This study investigates the effects of different levels of acute normobaric hypoxia on cognitive function and cerebral oxygenation in healthy young adults. Twenty-four participants aged 18–30 years were exposed to hypoxia with an inspired oxygen fraction (FiO2) equivalent to 20.9

Thermal stress caused by extreme heat or cold, challenges homeostasis and physiological limits of the body. However, through thermoregulatory mechanisms, the human body is able to adapt efficiently to both cold and hot environments. A growing body of evidence suggests that exposure to thermal stress may provide several health benefits, particularly in post-exercise recovery and in the management of cardiovascular or inflammatory diseases. Thermal strategies such as cold exposure and sauna bathing have been used for centuries to enhance recovery, with documented effects on improving cardiovascular health, reducing inflammation, and improving well-being. Although the effects of heat and cold exposures have been widely investigated, it remains uncertain whether combining these two stimuli offers greater, lesser, or simply different benefits compared with each modality alone. Relatively few studies directly compare these protocols. In this narrative review, we discuss the known therapeutic effects of heat and cold modalities, and explore their individual and combined physiological mechanisms. It also examines how contrast therapy may induce synergistic benefits or potentially negate the effects of each modality. While the combination of heat and cold therapy is promising, further research is needed to clarify whether the opposing physiological responses of each therapy may interfere with each other, thereby compromising their effectiveness.

Radon balneotherapy, a form of low-dose radiation treatment, has been utilized for decades in managing rheumatologic diseases, particularly in Central Europe and parts of Asia. Despite ongoing debate about its efficacy, developing research suggests that low-dose exposure to radon may exert anti-inflammatory and analgesic effects, with potential implications for musculoskeletal and cardiovascular health. This narrative review aims to synthesize current knowledge on the biological mechanisms underlying radon therapy, evaluate clinical evidence for its efficacy in rheumatologic conditions, and explore its potential impact on cardiovascular health. Risks, controversies, and regulatory restrictions are also addressed. Preclinical studies indicate that radon therapy modulates oxidative stress responses, immune signalling cascades, and pro-inflammatory cytokine profiles, thereby influencing tissue homeostasis and pain perception. Clinically, benefits have been observed in patients with rheumatoid arthritis, ankylosing spondylitis, and osteoarthritis, particularly with respect to pain alleviation, functional improvement, and quality of life. However, heterogeneity in treatment protocols, study quality, and confounding factors such as the use of heat, carbon dioxide, and/or other concurrent modalities limit generalizability and attributability. Evidence regarding cardiovascular safety remains sparse but suggests that low-dose exposure may have neutral or even protective effects under specific physiological conditions. In summary, radon balneotherapy may have a complementary role alongside other modalities like heat and negative air ions. However, the isolated therapeutic efficacy, long-term safety profile, and cardiovascular implications of radon balneotherapy remain insufficiently characterized. Higher quality multi-armed randomized controlled trials and isolated mechanistic investigations are needed to better delineate its biological mechanisms, optimize protocols, and define its clinical niche.

Obesity is a global public health problem, and new non-surgical or pharmacological treatments are being explored. Among these, cryostimulation has emerged as a new beneficial non-invasive method. Several studies have reported a greater decrease in skin temperature following cryostimulation in individuals with higher BMI or body fat percentage. The aim of this study was to evaluate the effect of a single 3-min whole-body cryostimulation (WBC) session on skin temperature and cold perception in male and female obese subjects. Skin temperature changes before and after the 3-min cryostimulation exposure were measured in twenty-one participants. Our results showed that the average skin temperature decreased by 12.9 °C without reaching dangerous levels. Individual characteristics such as sex and age should nevertheless be carefully considered to ensure the safety and efficacy of the treatment.

Whole-body cryostimulation (WBC) has recently been shown to improve autonomic nervous control of the cardiovascular system. This study aimed to investigate the acute and repeated effects of WBC on baroreflex sensitivity (BRS), heart rate variability (HRV), and blood pressure. Fifty male participants (22 ± 4 years) were randomly assigned to experimental (N = 25) and control groups (N = 25). The experimental group underwent 10 WBC sessions over two weeks, while cardiovascular responses were assessed before and after the 1st and the 10th session of WBC. Heart rate (HR), BRS, HRV, as well as systolic (SAP), diastolic (DAP) and mean arterial pressure (MAP) were measured. SAP and MAP values at rest significantly decreased by 7

BACKGROUND:Monitoring lifestyle habits and physiological metrics are essential for improving cardiovascular outcomes and supporting recovery after acute cardiac events. Sleep is acknowledged as a core component of cardiovascular health and a predictive tool of adverse outcomes following acute myocardial infarction (AMI). OBJECTIVE:The present study aimed to assess sleep metrics and explore the links between sleep patterns, heart rate variability (HRV) parameters, and traditional cardiovascular risk factors in patients with AMI. METHODS:Sixty male patients with AMI (56.77 ± 8.24 years) participated in this study. Cardiac autonomic function was assessed with short-term HRV analysis during the second week post-AMI. Physical activity level was assessed using accelerometers. Sleep quality and quantity were evaluated objectively using a wrist-worn accelerometer and subjectively by the Pittsburgh Sleep Quality Index. Chronotype was evaluated with the Horne and Otsberg questionnaire. RESULTS:Twenty post-AMI patients (33.3%) tended to experience poor sleep quality, with a sleep efficiency inferior to 85%. Thirty patients (50%) experienced short sleep duration, 16 (26.7%) had a healthy sleep duration (7-8 h), and 14 (23.3%) slept more than 8 h. Multiple regression analysis revealed that patients with healthy sleep quality and quantity exhibited higher HRV parameters, both in time and frequency domain values (p < 0.05). Low physical activity level was observed in patients with long sleep duration (p = 0.005) and evening chronotype (p = 0.022). CONCLUSION:Patients who spent more time performing moderate to vigorous physical activity tended to exhibit good sleep health and increased parasympathetic activity which are considered cardioprotective after AMI. TRIAL REGISTRATION:PACTR202208834230748.

Introduction:Physical exercise induces various metabolic changes, influencing energy expenditure and substrate utilization. Metabolomics provides a comprehensive understanding of the metabolic adaptations occurring in response to physical exercise and recovery. This study aimed to investigate metabolic adaptations in recreational athletes by analyzing the urine metabolome following a high intensity interval training (HIIT) program with or without repeated cryotherapy recovery. Method:In this study, urine metabolomics with 1H NMR spectroscopy was used to investigate the impact of sub-maximal cycling bout (SMC) at 60 % of power aerobic peak on urine metabolome before and after 4 weeks HIIT with or without cryostimulation recovery (WBC, N = 11; CTL, N = 12). Results:PCA analysis revealed a distinct separation between the urine NMR profiles of the WBC and the CTL groups induced by SMC. Targeted analyses showed no significant metabolic differences before SMC. However, post-SMC analysis revealed marked changes in lactate, acetate, acetone, urea, formate, citrate and adenine levels. The training program amplified these metabolic alterations in both groups. The WBC group exhibited significant changes in alanine, acetone and 2-hydroxyisobutyric acid, while the CTL group showed alterations in citrate. Conclusion:SMC triggers a variety of metabolic changes that reflect the body's efforts to maintain energy balance under stress. When combined with WBC, HIIT further enhances these adaptations, improving glycolytic capacity, fat metabolism, and the regulation of energy homeostasis.

ABSTRACTBackgroundEndothelial function (EndFx) is a core component of cardiovascular (CV) health and cardioprotection following acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (PCI).HypothesisAMI patients experience endothelial dysfunction (EndDys), associated with traditional CV risk factors and sleep patterns. EndFx may also predict short and mid‐term outcomes.MethodsEndFx was assessed in 63 patients (56.2 ± 7.6 years) using the Endothelium Quality Index (EQI). Sleep quality and quantity were evaluated using objective (actigraphy) and subjective (Pittsburgh Sleep Quality Index questionnaire) measures. Cardiorespiratory fitness was quantified through the 6‐min walking test. Cardiac function was assessed using the left ventricular ejection fraction.ResultsFollowing AMI, patients tended to experience EndDys (EQI = 1.4 ± 0.7). A severe EndDys was observed in 23.8% of patients (n = 15), while a mild EndDys was present in 63.49% (n = 40). Furthermore, EndDys was significantly associated with traditional CV risk factors (i.e., low physical activity level [12.8%], age [−4.2%], and smoking [−0.7%]) (R2 adjusted = 0.50, p < 0.001). Patients with EndDys had poor sleep quality (p = 0.001) and sleep efficiency (p = 0.016) compared to healthy persons. Patients with severe EndDys exhibited lower cardiorespiratory fitness compared to those with healthy EndFx (p = 0.017). Furthermore, during a follow‐up period (nearly 4 months) following PCI, major adverse cardiac events were observed in four patients with severe EndDys.ConclusionsOur results emphasize the importance of adequate sleep and an active lifestyle, notably physical activity practice, as modifiable elements to enhance EndFx, which is regarded as a predictive tool following AMI. However, other factors remain to be elucidated as predictors of CV risk.Trial RegistrationThe study protocol was registered in the Pan African Clinical Trial Registry under the trial ID: PACTR202208834230748.

The optimal Whole-body cryostimulation (WBC) exposure duration to reach the target skin temperature may vary depending on individual factors such as age, sex, and body mass index (BMI). Maintaining skin temperatures below 13.6°C is necessary to trigger significant cold-induced analgesia. The aim of our study is to investigate how these variables influence the duration required to reach the analgesic threshold temperature of 13.6°C during WBC. A randomized cross-over controlled trial was conducted with 90 healthy participants, categorized by age, sex, and BMI. Each participant underwent two sessions: a 4 min WBC exposure at -50°C and a control session. Skin temperature was measured using a thermal imaging camera before, during and after cold exposure. Significant differences in skin temperature were observed between groups. Among young participants, normal-weight men required 4 minutes of exposure to reach the analgesic threshold (p < 0.05), while normal-weight women reached it in 3 minutes (p < 0.01). Overweight young men needed 3 minutes and 30 seconds (p < 0.001), whereas overweight young women reached the threshold earlier, at 2 min and 30 s (p < 0.01). For senior participants, both normal-weight men and women reached the analgesic threshold at 3 minutes of exposure (p < 0.001). In contrast, overweight senior men and women needed only 2 minutes and 30 seconds to reach the target skin temperature (p < 0.01). The optimal WBC exposure duration for achieving analgesic effects varies significantly depending on individual characteristics, suggesting that WBC protocols should be tailored to maximize therapeutic benefits.

The aim of this study was to evaluate the effects of daily partial body cryostimulation exposures on sleep and recovery parameters in elite swimmers undergoing an intense training period. Twenty‐three elite French swimmers (7 females and 16 males) were involved in this controlled cross‐over protocol. The experiment took place during 2 weeks of intense training load. Each week (5 days and 5 nights) represented one of the two experimental conditions: partial body cryostimulation exposures (CRYO) or control sessions (CONT). Daily partial body cryostimulation exposure of 3 min at −110°C was performed (or not) during a consecutive period of 5 days, after the evening training session. Perceived wellness (anxiety, tiredness, depression and mood profile), sleep quality (via actimetry and cerebral recording) and nocturnal heart rate variability were evaluated. Collection of saliva samples permitted the measurement of C‐reactive protein and melatonin. Perceived anxiety, tiredness and depression were reduced after the CRYO week, concomitant with an improved mood profile. Recordings of cerebral activity during the night highlighted increased slow‐wave sleep duration in the first sleep cycle during the CRYO week. Other sleep parameters, including total sleep time, sleep latency, efficiency or movements during the night, remained unchanged. The concentration of C‐reactive protein in saliva was lower during the CRYO week compared with the CONT week. Moreover, sleep analysis allowed a distinction between better sleepers and poor sleepers. In the latter group, only poor sleepers among the male swimmers obtained a benefit on their sleep from cryotherapy. Repeated cryostimulation exposures during 1 week of intense training improved perceived wellness in elite swimmers, reduced inflammation, and modulated sleep architecture by increasing slow‐wave sleep duration.

Objective:To investigate the safety and effectiveness of early cardiopulmonary rehabilitation (ECR) combined with melatonin supplementation on functional capacity and sleep quality during hospitalization in patients with acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (PCI). Design:Single-blinded randomized controlled trial. Setting:Cardiology inpatient unit where patients were hospitalized after PCI. Participants:Forty-eight male patients (N=48) with AMI followed by PCI (mean age of 57.1±8.7y) were included and randomized into 3 groups: MELEX (ECR combined with 4 mg of exogenous melatonin), EX (ECR with placebo), and CON (control group with placebo). Interventions:Patients in the MELEX and EX groups participated in ECR, consisting of walking, passive and active range of motion, moderate-intensity strengthening exercises, and breathing exercises. The MELEX group received a daily 4 mg dose of melatonin, while the EX and CON groups received a placebo. Participants in CON group received usual care without engaging in ECR. Main Outcomes Measures:Functional capacity was evaluated by the 6-minute walking test (6mwt). Sleep quality was assessed by the Spiegel questionnaire. Rating of perceived exertion was evaluated using the Borg Scale. Assessments were conducted on the first day after PCI and at hospital discharge. Results:The 6mwt distance was better in the MELEX group than in the other groups exceeding the minimal clinically important differences (P<.001). Sleep quality was improved more in MELEX than EX and CON groups (P<.001). A strong-graded correlation was found between the 6mwt and Spiegel Score (r=0.730; P<.001). No adverse cardiac events related to ECR or melatonin supplementation were recorded during hospitalization. Conclusions:ECR combined with a daily 4 mg of melatonin supplementation was safe and effective in improving functional capacity and sleep quality in patients with AMI during hospitalization after PCI.

IntroductionMenstrual-related pain and sleep disturbances are widespread in women experiencing premenstrual syndrome and primary dysmenorrhea. Such disturbances could be alleviated through repeated whole-body cryostimulation (WBC) sessions. Therefore, this study aimed to assess the effect of menstrual-related pain on sleep parameters, and the impact of WBC exposures on pain and sleep.Materials and methodsPain and sleep were evaluated for two 5-day periods under different conditions (control vs. WBC), randomly assigned across two consecutive menstrual cycles. Measurements began when the first pain/symptom indicating the onset of the menstrual phase was experienced. Pain was rated using a scale, while sleep was assessed using accelerometers and questionnaires. Throughout the 5-day WBC exposure, women underwent 3-min exposure to intense ventilated cold air each evening. After data collection, participants were categorized into high (HP) or low/no pain (LP) groups based on control pain scores.ResultsTwenty-nine naturally menstruating women were assessed. Perceived sleep quality was lower in the HP group compared to the LP group during the control condition (Spiegel score: 20.1 ± 2.3 vs. 22.3 ± 1.9, respectively; Cohen's d = 1.1). Across both groups, perceived sleep quality improved with the number of WBC exposures (night1: 19.5 ± 3.2 vs. night5: 23.5 ± 3.8; Hedge's g = 1.10). In the HP group, pain was reduced in the WBC condition compared to the control condition. Changes in pain and perceived sleep quality following WBC were correlated (r = −0.86).DiscussionWomen experiencing higher menstrual-related pain reported poorer perceived sleep quality. Their pain was reduced by WBC exposures. This improvement was highly associated with the enhancement in sleep quality.

Over the two last decades, whole-body cryotherapy/cryostimulation (WBC) has emerged as an exciting non-pharmacological treatment influencing inflammatory events at a cellular and physiological level, which can result in improved sleep quality, faster neuromuscular recovery after high-intensity exercise, and chronic pain relief for patients suffering different types of diseases (fibromyalgia, rheumatism, arthritis). Some evidence even suggests that WBC has benefits on mental health (depression, anxiety disorders) and cognitive functions in both adults and older adults, due to increased circulating BDNF levels. Recently, some safety concerns have been expressed by influential public health authorities (e.g., FDA, INSERM) based on reports from patients who developed adverse events upon or following WBC treatment. However, part of the data used to support these claims involved individuals whose entire body (except head) was exposed to extreme cold vaporized liquid nitrogen while standing in a narrow bathtub. Such a procedure is known as partial-body cryotherapy (PBC), and is often erroneously mistaken to be whole-body cryotherapy. Although having similarities in terms of naming and pursued aims, these two approaches are fundamentally different. The present article reviews the available literature on the main safety concerns associated with the use of true whole-body cryotherapy. English- and French-language reports of empirical studies including case reports, case series, and randomized controlled trials (RCTs) were identified through searches of PubMed, Scopus, Cochrane, and Web of Science electronic databases. Five case reports and two RCTs were included for a total of 16 documented adverse events (AEs). A critical in-depth evaluation of these AEs (type, severity, context of onset, participant’s medical background, follow-up) is proposed and used to illustrate that WBC-related safety risks are within acceptable limits and can be proactively prevented by adhering to existing recommendations, contraindications, and commonsense guidelines.

Acceptable definitions of thermal sensation for cold and hot water immersion do not exist. The use of subjective thermal sensation scales remains unsolved with broad psycho-physiological, and semantic implications. We hypothesize that perception of thermal sensation could be a valid and reliable indicator for thermal strain during exposure in water. We aimed to provide a theoretical background for behavioral thermoregulation and neurocognition to support an integrated thermal sensation scale for estimation of thermal load during head-out water immersion. This research used a mixed methods approach. Domains were identified and items were measured for thermal load to examine the content validity. Thereafter, we formed an integrated scale based on standard 10,551 of International Organization for Standardization (ISO). Finally, we conducted a pilot study for the face validation of the scale based on a 30 min head-out water immersion at 26 °C in healthy adults (females, n = 4; males, n = 4; age: 22.6 ± 8.0 years; body mass, 67.7 ± 9.5 kg; height, 169.0 ± 5.6 cm). We identified three aspects (environment, physiological and behavioral thermoregulation) and a total of 18 items, of whom eight items (water temperature, immersion duration, core temperature, skin temperature, body heat storage, shivering, thermal sensation, and thermal comfort) were acceptable based on terms of scale-level content validity index (S-CVI = 92 %). Conditions incorporated into our scale included: icy < 12 °C, cold 12–24 °C, cool 24–29 °C, neutral 29–38 °C, warm 38–43 °C, and hot > 43 °C. We found excellent face validity based on a reported homogenous cool feeling and physiological thermoregulatory responses. Our study revealed our model could reasonably characterize body thermal load though whole-body thermal sensation based on well-established thermoregulatory mechanisms during water immersion. Further research is needed to validate the accuracy of our behavioral model in a variety of water temperatures and in a larger sample size.

We investigated how arm cooling modulates sensorimotor representations and sensorimotor control. Arm cooling induced changes in early kinematic parameters of pointing, suggesting an impact on feedforward processes or hand representation. Arm cooling induced changes in late kinematic parameters of pointing, suggesting an impact on feedback processes. Arm cooling also affected performance on a hand laterality task, suggesting that action representations were modified.

The objectives of the study were (i) to evaluate the effects of whole-body cryostimulation (WBC) after training as an effective tool to improve sleep and recovery and (ii) to determine which exposure schedule for WBC (immediately after training vs. 1h before bedtime) is the most appropriate to improve sleep and recovery. Twenty-two well-trained male athletes or triathletes (23.1 ± 3.5-years) were recruited in this controlled crossover protocol. Each participant completed the three experimental sessions, each composed of a running training session and one night of sleep analysis. Depending on the experimental condition, subjects were exposed-or not (CONT)-to WBC immediately after training (CRYO 7 p.m.) or 1h before going to bed (CRYO 10 p.m.). All participants were randomly assigned to each condition, spaced seven days apart. Sleep was monitored via actimetry, cerebral activity recordings, heart rate variability, body core temperature, and perceptual measurements. WBC after training did not modify subjective or objective sleep parameters compared to the control condition. However, WBC significantly improved cardiac parasympathetic activity. More specifically, it was more activated during the night following the CRYO 10 p.m. condition than in the other experimental conditions. Core body temperature (CBT) 1h after bedtime was the lowest in the CRYO 10 p.m. condition. This study confirmed the effectiveness of WBC as a recovery technique after intense evening training. We suggest that WBC may exhibit the most significant benefit on recovery if the session is performed 1h before bedtime, acting on subsequent parasympathetic activation and CBT drop.