Actual temperature during and thermal response after whole-body cryotherapy in cryo-cabin

Whole-body cryotherapy (WBC) involves exposing minimally dressed participants to very cold air (injecting liquid nitrogen with temperature −195 °C), either in a specially designed chamber (cryo-chamber) or cabin (cryo-cabin), for a short period of time. The aim of this study was to examine the actual temperature of the air in the cryo-cabin at different locations throughout the cabin by using human subjects and a manikin. Additionally, we monitored skin temperature before and for 60 min after the cryo-cabin session. Twelve subjects completed one 3 min cryo-cabin session. Temperature next to the skin was assessed during the session, while the skin temperature was monitored before, 3 min after and every 10 min for 60 min after completing the session. There was a statistically significant interaction (time×position) for temperature among the different body parts during the WBC, and for skin temperature among different body parts after the cryo-cabin session. Statistically significant time effects during and following cryo-cabin session were present for all body parts. We showed that actual temperature in the cryo-cabin is substantially different from the one reported by the manufacturer. Thermal response after cryo-cabin session is similar to response observed after cryo-chamber cold exposure reported in previously published studies. This could be of great practical value as cryo-cabins are less expensive and easier to use compared to cryo-chambers.     

Validation of a new whole-body cryotherapy chamber based on forced convection

Whole-body cryotherapy (WBC) and partial-body cryotherapy (PBC) are two methods of cold exposure (from −110 to −195 °C according to the manufacturers). However, temperature measurement in the cold chamber during a PBC exposure revealed temperatures ranging from −25 to −50 °C next to the skin of the subjects (using isolating layer placed between the sensor and the skin). This discrepancy is due to the human body heat transfer. Moreover, on the surface of the body, an air layer called the boundary layer is created during the exposure and limits heat transfer from the body to the cabin air. Incorporating forced convection in a chamber with a participant inside could reduce this boundary layer. The aim of this study was to explore the use of a new WBC technology based on forced convection (frontal unilateral wind) through the measurement of skin temperature. Fifteen individuals performed a 3-min WBC exposure at −40 °C with an average wind speed of 2.3 m s⁻¹. The subjects wore a headband, a surgical mask, underwear, gloves and slippers. The skin temperature of the participants was measured with a thermal camera just before exposure, just after exposure and at 1, 3, 5, 10, 15 and 20 min after exposure. Mean skin temperature significantly dropped by 11 °C just after exposure (p<0.001) and then significantly increased during the 20-min post exposure period (p<0.001). No critically low skin temperature was observed at the end of the cold exposure. This decrease was greater than the mean decreases in all the cryosauna devices with reported exposures between −140 °C and −160 °C and those in two other WBC devices with reported exposures between −60 °C and −110 °C. The use of this new technology provides the ability to reach decreases in skin temperature similar to other technologies. The new chamber is suitable and relevant for use as a WBC device.     

Effects of whole-body cryotherapy on serum mediators of inflammation and serum muscle enzymes in athletes

Whole-body cryotherapy (WBC) covers a wide range of therapeutic applications and consists of briefly exposing the body to extremely cold air. In sports medicine, WBC is used to improve recovery from muscle injury; however, empirical studies on its application to this area are lacking. To fill this gap, we compared changes in immunological parameters (C3, IgA, IgM, IgG, C-reactive protein, PGE2), cytokines (IL-2, IL-8, IL-10), adhesion molecules (sICAM-1), and muscle enzymes (creatine kinase [CK], lactate dehydrogenase [LAD]) before and after WBC in 10 top-level Italian National team rugby players. The subjects underwent five sessions on alternate days once daily for 1 week. During the study period, the training workload was the same as that of the previous weeks. Compared to baseline values, immunological parameters remained unchanged, while CK and LAD levels significantly decreased after treatment. No alterations in immunological function were observed but there is a decrease in pro-inflammatory cytokine/chemokine and an increase in anti-inflammatory cytokine.As measured by changes in serum CK and LAD concentrations, and cytokines pathway, short-term cold air exposure was found to improve recovery from exercise-induced muscle injury and/or damage associated with intense physical training.     

Time-course of changes in inflammatory response after whole-body cryotherapy multi exposures following severe exercise

The objectives of the present investigation was to analyze the effect of two different recovery modalities on classical markers of exercise-induced muscle damage (EIMD) and inflammation obtained after a simulated trail running race. Endurance trained males (n = 11) completed two experimental trials separated by 1 month in a randomized crossover design; one trial involved passive recovery (PAS), the other a specific whole body cryotherapy (WBC) for 96 h post-exercise (repeated each day). For each trial, subjects performed a 48 min running treadmill exercise followed by PAS or WBC. The Interleukin (IL) -1 (IL-1), IL-6, IL-10, tumor necrosis factor alpha (TNF-α), protein C-reactive (CRP) and white blood cells count were measured at rest, immediately post-exercise, and at 24, 48, 72, 96 h in post-exercise recovery. A significant time effect was observed to characterize an inflammatory state (Pre vs. Post) following the exercise bout in all conditions (p<0.05). Indeed, IL-1β (Post 1 h) and CRP (Post 24 h) levels decreased and IL-1ra (Post 1 h) increased following WBC when compared to PAS. In WBC condition (p<0.05), TNF-α, IL-10 and IL-6 remain unchanged compared to PAS condition. Overall, the results indicated that the WBC was effective in reducing the inflammatory process. These results may be explained by vasoconstriction at muscular level, and both the decrease in cytokines activity pro-inflammatory, and increase in cytokines anti-inflammatory.     

Acute effects of whole-body cryotherapy on sit-and-reach amplitude in women and men

Flexibility is an intrinsic property of body tissues, which among other factors determines the range of motion (ROM). A decrease in neural activation of the muscle has been linked with greater ROM. Cryotherapy is an effective technique to reduces neural activation. Hence, the aim of the present study was to evaluate if a single session of whole-body cryotherapy (WBC) affects ROM. 60 women and 60 men were divided into two groups (control and experimental). After the initial sit-and-reach test, experimental group performed a 150 s session of WBC, whereas the control group stayed in thermo-neutral environment. Immediately after, both groups performed another sit-and-reach test. A 3-way analysis of variance revealed statistically significant time × group and time × gender interaction. Experimental groups improved sit-and-reach amplitude to a greater extend than the control group. Our results support the hypothesis that ROM is increased immediately after a single session of WBC.     

Thermal responses during and after whole-body cryotherapy (−110°C)

The effect of whole-body cryotherapy (WBC) on rectal and skin temperatures was measured in healthy subjects before, during and after WBC exposure. WBC did not cause any significant change in rectal temperature. The lowest local skin temperatures were recorded in the forearm, 5.2 (2.8)°C, and in the calf, 5.3 (3.0)°C. WBC involves no risk for frostbites. After WBC, all skin temperatures recovered rapidly, indicating that the analgetic effects of WBC only occur during a limited period after the exposure.     

Influence of altitude, habitat and microhabitat on thermal adaptation of cicadas from Southwest Texas (Hemiptera: Cicadidae)

The thermal responses of 12 cicada species inhabiting Big Bend National Park, Texas, USA are investigated to determine the influence of altitude, habitat and microhabitat. The park provides an opportunity to analyze the thermal responses in animals from a variety of habitats and altitudinal gradients within a limited geographic range. The data suggest that thermal responses of cicadas are adaptations to their specific habitats. No thermal responses are significantly correlated with body size. The maximum voluntary tolerance temperature (an upper behavioral thermoregulatory point) and heat torpor temperatures show significant correlations with altitude. Variability in thermal responses can also be related to the characteristics of the microhabitat selected or the behavioral pattern of a species.     

The effects of whole-body cryotherapy on oxidative stress in multiple sclerosis patients

There is strong evidence that multiple sclerosis (MS) is characterized not only by immune mediated inflammatory reactions but also by neurodegenerative processes. Accumulated data indicate that oxidative stress (OS) plays a major role in this process. Generated in excess, reactive oxygen species (ROS) lead to oxidative stress and are involved in demyelination and axonal damage in MS. ROS generation may be inhibited partly by hypothermia, which is known as a potent putative neuroprotectant and may inhibit generating free radicals and oxidative stress. Whole-body cryotherapy (WBCT) treatment may improve both survival and neurological outcome in MS patients.     

Effects of thermal environment on sleep and circadian rhythm

ABSTRACT: The thermal environment is one of the most important factors that can affect human sleep. The stereotypical effects of heat or cold exposure are increased wakefulness and decreased rapid eye movement sleep and slow wave sleep. These effects of the thermal environment on sleep stages are strongly linked to thermoregulation, which affects the mechanism regulating sleep. The effects on sleep stages also differ depending on the use of bedding and/or clothing. In semi-nude subjects, sleep stages are more affected by cold exposure than heat exposure. In real-life situations where bedding and clothing are used, heat exposure increases wakefulness and decreases slow wave sleep and rapid eye movement sleep. Humid heat exposure further increases thermal load during sleep and affects sleep stages and thermoregulation. On the other hand, cold exposure does not affect sleep stages, though the use of beddings and clothing during sleep is critical in supporting thermoregulation and sleep in cold exposure. However, cold exposure affects cardiac autonomic response during sleep without affecting sleep stages and subjective sensations. These results indicate that the impact of cold exposure may be greater than that of heat exposure in real-life situations; thus, further studies are warranted that consider the effect of cold exposure on sleep and other physiological parameters.     

Comparative thermal adaptation in cicadas (Hemiptera: Cicadidae) inhabiting Mediterranean ecosystems

The thermal responses of cicadas inhabiting the Mediterranean ecosystems in Europe, North America, South Africa, and Australia are investigated. A total of 37 species and two subspecies from 17 genera representing eight tribes and three subfamilies of cicadas are investigated. The analysis includes species that are restricted to the Mediterranean ecosystem as well as those which also inhabit additional environments. The data suggest that cicadas adapt to the climate type regardless of particular types of plants within the various Mediterranean communities. Similarly, cicada thermal responses are independent of body size or taxonomic affinities. There is a wider range of body temperatures for the maximum voluntary tolerance temperature than for heat torpor or minimum flight temperatures. This diversity seems to be determined by the subdivision of the habitat used and the behavior of the species. All species possess relatively elevated heat torpor temperatures adapting to the general thermal characteristics of the Mediterranean ecosystem. The data suggest that cicadas adapt to the Mediterranean climate type regardless of the diversity of particular types of plants within the various communities, of body size or of taxonomic position.     

Effect of thermal exposure on physiological adaptability and seminal attributes of rams under semi-arid environment

Thermal stress in hot semi-arid environment is a major limitation of sheep production in tropical and sub-tropical climatic condition. The animals tend to maintain homeostasis through physiological adjustments in a hot environment (maximum temperature reaches up to 47.5 °C). Therefore, the present study was carried out to assess the effect of thermal exposure on physiological adaptability and seminal attributes of rams under semi-arid environment. The experiment was conducted for eight weeks involving sixteen Malpura crossbred rams (GMM: Garole X Malpura X Malpura). The rams were divided equally into two groups, designated as G1 and G2, respectively. The rams in G1 (Control) group were kept in a sheep shed under naturally prevailing environment without artificial manipulation of ambient temperature (Temperature 30.48±0.38 °C; Relative Humidity 28.59±1.15%). The rams of G2 group were exposed to different temperature at different hours of the day (38 °C at 1000–1100 h; 40 °C at 1100–1200 h; 42 °C at 12:00–1300 h; 43 °C at 1300–1400 h; 44 °C at 1400–1500 h and 42 °C at 1500–1600 h) in a climatic chamber for thermal exposure. Physiological responses, blood biochemical profile, blood endocrine profile, sexual behavior and seminal attributes were measured for both the groups. Thermal exposure significantly (P<0.05) increased the water intake; respiration rate, rectal temperature and skin temperature at afternoon in rams. Exposure of rams to thermal stress (G2) significantly (P<0.05) increased cortisol level and decreased tri-ido-thyronine level. The latency period after the first ejaculation, decreased significantly (P<0.05) in G2. The percentage of rapid motile sperm, linearity and average path velocity of sperm were also altered significantly (P<0.05) in thermal exposed rams as compared to control. However, comparable feed intake, body weight, and major blood biochemical parameters, as well as acceptable semen quality attributes of all the rams indicated that the Fec B gene introgressed Malpura cross rams adapted to the thermal exposure under semi-arid tropical climate.     

Effects of thermal stratification and mixing on reservoir water quality

In this study, the effect of thermal stratification on water quality in a reservoir has been investigated by field observations and statistical analysis. During the summer period, when stratification is evident, field observations indicate that the observed dissolved oxygen concentrations drop well below the standard limit of 5 mg l⁻¹ at the thermocline, leading to the development of anoxia. The reasons for variations in the dissolved oxygen concentrations were investigated. Variations of air temperature and other meteorological factors and lateral flows from side arms of the lake were found to be responsible for the increase of dissolved oxygen concentrations. It was also observed that turbidity peaked mostly in the thermocline region, closely related to the location of the maximum density gradient and thus low turbulence stabilizing the sediments in the vertical water column. Relatively cold sediment-laden water flowing into the lake after rain events also resulted in increased turbidity at the bottom of the lake. Nondimensional analysis widely used in the literature was used to identify the strength of the stratification, but this analysis alone was found insufficient to describe the evolution of dissolved oxygen and turbidity in the water column. Thus correlation of these parameters was investigated by multivariate analysis. Fall (partial mixing), summer (no mixing), and winter (well mixed) models describe the correlation structures between the independent variables (meteorological parameters) and the dependent variables (water-quality parameters). Statistical analysis results indicate that air temperature, one day lagged wind speed, and low humidity affected variation of water-quality parameters.     

Effects of whole-body cryotherapy vs. far-infrared vs. passive modalities on recovery from exercise-induced muscle damage in highly-trained runners

Enhanced recovery following physical activity and exercise-induced muscle damage (EIMD) has become a priority for athletes. Consequently, a number of post-exercise recovery strategies are used, often without scientific evidence of their benefits. Within this framework, the purpose of this study was to test the efficacy of whole body cryotherapy (WBC), far infrared (FIR) or passive (PAS) modalities in hastening muscular recovery within the 48 hours after a simulated trail running race. In 3 non-adjoining weeks, 9 well-trained runners performed 3 repetitions of a simulated trail run on a motorized treadmill, designed to induce muscle damage. Immediately (post), post 24 h, and post 48 h after exercise, all participants tested three different recovery modalities (WBC, FIR, PAS) in a random order over the three separate weeks. Markers of muscle damage (maximal isometric muscle strength, plasma creatine kinase [CK] activity and perceived sensations [i.e. pain, tiredness, well-being]) were recorded before, immediately after (post), post 1 h, post 24 h, and post 48 h after exercise. In all testing sessions, the simulated 48 min trail run induced a similar, significant amount of muscle damage. Maximal muscle strength and perceived sensations were recovered after the first WBC session (post 1 h), while recovery took 24 h with FIR, and was not attained through the PAS recovery modality. No differences in plasma CK activity were recorded between conditions. Three WBC sessions performed within the 48 hours after a damaging running exercise accelerate recovery from EIMD to a greater extent than FIR or PAS modalities.     

Three-dimensional model on thermal response of skin subject to laser heating

A three-dimensional (3D) multilayer model based on the skin physical structure is developed to investigate the transient thermal response of human skin subject to laser heating. The temperature distribution of the skin is modeled by the bioheat transfer equation, and the influence of laser heating is expressed as a source term where the strength of the source is a product of a Gaussian shaped incident irradiance, an exponentially shaped axial attenuation, and a time function. The water evaporation and diffusion is included in the model by adding two terms regarding the heat loss due to the evaporation and diffusion, where the rate of water evaporation is determined based on the theory of laminar boundary layer. Cryogen spray cooling (CSC) in laser therapy is studied, as well as its effect on the skin thermal response. The time-dependent equation is discretized using the finite difference method with the Crank–Nicholson scheme and the stability of the numerical method is analyzed. The large sparse linear system resulted from discretizing the governing partial differential equation is solved by a GMRES solver and the expected simulation results are obtained.     

Effect of thermal acclimation on thermal preference,resistance and locomotor performance of hatchling soft-shelled turtle

The significant influence of thermal acclimation on physiological and behavioral performance has been documented in many ectothermic animals, but such studies are still limited in turtle species. We acclimated hatchling soft-shelled turtles Pelodiscus sinensis under three thermal conditions （10, 20 and 30~C） for 4 weeks, and then measured selected body temperature （Tsel）, critical thermal minimum （CTMin） and maximum （CTM~x）, and locomotor performance at different body temperatures. Thermal acclimation significantly affected thermal preference and resistance of P sinensis hatchlings. Hatchling turtles accli- mated to 10~C selected relatively lower body temperatures and were less resistant to high temperatures than those acclimated to 20~C and 30~C. The turtles＇ resistance to low temperatures increased with a decreasing acclimation temperature. The thermal re- sistance range （i.e. the difference between CTM~x and CTMin, TRR） was widest in turtles acclimated to 20~C, and narrowest in those acclimated to 10~C. The locomotor performance of turtles was affected by both body temperature and acclimation tem- perature. Hatchling turtles acclimated to relatively higher temperatures swam faster than did those acclimated to lower temperatures. Accordingly, hatchling turtles acclimated to a particular temperature may not enhance the performance at that temperature. Instead, hatchlings acclimated to relatively warm temperatures have a better performance, supporting the ＂hotter is better＂ hypothesis.     

Effects of cold- and heat hardening on thermal resistance in Drosophila melanogaster

The effects of cold- and heat hardening on resistance to both low and high temperature stress was examined in Drosophila melanogaster lines selected for resistance to either cold or heat. The hardening effect was positive when the hardening was of the same type as the stress in all selection regimes. The effect of cold hardening on survival after heat stress was further examined in the lines selected for cold resistance and corresponding controls. A cross-protection effect (increased heat resistance after cold hardening) was present and this effect was lower in the lines selected for resistance to cold than in the controls. The level of Hsp70 expression induced by a non-lethal cold hardening was examined, showing that cold hardening induced Hsp70 expression. The results suggest that the cross-protection effect is at least partly due to Hsp70 expression induced by cold exposure.     

Effects of normobaric hypoxic bed rest on the thermal comfort zone

Future Lunar and Mars habitats will maintain a hypobaric hypoxic environment to minimise the risk of decompression sickness during the preparation for extra-vehicular activity. This study was part of a larger study investigating the separate and combined effects of inactivity associated with reduced gravity and hypoxia, on the cardiovascular, musculoskeletal, neurohumoural, and thermoregulatory systems. Eleven healthy normothermic young male subjects participated in three trials conducted on separate occasions: (1) Normobaric hypoxic ambulatory confinement, (2) Normobaric hypoxic bedrest and (3) Normobaric normoxic bedrest. Normobaric hypoxia was achieved by reduction of the oxygen fraction in the air (F_iO₂=0.141±0.004) within the facility, while the effects of reduced gravity were simulated by confining the subjects to a horizontal position in bed, with all daily routines performed in this position for 21 days. The present study investigated the effect of the interventions on behavioural temperature regulation. The characteristics of the thermal comfort zone (TCZ) were assessed by a water-perfused suit, with the subjects instructed to regulate the sinusoidally varying temperature of the suit within a range considered as thermally comfortable. Measurements were performed 5 days prior to the intervention (D-5), and on days 10 (D10) and 20 (D20) of the intervention. no statistically significant differences were found in any of the characteristics of the TCZ between the interventions (HAMB, HBR and NBR), or between different measurement days (D-5, D10, D20) within each intervention. rectal temperature remained stable, whereas skin temperature (T_sk) increased during all interventions throughout the one hour trial. no difference in T_sk between D-5, D10 and D20, and between HAMB, HBR and NBR were revealed. subjects perceived the regulated temperature as thermally comfortable, and neutral or warm. we conclude that regulation of thermal comfort is not compromised by hypoxic inactivity.     

Effects of osmolytes on arginine kinase from Euphausia superba: A study on thermal denaturation and aggregation

Investigations of energy-related enzymatic properties may provide valuable information about the mechanisms that are involved in the adaptation to extreme climatic environments. The protective effects of osmolytes on the thermal denaturation and aggregation of arginine kinase from E. superba (ESAK) was investigated. When the concentration of glycine, proline and glycerol increased, the relative activation was significantly enhanced, while the aggregation of ESAK during thermal denaturation was decreased. Spectrofluorometry results showed that the presence of these three osmolytes significantly decreased the tertiary structural changes of ESAK and that thermal denaturation directly induced ESAK aggregation. The results demonstrated that glycine, proline and glycerol not only prevented ESAK from inactivation and unfolding but also inhibited aggregation by stabilizing the ESAK conformation. We measured the ORF gene sequence of ESAK by RACE, and built the 3D structure of ESAK and osmolytes by homology models. The results showed that the docking energy was relatively low and that the clustering groups were spread to the surface of ESAK, indicating that osmolytes directly protect the surface of the protein. Our study provides important insight into the protective effects of osmolytes on ESAK folding.     

Effects of small heat shock proteins on the thermal denaturation and aggregation of F-actin

Effect of recombinant chicken small heat shock protein with molecular mass 24 kDa (Hsp24) and recombinant human small heat shock protein with molecular mass 27 kDa (Hsp27) on the heat-induced denaturation and aggregation of skeletal F-actin was analyzed by means of differential scanning calorimetry and light scattering. All small heat shock proteins did not affect thermal unfolding of F-actin measured by differential scanning calorimetry, but effectively prevented aggregation of thermally denatured actin. Small heat shock protein formed stable complexes with denatured (but not with intact) F-actin. The size of these highly soluble complexes was smaller than the size of intact F-actin filaments. It is supposed that protective effect of small heat shock proteins on the cytoskeleton is at least partly due to prevention of aggregation of denatured actin.