Effect of a precooling maneuver on body temperature and exercise performance

1981 ◽  
Vol 50 (4) ◽  
pp. 772-778 ◽  
Author(s):  
V. Schmidt ◽  
K. Bruck
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Peak Oxygen Uptake ◽  
Work Rate ◽  
Time To Exhaustion ◽  
Total Work ◽  
Mean Body Temperature ◽  
Deep Body Temperature ◽  
Sweat Secretion ◽  
Maximum Work

Twelve subjects exercised to exhaustion at an ambient temperature of 18 degrees C on a bicycle ergometer with the load being stepwise increased. On one day, exercise was preceded by a precooling maneuver. In the precooling tests, deep body temperature attained values of about 1 degree C lower than in the control tests. There was no indication of metabolic cold defense reactions being evoked throughout the exercise period. In the precooling tests, heart rate was significantly lower than in the controls, but the mean maximum work rate, peak oxygen uptake (VO2), time to exhaustion, and total work were not reduced, i.e., work rate and VO2 were increased for a given heart rate. In the three subjects with the lowest maximum work rates, total work and exhaustion time and, in two cases, maximum work rate were increased after precooling. The onset of sweating occurred at higher work rates but at lower core, mean skin, and mean body temperature after precooling. However, the accumulated sweat secretion was considerably smaller after precooling, indicating less thermoregulatory effort.

IMPAIRMENT OF SWEAT SECRETION IN MALNOURISHED INFANTS

PEDIATRICS ◽  
1954 ◽  
Vol 14 (6) ◽  
pp. 659-662
Author(s):  
E. KAHN ◽  
M. D. RAND ◽  
A. R. P. WALKER
Keyword(s):  
Heat Stress ◽  
Body Temperature ◽  
Close Correlation ◽  
Peripheral Circulation ◽  
Sweat Glands ◽  
Severe Malnutrition ◽  
Mean Body Temperature ◽  
Sweat Secretion ◽  
The Mean

Severely malnourished African infants are often feverish during hot summer weather. To elucidate the cause of this phenomenon, malnourished infants and controls were studied under standard conditions of heat stress with regard to sweat secretion and rise of body temperature. There was a marked impairment in the function of the sweat glands in the malnourished infants and the mean body temperature rose higher than that of the controls. The derangement of the sweat secretion was not related to the extent of the nutritional oedema. There was no close correlation between impairment of sweat secretion and rise in body temperature. The possible reasons for these observations are discussed. It is suggested that dysfunction of the sweat glands in severe malnutrition is caused by a poor peripheral circulation.

scholarly journals Mixing induces long-term hyperthermia in growing pigs

1999 ◽  
Vol 69 (3) ◽  
pp. 601-605 ◽  
Author(s):  
I. C. de Jong ◽  
E. Lambooij ◽  
S. M. Korte ◽  
H. J. Blokhuis ◽  
J. M. Koolhaas
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Growing Pigs ◽  
Activity Level ◽  
Long Term Effects ◽  
Deep Body Temperature ◽  
Sensitive Parameter ◽  
Effects Of Stress ◽  
Deep Body

AbstractThe purpose of this experiment was to determine whether body temperature is a sensitive parameter to measure long-term effects of stress in pigs. Mixing of unacquainted pigs is a severe stressor that has detrimental effects on health, production and welfare. We measured deep body temperature after mixing growing pigs. Five pigs of 15 weeks of age, each individually housed with a companion pig, were mixed with two unacquainted congeners. Deep body temperature, heart rate and activity were recorded by radiotelemetry 9 days prior to until 8 days after mixing. These parameters were also recorded in five control pigs (individually housed with a companion pig) during the same time span. Behaviour during the light period was recorded on videotape on the day of mixing and on three subsequent days. Mixing induced a significant rise in body temperature that lasted for 8 h after mixing. Although heart rate and general activity level did not significantly differ between mixed and control pigs, mixing significantly increased the frequency of fighting and reduced the frequency of eating. In conclusion, the present experiment shows that mixing induces a long-lasting hyperthermia in pigs. Thus, deep body temperature may be used as a sensitive parameter to measure long-term effects of stress in pigs.

The Efficacy of SPORTTM as a Dietary Supplement on Performance and Recovery in Trained Athletes

2000 ◽  
Vol 25 (1) ◽  
pp. 55-67 ◽  
Author(s):  
Brian W. Timmons ◽  
Ian J. Newhouse ◽  
Robert E. Thayer ◽  
Jim E. McAuliffe ◽  
Steve McIllwaine
Keyword(s):  
Heart Rate ◽  
Blood Lactate ◽  
Dietary Supplement ◽  
Exercise Bout ◽  
Peak Oxygen Uptake ◽  
Time To Exhaustion ◽  
Double Blind ◽  
Beneficial Effects ◽  
Key Words Blood Lactate ◽  
Time Periods

This study investigated the efficacy of SPORTTM (a popular dietary supplement) in improving performance and assisting recovery in 9 trained athletes. In a double-blind, crossover experiment, subjects ran at workloads of 60 and 80% of peak oxygen uptake [Formula: see text] for 5 min each with 5 min recovery after each bout and at 100% [Formula: see text] until exhaustion. Two capsules of either SPORTTM or a gelatin placebo were administered 1 hr prior to exercise and immediately after each workload. Heart rate (HR) and blood lactate (BLa) were measured at 1 hr prior to exercise, immediately after the 100% exercise bout and at 5, 10, 20, and 45 min during recovery. No significant differences between treatments on HR and BLa measures at any of the 6 time periods, or on subjects' time to exhaustion were found. Under the conditions of this experimental design, SPORTTM had no beneficial effects on performance or recovery in trained athletes. Key Words: blood lactate, dioscorea, heart rate, ergogenic aid, time to exhaustion

scholarly journals The association between body temperature and electrocardiographic parameters in normothermic healthy volunteers

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
G.J Hassing ◽  
B Fienieg ◽  
H.E.C Van Der Wall ◽  
G.J.P Van Westen ◽  
M.J.B Kemme ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Healthy Volunteers ◽  
Qt Interval ◽  
Drug Induced ◽  
Mean Body Temperature ◽  
Corrected Qt Interval ◽  
Healthy Humans ◽  
Surface Ecg ◽  
Qrs Duration

Abstract Introduction Previous studies have observed that hypo- and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including the corrected QT interval. Preclinical studies have shown that drugs that exert an effect on body temperature also exert an effect on the corrected QT interval. Therefore, increased characterization in healthy humans of the association between the corrected QT interval and body temperature within the normal body temperature range aids in understanding the mechanism behind drug induced corrected QT interval effects. The objective of this analysis was to evaluate the association between body temperature and electrocardiographical parameters in normothermic healthy volunteers. Methods Data from 3023 volunteers collected at our center were analyzed. Only subjects considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5–37.5 °C) and in sinus rhythm, were included in the analysis. Subjects were divided into body temperature quartiles for analysis and a linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable. Results Mean age was 33.8±17.5 years and mean body temperature was 36.6±0.4 °C. Body temperature was independently associated with age (standardized coefficient (SC)=−0.252, P<0.001), gender (SC=+0.208, P<0.001), heart rate (SC=+0.230, P<0.001), J-point elevation in lead V4 (SC=−0.118, P<0.001), and Fridericia corrected QT interval (SC=−0.061, P=0.002). Atrial and AV nodal parameters were not independently associated with body temperature. The effects of temperature on the surface ECG are displayed in figure 1. QT subinterval analysis revealed that only QRS duration (SC=−0.121, P<0.001) was independently associated with body temperature. Conclusion Body temperature in normothermic healthy volunteers was associated with heart rate, J-point amplitude in lead V4 and ventricular conductivity, primarily through a prolongation of the QRS duration. In contrast, atrial and AV nodal ECG parameters were not independently associated with body temperature. Funding Acknowledgement Type of funding source: None

Thermal adjustments of steers (Bos taurus) to abrupt changes in environmental temperature

1983 ◽  
Vol 100 (2) ◽  
pp. 305-314 ◽  
Author(s):  
J. A. McLean ◽  
A. J. Downie ◽  
C. D. R. Jones ◽  
D. P. Stombaugh ◽  
C. A. Glasbey
Keyword(s):  
Body Temperature ◽  
Indirect Calorimetry ◽  
Environmental Temperature ◽  
Heat Storage ◽  
Bos Taurus ◽  
Mean Body Temperature ◽  
Deep Body Temperature ◽  
Abrupt Changes ◽  
Deep Body ◽  
Body Heat

SUMMARYBody heat storage changes of cattle were measured by means of simultaneous direct and indirect calorimetry and by thermometry in an environment that alternated in temperature between 12 and 25 °C. When the calorimeter temperature was increased deep body temperature (Tc) increased by approximately 0–5 °C, mean surface temperature (Ts) by 3 °C and mean body temperature (determined from calorimetry, Tb) by 1 °C, but these increases were not fully sustained during the next 24 h. Changes in the three temperatures were related by the equation: δTb = αδTc+(1-α) δTs where a was found to be 0·89±0·027 (S.E.).

Muscle IMP accumulation during fatiguing submaximal exercise in endurance trained and untrained men

1999 ◽  
Vol 277 (1) ◽  
pp. R295-R300 ◽  
Author(s):  
Jacinta Baldwin ◽  
Rodney J. Snow ◽  
Michael F. Carey ◽  
Mark A. Febbraio
Keyword(s):  
Oxygen Uptake ◽  
Glycogen Content ◽  
Supply And Demand ◽  
Muscle Metabolism ◽  
Peak Oxygen Uptake ◽  
Submaximal Exercise ◽  
Work Rate ◽  
Time To Exhaustion ◽  
Training Status ◽  
Atp Supply

To examine the effect of training status on muscle metabolism during exercise, seven endurance-trained [peak oxygen uptake (V˙o2 peak) = 65.8 ± 2.4 ml ⋅ kg−1⋅ min−1] and six untrained (V˙o2 peak= 46.2 ± 1.9 ml ⋅ kg−1⋅ min−1) men cycled to fatigue at a work rate calculated to require 70%V˙o2 peak. Time to exhaustion was 36% longer ( P < 0.01) in trained (TR) compared with untrained (UT) men (148 ± 11 vs. 95 ± 8 min). Although intramuscular glycogen content was reduced ( P < 0.05) in both TR and UT at fatigue, IMP, a marker of a mismatch between ATP supply and demand, was only elevated ( P < 0.01) in UT muscle at fatigue and was approximately fourfold higher at this point in UT compared with TR. These data demonstrate that fatiguing submaximal exercise was associated with a similar low level of intramuscular glycogen in both TR and UT men, but a mismatch between ATP supply and demand only occurred in UT individuals.

scholarly journals Maximal oxygen uptake is not limited by a central nervous system governor

2007 ◽  
Vol 102 (2) ◽  
pp. 781-786 ◽  
Author(s):  
T. Brink-Elfegoun ◽  
L. Kaijser ◽  
T. Gustafsson ◽  
B. Ekblom
Keyword(s):  
Central Nervous System ◽  
Heart Rate ◽  
Nervous System ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Work Rate ◽  
Rate Pressure Product ◽  
Limiting Factor ◽  
Time To Exhaustion ◽  
The Central Nervous System

We tested the hypothesis that the work of the heart was not a limiting factor in the attainment of maximal oxygen uptake (V̇o2 max). We measured cardiac output (Q̇) and blood pressures (BP) during exercise at two different rates of maximal work to estimate the work of the heart through calculation of the rate-pressure product, as a part of the ongoing discussion regarding factors limiting V̇o2 max. Eight well-trained men (age 24.4 ± 2.8 yr, weight 81.3 ± 7.8 kg, and V̇o2 max 59.1 ± 2.0 ml·min−1·kg−1) performed two maximal combined arm and leg exercises, differing 10% in watts, with average duration of time to exhaustion of 4 min 50 s and 3 min 40 s, respectively. There were no differences between work rates in measured V̇o2 max, maximal Q̇, and peak heart rate between work rates (0.02 l/min, 0.3 l/min, and 0.8 beats/min, respectively), but the systolic, diastolic, and calculated mean BP were significantly higher (19, 5, and 10 mmHg, respectively) in the higher than in the lower maximal work rate. The products of heart rate times systolic or mean BP and Q̇ times systolic or mean BP were significantly higher (3,715, 1,780, 569, and 1,780, respectively) during the higher than the lower work rate. Differences in these four products indicate a higher mechanical work of the heart on higher than lower maximal work rate. Therefore, this study does not support the theory, which states that the work of the heart, and consequently V̇o2 max, during maximal exercise is hindered by a command from the central nervous system aiming at protecting the heart from being ischemic.

scholarly journals Influence of body temperature on the development of fatigue during prolonged exercise in the heat

1999 ◽  
Vol 86 (3) ◽  
pp. 1032-1039 ◽  
Author(s):  
José González-Alonso ◽  
Christina Teller ◽  
Signe L. Andersen ◽  
Frank B. Jensen ◽  
Tino Hyldig ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Skin Temperature ◽  
Prolonged Exercise ◽  
Heat Storage ◽  
Time To Exhaustion ◽  
Muscle Temperature ◽  
Rate Of Increase ◽  
Ergometer Exercise ◽  
Hot Environments

We investigated whether fatigue during prolonged exercise in uncompensable hot environments occurred at the same critical level of hyperthermia when the initial value and the rate of increase in body temperature are altered. To examine the effect of initial body temperature [esophageal temperature (Tes) = 35.9 ± 0.2, 37.4 ± 0.1, or 38.2 ± 0.1 (SE) °C induced by 30 min of water immersion], seven cyclists (maximal O2 uptake = 5.1 ± 0.1 l/min) performed three randomly assigned bouts of cycle ergometer exercise (60% maximal O2 uptake) in the heat (40°C) until volitional exhaustion. To determine the influence of rate of heat storage (0.10 vs. 0.05°C/min induced by a water-perfused jacket), four cyclists performed two additional exercise bouts, starting with Tes of 37.0°C. Despite different initial temperatures, all subjects fatigued at an identical level of hyperthermia (Tes = 40.1–40.2°C, muscle temperature = 40.7–40.9°C, skin temperature = 37.0–37.2°C) and cardiovascular strain (heart rate = 196–198 beats/min, cardiac output = 19.9–20.8 l/min). Time to exhaustion was inversely related to the initial body temperature: 63 ± 3, 46 ± 3, and 28 ± 2 min with initial Tes of ∼36, 37, and 38°C, respectively (all P < 0.05). Similarly, with different rates of heat storage, all subjects reached exhaustion at similar Tes and muscle temperature (40.1–40.3 and 40.7–40.9°C, respectively), but with significantly different skin temperature (38.4 ± 0.4 vs. 35.6 ± 0.2°C during high vs. low rate of heat storage, respectively, P < 0.05). Time to exhaustion was significantly shorter at the high than at the lower rate of heat storage (31 ± 4 vs. 56 ± 11 min, respectively, P < 0.05). Increases in heart rate and reductions in stroke volume paralleled the rise in core temperature (36–40°C), with skin blood flow plateauing at Tes of ∼38°C. These results demonstrate that high internal body temperature per se causes fatigue in trained subjects during prolonged exercise in uncompensable hot environments. Furthermore, time to exhaustion in hot environments is inversely related to the initial temperature and directly related to the rate of heat storage.

Sign in / Sign up

Export Citation Format

Share Document