_re was consistently greater than T_au when T_core was measured in hyperthermic individuals before, during, and postexercise. As T_core increased, T_au appeared to underestimate T_core as determined by T_re. Clinicians should be aware of this critical difference in temperature magnitude between these measurement techniques when assessing T_core in hyperthermic individuals during or postexercise.     

Changes in thermal homeostasis in humans due to repeated cold water immersions

The purpose of this study was to monitor changes in body and skin temperatures, heat production, subjective shivering, cold sensation and body fat content in humans after intermittent cold water immersion. Repeated exposures of young sportsmen to cold water (head out, 14 °C, 1 h, 3 times per week for 4–6 weeks) induced changes in regulation of thermal homeostasis. ‘‘Cold acclimated’’ subjects exhibited an hypothermic type of adaptation. Central and peripheral body temperatures at rest and during cold immersion were lowered. The metabolic response to cold was delayed and subjective shivering was attenuated. The observed hypothermia was due to the shift of the threshold for induction of cold thermogenesis to lower body temperatures. ‘‘Cold acclimated’’ subjects also showed a lowered cold sensation. Because of the observed physiological changes, about 20% of the total heat production was saved during one cold water immersion of ‘‘cold acclimated’’ subjects. Maximal aerobic and anaerobic performances were not altered. No change in the thermosensitivity of the body temperature controller, as assessed from the unchanged slope of the relation between the deep body temperature and total heat production, was observed. Changes in cold sensation and regulation of cold thermogenesis were noticed first after four cold water immersions and persisted for at least 2 weeks after termination of the adaptation procedure. A trend towards a small increase in the body fat content was also observed. This findll as the increased vasoconstriction, evidenced by the lowered skin temperature, indicate that slight changes in body insulation may also occur after ‘‘cold acclimation’’ in humans. Received: 30 December 1995/Received after revision and accepted: 25 March 1996     

Effects of cold stress on body temperature of immunosympathectomized mice

In Experiment 1, immunosympathectomized and injected control mice were immersed to the neck in 26°C water for 12 min, while in Experiment 2, they were briefly immersed and then exposed to 23.5°C air. In both experiments, the immunosympathectomized mice became colder than controls reflecting their relative inability to thermoregulate.     

Involvement of the parabrachial nucleus in thermogenesis induced by environmental cooling in the rat

The parabrachial nucleus (PBN), an integration site for autonomic regulation in the mesopontine brainstem, receives sensory information about cold temperatures from the skin. Here we investigated the role of the PBN in thermoregulation. Unilateral stimulation of the PBN (10–40 A, 5 min) immediately increased the rate of O₂ consumption (O₂) and heart rate, and the magnitude of these responses increased with the intensity of the stimulus in urethane-anesthetized rats. High-intensity (40 A) stimulation of the PBN increased the temperature of the interscapular brown adipose tissue and that of the colon but had no effect on that of the tail skin, although weaker stimulation was without effect on these temperatures. Next, we examined the effects of bilateral lesioning of the PBN on environmental cooling-induced thermogenesis in conscious rats. Exposure of PBN-lesioned rats to a cool (16.6°C) environment induced a significantly smaller increase in O₂ than did that of rats with a sham operation or with lesions made outside of the PBN, and resulted in a marked decrease in body temperature in PBN-lesioned rats but not in other rats. Both frequency and duration of gross motor activity in the cool environment were similar between PBN-lesioned and sham-operated rats. These results suggest that the PBN is involved in the central mechanisms of cooling-induced thermogenesis.     

腔道肿瘤微波热疗中有效治疗体积与冷却水温关系研究

肿瘤热疗可用活组织中的有效治疗深度ＥＴＤ（如： 定义为温度在４１～４５℃范围的距离）和有效治疗体积ＥＴＶ（定义为相应于有效治疗温度范围的体积）来衡量一次加热治疗的优劣及满意程度,但在实测时常难以实现。本文根据腔内水冷式微波偶极子辐射器近场辐射模型,求解生物介质热传导方程,运用数值计算方法得到水冷式腔道辐射器在等效组织模型中的稳态温度分布; 并对腔道肿瘤微波热疗时有效治疗体积与冷却水温关系进行仿真计算研究。结果表明：水冷可改善热区温度分布,使径向最高温度点由无水冷时贴近辐射器壁向组织深部迁移（本文示例当冷却水温Ｔｃ＝ １６℃时可达６ ｍ ｍ 以远）;径向治疗深度比无水冷时向组织内部扩展（上述冷却水温下可达３～４ ｍ ｍ 左右）; 相应的有效治疗体积则比无水冷时增加（上述条件下约为３９％ ）; 降低冷却水温（本文示例从１６℃降至１０℃）, 则相应的有效治疗深度又可向组织内部扩展; 有效治疗体积还可增加（约再增３３％ ）。由此引伸出在一次加热治疗时,若采取两步加热法, 即先用低功率、无水冷加热,后用高功率有循环水冷的加热程序,则总有效治疗体积可比完全无水冷时扩大１．２４ 倍（约增加４．３ ｃｍ ３）。本文模拟计算结果与相应的等效肌肉     

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.     

The trainability and contralateral response of cold-induced vasodilatation in the fingers following repeated cold exposure

Cold-induced vasodilatation (CIVD) is proposed to be a protective response to prevent cold injuries in the extremities during cold exposure, but the laboratory-based trainability of CIVD responses in the hand remains equivocal. Therefore, we investigated the thermal response across the fingers with repeated local cold exposure of the whole hand, along with the transferability of acclimation to the fingers of the contralateral hand. Nine healthy subjects immersed their right hand up to the styloid process in 8 degrees C water for 30 min daily for 13 days. The left hand was immersed on days 1 and 13. Skin temperature was recorded on the pads of the five fingertips and the dorsal surface of the hand. The presence of CIVD, defined as an increase in finger skin temperature of 0.5 degrees C at any time during cooling, occurred in 98.5% of the 585 (9 subjects x 5 sites x 13 trials) measurements. Seven distinct patterns of thermal responses were evident, including plateaus in finger temperature and superimposed waves. The number (N) of CIVD waves decreased in all digits of the right hand over the acclimation period (P = 0.02), from average (SD) values ranging from 2.7 (1.7) to 3 (1.4) in different digits on day 1, to 1.9 (0.9) and 2.2 (0.7) on day 13. Average (SD) finger skin temperature (T (avg)) ranged from 11.8 (1.4) degrees C in finger 5 to 12.7 (2.8) degrees C in finger 3 on day 1, and then decreased significantly (P < 0.001) over the course of the training immersions, attaining values ranging from 10.8 (0.9) degrees C in finger 4 to 10.9 (0.9) degrees C in finger 2 on day 13. In the contralateral hand, N was reduced from 2.5 to 1.5 (P < 0.01) and T (avg) by approximately 2 degrees C (P < 0.01). No changes were observed in thermal sensation or comfort of the hand over the acclimation. We conclude that, under conditions of whole-hand immersion in cold water, CIVD is not trainable and may lead to systemic attenuation of thermal responses to local cooling.     

Cold-induced vasodilatation in the foot is not homogenous or trainable over repeated cold exposure

Cold-induced vasodilatation (CIVD) is proposed to be a protective response to preserve tissue integrity in the extremities during cold exposure, but little research exists on either the trainability or the spatial pattern of CIVD response in the foot. We investigated the thermal response across the foot with repeated cold exposure. Ten healthy subjects immersed their left foot to the ankle in 8°C water for 30 min 5 days/week for 3 weeks. Skin temperature was recorded on the medial side of the nail bed of the 5 toes and the dorsum of the foot. The presence of CIVD, defined as an increase of 1°C at any time during cooling, was rare with our protocol. While a CIVD response was observed at least once in 8 of the 10 subjects, only 122 instances of CIVD were observed out of a total of 900 possible observations (10 subjects × 6 sites × 15 trials). Furthermore, thermal habituation was not evident, with toe temperatures at the end of each immersion (8–11°C) remaining near water temperature throughout the 15 sessions. Even within the two subjects exhibiting the most incidence of CIVD, high variability existed in the occurrence, magnitude, and/or onset times. Synchronicity was often observed where more than one toe exhibited CIVD, though the magnitude varied greatly (range 1–9°C). We conclude that, under realistic conditions of whole-foot immersion in cold water, CIVD is not a common or trainable response.     

Interactions between temperature and human leptin physiology in vivo and in vitro

To investigate the possibility that environmental temperature may exert physiologically significant direct, local effects on subcutaneous adipose tissue temperatures, and its secretion of leptin, we exposed healthy males (n=12) to repeated cold-water immersion (study 1), and also incubated surgically removed human subcutaneous adipose tissue samples (n=7) at 27°, 32° and 37°C (study 2). In vivo immersions were conducted over 15 days (60–90 min at 18°C). Regional body temperatures and plasma leptin concentrations were measured before and during immersion. Acute cold exposure suppressed plasma leptin concentration (25 min: –14%, 60 min: –22%, P=0.0001), whilst repeated cold-water immersion was associated with an increase of plasma leptin concentration relative to test day 1 (+19% day 8, +13% day 15, overall P=0.03). Leptin secretion in vitro decreased 3.7-fold as the incubation temperature decreased from 37° to 27°C (P=0.001). In a compartmental model of leptin turnover in vivo, the measured (local) temperature effect on leptin secretion in vitro was more than able to account for the observed cold-induced decrease in leptin concentration in vivo. We therefore conclude that acute and repeated cold-water immersions have separate and opposing effects on circulating leptin concentrations in humans. Under our experimental conditions, the local effects of reduced subcutaneous adipose tissue temperature may be a more important contributor to the acute effects observed in vivo, than the sympathetically mediated suppression of leptin secretion.     

Core temperature thresholds for hyperpnea during passive hyperthermia in humans

Humans have higher ventilation when they are hyperthermic but it is not known whether core temperature thresholds for ventilation exist, nor has a physiological rationale been presented for this response. To examine this question, ventilation was studied in relation to core temperatures in humans rendered hyperthermic in a warm bath. Seven subjects [mean (SE), 23.3 (1.4) years] wearing only shorts and a thick felt hat with ear flaps were immersed to the neck in a bath at 41 (0.5)°C for 25 min. Tympanic (T _ty), esophageal (T _es), thigh skin and forehead skin temperatures, heart rate, inspired minute ventilation (V _I at body temperature and pressure, saturated), ventilation frequency and oxygen consumption (VO₂ at standard temperature and pressure, dry) were recorded at 30-s intervals. At immersion V _I briefly increased to 18.6 (3.0)l·min^–1 returned to about the pre-immersion value,, and significantly increased to 19.3 (3.0) l·min^–1 by the end of immersion. VO₂ increased significantly from the pre-immersion value of 0.27 l·min^–1 to 0.67 l·min^–1 by the first 0.5 min of immersion, but then returned to its pre-immersion value. T _ty increased to 38.7 (0.2)°C and T _es increased to 39.0 (0.2)°C by the end of immersion. Core temperature thresholds for increases in V _I were evident at 38.1°C when expressed against T _ty and at 38.5°C when expressed against T _es. The results indicated that during body warming core temperature thresholds for V _I are reached and subsequently a hyperpnea was evident, despite VO₂ remaining at a resting value. This hyperpnea is seen as a thermoregulatory response likely to participate in selective brain cooling.     

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 total body core cooling on heat production of conscious goats

Experiments were performed to investigate the effect of general body core cooling on heat production at various air temperatures between +1°C and +56°C in conscious goats. An intravascular heat exchanger (IVHE) was used to alter body core temperature independently of air temperature. Heat loss via the IVHE caused a fall in body core temperature, the extent of which depended on the rate of extraction and air temperature. Irrespective of air temperature the decrease in body core temperature resulted in shivering and an increase in heat production, which eventually balanced the heat loss. During steady state conditions the extra heat production was approximately equal to that lost via the IVHE. The threshold body core temperature at which heat production increased in response to central cooling did not significantly alter with air temperature. However, the slopes of the curves describing this response were smaller at higher than at lower air temperatures, which indicated that central thermosensitivity decreased with increasing air temperature. Irrespective of air temperature the threshold temperatures for shivering were higher and the slopes of the curves were steeper than those previously found with combined cooling of the hypothalamus and spinal cord in the same species which indicated the existence of central thermosensors outside the above two mentioned areas.     

Roundtable on Preseason Heat Safety in Secondary School Athletics: Prehospital Care of Patients With Exertional Heat Stroke

ObjectiveFirst, we will update recommendations for the prehospital management and care of patients with exertional heat stroke (EHS) in the secondary school setting. Second, we provide action items to aid clinicians in developing best-practice documents and policies for EHS. Third, we supply practical strategies clinicians can use to implement best practice for EHS in the secondary school setting.Data SourcesAn interdisciplinary working group of scientists, physicians, and athletic trainers evaluated the current literature regarding the prehospital care of EHS patients in secondary schools and developed this narrative review. When published research was nonexistent, expert opinion and experience guided the development of recommendations for implementing life-saving strategies. The group evaluated and further refined the action-oriented recommendations using the Delphi method.ConclusionsExertional heat stroke continues to be a leading cause of sudden death in young athletes and the physically active. This may be partly due to the numerous barriers and misconceptions about the best practice for diagnosing and treating patients with EHS. Exertional heat stroke is survivable if it is recognized early and appropriate measures are taken before patients are transported to hospitals for advanced medical care. Specifically, best practice for EHS evaluation and treatment includes early recognition of athletes with potential EHS, a rectal temperature measurement to confirm EHS, and cold-water immersion before transport to a hospital. With planning, communication, and persistence, clinicians can adopt these best-practice recommendations to aid in the recognition and treatment of patients with EHS in the secondary school setting.     

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.     

Relationship between indices of adiposity obtained by peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in pre-pubertal children

Background/Aim: The study investigated the relationship between indices of adiposity measured by peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA) in pre-pubertal children.

Subjects and methods: DXA-derived per cent body fat (%BF) was measured in 284 boys and 288 girls, aged 7–10 years. Cross-sections of the forearm (n=427) and lower leg (n=560) were obtained by pQCT to measure total cross-sectional area of the limb (Total CSA), Muscle CSA, Fat CSA, %Fat CSA (Fat CSA/Total CSA×100) and muscle density.

Results: Peripheral QCT-derived %Fat CSA in the forearm and lower leg correlated strongly with DXA-derived %BF (r=0.83–0.89, p<0.01) in both boys and girls. However, forearm and lower leg %Fat CSA were higher than whole body %BF by 5% and 10%, respectively. A better prediction of whole-body %BF was achieved by including %Fat CSA, muscle density and height into a hierarchical regression model. Using sex-specific regression equations, 87.7% of the boys and 83.7% of the girls had a predicted %BF within 3% units of the %BF obtained by DXA.

Conclusion: In pre-pubertal children, pQCT measures of adiposity are strongly associated with whole-body per cent body fat. This reproducible method could be an alternative technique to estimate body composition in this population.     

外周胆碱能神经在大鼠应激性体温过高反应中的可能作用

目的： 探讨外周胆碱能神经在应激性体温过高反应中的作用。 方法： 用无线遥测技术观察皮下注射甲基东莨菪碱和吡啶斯的明对大鼠在开放环境中应激性体温过高和活动的影响，用分光光度技术测定血浆胆碱酯酶的活性。 结果： 外周胆碱能受体阻断剂甲基东莨菪碱能明显抑制开放环境中大鼠的应激性体温过高反应；外周抗胆碱酯酶剂吡啶斯的明能提高开放环境中大鼠的应激性体温过高反应，而血浆胆碱酯酶的活性降低52%；吡啶斯的明几乎可以抵消甲基东莨菪碱对开放应激性体温过高的抑制作用。这两种药物对暴露在开放环境大鼠的活动无明显影响。 结论： 吡啶斯的明和甲基东莨菪碱可以影响暴露到开放环境中大鼠的体温调节反应，提示外周胆碱能神经参与大鼠应激性体温过高反应的调节。     

Evidence against brain stem cooling by face fanning in severely hyperthermic humans

To achieve a hyperthermic state 11 subjects exercised at 35° C air temperature in a water-impermeable outfit, until their oesophageal temperature (T _es) exceeded 39° C. Changes of brain stem temperature were assessed by the interspike intervals of auditory evoked potentials, which depend on brain stem temperature. These were recorded at rest before exercise (condition A), after exercise during a period when heat loss from the face was prevented by covering the head with a plastic hood (condition B), and again during face fanning (condition C). An increase in T _es from 37.14±0.25° C to 39.05±0.15° C (A to B) produced a significant reduction in interspike intervals, indicating an increase in brain stem temperature. Changing from conditions B to C, T _es and interspike intervals remained constant, indicating no change of brain stem temperature in spite of face fanning. Thus, even in severely heat stressed humans face fanning is not able to lower brain stem temperature significantly below that of the rest of the body core.     

Body temperature and its effect on leukocyte mobilization, cytokines and markers of neutrophil activation during and after exercise

We investigated the influence of rectal temperature on the immune system during and after exercise. Ten well-trained male cyclists completed exercise trials (90 min cycling at 60% time trial) on three separate occasions: once in 18°C and twice in 32°C. Twenty minutes after the trials in 32°C, the cyclists sat for ∼20 min in cold water (14°C) on one occasion, whereas on another occasion they sat at room temperature. Rectal temperature increased significantly during cycling in both conditions, and was significantly higher after cycling in 32°C than in 18°C (P < 0.05). Leukocyte counts increased significantly during cycling but did not differ between the conditions. The concentrations of serum interleukin (IL)-6, IL-8 and IL-10, plasma catecholamines, granulocyte-colony stimulating factor, myeloperoxidase and calprotectin increased significantly following cycling in both conditions. The concentrations of serum IL-8 (25%), IL-10 (120%), IL-1 receptor antagonist (70%), tumour necrosis factor-α (17%), plasma myeloperoxidase (26%) and norepinephrine (130%) were significantly higher after cycling in 32°C than in 18°C. During recovery from exercise in 32°C, rectal temperature was significantly lower in response to sitting in cold water than at room temperature. However, immune changes during 90 min of recovery did not differ significantly between sitting in cold water and at room temperature. The greater rise in rectal temperature during exercise in 32°C increased the concentrations of serum IL-8, IL-10, IL-1ra, TNF-α and plasma myeloperoxidase, whereas the greater decline in rectal temperature during cold water immersion after exercise did not affect immune responses.