116 results found
Callovini A, Fornasiero A, Savoldelli A, et al., 2021, Effects of three-exercise sessions in the heat on endurance cycling performance, JOURNAL OF THERMAL BIOLOGY, Vol: 98, ISSN: 0306-4565
Roberts KA, Draijer R, Hopkins ND, et al., 2021, Impact of green tea on the deleterious cardiometabolic effects of 7-days unhealthy lifestyle in young healthy males., Physiol Rep, Vol: 9
PURPOSE: The aim of this study was to examine if catechin-rich green tea abrogates the negative effects of 7-days of physical inactivity and excessive calorie-intake on insulin homeostasis and peripheral vascular function. METHODS: Using a randomized, double-blind, crossover design, twelve healthy men (29 ± 6 yrs) underwent 7-days unhealthy lifestyle (UL), including physical inactivity (-50% steps/day) and overfeeding (+50% kcal/day). This was combined with green tea consumption (UL-tea; 3 doses/day) or placebo (UL-placebo). Before and after each intervention, we examined postprandial blood glucose and insulin (3-h after a 1,202 kcal meal) and upper and lower limb vascular function (flow-mediated dilation (FMD%)) and carotid artery reactivity (CAR%). RESULTS: UL-placebo increased postprandial glucose and insulin, while UL-tea decreased postprandial glucose and insulin (Time*Intervention interaction effects: both p < 0.05). UL-placebo decreased CAR% and femoral FMD%, while UL-tea prevented these effects (Time*Intervention interaction effects of p < 0.04 and p < 0.001, respectively). There was no main effect of Time or Time*Intervention interaction (both p > 0.05) for brachial FMD%. CONCLUSION: Seven days of physical inactivity and overfeeding impair insulin homeostasis and vascular function. These effects were mitigated by a daily intake of catechin-rich green tea.
Mawhinney C, Heinonen I, Low DA, et al., 2020, Changes in quadriceps femoris muscle perfusion following different degrees of cold-water immersion, JOURNAL OF APPLIED PHYSIOLOGY, Vol: 128, Pages: 1392-1401, ISSN: 8750-7587
Thomas SD, Carter HH, Jones H, et al., 2020, Effects of Acute Exercise on Cutaneous Thermal Sensation, INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, Vol: 17
Low DA, Jones H, Cable NT, et al., 2020, Historical reviews of the assessment of human cardiovascular function: interrogation and understanding of the control of skin blood flow, EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, Vol: 120, Pages: 1-16, ISSN: 1439-6319
Hesketh K, Shepherd SO, Strauss JA, et al., 2019, Passive heat therapy in sedentary humans increases skeletal muscle capillarization and eNOS content but not mitochondrial density or GLUT4 content, AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, Vol: 317, Pages: H114-H123, ISSN: 0363-6135
Woodward KA, Hopkins ND, Draijer R, et al., 2018, Acute black tea consumption improves cutaneous vascular function in healthy middle-aged humans, CLINICAL NUTRITION, Vol: 37, Pages: 242-249, ISSN: 0261-5614
Pecanha T, Forjaz CLM, Low DA, 2017, Additive effects of heating and exercise on baroreflex control of heart rate in healthy males, JOURNAL OF APPLIED PHYSIOLOGY, Vol: 123, Pages: 1555-1562, ISSN: 8750-7587
Low DA, Bailey TG, Cable NT, et al., 2016, Thermoregulatory responses to combined moderate heat stress and hypoxia, Microcirculation, Vol: 23, Pages: 487-494, ISSN: 1549-8719
OBJECTIVE: The aim of this study was to examine the cutaneous vascular and sudomotor responses to combined moderate passive heat stress and normobaric hypoxia. METHOD: Thirteen healthy young males, dressed in a water-perfused suit, underwent passive heating (Δcore temperature ~0.7 °C) twice (NORMOXIA; 20.9% O2 and HYPOXIA; 13% O2 ). Chest and forearm skin blood flow (SkBF; laser Doppler flux), local sweat rate (SR; capacitance hygrometry) and core (intestinal pill) and skin temperatures, were recorded. RESULTS: HYPOXIA reduced baseline oxygen saturation (98±1 vs. 89±6%, P<0.001) and elevated chest (P=0.03) and forearm SkBF (P=0.03) and HR (64±9 vs. 69±8 beats.min(-1) , P<0.01). During heating, mean body temperature (T¯BODY ) thresholds for SkBF (P=0.41) and SR (P=0.28) elevations were not different between trials. The SkBF: T¯BODY linear sensitivity during the initial phase of heating was lower at the Chest (P=0.035) but not different at the forearm (P=0.17) during HYPOXIA. With increasing levels of heating chest SkBF was not different (P=0.55) but forearm SkBF was lower on the forearm (P<0.01) during HYPOXIA. Chest (P=0.85) and forearm (P=0.79) SR: T¯BODY linear sensitivities were not different between trials. CONCLUSION: Whilst sudomotor responses and the initiation of cutaneous blood flow elevations are unaffected, hypoxia differentially effects regional SkBF responses during moderate passive heating. This article is protected by copyright. All rights reserved.
Bailey TG, Cable NT, Aziz N, et al., 2016, Exercise training reduces the frequency of menopausal hot flushes by improving thermoregulatory control, Menopause, Vol: 23, ISSN: 1072-3714
OBJECTIVE: Postmenopausal hot flushes occur due to a reduction in estrogen production causing thermoregulatory and vascular dysfunction. Exercise training enhances thermoregulatory control of sweating, skin and brain blood flow. We aimed to determine if improving thermoregulatory control and vascular function with exercise training alleviated hot flushes. METHODS: Twenty-one symptomatic women completed a 7-day hot flush questionnaire and underwent brachial artery flow-mediated dilation and a cardiorespiratory fitness test. Sweat rate and skin blood flow temperature thresholds and sensitivities, and middle cerebral artery velocity (MCAv) were measured during passive heating. Women performed 16 weeks of supervised exercise training or control, and measurements were repeated. RESULTS: There was a greater improvement in cardiorespiratory fitness (4.45 mL/kg/min [95% CI: 1.87, 8.16]; P = 0.04) and reduced hot flush frequency (48 hot flushes/wk [39, 56]; P < 0.001) after exercise compared with control. Exercise reduced basal core temperature (0.14°C [0.01, 0.27]; P = 0.03) and increased basal MCAv (2.8 cm/s [1.0, 5.2]; P = 0.04) compared with control. Sweat rate and skin blood flow thresholds occurred approximately 0.19°C and 0.17°C earlier, alongside improved sweating sensitivity with exercise. MCAv decreased during heating (P < 0.005), but was maintained 4.5 cm/s (3.6, 5.5; P < 0.005) higher during heating after exercise compared with control (0.6 cm/s [-0.4, 1.4]). CONCLUSIONS: Exercise training that improves cardiorespiratory fitness reduces self-reported hot flushes. Improvements are likely mediated through greater thermoregulatory control in response to increases in core temperature and enhanced vascular function in the cutaneous and cerebral circulations.
Bailey TG, Cable NT, Aziz N, et al., 2015, Exercise training reduces the acute physiological severity of post-menopausal hot flushes, Journal of Physiology - London, Vol: 594, Pages: 657-667, ISSN: 0022-3751
KEY POINTS: A post-menopausal hot flush consists of profuse physiological elevations in cutaneous vasodilatation and sweating that are accompanied by reduced brain blood flow. These responses can be used to objectively quantify hot flush severity. The impact of an exercise training intervention on the physiological responses occurring during a hot flush is currently unknown. In a preference-controlled trial involving 21 post-menopausal women, 16 weeks of supervised moderate intensity exercise training was found to improve cardiorespiratory fitness and attenuate cutaneous vasodilatation, sweating and the reductions in cerebral blood flow during a hot flush. It is concluded that the improvements in fitness that are mediated by 16 weeks of exercise training reduce the severity of physiological symptoms that occur during a post-menopausal hot flush. ABSTRACT: A hot flush is characterised by feelings of intense heat, profuse elevations in cutaneous vasodilatation and sweating, and reduced brain blood flow. Exercise training reduces self-reported hot flush severity, but underpinning physiological data are lacking. We hypothesised that exercise training attenuates the changes in cutaneous vasodilatation, sweat rate and cerebral blood flow during a hot flush. In a preference trial, 18 symptomatic post-menopausal women underwent a passive heat stress to induce hot flushes at baseline and follow-up. Fourteen participants opted for a 16 week moderate intensity supervised exercise intervention, while seven participants opted for control. Sweat rate, cutaneous vasodilatation, blood pressure, heart rate and middle cerebral artery velocity (MCAv) were measured during the hot flushes. Data were binned into eight equal segments, each representing 12.5% of hot flush duration. Weekly self-reported frequency and severity of hot flushes were also recorded at baseline and follow-up. Following training, mean hot flush sweat rate decreased by 0.04 mg cm(2) min(-1) at the chest (95% confide
Idiaquez J, Farias H, Torres F, et al., 2015, Autonomic symptoms in hypertensive patients with post-acute minor ischemic stroke, CLINICAL NEUROLOGY AND NEUROSURGERY, Vol: 139, Pages: 188-191, ISSN: 0303-8467
BackgroundMost studies regarding autonomic dysfunction in ischemic stroke are limited to heart rate and blood pressure changes during the acute phase. However, there are few data on quantitative assessment of autonomic symptoms. We sought to assess autonomic symptoms in hypertensive ischemic stroke patients.MethodsIn 100 hypertensive patients (45 with symptomatic ischemic stroke (6 months after stroke onset) and 55 without stroke), we assessed autonomic symptoms using the Scale for Outcomes in Parkinson disease-Autonomic (SCOPA-AUT).ResultsThe age (mean ± standard deviation) for the stroke group was 66 ± 12 and 63 ± 15 for the without stroke group (P = 0.8). Orthostatic hypotension occurred in 3.6% of the stroke group and 4.4% in the group without stroke. The total SCOPA-AUT score was higher in the stroke group compared with the group without stroke (P = 0.001). Domain scores for gastrointestinal (P = 0.001), urinary (P = 0.005) and cardiovascular (P = 0.001) were higher in the stroke group. No differences were found when comparing the total SCOPA-AUT scores for stroke subtypes (P = 0.168) and for lateralization (P = 0.6). SCOPA AUT scores were correlated with depression scores (P = 0.001) but not with stroke severity (P = 0.2).ConclusionAutonomic symptoms, especially, gastrointestinal, urinary and cardiovascular function, were significantly increased in hypertensive patients with minor ischemic stroke. Symptoms were associated with depression but not with the characteristic of the stroke.
Wingo JE, Low DA, Keller DM, et al., 2015, Combined facial heating and inhalation of hot air do not alter thermoeffector responses in humans, American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol: 309, Pages: R623-R627, ISSN: 0363-6119
The influence of thermoreceptors in human facial skin on thermoeffector responses is equivocal; furthermore, the presence of thermoreceptors in the respiratory tract and their involvement in thermal homeostasis has not been elucidated. This study tested the hypothesis that hot air directed on the face and inhaled during whole body passive heat stress elicits an earlier onset and greater sensitivity of cutaneous vasodilation and sweating than that directed on an equal skin surface area away from the face. Six men and two women completed two trials separated by ∼1 wk. Participants were passively heated (water-perfused suit; core temperature increase ∼0.9°C) while hot air was directed on either the face or on the lower leg (counterbalanced). Skin blood flux (laser-Doppler flowmetry) and local sweat rate (capacitance hygrometry) were measured at the chest and one forearm. During hot-air heating, local temperatures of the cheek and leg were 38.4 ± 0.8°C and 38.8 ± 0.6°C, respectively (P = 0.18). Breathing hot air combined with facial heating did not affect mean body temperature onsets (P = 0.97 and 0.27 for arm and chest sites, respectively) or slopes of cutaneous vasodilation (P = 0.49 and 0.43 for arm and chest sites, respectively), or the onsets (P = 0.89 and 0.94 for arm and chest sites, respectively), or slopes of sweating (P = 0.48 and 0.65 for arm and chest sites, respectively). Based on these findings, respiratory tract thermoreceptors, if present in humans, and selective facial skin heating do not modulate thermoeffector responses during passive heat stress.
Dawson EA, Low DA, Meeuwis IH, et al., 2015, Reproducibility of cutaneous vascular conductance responses to slow local heating assessed using seven-laser array probes, Microcirculation, Vol: 22, Pages: 276-284, ISSN: 1549-8719
OBJECTIVE: Gradual local heating of the skin induces a largely NO-mediated vasodilatation. However, use of this assessment of microvascular health is limited because little is known about its reproducibility. METHODS: Healthy volunteers (n = 9) reported twice to the laboratory. CVC, derived from laser Doppler flux and mean arterial pressure, was examined in response to a standardized local heating protocol (0.5°C per 150 second from 33°C to 42°C, followed by 20 minutes at 44°C). Skin responses were examined at two locations on the forearm (between-site). Heating was repeated after a break of 24-72 hours (between-day). Reproducibility of skin responses at 33-42°C is presented for absolute CVC and relative CVC responses corrected for maximal CVC at 44°C (%CVCmax ). RESULTS: Between-day reproducibility of baseline CVC and %CVCmax for both sites was relatively poor (22-30%). At 42°C, CVC and %CVCmax responses showed less variation (9-19%), whilst absolute CVC responses at 44°C were 14-17%. Between-day variation for %CVCmax increased when using data from site 1 on day 1, but site 2 on the subsequent day (25%). CONCLUSION: Day-to-day reproducibility of baseline laser Doppler-derived skin perfusion responses is poor, but acceptable when absolute and relative skin perfusion to a local gradual heating protocol is utilized and site-to-site variation is minimized.
Owens AP, David AS, Low DA, et al., 2015, Abnormal cardiovascular sympathetic and parasympathetic responses to physical and emotional stimuli in depersonalization disorder, Frontiers in Neuroscience, Vol: 9, ISSN: 1662-4548
Stuebner E, Vichayanrat E, Low DA, et al., 2015, Non-dipping nocturnal blood pressure and psychosis parameters in Parkinson disease, Clinical Autonomic Research, Vol: 25, Pages: 109-116, ISSN: 1619-1560
BackgroundNon-motor symptoms are increasingly recognized in Parkinson disease (PD) and include physical as well as psychological symptoms. A psychological condition that has been well studied in PD is psychosis. Cardiovascular autonomic dysfunction in PD can include a reversed or loss of blood pressure (BP) circadian rhythm, referred to as nocturnal non-dipping. The aim of this study was to determine the relationship between 24 h ambulatory blood pressure measurements (ABPM), i.e., absence or presence of nocturnal dipping, and psychosis scores in PD.MethodsTwenty-one patiens with PD underwent 24 h ABPM using an autonomic protocol. A decrease in nocturnal mean arterial blood pressure of less than 10 % was defined as non-dipping. Patients were interviewed (including the brief psychiatric rating scale; BPRS) for the assessment of psychosis.ResultsEleven patients were dippers and 10 were non-dippers. BPRS scores were higher in non-dippers, who, on average, met the criteria for psychosis (mean non-dipper BPRS: 34.3 ± 7.3 vs mean dipper BPRS: 27.5 ± 5.3; cutoff for “mildly ill” 31). There was a correlation between BPRS scores and non-dipping, indicating that those patients who had a blunted nocturnal fall in BP were more prone to psychotic symptoms (Pearson’s Correlation = 0.554, p = 0.009).ConclusionThese results suggest that, among PD patients, a non-dipping circadian rhythm is associated with more severe symptoms of psychosis than is a dipping circadian rhythm. This association warrants further investigation.
Vichayanrat E, Low DA, Stuebner E, et al., 2014, The usefulness of 24 h ambulatory blood pressure and heart rate monitoring (24 h-ABPM) in diagnosing orthostatic hypotension (OH) in patients with parkinsonian disorders, Joint Congress of European Neurology, Publisher: SPRINGER HEIDELBERG, Pages: S63-S63, ISSN: 0340-5354
Low DA, Vichayanrat E, Iodice V, et al., 2014, Exercise hemodynamics in Parkinson's disease and autonomic dysfunction, PARKINSONISM & RELATED DISORDERS, Vol: 20, Pages: 549-553, ISSN: 1353-8020
Vichayanrat E, Low DA, Stuebner E, et al., 2014, The usefulness of 24 hour ambulatory blood pressure and heart rate monitoring (24hr-ABPM) in diagnosing orthostatic hypotension (OH) in patients with parkinsonian disorders, Joint Congress of European Neurology, Publisher: WILEY-BLACKWELL, Pages: 86-86, ISSN: 1351-5101
Asahina M, Mathias CJ, Katagiri A, et al., 2014, Sudomotor and Cardiovascular Dysfunction in Patients with Early Untreated Parkinson's Disease, JOURNAL OF PARKINSONS DISEASE, Vol: 4, Pages: 385-393, ISSN: 1877-7171
Mawhinney C, Jones H, Joo CH, et al., 2013, Influence of Cold-Water Immersion on Limb and Cutaneous Blood Flow after Exercise, MEDICINE AND SCIENCE IN SPORTS AND EXERCISE, Vol: 45, Pages: 2277-2285, ISSN: 0195-9131
Low DA, 2013, The cerebovasculature: a smooth (muscle) operator?, JOURNAL OF PHYSIOLOGY-LONDON, Vol: 591, Pages: 4959-4960, ISSN: 0022-3751
Pearson J, Kalsi KK, Stoehr EJ, et al., 2013, Erratum to: Haemodynamic responses to dehydration in the resting and exercising human leg (vol 113, pg 1499, 2013), EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, Vol: 113, Pages: 2431-2432, ISSN: 1439-6319
Vichayanrat E, Low DA, Asahina M, et al., 2013, L-DOPS and the treatment of neurogenic orthostatic hypotension, Future Neurology, Vol: 8, Pages: 381-397, ISSN: 1479-6708
Asahina M, Vichayanrat E, Low DA, et al., 2013, Autonomic dysfunction in parkinsonian disorders: assessment and pathophysiology, JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY, Vol: 84, Pages: 674-680, ISSN: 0022-3050
Pearson J, Kalsi KK, Stoehr EJ, et al., 2013, Haemodynamic responses to dehydration in the resting and exercising human leg, EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY, Vol: 113, Pages: 1499-1509, ISSN: 1439-6319
Stuebner E, Vichayanrat E, Low DA, et al., 2013, Twenty-four hour non-invasive ambulatory blood pressure and heart rate monitoring in Parkinson’s Disease, Frontiers in Neurology, Vol: 4, ISSN: 1664-2295
Asahina M, Low DA, Mathias CJ, et al., 2013, Skin temperature of the hand in multiple system atrophy and Parkinson's disease, PARKINSONISM & RELATED DISORDERS, Vol: 19, Pages: 560-562, ISSN: 1353-8020
Mathias CJ, Low DA, Frankel HL, 2013, Autonomic disturbances in spinal cord lesions, Autonomic Failure, Publisher: Oxford University Press, Pages: 797-817, ISBN: 9780198566342
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