Influence of exercise hyperthermia on exercise breathing pattern

1979 ◽  
Vol 47 (5) ◽  
pp. 1039-1042 ◽  
Author(s):  
B. J. Martin ◽  
E. J. Morgan ◽  
C. W. Zwillich ◽  
J. V. Weil
Keyword(s):  
Breathing Pattern ◽  
Cycle Ergometer ◽  
The Body ◽  
Body Core Temperature ◽  
Inspiratory Time ◽  
Maximal Aerobic Capacity ◽  
Ergometer Exercise ◽  
Shallow Breathing ◽  
Body Core ◽  
Exercise Induced

Passive elevation of the body core temperature (Tc) induces rapid, shallow breathing in resting man. We wondered if exercise-induced Tc elevation would also lead to decreased tidal volume (VT) and increased breathing frequency (f) during exercise. To investigate this question, 10 subjects each performed 47 min of cycle ergometer exercise at 50--60% of the maximal aerobic capacity, with the work rate adjusted to maintain ventilation (VE) constant. This long ride raised mean Tc (rectal) 0.8 degrees C. Before and immediately after the long ride, ranges of VE and VT were obtained from short 6-min rides that progressed from unloaded pedaling to the anaerobic threshold. At the constant VE of the long ride, f rose and VT fell as Tc rose (P less than 0.05). The fall in VT was associated with a fall in inspiratory time (TI); drive (VT/TI) and timing (TI/Ttot)components of VE were unchanged. These effects were consistent over the entire range of VE obtained from the short 6-min rides. Passive heating in warm water to produce equal Tc elevation in the same subjects yielded similar exercise breathing-pattern changes. These findings suggest that increased Tc mediates the VT fall during prolonged exercise, possibly through stimulation of the central respiratory pacemaker.

Control of breathing during prolonged exercise

1981 ◽  
Vol 50 (1) ◽  
pp. 27-31 ◽  
Author(s):  
B. J. Martin ◽  
E. J. Morgan ◽  
C. W. Zwillich ◽  
J. V. Weil
Keyword(s):  
Core Temperature ◽  
Cycle Ergometer ◽  
Body Core Temperature ◽  
Heavy Exercise ◽  
Arterial Lactate ◽  
Arterial Ph ◽  
Ergometer Exercise ◽  
Constant Work Rate ◽  
Body Core

Ventilation (VE) climbs steadily throughout prolonged heavy exercise. While this VE "drift" has implications for the adequacy of gas exchange in long-term exercise, its mechanism remains unknown. We examined the behavior of previously proposed mediators of VE drift during one hour of cycle ergometer exercise at constant work rate requiring 2/3 VO2 max in 10 subjects. VE increased 13% from 12 to 61 min of exercise (P less than 0.05). Although body core temperature rose as VE rose, equal elevation of core temperature by passive means failed to increase exercise VE. Rising VE during the hour of exercise occurred despite unchanged arterial pH, PCO2, and lactate and despite unchanged VCO2. Thus, all of the VE increase was calculated to be due to increased dead space ventilation (VD). Tidal volume (VT) was unchanged, while VD/VT rose from 0.16 to 0.24 from 12 to 61 min of work (P less than 0.05). These results show that increased body core temperature does not mediate VE drift, and that changes in previously proposed mediators (arterial pH, arterial lactate, and VCO2) are not necessary for a slow VE rise to occur in prolonged heavy exercise.

Acute hypoosmolality attenuates the suppression of cutaneous vasodilation with increased exercise intensity

2005 ◽  
Vol 99 (3) ◽  
pp. 902-908 ◽  
Author(s):  
Hiroyuki Mitono ◽  
Hiroshi Endoh ◽  
Kazunobu Okazaki ◽  
Takashi Ichinose ◽  
Shizue Masuki ◽  
...  
Keyword(s):  
Exercise Intensity ◽  
Lactate Concentration ◽  
Plasma Osmolality ◽  
Young Male ◽  
Cycle Ergometer ◽  
The Body ◽  
Body Core Temperature ◽  
Temperature Threshold ◽  
Ergometer Exercise ◽  
Forearm Skin

We examined the hypothesis that elevation of the body core temperature threshold for forearm skin vasodilation (THFVC) with increased exercise intensity is partially caused by concomitantly increased plasma osmolality (Posmol). Eight young male subjects, wearing a body suit perfused with warm water to maintain the mean skin temperature at 34 ± 1°C (ranges), performed 20-min cycle-ergometer exercise at 30% peak aerobic power (V̇o2 peak) under isoosmotic conditions (C), and at 65% V̇o2 peak under isoosmotic (HEXIOS) and hypoosmotic (HEXLOS) conditions. In HEXLOS, hypoosmolality was attained by hypotonic saline infusion with DDAVP, a V2 agonist, before exercise. Posmol (mosmol/kgH2O) increased after the start of exercise in both HEX trials ( P < 0.01) but not in C. The average Posmol at 5 and 10 min in HEXIOS was higher than in C ( P < 0.01), whereas that in HEXLOS was lower than in HEXIOS ( P < 0.01). The change in THFVC was proportional to that in Posmol in every subject for three trials. The change in THFVC per unit change in Posmol (ΔTHFVC/ΔPosmol, °C·mosmol−1·kgH2O−1) was 0.064 ± 0.012 when exercise intensity increased from C to HEXIOS, similar to 0.086 ± 0.020 when Posmol decreased from HEXIOS to HEXLOS ( P > 0.1). Moreover, there were no significant differences in plasma volume, heart rate, mean arterial pressure, and plasma lactate concentration around THFVC between HEXIOS and HEXLOS ( P > 0.1). Thus the increase in THFVC due to increased exercise intensity was at least partially explained by the concomitantly increased Posmol.

Neuropeptide Y release from human heart is enhanced during prolonged exercise in hypoxia

1994 ◽  
Vol 76 (3) ◽  
pp. 1346-1349 ◽  
Author(s):  
L. Kaijser ◽  
J. Pernow ◽  
B. Berglund ◽  
J. Grubbstrom ◽  
J. M. Lundberg
Keyword(s):  
Neuropeptide Y ◽  
Coronary Sinus ◽  
Cycle Ergometer ◽  
Air Breathing ◽  
Ergometer Exercise ◽  
The Difference ◽  
Exercise Induced ◽  
Arterial O2 Saturation ◽  
Net Release ◽  
Coronary Sinus Blood

To evaluate the effect of hypoxemia on cardiac release of neuropeptide Y-like immunoreactivity (NPY-LI) and norepinephrine (NE), arterial and coronary sinus blood was sampled and coronary sinus blood flow was measured by thermodilution in nine healthy volunteers at rest and during supine cycle ergometer exercise while they breathed air and 12% O2, which reduced arterial O2 saturation to approximately 68%. Five subjects started to exercise for 30 min breathing air and continued for 30 min breathing 12% O2; four subjects breathed 12% O2 and air in the reverse order. The load was adjusted to give the same heart rate during O2 and air breathing. No significant cardiac net release of NPY-LI or NE was seen at rest. Exercise induced release of NPY-LI and NE. The net release of NPY-LI was 0.7 +/- 0.4 pmol/min during air breathing (average 12 and 30 min) and 2.8 +/- 0.6 pmol/min during 12% O2 breathing. The difference was not influenced by the order of the breathing periods. The NE coronary sinus-arterial difference was not significantly different between 12% O2 and air breathing, whereas the net release was significantly larger during 12% O2 breathing (0.6 +/- 0.1 vs. 0.4 +/- 0.1 nmol/min). Thus, NPY is released with NE from the heart during exercise. Arterial hypoxemia seems to be an additional stimulus of preferential NPY release.

Leg raise can detect exercise-induced pulmonary arterial wedge pressure elevation

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
C Nakata ◽  
A Goda ◽  
K Takeuchi ◽  
H Kikuchi ◽  
T Inami ◽  
...  
Keyword(s):  
Diastolic Dysfunction ◽  
Cycle Ergometer ◽  
Left Ventricular Diastolic Dysfunction ◽  
Left Ventricular ◽  
Hemodynamic Assessment ◽  
Ergometer Exercise ◽  
Ventricular Diastolic Dysfunction ◽  
Pulmonary Arterial ◽  
Exercise Induced ◽  
Wedge Pressure

Abstract Background Exercise-induced elevation of pulmonary arterial wedge pressure (PAWP) may show preclinical or exercise-induced left ventricular diastolic dysfunction. Invasive hemodynamic assessment during provocative maneuvers, like exercise and volume challenge, in these patients allows greater sensitivity to diagnose or exclude HFpEF. The aim of this study was to examine how the leg raise, which is a simple way to increase preload, can detect exercise-induced PAWP elevation. Methods Four hundred seventy-nine patients (60±14y.o, mean pulmonary arterial pressure (PAP) 19mmHg, PAWP 8mmHg, CTEPH /IPAH/CTD-PH/SOB unknown reason: 357/56/38/28pts) with near-normal PAP and normal PAWP at rest underwent symptom-limited exercise test using supine cycle ergometer with right heart catheter. Exercise-induced elevation in PAWP of over 20mmHg was defined as exercise-induced elevation group. Results ΔPAWP (after leg raise - rest) in the exercise-induced elevation group was significantly higher (6.0±4.1 vs. 2.7±3.9mmHg, p&lt;0.001, in the older (age≥60y.o) group (n=276); 3.4±3.5 vs. 1.9±3.4mmHg, p&lt;0.001, in the younger (age&lt;60y.o) group (n=203)) than that in the non-elevation group after legs raise for cycle ergometer exercise. The area under the ROC curve for ΔPAWP was 0.72 (95% CI: 0.65–0.78) in the older and 0.64 (95% CI: 0.53–0.75) in the younger. In the older, the cut-off value for detect exercise-induced PAWP elevation of ΔPAWP was 4mmHg, with 72% sensitivity and 58% specificity. On the other hand, in the younger, the cut-off value was 3mmHg, with 69% sensitivity and 59% specificity. Conclusion Leg raise can easily detect occult left ventricular diastolic dysfunction. Funding Acknowledgement Type of funding source: None

Transcapillary escape rate of albumin in humans during exercise-induced hypervolemia

1997 ◽  
Vol 83 (2) ◽  
pp. 407-413 ◽  
Author(s):  
Andrew Haskell ◽  
Ethan R. Nadel ◽  
Nina S. Stachenfeld ◽  
Kei Nagashima ◽  
Gary W. Mack
Keyword(s):  
Osmotic Pressure ◽  
Colloid Osmotic Pressure ◽  
Cycle Ergometer ◽  
Escape Rate ◽  
Albumin Concentration ◽  
Vascular Space ◽  
Transcapillary Escape Rate ◽  
Ergometer Exercise ◽  
Leg Muscle ◽  
Exercise Induced

Haskell, Andrew, Ethan R. Nadel, Nina S. Stachenfeld, Kei Nagashima, and Gary W. Mack. Transcapillary escape rate of albumin in humans during exercise-induced hypervolemia. J. Appl. Physiol. 83(2): 407–413, 1997.—To test the hypotheses that plasma volume (PV) expansion 24 h after intense exercise is associated with reduced transcapillary escape rate of albumin (TERalb) and that local changes in transcapillary forces in the previously active tissues favor retention of protein in the vascular space, we measured PV, TERalb, plasma colloid osmotic pressure (COPp), interstitial fluid hydrostatic pressure (Pi), and colloid osmotic pressure in leg muscle and skin and capillary filtration coefficient (CFC) in the arm and leg in seven men and women before and 24 h after intense upright cycle ergometer exercise. Exercise expanded PV by 6.4% at 24 h (43.9 ± 0.8 to 46.8 ± 1.2 ml/kg, P< 0.05) and decreased total protein concentration (6.5 ± 0.1 to 6.3 ± 0.1 g/dl, P < 0.05) and COPp (26.1 ± 0.8 to 24.3 ± 0.9 mmHg, P < 0.05), although plasma albumin concentration was unchanged. TERalb tended to decline (8.4 ± 0.5 to 6.5 ± 0.7%/h, P = 0.11) and was correlated with the increase in PV ( r = −0.69, P < 0.05). CFC increased in the leg (3.2 ± 0.2 to 4.3 ± 0.5 μl ⋅ 100 g−1 ⋅ min−1 ⋅ mmHg−1, P < 0.05), and Pi showed a trend to increase in the leg muscle (2.8 ± 0.7 to 3.8 ± 0.3 mmHg, P = 0.08). These data demonstrate that TERalb is associated with PV regulation and that local transcapillary forces in the leg muscle may favor retention of albumin in the vascular space after exercise.

scholarly journals Evaluation of Various Cooling Systems After Exercise-Induced Hyperthermia

2017 ◽  
Vol 52 (2) ◽  
pp. 108-116 ◽  
Author(s):  
Pearl M. S. Tan ◽  
Eunice Y. N. Teo ◽  
Noreffendy B. Ali ◽  
Bryan C. H. Ang ◽  
Iswady Iskandar ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Core Temperature ◽  
Cooling System ◽  
Rating Of Perceived Exertion ◽  
Body Core Temperature ◽  
Cooling Systems ◽  
Induced Hyperthermia ◽  
Objective Evidence ◽  
Body Core ◽  
Exercise Induced

Context: Rapid diagnosis and expeditious cooling of individuals with exertional heat stroke is paramount for survival. Objective: To evaluate the efficacy of various cooling systems after exercise-induced hyperthermia. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Twenty-two men (age = 24 ± 2 years, height = 1.76 ± 0.07 m, mass = 70.7 ± 9.5 kg) participated. Intervention(s): Each participant completed a treadmill walk until body core temperature reached 39.50°C. The treadmill walk was performed at 5.3 km/h on an 8.5% incline for 50 minutes and then at 5.0 km/h until the end of exercise. Each participant experienced 4 cooling phases in a randomized, repeated-crossover design: (1) no cooling (CON), (2) body-cooling unit (BCU), (3) EMCOOLS Flex.Pad (EC), and (4) ThermoSuit (TS). Cooling continued for 30 minutes or until body core temperature reached 38.00°C, whichever occurred earlier. Main Outcome Measure(s): Body core temperature (obtained via an ingestible telemetric temperature sensor) and heart rate were measured continuously during the exercise and cooling phases. Rating of perceived exertion was monitored every 5 minutes during the exercise phase and thermal sensation every minute during the cooling phase. Results: The absolute cooling rate was greatest with TS (0.16°C/min ± 0.06°C/min) followed by EC (0.12°C/min ± 0.04°C/min), BCU (0.09°C/min ± 0.06°C/min), and CON (0.06°C/min ± 0.02°C/min; P &lt; .001). The TS offered a greater cooling rate than all other cooling modalities in this study, whereas EC offered a greater cooling rate than both CON and BCU (P &lt; .0083 for all). Effect-size calculations, however, showed that EC and BCU were not clinically different. Conclusion: These findings provide objective evidence for selecting the most effective cooling system of those we evaluated for cooling individuals with exercise-induced hyperthermia. Nevertheless, factors other than cooling efficacy need to be considered when selecting an appropriate cooling system.

Selective regulation of brain and body temperatures in the squirrel monkey

1983 ◽  
Vol 245 (2) ◽  
pp. R293-R297 ◽  
Author(s):  
C. A. Fuller ◽  
M. A. Baker
Keyword(s):  
Squirrel Monkey ◽  
Brain Temperature ◽  
Human Subjects ◽  
Venous Blood ◽  
The Body ◽  
Body Core Temperature ◽  
Saimiri Sciureus ◽  
Brain Cooling ◽  
The Face ◽  
Body Core

Many panting mammals can cool the brain below body core temperature during heat stress. Studies on human subjects suggest that primates may also be able selectively to regulate brain temperature. We examined this possibility by measuring hypothalamic (Thy) and colonic (Tco) temperatures of unanesthetized squirrel monkeys (Saimiri sciureus) in two different experiments. First, Thy and Tco were examined at four different ambient temperatures (Ta) between 20 and 36 degrees C. Over this range of Ta, Thy was regulated within a narrower range than Tco. In the cold Ta, Tco was lower than Thy; whereas in warm Ta, Tco was higher than Thy. Second, monkeys maintained at 35 degrees C Ta were acutely exposed to cool air blown on the face or abdomen. Air directed at the face cooled Thy more and faster than Tco, whereas air directed at the abdomen cooled Tco and Thy at the same rate. The second experiment was repeated in anesthetized animals with a thermocouple in the right atrium, and the results showed that this brain cooling was not produced by cooling of blood in the body core. These data demonstrate that the squirrel monkey is capable of selectively regulating Thy. Further the results suggest that venous blood returning from the face may be involved in selective brain cooling in warm environments.

Restoration of thermoregulation after exercise

2017 ◽  
Vol 122 (4) ◽  
pp. 933-944 ◽  
Author(s):  
Glen P. Kenny ◽  
Ryan McGinn
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Current Knowledge ◽  
Thermal Control ◽  
The Body ◽  
Body Core Temperature ◽  
Whole Body ◽  
Temperature Sensitive ◽  
Internal Core ◽  
Body Core

Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body’s ability to dissipate heat during exercise. These include the activation of the body’s sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as phenotypic factors such as age, sex, acclimation, fitness, and chronic diseases (e.g., diabetes). The influence of these factors extends into recovery such that marked impairments in thermoregulatory function occur, leading to prolonged and sustained elevations in body core temperature. Irrespective of the level of hyperthermia, there is a time-dependent suppression of the body’s physiological ability to dissipate heat. This delay in the restoration of postexercise thermoregulation has been associated with disturbances in cardiovascular function which manifest most commonly as postexercise hypotension. This review examines the current knowledge regarding the restoration of thermoregulation postexercise. In addition, the factors that are thought to accelerate or delay the return of body core temperature to resting levels are highlighted with a particular emphasis on strategies to manage heat stress in athletic and/or occupational settings.

Linking Energy Levels in the Circadian Core Body Temperature Cycle to Human Health and Well-Being

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Kaufui Vincent Wong
Keyword(s):  
Heat Transfer ◽  
Core Body Temperature ◽  
Energy Levels ◽  
Well Being ◽  
The Body ◽  
Body Core Temperature ◽  
Temperature Cycle ◽  
Body Core ◽  
Core Body ◽  
Health And Well Being

The body core temperature is a measure of the health and well-being of a person. This temperature seldom varies from the average of 37 °C (98.6 °F) and has been used to gage a person’s wellness at any time. The current work reviews the published health and medical works about this topic, focusing on the effects of hypothermia, especially with respect to neurological issues. The controversy still exists, and the jury is out. A heat transfer researcher’s insight foresees the possible results and calls for more research in the field. In addition, a perspective is provided for a couple of traditional “truths” about related topics that have been challenged in recent times.

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