Pre-exercise hot water immersion increased circulatory heat shock proteins but did not alter muscle damage markers or endurance capacity after eccentric exercise.

Pre-exercise passive heating attenuates muscle damage caused by eccentric exercise in rats where the induction of heat shock proteins (HSPs) confers a myoprotective effect. We investigated whether pre-exercise hot water immersion (HWI) confers similar benefits in humans. Eleven recreational male athletes were immersed in 41°C water up to 60 min or until rectal temperatures reached 39.5°C. After a 6 h rest, the participants performed an eccentric downhill run for 1 h at -4% gradient to induce muscle damage. An endurance capacity test at 75% VO2max was conducted 18 h later. The control trial was similar except that participants were immersed at 34°C. Blood samples were collected to assess HSPs levels, creatine kinase, and lactate dehydrogenase activities. Plasma eHSP70 was higher post-immersion in HWI trials (1.3 ± 0.4 vs 1.1 ± 0.4; p = 0.005). Plasma eHSP27 was higher before (p = 0.049) and after (p = 0.015) endurance test in HWI. Leukocytic p-HSP27 was increased 18 h after HWI (0.97 ± 0.14 vs 0.67 ± 0.11; p = 0.04). Creatine kinase and lactate dehydrogenase activities were increased by 3-fold and 1.5-fold, respectively, after endurance test in HWI but did not differ across trials (p > 0.05). Mean heart rates were higher during eccentric run and endurance test in HWI as compared to control (p < 0.05). Endurance capacity was similar between trials (57.3 ± 11.5 min vs 55.0 ± 13.5 min; p = 0.564). Pre-exercise heating increased the expression of plasma eHSPs and leukocytic p-HSP27 but did not reduce muscle damage nor enhance endurance capacity.

Mapping of technological strategies for reducing social isolation in homebound older adults: A scoping review.

BACKGROUND: Homebound older adults (HOAs) are particularly vulnerable to social isolation and loneliness, which engender a poorer physical and mental health, and greater cognitive decline. The purpose of this review is to map the literature to identify potential technological strategies that reduce social isolation in HOAs, and to understand facilitators and barriers for adoption and implementation. METHODS: Six databases including PubMed (MEDLINE), Google Scholar, Cochrane Database, EBSCOHost, National Library ProQuest, Web of Science, and the Journal of Medical Internet Research were searched for relevant articles. Peer-reviewed literature published in English from Jan 2014 to Feb 2024 that employed technological strategies applicable to HOAs and assessed social isolation or connectedness as an outcome measure were included. RESULTS: 107 studies were reviewed and classified into different technological categories based on their functions and features. A social technology framework encompassing delivery, hardware, software, content, training, and support was conceptualized with core characteristics identified from the reviewed technological strategies. Cost and complexity of technology, and resource commitment were identified as barriers while user-friendliness, content curation and a supportive ecosystem may facilitate the adoption of a technological strategy to address social isolation in HOAs. CONCLUSION: There is a need for early and concerted effort to identify HOAs, provide technology training, and empower them to tap on the digital world to complement and/or supplement social interactions. Development of cost-effective and rapid-to-implement technology is vital for HOAs who are at highest risk to social isolation.

Elevated brain temperature under severe heat exposure impairs cortical motor activity and executive function.

BACKGROUND: Excessive heat exposure can lead to hyperthermia in humans, which impairs physical performance and disrupts cognitive function. While heat is a known physiological stressor, it is unclear how severe heat stress affects brain physiology and function. METHODS: Eleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal temperatures (Tre) attained 39.5°C, inducing exertional or passive hyperthermia, respectively. In a separate trial, blended ice was ingested before and during exercise as a cooling strategy. Data were compared to a control condition with seated rest (normothermic). Brain temperature (Tbr), cerebral perfusion, and task-based brain activity were assessed using magnetic resonance imaging techniques. RESULTS: Tbr in motor cortex was found to be tightly regulated at rest (37.3°C ± 0.4°C (mean ± SD)) despite fluctuations in Tre. With the development of hyperthermia, Tbr increases and dovetails with the rising Tre. Bilateral motor cortical activity was suppressed during high-intensity plantarflexion tasks, implying a reduced central motor drive in hyperthermic participants (Tre = 38.5°C ± 0.1°C). Global gray matter perfusion and regional perfusion in sensorimotor cortex were reduced with passive hyperthermia. Executive function was poorer under a passive hyperthermic state, and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital cortex. Conversely, ingestion of blended ice before and during exercise alleviated the rise in both Tre and Tbr and mitigated heat-related neural perturbations. CONCLUSION: Severe heat exposure elevates Tbr, disrupts motor cortical activity and executive function, and this can lead to impairment of physical and cognitive performance.

Effects of Medications on Heat Loss Capacity in Chronic Disease Patients: Health Implications Amidst Global Warming.

Pharmacological agents used to treat or manage diseases can modify the level of heat strain experienced by chronically ill and elderly patients via different mechanistic pathways. Human thermoregulation is a crucial homeostatic process that maintains body temperature within a narrow range during heat stress through dry (i.e., increasing skin blood flow) and evaporative (i.e., sweating) heat loss, as well as active inhibition of thermogenesis, which is crucial to avoid overheating. Medications can independently and synergistically interact with aging and chronic disease to alter homeostatic responses to rising body temperature during heat stress. This review focuses on the physiologic changes, with specific emphasis on thermolytic processes, associated with medication use during heat stress. The review begins by providing readers with a background of the global chronic disease burden. Human thermoregulation and aging effects are then summarized to give an understanding of the unique physiologic changes faced by older adults. The effects of common chronic diseases on temperature regulation are outlined in the main sections. Physiologic impacts of common medications used to treat these diseases are reviewed in detail, with emphasis on the mechanisms by which these medications alter thermolysis during heat stress. The review concludes by providing perspectives on the need to understand the effects of medication use in hot environments, as well as a summary table of all clinical considerations and research needs of the medications included in this review. SIGNIFICANCE STATEMENT: Long-term medications modulate thermoregulatory function, resulting in excess physiological strain and predisposing patients to adverse health outcomes during prolonged exposures to extreme heat during rest and physical work (e.g., exercise). Understanding the medication-specific mechanisms of altered thermoregulation has importance in both clinical and research settings, paving the way for work toward refining current medication prescription recommendations and formulating mitigation strategies for adverse drug effects in the heat in chronically ill patients.

Effects of Mindful Awareness Practice (MAP) on Subclinical Depressive and Anxiety Symptoms and General Cognitive Function in Older Adults with Mild Cognitive Impairment: A 5-Year Follow-Up of the MAP-Randomized Controlled Trial.

BACKGROUND: Few randomized controlled trials (RCTs) investigated the effects of mindfulness intervention on affective and cognitive symptoms in older adults with mild cognitive impairment (MCI). Furthermore, no RCTs on mindfulness followed participants beyond two years. OBJECTIVE: To examine the longitudinal effects of a mindful awareness practice (MAP) intervention on depressive, anxiety, and cognitive symptoms in MCI. METHODS: In this parallel-arm and assessor-blinded RCT, 55 community-dwelling older adults with MCI were randomized into the MAP or active control, i.e., health education program (HEP). Intervention sessions were conducted weekly for three months and monthly for the subsequent six months. Assessments and follow-up were conducted at baseline, 3-month, 9-month, and 5-year time points. Depressive, anxiety, and cognitive symptoms were measured using the Geriatric Depression Scale-15 (GDS-15), Geriatric Anxiety Inventory-20 (GAI-20), and Mini-Mental State Examination (MMSE), respectively. Linear-mixed models, following the intention-to-treat principle, were used for data analyses. RESULTS: A total of 55 participants aged 60 to 86 (Mean age: 71.3±6 years old) was recruited, with n = 28 allocated to the MAP arm and n = 27 allocated to the HEP arm. Compared to HEP, GDS-15, GAI-20, and MMSE scores did not differ significantly in MAP during follow-ups. CONCLUSION: Compared to HEP, MAP did not improve affective symptoms nor delay deteriorations in general cognition in community-dwelling older adults with MCI. Compared to our previous findings showing domain-specific improvements in MAP over HEP in attention and memory up to 9 months, this study highlights the importance of examining domain-specificity using detailed cognitive measures in non-pharmacological intervention with MCI.

Assessment of dehydration using body mass changes of elite marathoners in the tropics.

OBJECTIVES: The ACSM recommends drinking to avoid loss of body mass >2% during exercise to avert compromised performance. Our study aimed to assess the level of dehydration in elite runners following a city marathon in a tropical environment. DESIGN: Prospective cohort design. METHODS: Twelve elite runners (6 males, 6 females; age 24-41 y) had body mass measured to the nearest 0.01kg in their race attire immediately before and after the 2017 Standard Chartered Singapore Marathon 2017. Body mass change was corrected for respiratory water loss, gas exchange, and sweat retained in clothing, and expressed as % of pre-race mass (i.e. % dehydration). RESULTS: Data are expressed as means±SD (range). Dry bulb temperature and humidity were 27.9±0.1°C (27.4-28.3°C) and 79±2% (73-82%). Finish time was 155±10min (143-172min). Male runners finishing positions ranged from 2-12 out of 7627 finishers, whilst female runners placed 1-8 out of 1754 finishers. Body mass change (loss) and % dehydration for all runners were 2.5±0.5kg (1.8-3.5kg) and 4.6±0.9% (3.6-6.8%). Male runners experienced body mass loss of 2.8±0.5kg and 4.9±1.2% while females experienced body mass loss of 2.1±0.2kg and 4.3±0.6%. CONCLUSIONS: Despite experiencing dehydration (4.6% body mass loss) two-fold higher than current fluid replacement guidelines recommend (≤2%), elite male and female runners performed successfully and without medical complication in a hot weather marathon.