Is there evidence for nonthermal modulation of whole body heat loss during intermittent exercise?

2010 ◽  
Vol 299 (1) ◽  
pp. R119-R128 ◽  
Author(s):  
Glen P. Kenny ◽  
Daniel Gagnon
Keyword(s):  
Heat Loss ◽  
Intermittent Exercise ◽  
Progressive Increase ◽  
Cycle Ergometer ◽  
Lower Limbs ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Active Recovery ◽  
Mean Body Temperature ◽  
Passive Recovery

This study compared the effect of active, passive, and inactive recoveries on whole body evaporative and dry heat loss responses during intermittent exercise at an air temperature of 30°C and a relative humidity of 20%. Nine males performed three 15-min bouts of upright seated cycling at a fixed external workload of 150 W. The exercise bouts were separated by three 15-min recoveries during which participants 1) performed loadless pedaling (active recovery), 2) had their lower limbs passively compressed with inflatable sleeves (passive recovery), or 3) remained upright seated on the cycle ergometer (inactive recovery). Combined direct and indirect calorimetry was employed to measure rates of whole body evaporative heat loss (EHL) and metabolic heat production (M-W). Mean body temperature (Tb) was calculated from esophageal and mean skin temperatures, and mean arterial pressure (MAP) was measured continuously. Active and passive recoveries both reversed the reduction in MAP associated with inactive recovery ( P ≤ 0.05). This response was paralleled by greater levels of EHL during active (207 ± 53 W) and passive recoveries (203 ± 55 W) compared with the inactive condition (168 ± 53 W, P ≤ 0.05). However, the greater rate of EHL during active recovery was paralleled by a greater M-W (194 ± 16 W) compared with inactive recovery (149 ± 27 W, P ≤ 0.001). In contrast, M-W during passive recovery (139 ± 20 W) was not significantly different from the inactive condition ( P = 0.468). Furthermore, there were no differences in Tb between inactive and passive conditions during the recovery periods ( P = 0.820). As such, passive recovery resulted in greater levels of EHL for a given change in Tb compared with inactive recovery ( P ≤ 0.05). These results strongly suggest that the progressive increase in core temperature during successive exercise/rest cycles is primarily the result of a baroreflex-mediated attenuation of postexercise whole body evaporative heat loss.

scholarly journals Whole body heat loss is reduced in older males during short bouts of intermittent exercise

2013 ◽  
Vol 305 (6) ◽  
pp. R619-R629 ◽  
Author(s):  
Joanie Larose ◽  
Heather E. Wright ◽  
Jill Stapleton ◽  
Ronald J. Sigal ◽  
Pierre Boulay ◽  
...  
Keyword(s):  
Heat Loss ◽  
Heat Storage ◽  
Intermittent Exercise ◽  
Heat Content ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Middle Aged ◽  
Young Males ◽  
Body Heat ◽  
Older Males

Studies in young adults show that a greater proportion of heat is gained shortly following the start of exercise and that temporal changes in whole body heat loss during intermittent exercise have a pronounced effect on body heat storage. The consequences of short-duration intermittent exercise on heat storage with aging are unclear. We compared evaporative heat loss (H E) and changes in body heat content (ΔHb) between young (20–30 yr), middle-aged (40–45 yr), and older males (60–70 yr) of similar body mass and surface area, during successive exercise (4 × 15 min) and recovery periods (4 × 15 min) at a fixed rate of heat production (400 W) and under fixed environmental conditions (35°C/20% relative humidity). H E was lower in older males vs. young males during each exercise (Ex1: 283 ± 10 vs. 332 ± 11 kJ, Ex2: 334 ± 10 vs. 379 ± 5 kJ, Ex3: 347 ± 11 vs. 392 ± 5 kJ, and Ex4: 347 ± 10 vs. 387 ± 5 kJ, all P < 0.02), whereas H E in middle-aged males was intermediate to that measured in young and older adults (Ex1: 314 ± 13, Ex2: 355 ± 13, Ex3: 371 ± 13, and Ex4: 365 ± 8 kJ). H E was not significantly different between groups during the recovery periods. The net effect over 2 h was a greater ΔHb in older (267 ± 33 kJ; P = 0.016) and middle-aged adults (245 ± 16 kJ; P = 0.073) relative to younger counterparts (164 ± 20 kJ). As a result of a reduced capacity to dissipate heat during exercise, which was not compensated by a sufficiently greater rate of heat loss during recovery, both older and middle-aged males had a progressively greater rate of heat storage compared with young males over 2 h of intermittent exercise.

Exercise-rest cycles do not alter local and whole body heat loss responses

2011 ◽  
Vol 300 (4) ◽  
pp. R958-R968 ◽  
Author(s):  
Daniel Gagnon ◽  
Glen P. Kenny
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Intermittent Exercise ◽  
Sweat Rate ◽  
Heat Content ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Esophageal Temperature ◽  
Direct Calorimetry ◽  
Body Heat

Previous studies have suggested that greater core temperatures during intermittent exercise (Ex) are due to attenuated sweating [upper back sweat rate (SR)] and skin blood flow (SkBF) responses. We evaluated the hypothesis that heat loss is not altered during exercise-rest cycles (ER). Ten male participants randomly performed four 120-min trials: 1) 60-min Ex and 60-min recovery (60ER); 2) 3 × 20-min Ex separated by 20-min recoveries (20ER); 3) 6 × 10-min Ex separated by 10-min recoveries (10ER), or 4) 12 × 5-min Ex separated by 5-min recoveries (5ER). Exercise was performed at a workload of 130 W at 35°C. Whole body heat exchange was determined by direct calorimetry. Core temperature, SR (by ventilated capsule), and SkBF (by laser-doppler) were measured continuously. Evaporative heat loss (EHL) progressively increased with each ER, such that it was significantly greater ( P ≤ 0.05) at the end of the last compared with the first Ex for 5ER (299 ± 39 vs. 440 ± 41 W), 10ER (425 ± 51 vs. 519 ± 45 W), and 20ER (515 ± 63 vs. 575 ± 74 W). The slope of the EHL response against esophageal temperature significantly increased from the first to the last Ex within the 10ER (376 ± 56 vs. 445 ± 89 W/°C, P ≤ 0.05) and 20ER (535 ± 85 vs. 588 ± 28 W/°C, P ≤ 0.05) conditions, but not during 5ER (296 ± 96 W/°C vs. 278 ± 95 W/°C, P = 0.237). In contrast, the slope of the SkBF response against esophageal temperature did not significantly change from the first to the last Ex (5ER: 51 ± 23 vs. 54 ± 19%/°C, P = 0.848; 10ER: 53 ± 8 vs. 56 ± 21%/°C, P = 0.786; 20ER: 44 ± 20 vs. 50 ± 27%/°C, P = 0.432). Overall, no differences in body heat content and core temperature were observed. These results suggest that altered local and whole body heat loss responses do not explain the previously observed greater core temperatures during intermittent exercise.

Cardiac autonomic response during recovery using whole-body vibration after maximal cardiopulmonary exercise test (Respuesta cardiaca autónoma durante la recuperación utilizando vibración de cuerpo completo, después de una prueba de ejercicio cardiopulmo

Retos ◽  
2021 ◽  
Vol 42 ◽  
pp. 323-330
Author(s):  
Jorge Olivares Arancibia ◽  
Patricio Solis-Urra ◽  
Felipe Porras-López ◽  
Inti Federeci-Díaz ◽  
Fernando Rodríguez-Rodríguez ◽  
...  
Keyword(s):  
Heart Rate ◽  
Exercise Test ◽  
Whole Body Vibration ◽  
Cardiopulmonary Exercise Test ◽  
Autonomic Response ◽  
Whole Body ◽  
Education Student ◽  
Active Recovery ◽  
Passive Recovery ◽  
Cardiopulmonary Exercise

  In the last years the nervous and cardiovascular response to exercise has taken on an important relevance, both in sport and health field. In this line, accelerating cardiovascular appears to play a key role in various sports fields. The study aims to examine and compare the acute effect of whole-body vibration (WBV) on cardiac autonomic response after maximal exercise in university runners and physical education student. Twenty men participated in a cross-over study, 10 university runners team (UR) and 10 physical education student (PES) with ages around 18 to 24 years. In each condition, was perform an incremental cardiopulmonary exercise test followed (i) active recovery time using WBV (25 Hz and peak displacement of four mm) and (ii) passive recovery period (no WBV; 0 Hz—0 mm), separated by seven days. Active recovery consisted in one minute seated using WBV and one minute no WBV by six times (12 minutes) more five minutes of passive recovery, and passive recovery consisted in 17 min seated on platform without vibration. Active recovery had significant differences compare to passive recovery (P<0.05). Furthermore, in active recovery, PES had better heart rate response than UR group, however results were not significative. There was not a clear relation between the lineal components of heart rate variability (HRV) in our results. WBV has positive effect in participant’s recovery, however, is necessary establish protocols about the intensities and time adequate for allow accelerate recovery the parasympathetic reactivity, for that reason yet can’t conclude clearly respect to the more effectivity intensity WBV depending to characteristic of subject.  Resumen. En los últimos años la respuesta nerviosa y cardiovascular al ejercicio ha adquirido una relevancia importante, tanto en el ámbito del deporte como de la salud. Por tanto, la aceleración de la recuperación cardiovascular parece desempeñar un papel clave en varios campos. El objetivo del estudio es analizar y comparar el efecto agudo de la vibración de cuerpo completo (VCC), en la respuesta cardíaca autónoma después del ejercicio máximo en corredores universitarios (CU) y estudiantes de educación física (EEF). Veinte hombres participaron en un estudio cruzado, 10 CU y 10 EEF con edades entre 18 y 24 años. En cada evaluación, se realizó una prueba cardiopulmonar incremental seguida de (i) tiempo de recuperación activa usando VCC (25 Hz y desplazamiento máx. de cuatro mm) y (ii) período de recuperación pasiva (sin VCC; 0 Hz — 0 mm), separados por siete días. La recuperación activa consistió en un minuto sentado usando WBV y un minuto sin WBV seis veces (12 min), más cinco minutos de recuperación pasiva; la recuperación pasiva y esta consistió en 17 minutos sentado en plataforma sin vibración. La recuperación activa tuvo diferencias significativas en comparación con recuperación pasiva (p <0.05). Además, en recuperación activa, EEF tuvo una mejor respuesta de frecuencia cardíaca que el grupo CU, sin embargo, los resultados no fueron significativos. Por último, no se logró establecer una relación clara entre los componentes lineales de la variabilidad del ritmo cardiaco (VRC) en nuestros resultados. La VCC tiene un efecto positivo en la recuperación de los sujetos, sin embargo, es necesario establecer protocolos sobre las intensidades y tiempo adecuado para permitir acelerar la recuperación de la reactividad parasimpática, por esa razón aún no se puede concluir claramente respecto al mejor protocolo VVC dependiendo de la característica del sujeto.

Effect of heating rate on evaporative heat loss in the microwave-exposed mouse

1982 ◽  
Vol 53 (2) ◽  
pp. 316-323 ◽  
Author(s):  
C. J. Gordon
Keyword(s):  
Body Temperature ◽  
Heat Loss ◽  
Heat Dissipation ◽  
Dew Point ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Heat Absorption ◽  
Deep Body Temperature ◽  
The Difference ◽  
Body Heat

Male CBA/J mice were administered heat loads of 0–28 J X g-1 at specific absorption rates (SARs) of either 47 or 93 W X kg-1 by exposure to 2,450-MHz microwave radiation at an ambient temperature of 30 degrees C while evaporative heat loss (EHL) was continuously monitored with dew-point hygrometry. At an SAR of 47 W X kg-1 a threshold heat load of 10.5 J X g-1 had to be exceeded before EHL increased. An approximate doubling of SAR to 93 W X kg-1 reduced the threshold to 5.2 J X g-1. Above threshold the slopes of the regression lines were 1.15 and 0.929 for the low- and high-SAR groups, respectively. Thus the difference in threshold and not slope attributes to the significant increase in EHL when mice are exposed at a high SAR (P less than 0.02). In separate experiments a SAR of 47 W X kg-1 raised the deep body temperature of anesthetized mice at a rate of 0.026 degrees C X s-1, whereas 93 W X kg-1 raised temperature at 0.049 degrees C X s-1. Hence the sensitivity of the EHL mode of heat dissipation is directly proportional to the rate of heat absorption and to the rate of rise in body temperature. These data contradict the notion that mammals have control over whole-body heat exchange only (i.e., thermoregulation) but instead indicate that the EHL system is highly responsive to the rate of heat absorption (i.e., temperature regulation).

Evaluation of vapor permeation through garments during exercise

1985 ◽  
Vol 58 (3) ◽  
pp. 928-935 ◽  
Author(s):  
R. R. Gonzalez ◽  
K. Cena
Keyword(s):  
Heat Loss ◽  
Cycle Ergometer ◽  
Dew Point ◽  
Evaporative Heat Loss ◽  
Local Skin ◽  
Vapor Permeation ◽  
Skin Wettedness ◽  
Latent Heat Loss ◽  
Saturation Vapor ◽  
Practical Dimension

Five males [age 28 +/- 8 yr; maximum O2 uptake (VO2max) 50 +/- 6 ml O2 . kg-1 . min-1; body wt 70 +/- 3 kg; DuBois surface area 1.85 +/- 0.02 m2] exercised on a cycle ergometer, placed on a Potter scale, at 31% VO2max for up to 2 h at an ambient temperature (Ta) of 25 degrees C and a dew-point temperature of 15 degrees C. Air movement was varied from still air to 0.4 and 2 m/s. Each subject, in separate runs, wore a track suit (TS ensemble) of 60% polyester-40% cotton (effective clo = 0.5); a Gortex parka (GOR ensemble), covering a sweat shirt and bottom of TS (effective clo = 1.4); or the TS ensemble covered by polyethylene overgarment (POG ensemble). Esophageal, skin temperature (Tsk) at eight sites, and heart rate were continuously recorded. Dew-point sensors recorded temperatures under the garments at ambient and chest (windward site) and midscapular sites. Local skin wettedness (loc w) and ratio of evaporative heat loss (Esk) to maximum evaporative capacity were determined. An observed average effective permeation (Pe, W . m-2 . Torr-1) was calculated as Esk/loc w (Ps,sk - Pw), where w is the average of chest and back loc w and (Ps,sk - Pw) is the gradient of skin saturation vapor pressure at Tsk and Ta. Additionally, the local effective evaporative coefficient was determined for chest and back sites by Esk/(Ps,dpl - Pw). The GOR ensemble produced an almost as high a Pe as the TS ensemble (82–86% of Pe with TS in still air and 0.4- and 2-m/s conditions). Direct dew-point recording offers an easy practical dimension to the study of efficacy of latent heat loss and skin wettedness properties through garments.

Postexercise Activation of Muscle Metaboreceptors Modulates Whole-Body Evaporative Heat Loss

2017 ◽  
Vol 49 (5S) ◽  
pp. 449
Author(s):  
Brian J. Friesen ◽  
Martin P. Poirier ◽  
Dallon T. Lamarche ◽  
Andrew W. D’Souza ◽  
Jung-Hyun Kim ◽  
...  
Keyword(s):  
Heat Loss ◽  
Whole Body ◽  
Evaporative Heat Loss

scholarly journals Postexercise whole-body sweating increases during muscle metaboreceptor activation in young men

2018 ◽  
Vol 43 (4) ◽  
pp. 423-426 ◽  
Author(s):  
Brian J. Friesen ◽  
Martin P. Poirier ◽  
Dallon T. Lamarche ◽  
Andrew W. D’Souza ◽  
Jung-Hyun Kim ◽  
...  
Keyword(s):  
Heat Loss ◽  
Young Men ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Exercise Recovery ◽  
Isometric Handgrip ◽  
Natural Recovery ◽  
Ischemic Period ◽  
And Control ◽  
Late Stages

We assessed the effect of metaboreceptor activation on whole-body evaporative heat loss (WB-EHL) in 12 men (aged 24 ± 4 years) in the early-to-late stages of a 60-min exercise recovery in the heat. Metaboreceptor activation induced by 1-min isometric-handgrip (IHG) exercise followed by 5-min forearm ischemia to trap metabolites increased WB-EHL by 25%–31% and 26%–34% during the ischemic period relative to IHG-only and control (natural recovery only), respectively, throughout recovery. We show that metaboreceptor activation enhances WB-EHL in recovery.

Sprint Interval Training: Recovery Format, Enjoyment and Blood Pressure in Inactive Men

2021 ◽  
Vol 10 (3) ◽  
pp. 75-84
Author(s):  
Yuri Kriel ◽  
Hugo A. Kerhervé ◽  
Christopher David Askew ◽  
Colin Solomon
Keyword(s):  
Physical Activity ◽  
Blood Pressure ◽  
Interval Training ◽  
Cycle Ergometer ◽  
Sprint Interval Training ◽  
Active Recovery ◽  
Positive Health ◽  
Passive Recovery ◽  
Postexercise Recovery ◽  
Activity Enjoyment

ABSTRACT Background: While the efficacy of sprint interval training (SIT) to provide positive health effects in inactive populations is established, feasibility is associated with enjoyment and safety, which are dependent on the acute physiological and perceptual responses. The recovery format likely influences physiological and perceptual responses that occur during and immediately after SIT. It was hypothesized that during SIT interspersed with active recovery periods, enjoyment and blood pressure (BP) values would be higher compared with passive recovery periods, in inactive participants. Methods: Twelve males (mean ± SD; age 23 ± 3 y) completed 3 exercise sessions on a cycle ergometer in a randomized order on separate days: (a) SIT with passive recovery periods between 4 bouts (SITPASS), (b) SIT with active recovery periods between 4 bouts (SITACT), and (c) SITACT with the 4 SIT bouts replaced with passive periods. BP was measured immediately after each bout and every 2 min during a 6 min recovery. Physical activity enjoyment was measured during postexercise recovery. Results: There were no significant differences in physical activity enjoyment or systolic BP between SITPASS and SITACT. Diastolic BP was lower during recovery in SITACT (P = 0.025) and SITPASS (P = 0.027), compared with resting BP. Furthermore, diastolic BP was lower after 6 min of recovery following SITPASS, compared with SITACT (P = 0.01). Conclusion: Exercise enjoyment and acute systolic BP responses were independent of SIT recovery format in inactive men. Reductions in diastolic BP were greater and more prolonged after SIT protocols that included passive recovery periods.

scholarly journals Aging impairs heat loss, but when does it matter?

2015 ◽  
Vol 118 (3) ◽  
pp. 299-309 ◽  
Author(s):  
Jill M. Stapleton ◽  
Martin P. Poirier ◽  
Andreas D. Flouris ◽  
Pierre Boulay ◽  
Ronald J. Sigal ◽  
...  
Keyword(s):  
Aerobic Exercise ◽  
Surface Area ◽  
Heat Loss ◽  
Body Surface Area ◽  
Body Surface ◽  
Aerobic Fitness ◽  
Whole Body ◽  
Evaporative Heat Loss ◽  
Middle Aged ◽  
Direct Calorimetry

Aging is associated with an attenuated physiological ability to dissipate heat. However, it remains unclear if age-related impairments in heat dissipation only occur above a certain level of heat stress and whether this response is altered by aerobic fitness. Therefore, we examined changes in whole body evaporative heat loss (HE) as determined using whole body direct calorimetry in young ( n = 10; 21 ± 1 yr), untrained middle-aged ( n = 10; 48 ± 5 yr), and older ( n = 10; 65 ± 3 yr) males matched for body surface area. We also studied a group of trained middle-aged males ( n = 10; 49 ± 5 yr) matched for body surface area with all groups and for aerobic fitness with the young group. Participants performed intermittent aerobic exercise (30-min exercise bouts separated by 15-min rest) in the heat (40°C and 15% relative humidity) at progressively greater fixed rates of heat production equal to 300 (Ex1), 400 (Ex2), and 500 (Ex3) W. Results showed that HE was significantly lower in middle-aged untrained (Ex2: 426 ± 34; and Ex3: 497 ± 17 W) and older (Ex2: 424 ± 38; and Ex3: 485 ± 44 W) compared with young (Ex2: 472 ± 42; and Ex3: 558 ± 51 W) and middle-aged trained (474 ± 21; Ex3: 552 ± 23 W) males at the end of Ex2 and Ex3 ( P < 0.05). No differences among groups were observed during recovery. We conclude that impairments in HE in older and middle-aged untrained males occur at exercise-induced heat loads of ≥400 W when performed in a hot environment. These impairments in untrained middle-aged males can be minimized through regular aerobic exercise training.

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