Internal and external cooling methods and their effect on body temperature, thermal perception and dexterity

© 2018 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0191416© 2018 Maley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Objective The present study aimed to compare a range of cooling methods possibly utilised by occupational workers, focusing on their effect on body temperature, perception and manual dexterity. Methods Ten male participants completed eight trials involving 30 min of seated rest followed by 30 min of cooling or control of no cooling (CON) (34C, 58% relative humidity). The cooling methods utilised were: ice cooling vest (CV0), phase change cooling vest melting at 14C (CV14), evaporative cooling vest (CVEV), arm immersion in 10C water (AI), portable water-perfused suit (WPS), heliox inhalation (HE) and ice slushy ingestion (SL). Immediately before and after cooling, participants were assessed for fine (Purdue pegboard task) and gross (grip and pinch strength) manual dexterity. Rectal and skin temperature, as well as thermal sensation and comfort, were monitored throughout. Results Compared with CON, SL was the only method to reduce rectal temperature (P = 0.012). All externally applied cooling methods reduced skin temperature (P0.05). Conclusion The present study observed that ice ingestion or ice applied to the skin produced the greatest effect on rectal and skin temperature, respectively. AI should not be utilised if workers require subsequent fine manual dexterity. These results will help inform future studies investigating appropriate pre-cooling methods for the occupational worker.This project is financially supported by the US Government through the Technical Support Working Group within the Combating Terrorism Technical Support Office.Published versio

A case report on the physiological responses to extreme heat during Sicily's July 2023 heatwave

July 2023 has been confirmed as Earth's hottest month on record, and it was characterized by extraordinary heatwaves across southern Europe. Field data collected under real heatwave periods could add important evidence to understand human adaptability to extreme heat. However, field studies on human physiological responses to heatwave periods remain limited. We performed field thermo-physiological measurements in a healthy 37-years male undergoing resting and physical activity in an outdoor environment in the capital of Sicily, Palermo, during (July 21; highest level of local heat-health alert) and following (August 10; lowest level of local heat-health alert) the peak of Sicily's July 2023 heatwave. Results indicated that ~40 min of outdoor walking and light running in 33.8°C Wet Bulb Globe Temperature (WBGT) conditions (July 21) resulted in significant physiological stress (i.e., peak heart rate: 209 bpm; core temperature: 39.13°C; mean skin temperature: 37.2°C; whole-body sweat losses: 1.7 kg). Importantly, significant physiological stress was also observed during less severe heat conditions (August 10; WBGT: 29.1°C; peak heart rate: 190 bpm; core temperature: 38.48°C; whole-body sweat losses: 2 kg). These observations highlight the physiological strain that current heatwave conditions pose on healthy young individuals. This ecologically-valid empirical evidence could inform more accurate heat-health planning

Thermosensory mapping of skin wetness sensitivity across the body of young males and females at rest and following maximal incremental running

Key points: Humans lack skin receptors for wetness (i.e. hygroreceptors), yet we present a remarkable wetness sensitivity. Afferent inputs from skin cold-sensitive thermoreceptors are key for sensing wetness; yet, it is unknown whether males and females differ in their wetness sensitivity across their body and whether high intensity exercise modulates this sensitivity. We mapped sensitivity to cold, neutral and warm wetness across five body regions and show that females are more sensitive to skin wetness than males, and that this difference is greater for cold than warm wetness sensitivity. We also show that a single bout of maximal exercise reduced the sensitivity to skin wetness (i.e. hygro-hypoesthesia) of both sexes as a result of concurrent decreases in thermal sensitivity. These novel findings clarify the physiological mechanisms underpinning this fundamental human sensory experience. In addition, they indicate sex differences in thermoregulatory responses and will inform the design of more effective sport and protective clothing, as well as thermoregulatory models. Abstract: Humans lack skin hygroreceptors and we rely on integrating cold and tactile inputs from A-type skin nerve fibres to sense wetness. Yet, it is unknown whether sex and exercise independently modulate skin wetness sensitivity across the body. We mapped local sensitivity to cold, neutral and warm wetness of the forehead, neck, underarm, lower back and dorsal foot in 10 males (27.8 ± 2.7 years; 1.92 ± 0.1 m2 body surface area) and 10 females (25.4 ± 3.9 years; 1.68 ± 0.1 m2 body surface area), at rest and post maximal incremental running. Participants underwent our quantitative sensory test where they reported the magnitude of thermal and wetness perceptions (visual analogue scale) resulting from the application of a cold (5°C below skin temperature) wet (0.8 mL of water), neutral wet and warm wet (5°C above skin temperature) thermal probe (1.32 cm2) to five skin sites. We found that: (i) females were ∼14% to ∼17% more sensitive to cold-wetness than males, yet both sexes were as sensitive to neutral- and warm-wetness; (ii) regional differences were present for cold-wetness only, and these followed a craniocaudal increase that was more pronounced in males (i.e. the foot was ∼31% more sensitive than the forehead); and (iii) maximal exercise reduced cold-wetness sensitivity over specific regions in males (i.e. ∼40% decrease in foot sensitivity), and also induced a generalized reduction in warm-wetness sensitivity in both sexes (i.e. ∼4% to ∼6%). For the first time, we show that females are more sensitive to cold wetness than males and that maximal exercise induce hygro-hypoesthesia. These novel findings expand our knowledge on sex differences in thermoregulatory physiology

Independent and interactive effects of thermal stress and mental fatigue on manual dexterity

Many occupations and sports require high levels of manual dexterity under thermal stress and mental fatigue. Yet, multistressor studies remain scarce. We quantified the interactive effects of thermal stress and mental fatigue on manual dexterity. Seven males (21.1 \ub1 1.3 yr) underwent six separate 60-min trials characterized by a combination of three air temperatures (hot, 37C; neutral, 21C; cold, 7C) and two mental fatigue states (MF, mental fatigue induced by a 35-min cognitive battery; no-MF, no mental fatigue). Participants performed complex (O'Connor test) and simple (hand-tool test) manual tasks pre- and posttrial to determine stressor-induced performance changes. We monitored participants' rectal temperature and hand skin temperature (Thand) continuously and assessed the reaction time (handclick test) and subjective mental fatigue (5-point scale). Thermal stress (P < 0.0001), but not mental fatigue (P = 0.290), modulated Thand (heat, +3.3C [95% CI: +0.2, +6.5]; cold, 7.5C [10.7, 4.4]). Mental fatigue (P = 0.021), but not thermal stress (P = 0.646), slowed the reaction time (10%) and increased subjective fatigue. Thermal stress and mental fatigue had an interactive effect on the complex manual task (P = 0.040), with cold-no-MF decreasing the performance by 22% [39, 5], whereas neutral-MF, cold-MF, and heat-MF by 36% [53, 19], 34% [52, 17], and 36% [53, 19], respectively. Only mental fatigue decreased the performance in the simple manual task (30% [43, 16] across all thermal conditions; P = 0.002). Cold stress-induced impairments in complex manipulation increase with mental fatigue; yet combined stressors' effects are no greater than those of mental fatigue alone, which also impairs simple manipulation. Mental fatigue poses a greater challenge to manual dexterity than thermal stress

The effects of vibration during maximal graded cycling exercise: A pilot study

Whole Body Vibration training is studied and used in different areas, related to sport performance and rehabilitation. However, few studies have investigated the effects of Vibration (Vib) exposure on aerobic performance through the application of this concept to cycling exercise. A specifically designed vibrating cycloergometer, the powerBIKETM, was used to compare the effects of Vib cycling exercise and normal cycling on different physiological parameters during maximal graded exercise test. Twelve recreationally active male adults (25 ± 4.8 yrs; 181.33 ± 5.47 cm; 80.66 ± 11.91 kg) performed two maximal incremental cycling tests with and without Vib in a blockrandomized order. The protocol consisted of a 4 min warm up at 70 rev·min -1 followed by incremental steps of 3 min each. Cycling cadence was increased at each step by 10 rev·min -1 until participants reached their volitional exhaustion. Respiratory gases (VO 2, VCO 2), Heart Rate, Blood Lactate and RPE were collected during the test. Paired t-tests and Correlation Coefficients were used for statistical analysis. A significantly greater (P<0.05) response in the VO 2, HR, BLa and RPE was observed during the Vib trial compare to normal cycling. No significant differences were found in the maximal aerobic power (Vib 34.32 ± 9.70 ml·kg -1·min -1; no Vib 40.11 ± 9.49 ml·kg -1·min -1). Adding Vib to cycling exercise seems eliciting a quicker energetic demand during maximal exercise. However, mechanical limitations of the vibrating prototype could have affected the final outcomes. Future studies with more comparative setting are recommended to deeply appraise this concept. © Journal of Sports Science and Medicine (2012)

Biophysical, thermo-physiological and perceptual determinants of cool-seeking behaviour during exercise in younger and older women

Women continue to be under-represented in thermoregulatory research despite their undergoing unique physiological changes across the lifespan. This study investigated the biophysical, thermo-physiological, and perceptual determinants of cool-seeking behaviour during exercise in younger and older women. Eleven younger (25 ± 5 years; 1.7 ± 0.1 m; 63.1 ± 5.2 kg) and 11 older women (53 ± 6 years; 1.7 ± 0.1 m; 65.4 ± 13.9 kg) performed a 40-min incremental cycling test in a thermoneutral environment (22 ± 1.7°C; 36 ± 4% relative humidity). Throughout the test, participants freely adjusted the temperature of a cooling probe applied to their wrists to offset their thermal discomfort. We continuously recorded the probe–wrist interface temperature to quantify participants’ cool-seeking behaviour. We also measured changes in participants’ rate of metabolic heat production, core and mean skin temperatures, and skin wetness. Finally, we body-mapped participants’ skin heat, cold and wetness sensitivity. Our results indicated that: (1) older and younger women exhibited similar onset and magnitude of cool-seeking behaviour, despite older women presented reduced autonomic heat-dissipation responses (i.e., whole-body sweat losses); (2) older women's thermal behaviour was less determined by changes in core temperature (this being a key driver in younger women), and more by changes in multiple thermo-physiological and biophysical parameters (i.e., physical skin wetness, temperature and heat production); (3) older women did not present lower regional skin thermal and wetness sensitivity than younger women. We conclude that predictions of female cool-seeking behaviours based on thermo-physiological variables should consider the effects of ageing. These findings are relevant for the design of wearable cooling systems and sports garments that meet the thermal needs of women across the lifespan

A retrospective analysis of 1.011 percutaneous liver biopsies performed in patients with liver transplantation or liver disease: ultrasonography can reduce complications?

Objective: In the last decades, liver biopsy was the reference procedure for the diagnosis and follow-up of liver disease. Aim of present retrospective analysis was to assess the prevalence of complications and risk factors after Percutaneous Liver Biopsy (PLB) performed for diagnosis and staging in patients with chronic liver disease and for monitoring the graft in liver transplanted patients Patients and methods: Data were collected from a total of 1.011 PLB performed with the Menghini technique between January 2004 and December 2014 at the Hepatology and Transplant Units of the University of Rome Tor Vergata. The indications for biopsy were: follow-up of liver transplantation, chronic Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV), with or without Human Immunodeficiency Virus (HIV) and alcohol-related liver disease. Our patients were divided into two groups according to the biopsy indication: follow-up of liver transplantation (Group A) and chronic liver disease (Group B). All the procedures were performed in Day Hospital regimen. After the biopsy, patients remained in bed for about 4-6 hours. In the absence of complications, they were then discharged on the same day. Results: The most frequent complication after biopsy was pain (Group A n. 57, 8.8%; Group B n. 105, 29.0%), hypotension as a result of a vasovagal reaction resolved spontaneously (Group A n. 7, 1.1%; Group B n. 6, 1.7%), and intrahepatic bleeding resolved with conservative therapy (Group A n. 1, 0.2%; Group B n. 6, 1.7%). Two cases of pneumothorax in the Group A (0.3%) were treated with a chest tube. Other complications did not have a significant impact. Also, we did not observe statistically significant differences in patients who underwent PLB without and with ultrasound guidance. Conclusions: Liver biopsy is not a replaceable tool in diagnosis and follow-up of several chronic liver diseases. The Menghini technique with the percutaneous trans costal approach, might be preferred because less traumatic and related with a low occurrence of minor and major complications. According to our case load and comparing our findings with the previous published data, we speculate that ultrasound guidance is not crucial in the prevention of major complications

Skin wetness perception across body sites in children and adolescents aged 7–16 years old

Human skin wetness perception relies on the multisensory integration of thermal and mechanical cues during contact with moisture. Yet, it is unknown whether children and adolescents perceive skin wetness similarly to younger and older adults. We investigated skin wetness perceptions across the forehead, neck, forearm, and foot dorsum in 12 children/adolescents (4F/8M; 12 ± 3 years), 41 younger (21F/20M; 25 ± 3 years), and 21 older adults (11F/10M; 56 ± 6 years), during two established quantitative sensory tests. Our results indicated that, given the same moisture content (0.8 mL of water), very cold-wet stimuli applied to the forearm were perceived by all groups as wetter than neutral-wet (mean difference: 35.5 mm on a 100-mm visual analogue scale for wetness [95% CI: 22.3, 38.7]; P < 0.0001; ∼35% difference) and very hot-wet stimuli (mean difference: 22.7 mm [95% CI: 14.5, 40.9]; P < 0.0001; ∼23% difference). Children/adolescents also reported greater wetness perceptions than older adults during cold-wet stimulation of the forehead, neck and foot dorsum (mean difference: 20.6 mm; 95% CI: 1.5, 39.7; P = 0.031; ∼21% difference). In all age groups, the foot dorsum presented higher cold-wet sensitivity (mean difference: 11.1mm [95%CI 2.2, 20.0] p = 0.010; ~11% difference) and lower warm-wet sensitivity than the neck (mean difference: 12.9mm [95%CI 2.8, 23.0] p = 0.008; ~13% difference). We conclude that wetness perceptions in children/adolescents (age range: 7–16 years) are similar to those of adults in that both present (1) a characteristic U-shaped relationship between stimulus temperature and perceived wetness magnitude and (2) similar body regional patterns. These findings provide novel evidence on age-dependent variations in wetness perception which could inform user-centred innovation in thermal protection and garment design

Skin wetness sensitivity across body sites commonly affected by pain in people with migraine

Objective: The objective of this study was to evaluate skin wetness perception and thermal sensitivity in people with migraine and similar healthy controls.Background: Environmental triggers, such as cold and humidity, are known triggers for pain in people with migraine. Sensory inputs might be implicated in such heightened responses to cold-humid environments, such that a migraine-induced hypersensitivity to cold wetness could be present in people with migraine. However, we lack empirical evidence on skin thermal and wetness sensitivity across skin sites commonly associated with reported pain in migraine, such as the forehead.Methods: This prospective cross-sectional observational study, conducted in a university hospital setting, evaluated skin wetness perceptions and thermal sensations to wet non-noxious warm-wet, neutral-wet, and cold-wet stimuli applied to the forehead, the posterior neck, and the index finger pad of 12 patients with migraine (mean and standard deviation for age 44.5 +/- 13.2 years, 7/12 [58%] women) and 36 healthy controls (mean and standard deviation for age 39.4 +/- 14.6 years, 18/36 [50%] women).Results: On the forehead, people with migraine reported a significantly higher wetness perception than healthy controls across all thermal stimulus (15.1 mm, 95% confidence interval [CI]: 1.8 to 28.5, p = 0.027, corresponding to similar to 15% difference), whereas no significant differences were found on the posterior neck nor on the index finger pad. We found no differences among groups in overall thermal sensations (-8.3 mm, 95% CI: -24.0 to 7.3, p = 0.291; -7.8 mm, 95% CI: -25.3 to 9.7, p = 0.375; and 12.4 mm, 95% CI: -4.0 to 28.9, p = 0.133; forehead, posterior neck, and index finger, respectively).Conclusion: These findings indicate that people with migraine have a heightened sensitivity to skin wetness on the forehead area only, which is where pain attacks occur. Future studies should further explore the underlying mechanisms (e.g., TRPM8-mediated cold-wet allodynia) that lead to greater perception of wetness in people with migraine to better understand the role of environmental triggers in migraine

Cutaneous thermosensory mapping of the female breast and pelvis

Differences in skin thermal sensitivity have been extensively mapped across areas of the human body, including the torso, limbs, and extremities. Yet, there are parts of the female body, such as the breast and the pelvis for which we have limited thermal sensitivity data. The aim of this study was to map cutaneous warm and cold sensitivity across skin areas of the breast and pelvis that are commonly covered by female underwear. Twelve young females (21.9 ± 3.2 years) reported on a 200 mm visual analogue scale the perceived magnitude of local thermal sensations arising from short-duration (10 s) static application of a cold [5 °C below local skin temperature (Tsk)] or warm (5 °C above local Tsk) thermal probe (25 cm2) in seventeen locations over the breast and pelvis regions. The data revealed that thermal sensitivity to the warm probe, but not the cold probe, varied by up to 25% across the breast [mean difference between lowest and highest sensitivity location was 51 mm (95% CI:14, 89; p &lt; 0.001)] and up to 23% across the pelvis [mean difference between lowest and highest sensitivity location: 46 mm (95% CI:9, 84; p = 0.001)]. The regional differences in baseline Tsk did not account for variance in warm thermal sensitivity. Inter-individual variability in thermal sensitivity ranged between 24 and 101% depending on skin location. We conclude that the skin across the female breast and pelvis presents a heterogenous distribution of warm, but not cold, thermal sensitivity. These findings may inform the design of more comfortable clothing that are mapped to the thermal needs of the female body