Thermal and hemodynamic response to whole-body cryostimulation in healthy subjects

The effects of cold exposure (cold water immersion, whole- and partial- body cryostimulation) on cardiovascular and cardiac autonomic control responses in healthy individuals: A systematic review, meta-analysis and meta-regression

BACKGROUND

Cryostimulation and cold-water immersion (CWI) have recently gained widespread attention due to their association with changes in cardiovascular and cardiac autonomic control responses. Therefore, the aim of the present systematic review and meta-analysis was to identify the global impact of such cold exposures on cardiovascular and cardiac autonomic activity.

METHODS

Three databases (PubMed, Embase, Web-of-Science) were used. Studies were eligible for inclusion if they were conducted on healthy participants using cryostimulation and/or CWI. The outcomes included measurements of blood pressure (BP), heart rate (HR), and heart rate variability (HRV) indices: RR interval (RR), Root mean square of successive RR interval differences (RMSSD), low frequency band (LF), high frequency band (HF), and LF/HF ratio.

RESULTS

Among the 27 articles included in our systematic literature review, only 24 were incorporated into the meta-analysis. Our results reveal a significant increase in HRV indices: RMSSD (Standardized mean difference (SMD) = 0.61, p < 0.001), RR (SMD = 0.77, p < 0.001), and HF (SMD = 0.46, p < 0.001), as well as significantly reduced LF (SMD = -0.41, p < 0.001) and LF/HF ratio (SMD = -0.25, p < 0.01), which persisted up to 15 min following cold exposure. Significantly decreased heart rate (SMD = -0.16, p < 0.05), accompanied by slightly increased mean BP (SMD = 0.28, p < 0.001), was also observed. These results seem to depend on individual characteristics and the cooling techniques.

CONCLUSION

Our meta-analysis suggests that cryostimulation and/or CWI exposure enhance parasympathetic nervous activity. There is scarce scientific literature regarding the effect of individual characteristics on cold-induced physiological responses.

Effects of whole-body cryotherapy and static stretching are maintained 4 weeks after treatment in most patients with chronic fatigue syndrome

In the previous study, whole-body cryotherapy (WBC)+static stretching (SS) has been shown to reduce the severity of some symptoms in Chronic Fatigue Syndrome (CFS) noted just after the therapy. Here we consider the effects of treatment and explore the sustainability of symptom improvements at four weeks (one-month) follow-up. Twenty-two CFS patients were assessed one month after WBC + SS programme. Parameters related to fatigue (Chalder Fatigue Questionnaire (CFQ), Fatigue Impact Scale (FIS), Fatigue Severity Scale (FSS)), cognitive function (Trial Making test part A and B (TMT A and TMT B and its difference (TMT B-A)), Coding) hemodynamic, aortic stiffness (aortic systolic blood pressure (sBP aortic)) and autonomic nervous system functioning were measured. TMT A, TMT B, TMT B-A and Coding improved at one month after the WBC + SS programme. WBC + SS had a significant effect on the increase in sympathetic nervous system activity in rest. WBC + SS had a significant, positive chronotropic effect on the cardiac muscle. Peripheral and aortic systolic blood pressure decreased one month after WBC + SS in comparison to before. Effects of WBC + SS on reduction of fatigue, indicators of aortic stiffness and symptoms severity related to autonomic nervous system disturbance and improvement in cognitive function were maintained at one month. However, improvement in all three fatigue scales (CFQ, FIS and FSS) was noted in 17 of 22 patients. In addition, ten patients were treated initially but they were not assessed at 4 weeks, and are thus not included in the 22 patients who were examined on follow-up. The overall effects of WBC + SS noted at one month post-treatment should be interpreted with caution.

Whole-body cryotherapy as a treatment for chronic medical conditions?

INTRODUCTION

Whole-body cryotherapy (WBC) is a controlled exposure of the whole body to cold to gain health benefits. In recent years, data on potential applications of WBC in multiple clinical settings have emerged.

SOURCES OF DATA

PubMed, EBSCO and Clinical Key search using keywords including terms 'whole body', 'cryotherapy' and 'cryostimulation'.

AREAS OF AGREEMENT

WBC could be applied as adjuvant therapy in multiple conditions involving chronic inflammation because of its potent anti-inflammatory effects. Those might include systemic inflammation as in rheumatoid arthritis. In addition, WBC could serve as adjuvant therapy for chronic inflammation in some patients with obesity.

AREAS OF CONTROVERSY

WBC probably might be applied as an adjuvant treatment in patients with chronic brain disorders including mild cognitive impairment and general anxiety disorder and in patients with depressive episodes and neuroinflammation reduction as in multiple sclerosis. WBC effects in metabolic disorder treatment are yet to be determined. WBC presumably exerts pleiotropic effects and therefore might serve as adjuvant therapy in multi-systemic disorders, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

GROWING POINTS

The quality of studies on the effects of WBC in the clinical setting is in general low; hence, randomized controlled trials with adequate sample size and longer follow-up periods are needed.

AREAS ARE TIMELY FOR DEVELOPING RESEARCH

Further studies should examine the mechanism underlying the clinical efficacy of WBC. Multiple conditions might involve chronic inflammation, which in turn could be a potential target of WBC. Further research on the application of WBC in neurodegenerative disorders, neuropsychiatric disorders and ME/CFS should be conducted.

A single session of whole-body cryotherapy boosts maximal cycling performance and enhances vagal drive at rest

Whole-body cryotherapy (WBC) has been reported to maximize physical recovery after exercise and reduce the ensuing muscle damage. In addition, WBC triggers cardiovascular responses leading to an increased vagal drive. Here we tested whether WBC may boost exercise performance as well as post-exercise recovery. Moreover, we compared the effects of WBC and exercise on sympathovagal balance and tested whether these two factors may interact. ECG was recorded in 28 healthy adults who underwent rest, all-out effort on a cycloergometer, 5 min recovery and again rest. After 3-5 days, WBC (3 min exposure to - 150 °C air) was applied and the whole procedure repeated. Total exercise duration was split into the time needed to reach peak power output (t_PEAK) and the time to exhaustion (t_EXH). The post-exercise exponential decay of HR was characterized by its delay from exercise cessation (t_DELAY) and by its time constant (τ_OFF). Sympathovagal balance was evaluated by measuring HR variability power in the low (LF) and high (HF) frequency bands, both before exercise and after recovery from it. Sympathetic vs. vagal predominance was assessed by the sympathovagal index LFnu. Paired t-tests indicated that WBC increased t_EXH and reduced t_DELAY, speeding up the HR recovery. These results suggest that WBC may be exploited to boost exercise performance by about 12-14%. ANOVA on HR variability confirmed that exercise shifted the sympathovagal balance towards sympathetic predominance, but it also highlighted that WBC enhanced vagal drive at rest, both before exercise and after full recovery, covering ~ 70% of the exercise effect.

Combination of whole body cryotherapy with static stretching exercises reduces fatigue and improves functioning of the autonomic nervous system in Chronic Fatigue Syndrome

BACKGROUND

The aim of this study was to explore the tolerability and effect of static stretching (SS) and whole body cryotherapy (WBC) upon fatigue, daytime sleepiness, cognitive functioning and objective and subjective autonomic nervous system functioning in those with Chronic Fatigue Syndrome (CFS) compared to a control population.

METHODS

Thirty-two CFS and eighteen healthy controls (HC) participated in 2 weeks of a SS + WBC programme. This programme was composed of five sessions per week, 10 sessions in total.

RESULTS

A significant decrease in fatigue was noted in the CFS group in response to SS + WBC. Some domains of cognitive functioning (speed of processing visual information and set-shifting) also improved in response to SS + WBC in both CFS and HC groups. Our study has confirmed that WBC is well tolerated by those with CFS and leads to symptomatic improvements associated with changes in cardiovascular and autonomic function.

CONCLUSIONS

Given the preliminary data showing the beneficial effect of cryotherapy, its relative ease of application, good tolerability, and proven safety, therapy with cold exposure appears to be an approach worth attention. Further studies of cryotherapy as a potential treatment in CFS is important in the light of the lack of effective therapeutic options for these common and often disabling symptoms.

Infrared Thermography as a Non-Invasive Tool in Musculoskeletal Disease Rehabilitation—The Control Variables in Applicability—A Systematic Review

In recent years, the usefulness of infrared thermography (IRT) as a valuable supplementary imaging method in medical diagnostics, as well as for assessing the effects of the treatment of musculoskeletal injuries, has been increasingly confirmed. At the same time, great importance is attached to the standards of thermographic research, the fulfillment of which determines the correct methodology and interpretation of the results. This article discusses the medical applications of infrared thermography in musculoskeletal system diseases, with particular emphasis on its usefulness in assessing the therapeutic effects of physical treatments used in rehabilitation. The literature from the last decade that is available in the Medline and Web of Science databases has been reviewed. Among the physiotherapeutic methods used, the following were selected that directly affect the musculoskeletal system: cryotherapy, laser therapy, electrotherapy, diathermy, and massage. The article summarizes all the guidelines and recommendations for IR imaging in medicine and rehabilitation.

Pre-Exercise Whole- or Partial-Body Cryotherapy Exposure to Improve Physical Performance: A Systematic Review

Whole- (WBC) and partial-body cryotherapy (PBC) are commonly used sports medicine modalities for the treatment of injury and exercise recovery. Physiological and perceptual effects have the potential to be utilised in a novel application that involves pre-exercise WBC and PBC exposure to improve physical performance. A systematic literature search of multiple databases was conducted in July 2021 to identify and evaluate the effects of pre-exercise exposure of WBC or PBC on physical performance measures, and any potential translational effects. The following inclusion criteria were applied: (1) use of WBC or PBC exposure pre-exercise, (2) use of WBC or PBC in healthy and/or athletic populations, (3) control group was used in the data collection, and (4) investigated physiological, psychosocial or direct physical performance impacts of pre-exercise cryotherapy exposure. A total of 759 titles were identified, with twelve relevant studies satisfying the inclusion criteria after full-text screening. The twelve studies were categorised into three key areas: performance testing (n = 6), oxidative stress response (n = 4) and lysosomal enzyme activity (n = 2). The potential for eliciting favourable physical and physiological responses from pre-exercise WBC or PBC is currently unclear with a paucity of good quality research available. Furthermore, a lack of standardisation of cryotherapy protocols is a current challenge.

Impact of acute partial-body cryostimulation on cognitive performance, cerebral oxygenation, and cardiac autonomic activity

We assessed the effects of a 3-min partial-body cryostimulation (PBC) exposure—where the whole body is exposed to extreme cold, except the head—on cognitive inhibition performance and the possible implications of parasympathetic cardiac control and cerebral oxygenation. In a randomized controlled counterbalanced cross-over design, eighteen healthy young adults (nine males and nine females) completed a cognitive Stroop task before and after one single session of PBC (3-min exposure at − 150 °C cold air) and a control condition (3 min at room temperature, 20 °C). During the cognitive task, heart rate variability (HRV) and cerebral oxygenation of the prefrontal cortex were measured using heart rate monitoring and near-infrared spectroscopy methods. We also recorded the cerebral oxygenation during the PBC session. Stroop performance after PBC exposure was enhanced (562.0 ± 40.2 ms) compared to pre-PBC (602.0 ± 56.4 ms; P < 0.042) in males only, accompanied by an increase (P < 0.05) in HRV indices of parasympathetic tone, in greater proportion in males compared to females. During PBC, cerebral oxygenation decreased in a similar proportion in males and females but the cerebral extraction (deoxyhemoglobin: ΔHHb) remained higher after exposure in males, only. These data demonstrate that a single PBC session enhances the cognitive inhibition performance on a Stroop task in males, partly mediated by a greater parasympathetic cardiac control and greater cerebral oxygenation. The effects of PBC on cognitive function seem different in females, possibly explained by a different sensitivity to cold stimulation.

The use of whole-body cryotherapy: time- and dose-response investigation on circulating blood catecholamines and heart rate variability

Purpose

A predominance of parasympathetic drive is observed following cold exposure. Such modulation of the autonomic nervous system (ANS) is associated with faster post-exercise recovery. Within this context, whole-body cryotherapy (WBC) has been spreading in sport medicine, though the optimal temperature and frequency are unclear. The aim of this study was to examine the effects of different cryotherapy conditions on the sympathovagal balance.

Methods

Forty healthy males were randomly assigned into five different groups (− 110 °C, − 60 °C, − 10 °C, control temperature [≃ 24 °C]) and undertook 5 WBC sessions over 5 consecutive days. Cardiac autonomic activity was assessed through heart rate variability (HRV) using power density of high frequency (HF), root-mean square difference of successive R–R intervals (RMSSD) and sympathovagal balance (LF/HF). Systemic sympathetic activity was assessed via circulating blood catecholamines.

Results

Mean weekly RMSSD (pre: 48 ± 22 ms, post: 68 ± 29 ms) and HF (pre: 607 ± 692 ms², post: 1271 ± 1180 ms²) increased (p < 0.05) from pre to post WBC, only in the − 110 °C condition. A rise in plasma norepinephrine was found after the first − 110 °C WBC session only (pre: 173 ± 98, post: 352 ± 231 ng L⁻¹, p < 0.01); whereas, it was not significant after the 5th session (pre: 161 ± 120, post: 293 ± 245 ng L⁻¹, p = 0.15).

Conclusion

These results suggest that one − 110 °C WBC exposure is required to stimulate the ANS. After five daily exposures, a lower autonomic response was recorded compared to day one, therefore suggesting the development of physiological habituation to WBC.

Critical Evaluation of Whole-Body Cryostimulation Protocol in Race Horses

Cold therapy is commonly used to relieve pain and inflammation and to aid in muscle recovery after exercise in human medicine. A number of applications have also been observed in veterinary practice. In this article, a critical evaluation of equine protocol applied with a new commercial concept of equine whole-body cryostimulation (WBC) was made. With this new concept of WBC, the protocol usually utilized for relieving pain and discomfort in humans has been extended to horses. The investigations described herein focus on the reduction of horse skin temperature when applying human WBC protocols. Based on infrared thermography measurements, results show that exposing a horse for 3 minutes to a temperature of -140°C, which are conventional parameters used for humans, does not induce sufficient skin thermal gradients in horses. Consequently, beneficial cold reflexes such as vasomotor, neuroconduction, and biochemical reactions cannot be triggered. Further investigations should therefore be carried out to design an adequate protocol specifically aimed at horses.

Essential oil inhaler (AromaStick®) improves heat tolerance in the Hot Immersion Test (HIT). Results from two randomized, controlled experiments

BACKGROUND

A recent review article on an aromatherapeutic inhaler demonstrated clinical effects on a number of bodily systems, like the cardiovascular system, the respiratory system, the nervous system and the endocrine system.

OBJECTIVE

This paper extends these findings and investigates whether specially designed essential oils inhalers are capable to counter experimentally induced stressful heat sensations.

METHOD

Two prospective, randomized, controlled experiments using the Hot Immersion Test Paradigm (HIT) were conducted to investigate whether deep odor inhalations increase heat tolerance.

RESULTS

In both experiments, the inhaler strongly prolonged pain tolerance and increased blood oxygenation (1 < d < 1.3). In the second experiment, the inhaler also increased heart rate variability (d = 1.3) as a mechanism to cope with heat stress.

CONCLUSION

The ability to resist a stressful thermal stimulus can be exogenously improved by short and deep inhalations of essential scents directly delivered to the olfactory system.

Whole-Body Cryotherapy: Potential to Enhance Athlete Preparation for Competition?

The final hours of preparation before competition are important for performance. Recovery, preparation and warm up protocols are evolving continuously and include passive and active modalities often developed by "trial and error" approaches. Passive modalities, such as whole-body cryotherapy (WBC), have the potential to enhance both recovery and preparation. Whole-body cryotherapy has generally been used within a recovery setting after competition or strenuous training for athletes, and in clinical settings for the general population. However, the acute hormonal, anti-inflammatory, perceptual and psychological responses yielded by a single, or repeated, bouts of WBC indicate that this practice could enhance an athlete's competition readiness when used alongside traditional elements of active warm-ups in the hours before competition in addition to aiding recovery in the hours after. Here we summarize and evaluate the acute effects of WBC exposures on physiological, performance and perceptual responses, and examine the likelihood these responses could theoretically translate into enhanced athletic performance. The potential to enhance an athlete's performance using acute passive WBC exposure is a novel intervention that requires further investigation.

Whole body and partial body cryotherapies - lessons from human practice and possible application for horses

Whole body and partial body cryotherapies (WBC and PBC) have been successfully used in human medicine, and currently also are being proposed in veterinary practice.

In horses, only the partial body cryotherapy provided in cryosauna is considered, due to the technical conditions. These therapies have been dedicated to human patients with rheumatic and inflammatory diseases as well as an assistance during training in athletes. The anti-inflammatory effects have been demonstrated clinically and indicated by the changes in several hematological and immunological parameters, however, various patterns have been described, depending on the protocols and the treating subjects. The numbers of white blood cells and the differential counts either increased or remained unchanged but the cytokine concentrations generally changed towards various anti-inflammatory profiles and the modifications of immunological molecules having paracrine effects have been reported.

In equine practice, local cold therapies have been successfully used, so the therapy in cryosauna, which allows for a much shorter procedure with much lower temperature seems promising.

Abdominal Aortic Dissection and Cold-Intolerance After Whole-Body Cryotherapy: A Case Report

Whole-body cryotherapy (WBC) involves short exposures to air temperatures below -100°C and is purported to enhance recovery after exercise and accelerate rehabilitation after injury. It is generally considered a procedure with few side effects, but there are no large studies that have established its safety profile. We present the case of a 56-year-old patient who developed an abdominal aortic dissection after receiving 15 sessions of WBC. The patient had no other strong risk factors for aortic dissection. Exposure to cold temperatures, including WBC, has multiple hemodynamic effects, including increases in blood pressure, heart rate, and an adrenergic response. We suggest that these changes could act as a trigger for the onset of aortic dissections. This could be the first reported cardiovascular complication associated with WBC.

Theoretical modeling of time-dependent skin temperature and heat losses during whole-body cryotherapy: A pilot study

This article establishes the basics of a theoretical model for the constitutive law that describes the skin temperature and thermolysis heat losses undergone by a subject during a session of whole-body cryotherapy (WBC). This study focuses on the few minutes during which the human body is subjected to a thermal shock. The relationship between skin temperature and thermolysis heat losses during this period is still unknown and have not yet been studied in the context of the whole human body. The analytical approach here is based on the hypothesis that the skin thermal shock during a WBC session can be thermally modelled by the sum of both radiative and free convective heat transfer functions. The validation of this scientific approach and the derivation of temporal evolution thermal laws, both on skin temperature and dissipated thermal power during the thermal shock open many avenues of large scale studies with the aim of proposing individualized cryotherapy protocols as well as protocols intended for target populations. Furthermore, this study shows quantitatively the substantial imbalance between human metabolism and thermolysis during WBC, the explanation of which remains an open question.

Sarcopenia: Monitoring, Molecular Mechanisms, and Physical Intervention

According to European Working Group on Sarcopenia in Older People (EWGSOP) sarcopenia includes both a loss of muscle strength and a decline in functional quality in addition to the loss of muscle protein mass. In order to develop strategies to prevent and treat sarcopenia, the risk factors and causes of sarcopenia must be identified. Age-related muscle loss is characterized by the contribution of multiple factors, and there is growing evidence for a prominent role of low-grade chronic inflammation in sarcopenia. The elderly who are less physically active are more likely to have lower skeletal muscle mass and strength and are at increased risk of developing sarcopenia. Resistance training added to aerobic exercise or high-intensity interval training promote numerous changes in skeletal muscle, many of which may help to prevent or reverse sarcopenia. In this review, we provided current information on definition and monitoring, molecular mechanisms, and physical intervention to counteract sarcopenia.

Whole-body cryostimulation increases parasympathetic outflow and decreases core body temperature

The cardiovascular, autonomic and thermal response to whole-body cryostimulation exposure are not completely known. Thus the aim of this study was to evaluate objectively and noninvasively autonomic and thermal reactions observed after short exposure to very low temperatures. We examined 25 healthy men with mean age 30.1 ± 3.7 years and comparable anthropomorphical characteristic. Each subject was exposed to cryotherapeutic temperatures in a cryogenic chamber for 3 min (approx. -120 °C). The cardiovascular and autonomic parameters were measured noninvasively with Task Force Monitor. The changes in core body temperature were determined with the Vital Sense telemetric measurement system. Results show that 3 min to cryotherapeutic temperatures causes significant changes in autonomic balance which are induced by peripheral and central blood volume changes. Cryostimulation also induced changes in core body temperature, maximum drop of core temperature was observed 50-60 min after the stimulation. Autonomic and thermal reactions to cryostimulation were observed up to 6 h after the exposure and were not harmful for examined subjects.