Heat storage in horses during submaximal exercise before and after humid heat acclimation

2000 ◽  
Vol 89 (6) ◽  
pp. 2283-2293 ◽  
Author(s):  
Raymond J. Geor ◽  
Laura Jill McCutcheon ◽  
Gayle L. Ecker ◽  
Michael I. Lindinger
Keyword(s):  
Heat Stress ◽  
Heat Storage ◽  
Heat Acclimation ◽  
Exercise Duration ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Exercise Tests ◽  
Before And After ◽  
Uncompensable Heat Stress ◽  
Globe Temperature

The effect of humid heat acclimation on thermoregulatory responses to humid and dry exercise-heat stress was studied in six exercise-trained Thoroughbred horses. Horses were heat acclimated by performing moderate-intensity exercise for 21 days in heat and humidity (HH) [34.2–35.7°C; 84–86% relative humidity (RH); wet bulb globe temperature (WBGT) index ∼32°C]. Horses completed exercise tests at 50% of peak O2 uptake until a pulmonary arterial temperature (Tpa) of 41.5°C was attained in cool dry (CD) (20–21.5°C; 45–50% RH; WBGT ∼16°C), hot dry (HD 0) [32–34°C room temperature (RT); 45–55% RH; WBGT ∼25°C], and HH conditions (HH 0), and during the second hour of HH on days 3, 7, 14, and 21, and in HD on the 18th day (HD 18) of heat acclimation. The ratios of required evaporative capacity to maximal evaporative capacity of the environment (Ereq/Emax) for CD, HD, and HH were ∼1.2, 1.6, and 2.5, respectively. Preexercise Tpa and rectal temperature were ∼0.5°C lower ( P < 0.05) on days 7, 14, and 21 compared with day 0. With exercise in HH, there was no effect of heat acclimation on the rate of rise in Tpa (and therefore exercise duration) nor the rate of heat storage. In contrast, exercise duration was longer, rate of rise in Tpa was significantly slower, and rate of heat storage was decreased on HD 18 compared with HD 0. It was concluded that, during uncompensable heat stress in horses, heat acclimation provided modest heat strain advantages when Ereq/Emax was ∼1.6, but at higher Ereq/Emax no advantages were observed.

scholarly journals Exploring the Variability in Acute Glycemic Responses to Exercise in Type 2 Diabetes

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Tasuku Terada ◽  
Alanna Friesen ◽  
Baljot S. Chahal ◽  
Gordon J. Bell ◽  
Linda J. McCargar ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Exercise Duration ◽  
Moderate Intensity ◽  
Exercise Session ◽  
Moderate Intensity Exercise ◽  
Before And After ◽  
Capillary Glucose ◽  
High Intensity Interval ◽  
Exercise Induced

Aim. To explore the factors associated with exercise-induced acute capillary glucose (CapBG) changes in individuals with type 2 diabetes (T2D).Methods. Fifteen individuals with T2D were randomly assigned to energy-matched high intensity interval exercise (HI-IE) and moderate intensity continuous exercise (MI-CE) interventions and performed a designated exercise protocol 5 days per week for 12 weeks. The duration of exercise progressed from 30 to 60 minutes. CapBG was measured immediately before and after each exercise session. Timing of food and antihyperglycemic medication intake prior to exercise was recorded.Results. Overall, the mean CapBG was lowered by 1.9 mmol/L (P<0.001) with the change ranging from −8.9 to +2.7 mmol/L. Preexercise CapBG (44%;P<0.001), medication (5%;P<0.001), food intake (4%;P=0.043), exercise duration (5%;P<0.001), and exercise intensity (1%;P=0.007) were all associated with CapBG changes, explaining 59% of the variability.Conclusion. The greater reduction in CapBG seen in individuals with higher preexercise CapBG may suggest the importance of exercise in the population with elevated glycemia. Lower blood glucose can be achieved with moderate intensity exercise, but prolonging exercise duration and/or including brief bouts of intense exercise accentuate the reduction, which can further be magnified by performing exercise after meals and antihyperglycemic medication. This trial is registered with ClinicalTrial.govNCT01144078.

scholarly journals Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation

2016 ◽  
Vol 311 (6) ◽  
pp. H1520-H1529 ◽  
Author(s):  
Sinead T. J. McDonagh ◽  
Anni Vanhatalo ◽  
Jonathan Fulford ◽  
Lee J. Wylie ◽  
Stephen J. Bailey ◽  
...  
Keyword(s):  
Exercise Tolerance ◽  
Peak Power ◽  
Blood Donation ◽  
Hemoglobin Concentration ◽  
Moderate Intensity ◽  
Beetroot Juice ◽  
Moderate Intensity Exercise ◽  
Exercise Tests ◽  
Dietary Nitrate ◽  
Nitrate Supplementation

We tested the hypothesis that dietary nitrate (NO3−)-rich beetroot juice (BR) supplementation could partially offset deteriorations in O2transport and utilization and exercise tolerance after blood donation. Twenty-two healthy volunteers performed moderate-intensity and ramp incremental cycle exercise tests prior to and following withdrawal of ∼450 ml of whole blood. Before donation, all subjects consumed seven 70-ml shots of NO3−-depleted BR [placebo (PL)] in the 48 h preceding the exercise tests. During the 48 h after blood donation, subjects consumed seven shots of BR (each containing 6.2 mmol of NO3−, n = 11) or PL ( n = 11) before repeating the exercise tests. Hemoglobin concentration and hematocrit were reduced by ∼8–9% following blood donation ( P < 0.05), with no difference between the BR and PL groups. Steady-state O2uptake during moderate-intensity exercise was ∼4% lower after than before donation in the BR group ( P < 0.05) but was unchanged in the PL group. The ramp test peak power decreased from predonation (341 ± 70 and 331 ± 68 W in PL and BR, respectively) to postdonation (324 ± 69 and 322 ± 66 W in PL and BR, respectively) in both groups ( P < 0.05). However, the decrement in performance was significantly less in the BR than PL group (2.7% vs. 5.0%, P < 0.05). NO3−supplementation reduced the O2cost of moderate-intensity exercise and attenuated the decline in ramp incremental exercise performance following blood donation. These results have implications for improving functional capacity following blood loss.

Heat acclimation, aerobic fitness, and hydration effects on tolerance during uncompensable heat stress

1998 ◽  
Vol 84 (5) ◽  
pp. 1731-1739 ◽  
Author(s):  
Stephen S. Cheung ◽  
Tom M. McLellan
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Aerobic Fitness ◽  
Protective Clothing ◽  
Sweat Rate ◽  
Heat Acclimation ◽  
Short Term ◽  
Chemical Protective Clothing ◽  
Uncompensable Heat Stress ◽  
C 30

—The purpose of the present study was to determine the separate and combined effects of aerobic fitness, short-term heat acclimation, and hypohydration on tolerance during light exercise while wearing nuclear, biological, and chemical protective clothing in the heat (40°C, 30% relative humidity). Men who were moderately fit [(MF); <50 ml ⋅ kg−1 ⋅ min−1maximal O2 consumption; n = 7] and highly fit [(HF); >55 ml ⋅ kg−1 ⋅ min−1maximal O2 consumption; n = 8] were tested while they were euhydrated or hypohydrated by ∼2.5% of body mass through exercise and fluid restriction the day preceding the trials. Tests were conducted before and after 2 wk of daily heat acclimation (1-h treadmill exercise at 40°C, 30% relative humidity, while wearing the nuclear, biological, and chemical protective clothing). Heat acclimation increased sweat rate and decreased skin temperature and rectal temperature (Tre) in HF subjects but had no effect on tolerance time (TT). MF subjects increased sweat rate but did not alter heart rate, Tre, or TT. In both MF and HF groups, hypohydration significantly increased Tre and heart rate and decreased the respiratory exchange ratio and the TT regardless of acclimation state. Overall, the rate of rise of skin temperature was less, while ΔTre, the rate of rise of Tre, and the TT were greater in HF than in MF subjects. It was concluded that exercise-heat tolerance in this uncompensable heat-stress environment is not influenced by short-term heat acclimation but is significantly improved by long-term aerobic fitness.

scholarly journals KADAR KLORIDA SERUM PADA LATIHAN FISIK INTENSITAS SEDANG MAHASISWA FAKULTAS KEDOKTERAN UNIVERSITAS SAM RATULANGI

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Roy Johannes ◽  
Diana S. Purwanto ◽  
Stefana H. M. Kaligis
Keyword(s):  
Sampling Method ◽  
Extracellular Fluid ◽  
T Test ◽  
Moderate Intensity ◽  
Electrolyte Balance ◽  
Moderate Intensity Exercise ◽  
Paired Sample ◽  
Purposive Sampling ◽  
Serum Chloride ◽  
Before And After

Abstract: Chloride as the major anion in the extracellular fluid plays a role in maintaining fluid and electrolyte balance. One of the factors that influence the levels of serum chloride is sweating during physical exercise. This study aimed to determine  the differenceof serum chloride levels before and after moderate intensity exercise in the students of Faculty of Medicine year 2010 Sam Ratulangi University. This is a pre-exsperimental research with pretest and posttest design with 30 students as samples. The samples were chosen using purposive sampling method and the results were analyzed using paired-sample t-test. The results showed the average levels of serum chloride before and after moderate intensity exercise are 106,10 mEq/L and 107,37 mEq/L while paired-sample t-test significance value (p) is 0,000. From the results can be concluded that there is a significant differences in serum chloride levels before and after moderate intensity exercise in the students of Faculty of Medicine year 2010 Sam Ratulangi University. Keyword: serum chloride, moderate intensity exercise, student of Faculty of Medicine Sam Ratulangi University   Abstrak: Klorida sebagai anion utama dalam cairan ekstraselular berperan dalammemelihara keseimbangan cairan dan elektrolit. Salah satu faktor yang mempengaruhi kadar klorida serum yaitu keluarnya keringat saat melakukan latihan fisik. Tujuan penelitian ini untuk mengetahui perbedaan kadar klorida serum sebelum dan sesudah latihan fisik intensitas sedang pada mahasiswa Fakultas Kedokteran Universitas Sam Ratulangi angkatan 2010. Penelitian ini merupakan penelitian pre-eksperimental dengan pretest-posttest design, dengan jumlah sampel 30 orang. Sampel penelitian dipilih dengan purposive sampling dan dianalisis dengan uji t berpasangan. Hasil yang diperoleh menunjukkan bahwa rata-rata kadar klorida serum sebelum melakukan latihan fisik intensitas sedang adalah 106,10mEq/L, sedangkan rata-rata kadar klorida serum sesudah melakukan latihan fisik intensitas sedang adalah 107,37 mEq/L. Nilai signifikansi uji t berpasangan pada penelitian ini adalah p=0,000. Dari penelitian ini dapat disimpulkan bahwa terdapat perbedaan signifikan kadar klorida serum sebelum dan sesudah latihan fisik intensitas sedang pada mahasiswa Fakultas Kedokteran Universitas Sam Ratulangi Angkatan 2010. Kata kunci: klorida serum, latihan fisik intensitas sedang, mahasiswa Fakultas Kedokteran Universitas Sam Ratulangi

scholarly journals Hippocampal Blood Flow Is Increased After 20 min of Moderate-Intensity Exercise

2019 ◽  
Vol 30 (2) ◽  
pp. 525-533 ◽  
Author(s):  
J J Steventon ◽  
C Foster ◽  
H Furby ◽  
D Helme ◽  
R G Wise ◽  
...  
Keyword(s):  
Blood Flow ◽  
Temporal Dynamics ◽  
Therapeutic Potential ◽  
Cerebrovascular Reactivity ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Exercise Interventions ◽  
Before And After ◽  
Exercise Induced

Abstract Long-term exercise interventions have been shown to be a potent trigger for both neurogenesis and vascular plasticity. However, little is known about the underlying temporal dynamics and specifically when exercise-induced vascular adaptations first occur, which is vital for therapeutic applications. In this study, we investigated whether a single session of moderate-intensity exercise was sufficient to induce changes in the cerebral vasculature. We employed arterial spin labeling magnetic resonance imaging to measure global and regional cerebral blood flow (CBF) before and after 20 min of cycling. The blood vessels’ ability to dilate, measured by cerebrovascular reactivity (CVR) to CO2 inhalation, was measured at baseline and 25-min postexercise. Our data showed that CBF was selectively increased by 10–12% in the hippocampus 15, 40, and 60 min after exercise cessation, whereas CVR to CO2 was unchanged in all regions. The absence of a corresponding change in hippocampal CVR suggests that the immediate and transient hippocampal adaptations observed after exercise are not driven by a mechanical vascular change and more likely represents an adaptive metabolic change, providing a framework for exploring the therapeutic potential of exercise-induced plasticity (neural, vascular, or both) in clinical and aged populations.

Heat acclimation and hypohydration: involvement of central angiotensin II receptors in thermoregulation

1999 ◽  
Vol 277 (1) ◽  
pp. R47-R55 ◽  
Author(s):  
Michal Horowitz ◽  
Pavel Kaspler ◽  
Eckhart Simon ◽  
Ruediger Gerstberger
Keyword(s):  
Blood Flow ◽  
Heat Stress ◽  
Angiotensin Ii ◽  
Heat Acclimation ◽  
Angiotensin Ii Receptors ◽  
Ang Ii ◽  
Biphasic Response ◽  
Temperature Thresholds ◽  
Before And After ◽  
Tail Blood

This investigation attempted to confirm the involvement of central ANG II-ergic signals in thermoregulation. Experiments were conducted on rats undergoing short (STHA)- and long (LTHA)-term heat acclimation, with and without superimposed hypohydration. Vasodilatation (VTsh) and salivation (STsh) temperature thresholds, tail blood flow, and heat endurance were measured in conscious rats during heat stress (40°C) before and after losartan (Los), an ANG II AT1-selective receptor antagonist, administration either to the lateral ventricle or intravenously. Heat acclimation alone resulted in decreased VTsh. STsh decreased during STHA and resumed the preacclimation value, together with markedly increased heat endurance on LTHA. Hypohydration did not affect this biphasic response, although STsh was elevated in all groups. The enhanced heat endurance attained by LTHA was blunted. Neither Los treatment affected the nonacclimated rats. In the heat-acclimated, euhydrated rats, intracerebroventricular Los resulted in decreased VTsh, whereas intravenous Los resulted in elevated STsh. Both intracerebroventricular and intravenous Los led to markedly enhanced heat endurance of the LTHA hypohydrated rats. It is concluded that the LTHA group showed a loss of the benefits acquired by acclimation on hypohydration, whereas the STHA rats, which show an accelerated autonomic excitability in that phase, gained some benefit. It is suggested that ANG II modulates thermoregulation in conditions of chronic adjustments. Central ANG II signals may lead to VTsh upshift, whereas circumventricular structures, activated via circulating ANG II, decrease STsh. On hypohydration these responses seem to be desensitized.

Affect and Self-Efficacy Responses During Moderate-Intensity Exercise Among Low-Active Women: The Effect of Cognitive Appraisal

2010 ◽  
Vol 32 (2) ◽  
pp. 154-175 ◽  
Author(s):  
Amy S. Welch ◽  
Angie Hulley ◽  
Mark Beauchamp
Keyword(s):  
Self Efficacy ◽  
Acute Exercise ◽  
Cognitive Appraisal ◽  
Ventilatory Threshold ◽  
Rebound Effect ◽  
Exercise Program ◽  
Exercise Duration ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Ergometer Exercise

To investigate the relationship between cognitive and affective responses during acute exercise, 24 low-active females completed two 30-min bouts of cycle ergometer exercise at 90% of the ventilatory threshold. In one condition participants had full knowledge of the exercise duration (KD); in the other, exercise duration was unknown (UD). Affect and self-efficacy were measured before and every 3 min during exercise, and affect was also measured postexercise. Affect declined throughout the first half of both conditions, and continued its decline until the end of the UD condition, when a rebound effect was observed. Self-efficacy during exercise displayed a similar pattern. Hierarchical regression analyses demonstrated that during-exercise self-efficacy was a stronger predictor of during-exercise affect than preexercise self-efficacy, and that this relationship was strongest at the end of exercise when duration was unknown. These results indicate that repetitive cognitive appraisal of self and the task could impact the exercise experiences of low-active women during the adoption phase of an exercise program.

scholarly journals Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure

2016 ◽  
Vol 311 (6) ◽  
pp. H1530-H1539 ◽  
Author(s):  
Victor M. Niemeijer ◽  
Ruud F. Spee ◽  
Thijs Schoots ◽  
Pieter F. F. Wijn ◽  
Hareld M. C. Kemps
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Chronic Heart Failure ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Oxygen Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Exercise Tests ◽  
Mean Response Time

The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.

Exercise intensity dependent relevance of protective textile properties for human thermo-physiology

2016 ◽  
Vol 87 (12) ◽  
pp. 1425-1434 ◽  
Author(s):  
Piero Fontana ◽  
Fabio Saiani ◽  
Marc Grütter ◽  
Jean-Philippe Croset ◽  
André Capt ◽  
...  
Keyword(s):  
Functional Properties ◽  
Exercise Intensity ◽  
Human Subject ◽  
Core Body Temperature ◽  
Physiological Responses ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Exercise Tests ◽  
Physiological Relevance ◽  
Low Intensity Exercise

During firefighting, thermoregulation is challenged due to a combination of harsh environmental conditions, high metabolic rates and personal protective clothing (PPC). Consequently, investigations of thermoregulation in firefighters should not only consider climate and exercise intensity, but technical properties of textiles too. Therefore, laboratory textile performance simulations may provide additional insights into textile-dependent thermoregulatory responses to exercise. In order to investigate the thermo-physiological relevance of textile properties and to test how different garments affect thermoregulation at different exercise intensities, we analyzed the results of a standard laboratory test and human subject trials by relating functional properties of textiles to thermo-physiological responses. Ten professional, healthy, male firefighters (age: 43 ± 6 y, weight: 84.3 ± 10.3kg, height: 1.79 ± 0.05m) performed low and moderate intensity exercise wearing garments previously evaluated with a sweating torso system to characterize thermal and evaporative properties. Functional properties of PPC and the control garment differed markedly. Consequently, skin temperature was higher using PPC at both exercise intensities (low: 36.27 ± 0.32 versus 36.75 ± 0.15℃, P < 0.05; moderate: 36.53 ± 0.34 versus 37.18 ± 0.23℃, P < 0.001), while core body temperature was only higher for PPC at moderate (37.54 ± 0.24 versus 37.83 ± 0.27℃, P < 0.05), but not low-intensity exercise (37.26 ± 0.21 versus 37.21 ± 0.19, P = 0.685). Differences in thermal and evaporative properties between textiles are reflected in thermo-physiological responses during human subject trials. However, an appropriate exercise intensity has to be chosen in order to challenge textile performance during exercise tests.

scholarly journals Effect of Resistance Training with Different Intensities on Airway Resistance Indices and Fatigue and Muscular Endurance in Women with Multiple Sclerosis (MS)

Thrita ◽  
2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Ameneh Balavi ◽  
Mohsen Ghanbarzade
Keyword(s):  
Multiple Sclerosis ◽  
Resistance Training ◽  
Airway Resistance ◽  
Exercise Program ◽  
Moderate Intensity ◽  
Control Group ◽  
Moderate Intensity Exercise ◽  
Lack Of Information ◽  
Before And After ◽  
Training Exercises

Background: Airways resistance and broncho-spasm due to exercise are very common. Factors such as exercise, temperature, humidity, air pollution, and disease affect this complication. This study was performed due to the increase in physical disability of muscle weakness in patients with MS and the lack of information on the effect of different strength training exercises on air resistance. Objectives: The current study aimed to investigate the effect of resistance training with different intensities on airway resistance indices of women with MS. Methods: Thirty six women with Multiple sclerosis who had a disability criterion ranged from 1 to 4 (based on Krutzke’s disability scale) were sampled using the targeted and purposive sampling methods. They were selected based on the initial health conditions and then were randomly assigned to each of the three groups (each consisting of 12 participants). The first group received resistance training for 12 weeks, three sessions a week with intensity 60% 1RM, and the second group received resistance training for 12 weeks, three sessions a week with intensity 80% 1RM. Those in the control group didn’t have an exercise program. Results: Airway resistance indices were measured both before and after 12 weeks of resistance training, airway resistance indices in both groups was significantly decreased, and these changes were significant in both experimental groups as compared to the control group. Conclusions: According to the findings, in addition to improving balance, fatigue, and muscle endurance, high-intensity resistance training had similar effects to moderate-intensity exercise on pulmonary function indices in women with MS.

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