Sauna

Objectives, design and main findings until 2020 from the Rotterdam Study

M. Arfan Ikram, Guy Brusselle, Mohsen Ghanbari +14 more · European Journal of Epidemiology · 2020 · 472 citations

The Rotterdam Study is an ongoing prospective cohort study that started in 1990 in the city of Rotterdam, The Netherlands. The study aims to unravel etiology, preclinical course, natural history and potential targets for intervention for chronic diseases in mid-life and late-life. The study focuses on cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1700 research articles and reports. This article provides an update on the rationale and design of the study. It also presents a summary of the major findings from the preceding 3 years and outlines developments for the coming period.

Effect of cold and heat therapies on pain relief in patients with delayed onset muscle soreness: A network meta-analysis

Yutan Wang, Hongmei Lü, Sijun Li +7 more · Journal of Rehabilitation Medicine · 2021 · 37 citations

Hot packs provide the best pain relief for delayed onset muscle soreness (DOMS) within the first 48 hours after exercise, while cryotherapy (whole-body or partial-body cold exposure) works best after 48 hours — but the evidence is weak and based on small, low-quality studies, so you should treat these rankings as provisional rather than definitive.

Interoception, contemplative practice, and health

Norman A. S. Farb, Jennifer Daubenmier, Cynthia Price +6 more · Frontiers in Psychology · 2015 · 613 citations

Interoception can be broadly defined as the sense of signals originating within the body. As such, interoception is critical for our sense of embodiment, motivation, and well-being. And yet, despite its importance, interoception remains poorly understood within modern science. This paper reviews interdisciplinary perspectives on interoception, with the goal of presenting a unified perspective from diverse fields such as neuroscience, clinical practice, and contemplative studies. It is hoped that this integrative effort will advance our understanding of how interoception determines well-being, and identify the central challenges to such understanding. To this end, we introduce an expanded taxonomy of interoceptive processes, arguing that many of these processes can be understood through an emerging predictive coding model for mind-body integration. The model, which describes the tension between expected and felt body sensation, parallels contemplative theories, and implicates interoception in a variety of affective and psychosomatic disorders. We conclude that maladaptive construal of bodily sensations may lie at the heart of many contemporary maladies, and that contemplative practices may attenuate these interpretative biases, restoring a person's sense of presence and agency in the world.

The effects of cold water immersion with different dosages (duration and temperature variations) on heart rate variability post-exercise recovery: A randomized controlled trial

Aline Castilho de Almeida, Aryane Flauzino Machado, Maíra Campos de Albuquerque +5 more · Journal of science and medicine in sport · 2015 · 38 citations

Cold water immersion for 15 minutes at 14°C was the most effective dose for accelerating heart rate variability (HRV) recovery after intense exercise, with several HRV indices returning to baseline faster than passive recovery — but colder water (9°C) or shorter durations (5 minutes) did not provide additional benefit and sometimes performed worse.

Physical and Mental Effects of Bathing: A Randomized Intervention Study

Yasuaki Goto, Shinya Hayasaka, Shigeo Kurihara +1 more · Evidence-based Complementary and Alternative Medicine · 2018 · 41 citations

A randomized crossover study found that 2 weeks of daily 10-minute warm immersion baths significantly improved subjective fatigue, stress, pain, mood, and quality of life compared to showering, suggesting a simple way to boost well-being.

The low-temperature effect on sports regeneration

Robert Trybulski, Andriy Vovkanych, Olha Bas +1 more · Fisioterapia em Movimento · 2023 · 6 citations

Cold therapy (ice baths, cold water immersion, cryotherapy) reliably reduces pain and inflammation after intense exercise and helps restore sprint performance within 24 hours, but it does little to improve muscle strength, endurance, or lactate clearance — so it's useful for recovery between explosive efforts, not for building strength or stamina.

Active aging – resilience and external support as modifiers of the disablement outcome: AGNES cohort study protocol

Taina Rantanen, Milla Saajanaho, Laura Karavirta +14 more · BMC Public Health · 2018 · 111 citations

BACKGROUND: Population aging increases the need for knowledge on positive aspects of aging, and contributions of older people to their own wellbeing and that of others. We defined active aging as an individual's striving for elements of wellbeing with activities as per their goals, abilities and opportunities. This study examines associations of health, health behaviors, health literacy and functional abilities, environmental and social support with active aging and wellbeing. We will develop and validate assessment methods for physical activity and physical resilience suitable for research on older people, and examine their associations with active aging and wellbeing. We will examine cohort effects on functional phenotypes underlying active aging and disability. METHODS: For this population-based study, we plan to recruit 1000 participants aged 75, 80 or 85 years living in central Finland, by drawing personal details from the population register. Participants are interviewed on active aging, wellbeing, disability, environmental and social support, mobility, health behavior and health literacy. Physical activity and heart rate are monitored for 7 days with wearable sensors. Functional tests include hearing, vision, muscle strength, reaction time, exercise tolerance, mobility, and cognitive performance. Clinical examination by a nurse and physician includes an electrocardiogram, tests of blood pressure, orthostatic regulation, arterial stiffness, and lung function, as well as a review of chronic and acute conditions and prescribed medications. C-reactive protein, small blood count, cholesterol and vitamin D are analyzed from blood samples. Associations of factors potentially underlying active aging and wellbeing will be studied using multivariate methods. Cohort effects will be studied by comparing test results of physical and cognitive functioning with results of a cohort examined in 1989-90. CONCLUSIONS: The current study will renew research on positive gerontology through the novel approach to active aging and by suggesting new biomarkers of resilience and active aging. Therefore, high interdisciplinary impact is expected. This cross-sectional study will not provide knowledge on temporal order of events or causality, but an innovative cross-sectional dataset provides opportunities for emergence of novel creative hypotheses and theories.

Optimizing recovery strategies for winter athletes: insights for Milano-Cortina 2026 Olympic Games

Peter Edholm, Niels Ørtenblad, Hans‐Christer Holmberg +1 more · Sport Sciences for Health · 2024 · 5 citations

This narrative umbrella review of 21 meta-analyses and systematic reviews found that sleep and nutrition are the only recovery strategies with consistent, high-quality evidence for improving recovery in winter athletes, while physical methods like cold-water immersion and massage show context-specific benefits for pain relief but not performance restoration, and stretching, sauna, and contrast therapy lack robust evidence.

Effects of Whole-Body Cryotherapy vs. Far-Infrared vs. Passive Modalities on Recovery from Exercise-Induced Muscle Damage in Highly-Trained Runners

Christophe Hausswirth, Julien Louis, François Bieuzen +4 more · PLoS ONE · 2011 · 234 citations

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.

Tuning pathological brain oscillations with neurofeedback: a systems neuroscience framework

Tomas Ros, Bernard J. Baars, Ruth A. Lanius +1 more · Frontiers in Human Neuroscience · 2014 · 257 citations

Neurofeedback (NFB) is emerging as a promising technique that enables self-regulation of ongoing brain oscillations. However, despite a rise in empirical evidence attesting to its clinical benefits, a solid theoretical basis is still lacking on the manner in which NFB is able to achieve these outcomes. The present work attempts to bring together various concepts from neurobiology, engineering, and dynamical systems so as to propose a contemporary theoretical framework for the mechanistic effects of NFB. The objective is to provide a firmly neurophysiological account of NFB, which goes beyond traditional behaviorist interpretations that attempt to explain psychological processes solely from a descriptive standpoint whilst treating the brain as a "black box". To this end, we interlink evidence from experimental findings that encompass a broad range of intrinsic brain phenomena: starting from "bottom-up" mechanisms of neural synchronization, followed by "top-down" regulation of internal brain states, moving to dynamical systems plus control-theoretic principles, and concluding with activity-dependent as well as homeostatic forms of brain plasticity. In support of our framework, we examine the effects of NFB in several brain disorders, including attention-deficit hyperactivity (ADHD) and post-traumatic stress disorder (PTSD). In sum, it is argued that pathological oscillations emerge from an abnormal formation of brain-state attractor landscape(s). The central thesis put forward is that NFB tunes brain oscillations toward a homeostatic set-point which affords an optimal balance between network flexibility and stability (i.e., self-organised criticality (SOC)).

Exercise and the Cardiovascular System

Saeid Golbidi, Ismail Laher · Cardiology Research and Practice · 2012 · 71 citations

There are alarming increases in the incidence of obesity, insulin resistance, type II diabetes, and cardiovascular disease. The risk of these diseases is significantly reduced by appropriate lifestyle modifications such as increased physical activity. However, the exact mechanisms by which exercise influences the development and progression of cardiovascular disease are unclear. In this paper we review some important exercise-induced changes in cardiac, vascular, and blood tissues and discuss recent clinical trials related to the benefits of exercise. We also discuss the roles of boosting antioxidant levels, consequences of epicardial fat reduction, increases in expression of heat shock proteins and endoplasmic reticulum stress proteins, mitochondrial adaptation, and the role of sarcolemmal and mitochondrial potassium channels in the contributing to the cardioprotection offered by exercise. In terms of vascular benefits, the main effects discussed are changes in exercise-induced vascular remodeling and endothelial function. Exercise-induced fibrinolytic and rheological changes also underlie the hematological benefits of exercise.

ISSN exercise & sports nutrition review update: research & recommendations

Chad M. Kerksick, Susan M. Kleiner, Jaci N Davis +12 more · UNC Libraries · 2019 · 92 citations

Abstract Background Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words ‘sport nutrition’. Consequently, staying current with the relevant literature is often difficult. Methods This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches. Conclusions This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.

Review of Stress Detection Methods Using Wearable Sensors

Georgios V. Taskasaplidis, Dimitris A. Fotiadis, Panagiotis D. Bamidis · IEEE Access · 2024 · 80 citations

Stress is a significant factor that affects well-being and health. Factors that trigger stress include work, social interactions, and economic and environmental factors. Stress may cause lower labor productivity, physical and mental health problems, and malfunctions in all social aspects of life. Psychosomatic health can be improved if proper stress detection mechanisms are present in daily life and stress reduction methods can occur. Wearable sensors are currently used in many commercial and scientific applications in a non-destructive or annoying manner. These devices are used in daily routines. In this paper, a comprehensive review of the latest literature and developments in stress detection methods is presented through extensive and holistic research on stress response, both at the level of the autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal axis (HPA). This study focused on the exploitation of various methods, technologies, and data analysis systems to understand stress in a multifaceted and comprehensive manner. Various stress-related factors are presented along with biological signal measurements, and physical secretions or biomarkers are primarily used for stress detection. Furthermore, the manner in which body movement and posture measurements may be related to stress was investigated, together with speech and hand tremors. Various stress-detection technologies have been analyzed, and existing data analysis methods that can be applied to stress-detection systems have been highlighted. This review serves as a reference and guideline for exploring this area of interest, identifying research opportunities, and offering ideas, options, and suggestions for optimized solutions regarding future applications and research.

2020 ESC Guidelines on Sports Cardiology and Exercise in Patients with Cardiovascular Disease

Antonio Pelliccia, Sanjay Sharma, Sabiha Gati +21 more · Revista Española de Cardiología (English Edition) · 2021 · 50 citations

Breathing: a Powerfull Tool for Physical & Neuropsychological Regulation. The role of Mobile Apps

Athanasios Drigas, Eleni Mitsea · Technium Social Sciences Journal · 2022 · 79 citations

Breathing, although unconscious and often overlooked, is a central aspect of our whole being and one of our most vital functions. This review paper aims at investigating the physiological as well as the neuropsychological benefits of breathing training techniques. In addition, we examine the effectiveness of mobile breathing applications in upgrading human health and wellness. Finally, we discuss the role of metacognition in breathing, as the only means people have to gain awareness of the profound powers of breath and take conscious control of their health.

Heart Rate Variability, Risk-Taking Behavior and Resilience in Firefighters During a Simulated Extinguish-Fire Task

Rebecca Prell, Oliver Opatz, Giampiero Merati +3 more · Frontiers in Physiology · 2020 · 33 citations

Firefighters face a high-risk potential, thus their psychological ability to cope with critical or traumatic events is a crucial characteristic. This study examines correlations between cardiac autonomic modulation, risk-taking behavior, and resilience in professional firefighters. Twenty male professional firefighters underwent a 20 min beat-to-beat heart rate (HR) monitoring at baseline at morning upon awakening, then before, during and after a realistic deployment in a container, systematically set on fire. Risk-taking behavior, resilience and subjective stress were assessed by specific validated tools after deployment: the Risk-taking scale (R-1), the Resilience Scale (RS-13), and the multi-dimensional NASA-Task Load Index. The cardiac autonomic modulation at rest and in response to stress was assessed by classic indexes of heart rate variability (HRV) as RMSSD and LF/HF ratio. Results showed that: (i) risk-taking behavior correlated with a withdrawal in vagal indices, shifted the baseline sympathovagal balance toward sympathetic predominance (LF/HF ratio r(8)=0.522, p=.01), and increased HR mean both in baseline and during physical exercise (r(8)=0.526, p=.01 and r(8)=0.445, p=.05 respectively); (ii) resilience was associated with higher vagal indices (RMSSD r(18)=0.288, p=.04), and with a baseline sympathovagal balance shifted toward parasympathetic predominance (LF/HF ratio r(18)=-0.289, p=.04); (iii) the physical workload of firefighting led to a significantly increased mean HR (p=.002; +22 bpm, 95% CI [9.70, 35.82]) in comparison to the firefighters who did not exercise, which lasted in the recovery phase (p=.005 +24 bpm; 95% CI [8.62, 41.16]). Associations of risk-taking behavior and resilience with cardiac autonomic modulation could be demonstrated, showing that HRV may be a valuable monitoring tool in this specific population; however further studies are warranted for validation.

The Role of Sauna Bathing in Ischemic Heart Disease: A Narrative Review of Therapeutic Potential, Physiological Mechanisms, and Emerging Clinical Applications

Georges El Hachem, Jad Rafic Slim, Bashir Imam +8 more · Cureus · 2025 · 1 citations

This narrative review suggests that consistent use of Finnish or far-infrared saunas may offer cardiovascular benefits similar to moderate exercise for individuals with Ischemic Heart Disease (IHD), improving heart function and vascular health, making it a potential adjunctive therapy, especially for those unable to exercise, though more rigorous research is needed to establish definitive protocols and effectiveness.

The effects of foam rolling vs massage as recovery tools among UiTM Perlis FC footballers

Roslan Muhammad Nuh Sharid, Zuraimy Muhammad Hazim, Abdul Halim Mohd Hazwan Zikri +2 more · Jurnal Intelek · 2024 · 1 citations

Foam rolling for 20 minutes immediately after football training improved jump height, agility, and perceived recovery more than massage or passive rest when measured 24 hours later, but the study was too small and short to prove these effects are reliable or lasting.

Resolution of inflammation in chronic disease via restoration of the heat shock response (HSR)

Helena Trevisan Schroeder, Carlos Henrique de Lemos Muller, Thiago Gomes Heck +2 more · Cell Stress and Chaperones · 2024 · 13 citations

Effective resolution of inflammation via the heat shock response (HSR) is pivotal in averting the transition to chronic inflammatory states. This transition characterizes a spectrum of debilitating conditions, including insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments. This manuscript explores a range of physiological, pharmacological, and nutraceutical interventions aimed at reinstating the HSR in the context of chronic low-grade inflammation, as well as protocols to assess the HSR. Monitoring the progression or suppression of the HSR in patients and laboratory animals offers predictive insights into the organism's capacity to combat chronic inflammation, as well as the impact of exercise and hyperthermic treatments (e.g., sauna or hot tub baths) on the HSR. Interestingly, a reciprocal correlation exists between the expression of HSR components in peripheral blood leukocytes (PBL) and the extent of local tissue proinflammatory activity in individuals afflicted by chronic inflammatory disorders. Therefore, the Heck index, contrasting extracellular 70 kDa family of heat shock proteins (HSP70) (proinflammatory) and intracellular HSP70 (anti-inflammatory) in PBL, serves as a valuable metric for HSR assessment. Our laboratory has also developed straightforward protocols for evaluating HSR by subjecting whole blood samples from both rodents and human volunteers to ex vivo heat challenges. Collectively, this discussion underscores the critical role of HSR disruption in the pathogenesis of chronic inflammatory states and emphasizes the significance of simple, cost-effective tools for clinical HSR assessment. This understanding is instrumental in the development of innovative strategies for preventing and managing chronic inflammatory diseases, which continue to exert a substantial global burden on morbidity and mortality.

Effects of Water Immersion Methods on Postexercise Recovery of Physical and Mental Performance

Essi K. Ahokas, Johanna K. Ihalainen, Heikki Kyröläinen +1 more · The Journal of Strength and Conditioning Research · 2019 · 24 citations

Ahokas, EK, Ihalainen, JK, Kyröläinen, H, and Mero, AA. Effects of water immersion methods on postexercise recovery of physical and mental performance. J Strength Cond Res 33(6): 1488-1495, 2019-The aim of this study was to compare the effectiveness of 3 water immersion interventions performed after active recovery compared with active recovery only on physical and mental performance measures and physiological responses. The subjects were physically active men (age 20-35 years, mean ± SD 26 ± 3.7 years). All subjects performed a short-term exercise protocol, including maximal jumps and sprinting. Four different recovery methods (10 minutes) were used in random order: cold water immersion (CWI, 10° C), thermoneutral water immersion (TWI, 24° C), and contrast water therapy (CWT, alternately 10° C and 38° C). All these methods were performed after an active recovery (10-minute bicycle ergometer; heart rate [HR] 120-140 b·min, 60-73% from age-calculated maximum HR), and the fourth method was active recovery (ACT) only. Within 96 hours after exercise bouts, recovery was assessed through a 30-m maximal sprint test, maximal countermovement jump (CMJ), self-perceived muscle soreness and relaxation questionnaires, and blood lactate, creatine kinase, testosterone, cortisol, and catecholamine levels. The self-perceived feeling of relaxation after 60-minute recovery was better (p < 0.05) after CWI and CWT than ACT and TWI. Statistically significant differences were not observed between the recovery methods in any other marker. In the 30-m sprint test, however, slower running time was found in ACT (p < 0.001) and CWT (p = 0.005), and reduced CMJ results (p < 0.05) were found in ACT when the results were compared with baseline values. Based on these findings, it can be concluded that CWI and CWT improve the acute feeling of relaxation that can play a positive role in athletes' performance and well-being.

Influence of post-exercise hot-water therapy on adaptations to training over 4 weeks in elite short-track speed skaters

Thibaut Méline, Robert Solsona, Jean‐Philippe Antonietti +3 more · Journal of Exercise Science & Fitness · 2021 · 16 citations

This study aimed to investigate the effects of regular hot water bathing (HWB), undertaken 10 min after the last training session of the day, on chronic adaptations to training in elite athletes. Six short-track (ST) speed skaters completed four weeks of post-training HWB and four weeks of post-training passive recovery (PR) according to a randomized cross-over study. During HWB, participants sat in a jacuzzi (40 °C; 20 min). According to linear mixed models, maximal isometric strength of knee extensor muscles was significantly increased for training with HWB (p < 0.0001; d = 0.41) and a tendency (p = 0.0529) was observed concerning V˙O2max. No significant effect of training with PR or HWB was observed for several variables (p > 0.05), including aerobic peak power output, the decline rate of jump height during 1 min-continuous maximal countermovement jumps (i.e. anaerobic capacity index), and the force-velocity relationship. Regarding specific tasks on ice, a small effect of training was found on both half-lap time and total time during a 1.5-lap all-out exercise (p = 0.0487; d = 0.23 and p = 0.0332; d = 0.21, respectively) but no additional effect of HWB was observed. In summary, the regular HWB protocol used in this study can induce additional effects on maximal isometric strength without compromising aerobic and anaerobic adaptations or field performance in these athletes.

Regular postexercise sauna bathing does not improve heart rate variability: A multi-arm randomized controlled trial.

Lee E, Ketelhut S, Wiklund P +4 more · Physiol Rep · 2025 · 2 citations

Acute effects of leg heat therapy on walking performance and cardiovascular and inflammatory responses to exercise in patients with peripheral artery disease

Jacob C. Monroe, Qifan Song, Michael S. Emery +3 more · Physiological Reports · 2020 · 15 citations

Lower-extremity peripheral artery disease (PAD) is associated with increased risk of cardiovascular events and impaired exercise tolerance. We have previously reported that leg heat therapy (HT) applied using liquid-circulating trousers perfused with warm water increases leg blood flow and reduces blood pressure (BP) and the circulating levels of endothelin-1 (ET-1) in patients with symptomatic PAD. In this sham-controlled, randomized, crossover study, sixteen patients with symptomatic PAD (age 65 ± 5.7 years and ankle-brachial index: 0.69 ± 0.1) underwent a single 90-min session of HT or a sham treatment prior to a symptom-limited, graded cardiopulmonary exercise test on the treadmill. The primary outcome was the peak walking time (PWT) during the exercise test. Secondary outcomes included the claudication onset time (COT), resting and exercise BP, calf muscle oxygenation, pulmonary oxygen uptake (V̇O2), and plasma levels of ET-1, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Systolic, but not diastolic BP, was significantly lower (~7 mmHg, p < .05) during HT when compared to the sham treatment. There was also a trend for lower SBP throughout the exercise and the recovery period following HT (p = .057). While COT did not differ between treatments (p = .77), PWT tended to increase following HT (CON: 911 ± 69 s, HT: 954 ± 77 s, p = .059). Post-exercise plasma levels of ET-1 were also lower in the HT session (CON: 2.0 ± 0.1, HT: 1.7 ± 0.1, p = .02). Calf muscle oxygenation, V̇O2, COT, IL-6, and TNF-α did not differ between treatments. A single session of leg HT lowers BP and post-exercise circulating levels of ET-1 and may enhance treadmill walking performance in symptomatic PAD patients.

Skeletal muscle angiogenic, regulatory, and heat shock protein responses to prolonged passive hyperthermia of the human lower limb

Oliver R. Gibson, Rónan Astin, Zudin Puthucheary +4 more · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2022 · 13 citations

Passive hyperthermia induces a range of physiological responses including augmenting skeletal muscle mRNA expression. This experiment aimed to examine gene and protein responses to prolonged passive leg hyperthermia. Seven young participants underwent 3 h of resting unilateral leg heating (HEAT) followed by a further 3 h of rest, with the contralateral leg serving as an unheated control (CONT). Muscle biopsies were taken at baseline (0 h), and at 1.5, 3, 4, and 6 h in HEAT and 0 and 6 h in CONT to assess changes in selected mRNA expression via qRT-PCR, and HSP72 and VEGFα concentration via ELISA. Muscle temperature ( T m ) increased in HEAT plateauing from 1.5 to 3 h (+3.5 ± 1.5°C from 34.2 ± 1.2°C baseline value; P &lt; 0.001), returning to baseline at 6 h. No change occurred in CONT. Endothelial nitric oxide synthase (eNOS), Forkhead box O1 (FOXO-1), Hsp72, and VEGFα mRNA increased in HEAT ( P &lt; 0.05); however, post hoc analysis identified that only Hsp72 mRNA statistically increased (at 4 h vs. baseline). When peak change during HEAT was calculated angiopoietin 2 (ANGPT-2) decreased (−0.4 ± 0.2-fold), and C-C motif chemokine ligand 2 (CCL2) (+2.9 ± 1.6-fold), FOXO-1 (+6.2 ± 4.4-fold), Hsp27 (+2.9 ± 1.7-fold), Hsp72 (+8.5 ± 3.5-fold), Hsp90α (+4.6 ± 3.7-fold), and VEGFα (+5.9 ± 3.1-fold) increased from baseline (all P &lt; 0.05). At 6 h T m were not different between limbs ( P = 0.582; CONT = 32.5 ± 1.6°C, HEAT = 34.3 ± 1.2°C), and only ANGPT-2 ( P = 0.031; −1.3 ± 1.4-fold) and VEGFα ( P = 0.030; 1.1 ± 1.2-fold) differed between HEAT and CONT. No change in VEGFα or HSP72 protein concentration were observed over time; however, peak change in VEGFα did increase ( P &lt; 0.05) in HEAT (+140 ± 184 pg·mL −1 ) versus CONT (+7 ± 86 pg·mL −1 ). Passive hyperthermia transiently augmented ANGPT-2, CCL2, eNOS, FOXO-1, Hsp27, Hsp72, Hsp90α and VEGFα mRNA, and VEGFα protein.

Heart Rate and Body Temperature Evolution in an Interval Program of Passive Heat Acclimation at High Temperatures (100 ± 2 °C) in a Sauna

Jesús Siquier-Coll, Ignacio Bartolomé, Mario Pérez-Quintero +3 more · International Journal of Environmental Research and Public Health · 2023 · 8 citations

Heat exposure provokes stress on the human body. If it remains constant, it leads to adaptations such as heat acclimation. This study aims to observe the evolution of heart rate (HR), core temperature (Tcore), and skin temperature (Tskin) in an intervallic program of exposure to extreme heat. Twenty-nine healthy male volunteers were divided into a control group (CG; n = 14) and an experimental group (EG; n = 15). EG experienced nine sessions (S) of intervallic exposure to high temperatures (100 ± 2 °C), whereas CG was exposed to ambient temperatures (22 ± 2 °C). HR, Tskin, and Tcore were monitored in S1, 4, 5, 8, and 9. An important increase in HR occurred in the S4 compared to the rest (p &lt; 0.05) in EG. A lower HR was discovered in S8 and S9 compared to S4 and in S9 in relation to S1 (p &lt; 0.05) in EG. EG experiences a gradual decrease in Tcore and Tskin, which was detected throughout the assessments, although it was only significant in the S8 and S9 (p &lt; 0.05). Interval exposure to heat at 100 ± 2 °C elicits stress on the human organism, fundamentally increasing Tcore, Tskin, and FC. This recurring stress in the full program caused a drop in the thermoregulatory response as an adaptation or acclimation to heat.

A study on neural changes induced by sauna bathing: Neural basis of the “totonou” state

Ming Chang, Takuya Ibaraki, Yasushi Naruse +1 more · PLoS ONE · 2023 · 11 citations

Saunas are becoming increasingly popular worldwide, being an activity that promotes relaxation and health. Intense feelings of happiness have been reported shortly after enjoying a hot sauna and cold water, what is known in Japan as the "totonou" state. However, no research has investigated what occurs in the brain during the "totonou" state. In the present study, participants underwent a sauna phase, consisting of three sets of alternating hot sauna, cold water, and rest. We elucidated changes in brain activity and mood in the "totonou" state by measuring and comparing brain activity and emotional scales before and after the sauna phase and during the rest phase in each set. We found significant increases in theta and alpha power during rest and after the sauna phase compared to before the sauna phase. Moreover, in an auditory oddball task, the p300 amplitude decreased significantly and MMN amplitude increased significantly after the sauna phase. The increase in MMN indicates higher activation of the pre-attentional auditory process, leading to a decrease in attention-related brain activity P300. Hence, the brain reaches in a more efficient state. Further, the response time in behavioral tasks decreased significantly. In addition, the participants' subjective responses to the questionnaire showed significant changes in physical relaxation and other indicators after being in the sauna. Finally, we developed an artificial intelligence classifier, obtaining an average accuracy of brain state classification of 88.34%. The results have potential for future application.

The Influence of Ambient Temperature Changes on the Indicators of Inflammation and Oxidative Damage in Blood after Submaximal Exercise

Marta Pawłowska, Celestyna Mila-Kierzenkowska, Tomasz Boraczyński +6 more · Antioxidants · 2022 · 11 citations

Physical activity has a positive effect on human health and well-being, but intense exercise can cause adverse changes in the organism, leading to the development of oxidative stress and inflammation. The aim of the study was to determine the effect of short-term cold water immersion (CWI) and a sauna bath as methods of postexercise regeneration on the indicators of inflammation and oxidative damage in the blood of healthy recreational athletes. Forty-five male volunteers divided into two groups: ‘winter swimmers’ who regularly use winter baths (n = 22, average age 43.2 ± 5.9 years) and ‘novices’ who had not used winter baths regularly before (n = 23, mean age 25 ± 4.8 years) participated in the study. The research was divided into two experiments, differing in the method of postexercise regeneration used, CWI (Experiment I) and a sauna bath (Experiment II). During Experiment I, the volunteers were subjected to a 30-min aerobic exercise, combined with a 20-min rest at room temperature (RT-REST) or a 20-min rest at room temperature with an initial 3-min 8 °C water bath (CWI-REST). During the Experiment II, the volunteers were subjected to the same aerobic exercise, followed by a RT-REST or a sauna bath (SAUNA-REST). The blood samples were taken before physical exercise (control), immediately after exercise and 20 min after completion of regeneration. The concentrations of selected indicators of inflammation, including interleukin 1β (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 8 (IL-8), interleukin 10 (IL-10), transforming growth factor β1 (TGF-β1) and tumor necrosis factor α (TNF-α), as well as the activity of indicators of oxidative damage: α1-antitrypsin (AAT) and lysosomal enzymes, including arylsulfatase A (ASA), acid phosphatase (AcP) and cathepsin D (CTS D), were determined. CWI seems to be a more effective post-exercise regeneration method to reduce the inflammatory response compared to a sauna bath. A single sauna bath is associated with the risk of proteolytic tissue damage, but disturbances of cellular homeostasis are less pronounced in people who regularly use cold water baths than in those who are not adapted to thermal stress.

Intermittent living; the use of ancient challenges as a vaccine against the deleterious effects of modern life – A hypothesis

Leo Pruimboom, Frits A.J. Muskiet · Medical Hypotheses · 2018 · 28 citations

Chronic non-communicable diseases (CNCD) are the leading cause of mortality in developed countries. They ensue from the sum of modern anthropogenic risk factors, including high calorie nutrition, malnutrition, sedentary lifestyle, social stress, environmental toxins, politics and economic factors. Many of these factors are beyond the span of control of individuals, suggesting that CNCD are inevitable. However, various studies, ours included, show that the use of intermittent challenges with hormetic effects improve subjective and objective wellbeing of individuals with CNCD, while having favourable effects on immunological, metabolic and behavioural indices. Intermittent cold, heat, fasting and hypoxia, together with phytochemicals in multiple food products, have widespread influence on many pathways related with overall health. Until recently, most of the employed challenges with hormetic effects belonged to the usual transient live experiences of our ancestors. Our hypothesis; we conclude that, whereas the total inflammatory load of multi-metabolic and psychological risk factors causes low grade inflammation and aging, the use of intermittent challenges, united in a 7-10 days lasting hormetic intervention, might serve as a vaccine against the deleterious effects of chronic low grade inflammation and it's metabolic and (premature) aging consequences.

Six weeks of localized passive heat therapy elicits some exercise‐like improvements in resistance artery function

Jamie P. Kaluhiokalani, Taysom E. Wallace, Mohadeseh Ahmadi +9 more · The Journal of Physiology · 2024 · 7 citations

Abstract The purpose of this study was to examine the effects of 6 weeks of localized, muscle‐focused (quadriceps femoris) passive heat therapy (PHT) on resistance artery function, exercise haemodynamics and exercise performance relative to knee extension (KE) exercise training (EX). We randomized 34 healthy adults (ages 18–36; n = 17 female, 17 male) to receive either PHT or sham heating sessions (120 min, 3 days/week), or EX (40 min, 3 days/week) over 6 weeks. Blood flow was assessed with Doppler ultrasound of the femoral artery during both passive leg movement (PLM) and a KE graded exercise test. Muscle biopsies were taken from the vastus lateralis at baseline and after 6 weeks. Peak blood flow during PLM increased to the same extent in both the EX (∼10.5% increase, P = 0.009) and PHT groups (∼8.5% increase, P = 0.044). Peak flow during knee extension exercise increased in EX (∼19%, P = 0.005), but did not change in PHT ( P = 0.523) and decreased in SHAM (∼7%, P = 0.020). Peak vascular conductance during KE increased by ∼25% in EX ( P = 0.030) and PHT ( P = 0.012). KE peak power increased in EX by ∼27% ( P = 0.001) but did not significantly change in PHT and SHAM groups. Expression of endothelial nitric oxide synthase increased significantly in both EX ( P = 0.028) and PHT ( P = 0.0095), but only EX resulted in increased angiogenesis. In conclusion, 6 weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not yield significant improvements in performance. image Key points Many for whom exercise would be most beneficial are either unable to exercise or have a very low exercise tolerance. In these cases, an alternative treatment to combat declines in resistance artery function is needed. We tested the hypothesis that passive heat therapy (PHT) would increase resistance artery function, improve exercise haemodynamics and enhance exercise performance compared to a sham treatment, but less than aerobic exercise training. This report shows that 6 weeks of localized PHT improved resistance artery function at rest and during exercise to the same extent as exercise training but did not improve exercise performance. Additionally, muscle biopsy analyses revealed that endothelial nitric oxide synthase expression increased in both PHT and exercise training groups, but only exercise resulted in increased angiogenesis. Our data demonstrate the efficacy of applying passive heat as an alternative treatment to improve resistance artery function for those unable to receive the benefits of regular exercise.

Effects of a Graphene Heating Device on Fatigue Recovery of Biceps Brachii

Wenming Liu, Xiaohui Jiang, Zhiran Yu +3 more · Bioengineering · 2023 · 7 citations

Far-infrared (FIR) is considered to be an ideal method to promote fatigue recovery due to its high permeability and strong radiation. In this paper, we report a flexible and wearable graphene heating device to help fatigue recovery of human exercise by using its high FIR divergence property. This study compares two different fatigue recovery methods, graphene far-infrared heating device hot application and natural recovery, over a 20 min recovery time among the male colleges' exhaustion exercise. Experimental results show that the achieved graphene device holds excellent electro-thermal radiation conversion efficiency of 70% and normal total emissivity of 89%. Moreover, the graphene FIR therapy in our work is more energy-efficient, easy to use, and wearable than traditional fatigue recovery methods. Such an anti-fatigue strategy offers new opportunities for enlarging potential applications of graphene film in body science, athletic training recovery, and wearable devices.

Prophylactic Effects of Sauna on Delayed-Onset Muscle Soreness of the Wrist Extensors

Peanchai Khamwong, Aatit Paungmali, Ubon Pirunsan +1 more · Asian Journal of Sports Medicine · 2015 · 18 citations

BACKGROUND: High-intensity of exercise or unaccustomed eccentric exercise can cause the phenomenon of Exercise-Induced Muscle Damage (EIMD) which usually results in cramps, muscle strain, impaired muscle function and delayed-onset muscle soreness. OBJECTIVES: This study investigated the prophylactic effects of sauna towards the symptoms associated with muscle damage from eccentric exercises of wrist extensor muscle group. PATIENTS AND METHODS: A total of twenty-eight subjects (mean age 20.9 years old, SD = 1.6) were randomly divided into the sauna group (n = 14) and the control group (n = 14). In the sauna group, subjects received sauna before eccentric exercise of the wrist extensor. The eccentric exercises were conducted on the non-dominant arm by using an isokinetic dynamometer. Pain Intensity (PI), Pressure Pain Threshold (PPT) and passive range of motion of wrist flexion (PF-ROM) and extension (PE-ROM) were measured as pain variables. Grip Strength (GS) and Wrist Extension Strength (WES) were measured as variables of wrist extensor muscle function. All the measurements were performed at baseline, immediately after and from 1st to 8th days after the exercise-induced muscle damage. RESULTS: The sauna group significantly demonstrated a lower deficit in ROM (passive flexion and passive extension), GS and WES following exercise than that of the control group (P < 0.05). CONCLUSIONS: Sauna application prior to the exercise-induced muscle damage demonstrated effectiveness in reduction of sensory impairment (PF-ROM and PE-ROM) and improvement of muscle functions (GS, and WES) in wrist extensor muscle group.

Standalone sauna vs exercise followed by sauna on cardiovascular function in non‐naïve sauna users: A comparison of acute effects

Earric Lee, Joel Kostensalo, Peter Willeit +5 more · Health Science Reports · 2021 · 9 citations

Abstract Background and aims Sauna bathing and aerobic exercise have each been shown to affect cardiovascular function. However, direct comparisons between standalone sauna bathing and a combination of exercise and sauna on vascular indices remain limited. Therefore, we conducted a cross‐over study using matched durations to explore the hemodynamic changes of sauna exposure when compared to a combination of aerobic exercise and sauna exposure. Methods Participants (N = 72) with at least one cardiovascular risk factor underwent, on two separate occasions: (a) a 30‐minute sauna at 75°C (SAUNA) and (b) the combination of a 15‐minute cycling exercise at 75% maximum heart rate followed by 15‐minute sauna exposure (EX+SAUNA). Relative changes to arterial stiffness (PWV), augmentation index (Alx), brachial systolic and diastolic blood pressure (SBP and DBP), central SBP (cSBP), mean arterial pressure (MAP), and heart rate (HR) were compared PRE‐POST and pre‐ to 30‐minutes post‐intervention (PRE‐POST30). Results Baseline SBP and DBP were 143 (SD 18) mmHg and 86 (SD 10) mmHg, respectively. From PRE‐POST, SAUNA had lower DBP (mean difference [95% CI] 2.5 [1.0, 4.1], P = .002) and MAP (2.5 [0.6, 4.3], P = .01). However, EX+SAUNA had lower SBP (−2.7 [−4.8, −0.5], P = .02), DBP (−1.8 [−3.3, −0.4], P = .01), and MAP (−2.0 [−3.5, −0.5], P = .009) PRE‐POST30. There were no statistically significant differences between SAUNA and EX+SAUNA for other measured parameters. Conclusion This study demonstrated that when matched for duration, EX+SAUNA and SAUNA elicit comparable acute hemodynamic alterations in middle‐aged participants with cardiovascular risk factors. The sauna is a suitable option for acute blood pressure reductions in those who are unable to perform aerobic exercise, and may be a viable lifestyle treatment option to improve blood pressure control.

Effect of Handgrip Training in Extreme Heat on the Development of Handgrip Maximal Isometric Strength among Young Males

Ignacio Bartolomé, Jesús Siquier-Coll, Mario Pérez-Quintero +3 more · International Journal of Environmental Research and Public Health · 2021 · 9 citations

The aim of this study was to evaluate the acute and adaptive effects of passive extreme heat (100 ± 3 °C) exposition in combination with a strength training protocol on maximal isometric handgrip strength. Fifty-four untrained male university students participated in this investigation. Twenty-nine formed the control group (NG) and 25 the heat-exposed group (HG). All the participants performed a 3-week isotonic handgrip strength training program twice a week with a training volume of 10 series of 10 repetitions with 45-s rest between series, per session. All the subjects only trained their right hand, leaving their left hand untrained. HG performed the same training protocol in hot (100 ± 3 °C) conditions in a dry sauna. Maximal isometric handgrip strength was evaluated each training day before and after the session. NG participants did not experience any modifications in either hand by the end of the study while HG increased maximal strength values in both hands (p &lt; 0.05), decreased the difference between hands (p &lt; 0.05), and recorded higher values than the controls in the trained (p &lt; 0.05) and untrained (p &lt; 0.01) hands after the intervention period. These changes were not accompanied by any modification in body composition in either group. The performance of a unilateral isotonic handgrip strength program in hot conditions during the three weeks induced an increase in maximal isometric handgrip strength in both hands without modifications to bodyweight or absolute body composition.

The influence of extreme thermal stress on the physiological and psychological characteristics of young women who sporadically use the sauna: practical implications for the safe use of the sauna

Robert Podstawski, Krzysztof Borysławski, Natalia Maja Józefacka +4 more · Frontiers in Public Health · 2024 · 6 citations

Background: Many individuals who use the sauna at a temperature of 120°C of higher are not aware of the negative consequences of extreme thermal stress. Despite extensive research into sauna use, the impact of extreme thermal stress on the physiological and psychological characteristics of sauna users have not been examined to date. Aim: The aim was to determine the effect of 20 min sauna sessions with a temperature of 80°C and 120°C on the physiological and psychological characteristics of women who sporadically visit the sauna. Methods: The study was conducted on 22 full-time female university students. Physical activity (PA) levels were evaluated with the Polish short version of the International Physical Activity Questionnaire (IPAQ). Anthropometric characteristics were measured before the first sauna session by the InBody270 body composition analyzer. Physiological parameters, including heart, energy expenditure, physical effort, and blood pressure (systolic blood pressure - SBP, and diastolic blood pressure - DBP), were assessed indirectly using Polar V800 heart rate monitors and the Omron M6 Comfort blood pressure monitor. The participants' wellbeing was assessed with the Profile of Mood States (POMS) questionnaire. The presence of significant correlations between heat exhaustion and heat stress variables and syncope during the second sauna session was examined with the use of classification and regression trees (CRT) and the cross-validation technique. Results: < 0.001) increase in vigor with a simultaneous decrease in tension, depression, anger, fatigue, and confusion. In turn, sauna bathing at a temperature of 120°C had an opposite effect on the above mood parameters. Vomiting and confusion were the main predictors of syncope that occurred in some of the surveyed women. Conclusion: Excessive air temperature can induce symptoms characteristic of heat exhaustion and heat stress nausea, heavy sweating, fast weak or strong HR, high body temperature, and confusion. Therefore, sauna bathing at a temperature of 80°C can be recommended to women who sporadically use the sauna, whereas exposure to a temperature of 120°C is not advised in this group of sauna users. The present findings provide highly valuable inputs for managing wellness and SPA centers.

Far-Infrared Radiation with Sauna Method Improves Recovery of Fatigue and Muscle Damage in Athletes After Submaximal Physical Exercise

Oce Wiriawan, Hari Setijono, Shidqi Hamdi Pratama Putera +4 more · Retos · 2024 · 6 citations

Muscle damage is one of the most frequent causes of decreased physical ability in training. Injuries during exercise are caused by damage to soft tissue, such as muscles. This can occur if recovery is inadequate in an exercise program. Incomplete recovery can reduce an athlete's performance. This study aims to determine the effect of far-infrared radiation (FIR) in improving fatigue and muscle cell damage in athletes after submaximal physical exercise. A total of 16 male athletes, aged 18-23 years were recruited to participate in the study and were given physical exercise at submaximal intensity (80% HRmax) for 30 minutes using a treadmill. The administration of FIR 45ºC was carried out immediately after submaximal intensity exercise for 30 minutes, while the recovery control group was carried out lying down without additional intervention. Measurement of fatigue levels uses the lactic acid (LA) parameter with the Accutrend Plus Meter, while measuring muscle cell damage uses the MDA level parameter using the Thiobarbituric acid reactive substance (TBARs) method. The data analysis technique uses the independent sample t-test with a significance level of 5%. The results showed that there was a significant difference in mean post-treatment LA between the control (CTR) vs. recovery group with FIR 45ºC for 30 minutes (EXP) 3.48±1.62 mmol/L vs. 3.48±1.62 mmol/L, p=0.035. Mean post-treatment MDA levels between CTR vs. EXP 0.45±0.19 ng/mL vs. 0.24±0.03 ng/mL, p=0.011. Far-infrared radiation using the sauna method has been proven effective in reducing lactic acid and MDA levels after submaximal physical exercise. Keywords: Far-infrared radiation, lactic acid, MDA levels, submaximal physical exercise

Passive Whole-Body Hyperthermia Increases Aerobic Capacity and Cardio-Respiratory Efficiency in Amateur Athletes

M. A. Zapara, Е. Н. Дудник, Vlada G. Samartseva +3 more · Health · 2020 · 8 citations

Objective: The research was carried out to test the influence of adaptation to passive whole body hyperthermia (PH) on physical capacity and cardio-respiratory efficiency in men-amateur athletes under the testing load of increasing intensity in laboratory thermal-neutral conditions. Twenty-eight amateur athletes (males, mean age 20.2 ± 2.1 y.o., game-based kinds of sports—football, handball, training experience—4 - 7 years) were randomized into two groups: experimental (14 people), who underwent 24 PH procedures, and control (14 people), who underwent 24 light training sessions in interval regime on elliptical gym apparatus. Results: Adaptation to PH was accompanied by moderate increase of aerobic efficiency and cardio-respiratory endurance in amateur athletes under thermally neutral conditions, while interval training in the control group showed no reliable changes in efficiency. Conclusion: A 10-week course of PH procedures leads to the increase of peak oxygen consumption, oxygen consumption at the level of anaerobic threshold, and heart efficiency (enhancement of oxygen pulse values), as well as efficiency of pulmonary ventilation and bronchial conductance, which we consider to be cross effects of adaptation to passive whole-body repetitive hyperthermia.

Support Your Recovery Needs (SYRN) – a systemic approach to improve sport performance

Jakub Grzegorz Adamczyk · Biomedical Human Kinetics · 2023 · 11 citations

Abstract Study aim : The aim of this study was to present the Support Your Recovery Needs (SYRN) recovery system based on scientifically confirmed methods, addressing the needs of athletes based on their subjective feelings of fatigue after training or competition. Material and methods : The literature on supporting post-exercise recovery was reviewed. This was followed by an analysis of the effectiveness of selected methods. A time factor was imposed on the selected methods for which efficacy was confirmed. Depending on the type of stimulus and the time of its application, regenerative effects were assigned point values. Results : Within the SYRN approach over a dozen treatments and actions promoting post-exercise recovery have been identified. Conclusions : A methodical and organized approach should allow for the selection of recovery support methods based on their effectiveness, appropriate timing, and the combination of various methods to enhance post-exercise recovery and performance.

Athlete and practitioner prevalence, practices, and perceptions of passive heating in sport

Campbell Menzies, Neil D. Clarke, Christopher J. A. Pugh +3 more · Sport Sciences for Health · 2022 · 7 citations

A Randomized Controlled Trial of Massage and Pneumatic Compression for Ultramarathon Recovery.

Hoffman MD, Badowski N, Chin J +1 more · J Orthop Sports Phys Ther · 2016 · 60 citations

Muscle cooling: too much of a good thing?

Chris Mawhinney, Robert Allan · The Journal of Physiology · 2018 · 3 citations

It is well documented that strenuous exercise exerts stress on the body, which may lead to physiological impairments and associated reductions in muscle function and fatigue, in the hours and days post-exercise. Whilst fatigue is specific to the mode, intensity and duration of exercise, a failure in any of the related neural, metabolic or mechanical processes may hinder subsequent athletic performance, particularly when insufficient restoration periods are provided. This has led to significant interest in recovery strategies to ameliorate post-exercise fatigue and to optimize an athlete's physical capabilities. During prolonged high-intensity exercise, the substantial reliance on oxidative glycolytic phosphorylation may lead to fatigue via depletion of local muscle and liver glycogen stores. The low glycogen levels not only compromise the rate of adenosine triphosphate (ATP) regeneration but may have a glycogen-dependent role in excitation–contraction coupling failure, proposed to cause fatigue by impairing Ca2+ release from the sarcoplasmic reticulum (Ørtenblad et al. 2011). Consequently, it is important that post-exercise glycogen stores are sufficiently replenished before the next bout of exercise to limit the effects of fatigue on muscle function and performance. Passive recovery methods, which do not raise metabolism (i.e. without muscle activation), may therefore be more suitable to maximize the rate of post-exercise glycogen resynthesis when only a short recovery period is permitted. A popular and widely used passive recovery method, cold water immersion (CWI), is thought to expedite recovery via associated reductions in tissue temperature to benefit recovery outcomes. Importantly, local changes in muscle temperature (heating or cooling) may influence enzymatic activity and affect rates of intramuscular glycogen synthesis or breakdown. It has therefore become of interest to relate changes in intramuscular temperature to local muscle glycogen kinetics to quantitatively assess the impact of applied recovery strategies, especially methods that can markedly alter tissue temperature, i.e. CWI. In a recent study published in The Journal of Physiology, Cheng & colleagues (2017) investigated whether the manipulation of intramuscular temperature affected the acute recovery of exercise performance following fatigue induced by endurance exercise. In a randomized cross-over designed study, subjects initially performed 3 × 5 min all-out arm exercise at 100 rpm (fatigue test) before completing 4 × 15 min bouts of exhaustive arm cycling exercise at 50% (endurance exercise). This was followed by a 2 h recovery period, where each arm was either (1) continuously perfused with ice-chilled water using modified arm cuffs (cooling), or (2) maintained at physiological temperature (∼33°C) using modified arm cuffs (control), or (3) heated to 5°C above physiological temperature (∼38°C) using a temperature-controlled bath (heating). During the recovery period, intramuscular triceps brachii temperature (1.5 cm depth) was continuously recorded and subjects were provided with 1.1 g (kg body weight)−1 h−1 of carbohydrates to maximize glycogen repletion. The fatigue test was then repeated to determine if the recovery intervention had an effect on muscle function. The main findings showed that the maintenance of power output (i.e. endurance) during the arm cycling fatigue test was markedly preserved (increased in the final set) when each arm was heated to an intramuscular temperature of ∼38°C, compared with cooling the muscle (i.e. to as low as 15°C). In order to identify the cellular mechanisms underlying the temperature-dependent recovery of muscle force and [Ca2+]i after fatigue, the authors carried out a series of isolated mouse whole muscle experiments, obtaining intact single flexor digitorum brevis (FDB) muscle fibres from hindlimbs. The fibres were initially stimulated with tetani of 350 ms duration once every minute at 30, 70 and 120 Hz, with peak force and spatial and time-averaged [Ca2+]i (fluorescent indicator indo-1) measured during tetani. To markedly decrease glycogen, fibres were perfused with glucose-free Tyrode solution before being repeatedly stimulated for ∼12 min with 350 ms (70 Hz) tetani at 10 s intervals until force had decreased to 30% of starting values. The fibres were then perfused with glucose-containing Tyrode solution for up to 2 h at 16°C (15°C below FDB muscle temperature), 26°C (5°C below FDB muscle temperature), 31°C (∼FDB muscle temperature) or 36°C (5°C above FDB muscle temperature). Additional isolated fibres were also perfused with glucose-free Tyrode solution, at the same temperatures, to assess whether force recovery was dependent on restoration of glycogen per se. During the recovery period, fibres were stimulated every 30 min by repeating the tetani (350 ms every 1 min) applied at 30, 70 and 120 Hz, to assess recovery of contractile muscle function. Upon completion of the 2 h recovery period, the fibres were again exposed to the glycogen-depleting fatiguing stimulation protocol to elucidate the effects of the different perfusion temperatures on glucose availability and muscle fatigue. A further experiment determined the effects of temperature on muscle glycogen content using a fluorometric glycogen assay. Whole FDB muscles were fatigued in glucose-free Tyrode solution with repeated 70 Hz tetani at 31°C using both moderate (700 ms duration contractions every 10 s for 150 tetani) and severe (1 s contractions every 5 s for 300 tetani) glycogen depleting protocols. The fatigued muscles were subsequently assessed for the extent of glycogen depletion with additional isolated FDB muscles, which were not prior stimulated, used to represent glycogen content before fatigue. The stimulated muscles were then bathed in 26°C or 36°C Tyrode solution containing glucose for a duration of 30 min to assess glycogen resynthesis. Supporting the results in the human experiment, it was observed that measurements of submaximal force (30 and 70 Hz), tetanic myoplasmic free Ca2+ (30, 70 and 120 Hz) and fatigue resistance (number of contractions performed) were all reduced when glucose-containing Tyrode solution was perfused into the fibres at temperatures of 16 and 26°C (i.e. cooling below FDB physiological temperature), but better maintained after the perfusion temperature was raised to 36°C (i.e. heating above physiological FDB temperature). This confirmed the authors’ earlier findings that contractile force was dependent on muscle fibre temperature by influencing the rate of glycogen resynthesis, which in turn modified the release of tetanic [Ca2+]i. Indeed, in the absence of perfused glucose, tetanic myoplasmic free Ca2+ and force were considerably impaired. In addition, after the severe glycogen depletion protocol, muscle glycogen content was greater at the end of the 30 min recovery period after perfusion with glucose at 36°C compared with 26°C, indicating a greater rate of glycogen resynthesis at the higher temperature. Taking the results together, the authors therefore concluded that the lower contractile force recorded at the lower frequencies (30 and 70 Hz) demonstrated that the fatigue protocol was both glucose and temperature dependent. Cheng and colleagues’ observations that greater reductions in intramuscular temperature decrease both the rate of glycogen resynthesis and contractile force challenges the use of CWI as a recovery strategy, since its application is partly based on expediting these aspects of recovery in the acute post-exercise period. However, it must be stated that the design of Cheng and colleagues utilized a 2 h recovery period (cooling or heating), whereas most CWI protocols are typically applied over much shorter durations (i.e. 10–15 min) that do not permit intramuscular temperatures to reach such low values (i.e. ∼15°C). Previous work in our laboratory (Gregson et al. 2013) has shown 10 min of 8°C CWI does not negatively impact on the rate of glycogen resynthesis compared with seated rest (control) after initially depleting muscle glycogen content with a cycling exercise protocol. The disparity in our findings is likely related to the shorter duration of cooling influencing muscle temperature to a lesser degree, with deep intramuscular temperature only reduced to ∼30°C in our study. Thus the negative implications for contraction kinetics and muscle glycogen resynthesis highlighted by Cheng et al. may not be apparent in recovery protocols regularly used in research and practice because of shorter cooling durations (10–15 min) and smaller decreases in intramuscular temperature (to ∼30°C). This perhaps highlights the need to identify the extent of intramuscular cooling required to impair post-exercise recovery of skeletal muscle contractile function and metabolism, as opposed to improve recovery. Moreover it emphasizes the need for context to be applied to mechanistic results before they can be applied appropriately in practice. In Cheng et al.’s study there was no reported reduction in core temperature or increase in oxygen uptake during the 2 h arm-cooling period. It would be expected with a greater skin exposure to CWI (i.e. lower body or sternum CWI) that core body temperature would decrease over a similar cooling duration. In an attempt to maintain core body temperature, shivering thermogenesis requires a contribution from muscle glycogen stores as a fuel source (Haman et al. 2005). Consequently, a prolonged duration of post-exercise CWI cooling, which leads to a drop in core body temperature and onset of shivering, may potentially decrease the rate of glycogen resynthesis. Moreover, Cheng and colleagues utilized upper limbs only, constituting a small area of muscle mass. It should be noted that the potential for heat loss is greater when a larger muscle mass is cooled (i.e. lower limbs) and an understanding of the implications this may have for shivering thermogenesis and muscle glycogen utilization becomes essential for those utilizing cooling as a method of athletic recovery. Interestingly, it has also been reported that both 10°C and 20°C CWI applied over 30 min exacerbates blood pro-inflammatory markers (interleukin-8, myeloperoxidase) 2 h post-exercise compared with the same temperatures applied over a 10 min duration (White et al. 2014). This suggests that longer CWI protocols may increase the inflammatory response and associated oedema and swelling, possibly leading to secondary damage in muscle fibres, a reduction in muscle force generating capacity and an increased sensation of muscle pain (i.e. delayed onset muscle soreness). Importantly, in athletic settings, an excessive duration of cooling, such as the 2 h utilized by Cheng and colleagues, loses its practicality as a post-exercise recovery strategy due to the time investment of the athlete, impaired contraction kinetics and metabolic recovery with a potential for further negative implications via exacerbated humoral inflammatory markers. The authors’ findings of an increased rate of glycogen reysnthesis and improved muscle function with higher intramuscular temperatures partly justifies the recent anecdotal interest surrounding hot baths and saunas to aid post-exercise recovery. Moreover, data from Cheng and colleagues add interesting and commendable detail to the already established notion of improved muscle force generation and function at higher intramuscular temperatures. The direct application of the results to post-exercise recovery in athletes needs careful attention. In the future, it is expected that the selection of hot and cold therapies will be dependent on the athlete's individual needs and based on the main goals of the recovery session, i.e. to reduce inflammation, enhance fuel repletion and/or promote cellular adaptations. None declared. Both authors have approved the final version of the manuscript and agree to be accountable for all aspects of the work. All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed. We would like to thank Prof. Warren Gregson, Dr David Low, Prof. Helen Jones, Dr Adam Sharples and Dr James Morton for their guidance and support throughout the PhD process, leading us to this point.

Comparison of 1-hour floatation-REST versus conventional napping on heart rate variability in active individuals.

Besson C, De Stefani G, Baggish AL +3 more · BMJ Open Sport Exerc Med · 2024 · 1 citations

Phase-change material cooling blanket: A feasible cooling choice during transport after exercise-induced hyperthermia.

Wang X, Shang X, Li X +8 more · J Therm Biol · 2023 · 4 citations

Benefits of a Three-Day Bamboo Forest Therapy Session on the Physiological Responses of University Students.

Zeng C, Lyu B, Deng S +5 more · Int J Environ Res Public Health · 2020 · 74 citations

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

Theurot D, Dugué B, Douzi W +3 more · Sci Rep · 2021 · 26 citations

Once- and twice-daily heat acclimation confer similar heat adaptations, inflammatory responses and exercise tolerance improvements.

Willmott AGB, Hayes M, James CA +3 more · Physiol Rep · 2018 · 33 citations

Effects of heated hydrotherapy on muscle HSP70 and glucose metabolism in old and young vervet monkeys.

Kavanagh K, Davis AT, Jenkins KA +1 more · Cell Stress Chaperones · 2016 · 27 citations