Fluid ingestion is more effective in preventing hyperthermia in aerobically trained than untrained individuals during exercise in the heat

2013 ◽  
Vol 38 (1) ◽  
pp. 73-80 ◽  
Author(s):  
Ricardo Mora-Rodriguez ◽  
Nassim Hamouti ◽  
Juan Del Coso ◽  
Juan F. Ortega
Keyword(s):  
Heart Rate ◽  
Heat Production ◽  
Fluid Replacement ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Fluid Ingestion ◽  
Metabolic Heat ◽  
Heat Production Rate ◽  
Cardiovascular Strain ◽  
Aerobically Trained

It is unclear if fluid ingestion during exercise in the heat alleviates the thermoregulatory and cardiovascular strain similarly in aerobically trained and untrained individuals. It is also unknown at what exercise intensity the effects of rehydration are greater. Ten aerobically trained (T) and 10 healthy untrained (UT) subjects ([Formula: see text]O2peak, 60 ± 6 vs. 44 ± 3 mL O2·kg−1·min−1, respectively; P < 0.05) pedalled in a hot, dry environment (36 ± 1 °C; 25% ± 2% relative humidity; airflow, 2.5 m·s−1) at 40%, 60%, and 80% [Formula: see text]O2peak while ingesting fluids (Fluid). The results were compared with those from our previous study [Mora-Rodriguez et al., Eur. J. Appl. Physiol. 109(5): 973–981 (2010)] with no fluid ingestion (No Fluid). Subjects were not heat-acclimated. At 40% [Formula: see text]O2peak, Fluid reduced rectal temperature (TRE) in T and UT (0.31 ± 0.08 and 0.32 ± 0.07 °C; respectively). At 60% [Formula: see text]O2peak, Fluid reduced TRE in T more than in UT (0.30 ± 0.10 °C vs. 0.18 ± 0.10 °C; P < 0.05) but had no effect at 80% [Formula: see text]O2peak in any group. At similar relative intensity, heart rates (HR) were similar between groups. Fluid lowered heart rate (i.e., HR) similarly in the T and UT at 40% and 60% [Formula: see text]O2peak (11% and 6%, respectively; P < 0.05) but not at 80% [Formula: see text]O2peak (P > 0.05). At similar metabolic heat production (i.e., 60% for T vs. 80% [Formula: see text]O2peak for UT), Fluid lowered TRE only in the T individuals (P < 0.05). In summary, rehydration during low- and moderate-intensity exercise reduces TRE and HR more than during high-intensity exercise (80% [Formula: see text]O2peak) in T and UT subjects. Fluid replacement is more effective on preventing the rise in TRE in T than in UT individuals during moderate-intensity exercise (60% [Formula: see text]O2peak), as well as when exercising at a similar heat production rate.

Acclimatization of calves to a hot dry environment

1959 ◽  
Vol 52 (3) ◽  
pp. 296-304 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Rectal Temperature ◽  
Heat Production ◽  
Metabolic Heat Production ◽  
Metabolic Heat ◽  
Physiological Reactions

1. Three calves were individually exposed in a climatic room to an environment of 45° C. dry-bulb and 28° C. wet-bulb temperature for 21 successive days up to 5 hr. each day.2. In the 21-day period, mostly during the first half of it, the following changes in the physiological reactions of the animals were observed: progressive reductions in rectal temperature, in heart rate and in respiratory rate with a change of breathing from a laboured to a less laboured type.3. It was suggested that a decrease in metabolic heat production might play a part in the observed acclimatization.

The accuracy of fitness watches for the measurement of heart rate and energy expenditure during moderate intensity exercise

2021 ◽  
Vol 61 (2) ◽  
Author(s):  
Andrew R. JAGIM ◽  
Nicolas KOCH-GALLUP ◽  
Clayton L. CAMIC ◽  
Leah KROENING ◽  
Charles NOLTE ◽  
...  
Keyword(s):  
Heart Rate ◽  
Energy Expenditure ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

scholarly journals Psychrometric limits and critical evaporative coefficients for exercising older women

2020 ◽  
Vol 129 (2) ◽  
pp. 263-271 ◽  
Author(s):  
W. Larry Kenney
Keyword(s):  
Older Women ◽  
Heat Balance ◽  
Moderate Intensity ◽  
Evidence Based ◽  
Moderate Intensity Exercise ◽  
Metabolic Heat ◽  
Safety Interventions ◽  
Environmental Limits ◽  
Hot Environments ◽  
Heat Events

This study is the first to describe, graphically and quantitatively, critical environmental limits for women between the ages of 62 and 80 yr based on the biophysics of heat exchange. These psychrometric limit lines define combinations of ambient temperature and humidity above which human heat balance cannot be maintained for a given metabolic heat production. These limits, and associated critical evaporative coefficients ( Ke′), can be used to model low- to moderate-intensity exercise responses in hot environments and have directly translatable data that can be used for evidence-based policy decisions, to prepare for impending heat events, and for implementation of other safety interventions.

Eight weeks of moderate-intensity exercise training increases heart rate variability in sedentary postmenopausal women

2004 ◽  
Vol 147 (5) ◽  
pp. e8-e15 ◽  
Author(s):  
Radim Jurca ◽  
Timothy S Church ◽  
Gina M Morss ◽  
Alexander N Jordan ◽  
Conrad P Earnest
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Exercise Training ◽  
Postmenopausal Women ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise

Age alters regional distribution of blood flow during moderate-intensity exercise

1995 ◽  
Vol 79 (4) ◽  
pp. 1112-1119 ◽  
Author(s):  
W. L. Kenney ◽  
C. W. Ho
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Skin Blood Flow ◽  
Forearm Blood Flow ◽  
Regional Distribution ◽  
Splanchnic Blood Flow ◽  
Moderate Intensity ◽  
Plasma Norepinephrine ◽  
Moderate Intensity Exercise

During dynamic exercise in warm environments, requisite increases in skin and active muscle blood flows are supported by increasing cardiac output (Qc) and redistributing flow away from splanchnic and renal circulations. To examine the effect of age on these responses, six young (Y; 26 +/- 2 yr) and six older (O; 64 +/- 2 yr) men performed upright cycle exercise at 35 and 60% of peak O2 consumption (VO2peak) in 22 and 36 degrees C environments. To further isolate age, the two age groups were closely matched for VO2peak, weight, surface area, and body composition. Measurements included heart rate, Qc (CO2 rebreathing), skin blood flow (from increases in forearm blood flow (venous occlusion plethysmography), splanchnic blood flow (indocyanine green dilution), renal blood flow (p-amino-hippurate clearance), and plasma norepinephrine concentration. There were no significant age differences in Qc; however, in both environments the O group maintained Qc at a higher stroke volume and lower heart rate. At 60% VO2peak, forearm blood flow was significantly lower in the O subjects in each environment. Splanchnic blood flow fell (by 12–14% in both groups) at the lower intensity, then decreased to a greater extent at 60% VO2peak in Y than in O subjects (e.g., -45 +/- 2 vs. -33 +/- 3% for the hot environment, P < 0.01). Renal blood flow was lower at rest in the O group, remained relatively constant at 35% VO2peak, then decreased by 20–25% in both groups at 60% VO2peak. At 60% VO2peak, 27 and 37% more total blood flow was redistributed away from these two circulations in the Y than in the O group at 22 and 36 degrees, respectively. It was concluded that the greater increase in skin blood flow in Y subjects is partially supported by a greater redistribution of blood flow away from splanchnic and renal vascular beds.

scholarly journals Effect of short moderate intensity exercise bouts on cardiovascular function and maximal oxygen consumption in sedentary older adults

2020 ◽  
Vol 6 (1) ◽  
pp. e000672 ◽  
Author(s):  
Karani Magutah ◽  
Kihumbu Thairu ◽  
Nilesh Patel
Keyword(s):  
Blood Pressure ◽  
Older Adults ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Systolic Blood Pressure ◽  
Maximal Oxygen Consumption ◽  
Cardiovascular Function ◽  
Moderate Intensity ◽  
Group Differences ◽  
Moderate Intensity Exercise

AimTo investigate effect of <10 min moderate intensity exercise on cardiovascular function and maximal oxygen consumption (V˙ O2max) among sedentary adults.MethodsWe studied 53 sedentary urbanites aged ≥50 years, randomised into: (1) male (MS) and (2) female (FS) undertaking three short-duration exercise (5–10 min) daily, and (3) male (ML) and (4) female (FL) exercising 30–60 min 3–5 days weekly. Resting systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate and V˙ O2max were measured at baseline and 8 weekly for 24 weeks.ResultsAt baseline, 50% MS, 61.5% ML, 53.8% FS and 53.8% FL had SBP ≥120 mm Hg, and 14.3% MS, 53.8% ML, 23.1% FS and 38.5% FL had DBP ≥80 mm Hg. At 24 weeks, where SBP remained ≥120 mm Hg, values decreased from 147±19.2 to 132.3±9.6 mm Hg (50% of MS), from 144±12.3 to 128±7.0 mm Hg (23.1% of ML), from 143.1±9.6 to 128.0±7.0 mm Hg (53.8% of FS) and from 152.3±23.7 to 129±3.7 mm Hg (30.8% of FL). For DBP ≥80 mm Hg, MS and FS percentages maintained, but values decreased from 101±15.6 to 84.5±0.7 mm Hg (MS) and 99.0±3.6 to 87.7±4.9 mm Hg (FS). In ML and FL, percentage with DBP ≥80 mm Hg dropped to 15.4% (86.1±6.5 to 82.5±3.5 mm Hg) and (91.4±5.3 to 83.5±0.71 mm Hg). V˙ O2max increased from 26.1±4.4 to 32.0±6.2 for MS, from 25.8±5.1 to 28.8±5.4 for ML (group differences p=0.02), from 20.2±1.8 to 22.7±2.0 for FS and from 21.2±1.9 to 24.2±2.7 for FL (groups differences p=0.38).ConclusionAccumulated moderate intensity exercise bouts of <10 min confer similar-to-better cardiovascular and V˙ O2max improvements compared with current recommendations among sedentary adults.

Heart rate response to exercise and cardiorespiratory fitness of young women at high familial risk for hypertension: effects of interval vs continuous training

2011 ◽  
Vol 18 (6) ◽  
pp. 824-830 ◽  
Author(s):  
Emmanuel G Ciolac ◽  
Edimar A Bocchi ◽  
Julia MD Greve ◽  
Guilherme V Guimarães
Keyword(s):  
Heart Rate ◽  
Exercise Training ◽  
Cardiorespiratory Fitness ◽  
Familial Risk ◽  
Moderate Intensity ◽  
Hypertensive Disorder ◽  
Moderate Intensity Exercise ◽  
Continuous Training ◽  
Response To Exercise

Exercise training is an effective intervention for treating and preventing hypertension, but its effects on heart rate (HR) response to exercise and cardiorespiratory fitness (CRF) of non-hypertensive offspring of hypertensive parents (FH+) has not been studied. We compared the effects of three times per week equal-volume high-intensity aerobic interval (AIT) and continuous moderate-intensity exercise (CME) on HR response to exercise and CRF of FH+. Forty-four young FH+ women (25.0 ± 4.4 years) randomized to control (CON; n = 12), AIT (80–90% of VO2MAX; n = 16), or CME (50–60% of VO2MAX; n = 16) performed a graded exercise test (GXT) before and after 16 weeks of follow-up to evaluate HR response to exercise and several parameters of CRF. Resting, maximal, and reserve HR did not change after the follow-up in all groups. HR recovery (difference between HRMAX and HR at 1 minute of GXT recovery phase) improved only after AIT (11.8 ± 4.9 vs. 20.6 ± 5.8 bpm, p < 0.01). Both exercise programmes were effective for improving CRF parameters, but AIT was more effective than CME for improving oxygen consumption at the respiratory compensation point (VO2RCP; 22.1% vs. 8.8%, p = 0.008) and maximal effort (VO2MAX; 15.8% vs. 8.0%, p = 0.036), as well as tolerance time (TT) to reach anaerobic threshold (TTAT; 62.0 vs. 37.7, p = 0.048), TTRCP (49.3 vs. 32.9, p = 0.032), and TTMAX (38.9 vs. 29.2, p = 0.042). Exercise intensity was an important factor in improving HR recovery and CRF of FH+women. These findings may have important implications for designing exercise-training programmes for the prevention of an inherited hypertensive disorder.

Acclimatization of calves to a hot humid environment

1959 ◽  
Vol 52 (3) ◽  
pp. 305-312 ◽  
Author(s):  
W. Bianca
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Respiratory Rate ◽  
Skin Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Metabolic Heat ◽  
Hot Environment ◽  
Humid Environment ◽  
Physiological Reactions

1. Three calves were exposed in a climatic room to an environment of 40° C. dry-bulb and 38° C. wet-bulb temperature for up to 110 min. each day for 1-2 weeks.2. These exposures produced progressive changes in the physiological reactions of the animals to heat:(a) Rectal temperature and skin temperature (for a given time of exposure) declined. In consequence there was a marked increase in the tolerance time, i.e. in the time for which the animals could withstand the hot environment before reaching a rectal temperature of 42° C.(b) Respiratory rate rose earlier and assumed higher levels (for given levels of body temperature).(c) Heart rate decreased markedly.3. These changes are discussed in relation to heat loss and heat production and have been interpreted as reflecting chiefly a reduction in the metabolic heat production of the animals.

scholarly journals Preliminary Data on the Prophylaxis of Severe Forms of Covid-19 Through Exercise

2021 ◽  
Vol 66 (1) ◽  
pp. 79-84
Author(s):  
Bogdan-Alexandru Hagiu ◽  
Iulian Dumitru Turculeț ◽  
Iulian Marius Dumitru
Keyword(s):  
Heart Rate ◽  
Preliminary Data ◽  
Aerobic Training ◽  
The Elderly ◽  
Moderate Intensity ◽  
Intense Exercise ◽  
Moderate Intensity Exercise ◽  
Mature Adults ◽  
Determining Factor ◽  
At Home

"ABSTRACT. Independent studies suggest the possibility of prophylaxis of severe forms of COVID-19 through moderate-intensity exercise. There is the fear that intense exercise could increase the risk of the virus entering the cell, a determining factor being hypoxia. As a result, in this paper we aimed to assess the heart rate and oxygen saturation of the blood in the case of Kangoo Jumps and aerobic training at home. Kangoo Jumps workouts practiced in such a way as to avoid in principle the high intensity of the effort, do not produce transient hypoxia, not even in subjects whose heart rate indicated an intense effort. Preliminary data show that aerobics at home does not produce hypoxia in mature adults and the elderly, and heart rates do not exceed the limit of moderate intensity; however, additional studies are required for both categories of exercises under study."

scholarly journals The effect of moderate versus high intensity exercise on heart rate variability in sedentary office workers

2021 ◽  
Vol 16 (1) ◽  
pp. 16-23
Author(s):  
Vibha Gangwar ◽  
Manish Kumar Verma ◽  
Ritesh Singh Gangwar ◽  
Nitin Ashok John ◽  
Rajani Bala Jasrotia
Keyword(s):  
Heart Rate ◽  
Exercise Training ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Office Workers ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Group I ◽  
Before And After ◽  
Group Ii

Background: Sedentary behavior is one of the leading modifiable risk factors for cardiovascular disease and all-cause mortality. Physical exercise exerts beneficial physiological effects on cardiovascular fitness. Different grades of physical exercise have different effects on cardiovascular health. Objective: To compare the effect of moderate and high intensity exercise training on heart rate variability (HRV) in sedentary office workers. Methods: This study was conducted on 40 healthy sedentary volunteers aged between 20-40 years of both the genders. Participants were distributed into two groups of 20 subjects each. Subjects of group I and group II performed moderate intensity and high intensity exercise respectively on bicycle ergometer for 12 weeks. Their 5- minute ECG recording was done by three channel physiograph, and frequency domain indices of HRV and heart rate (HR) were analyzed and compared before and after exercise training. Their blood pressure was also recorded and compared before and after exercise training. Independent sample t-test and paired sample ttest were used for statistical analysis. Results: HF, systolic and diastolic blood pressure reduced significantly after exercise in group II (p=0.015, 0.005, and 0.015 respectively) while HR and LF/HF ratio reduced in both group I and group II (p=0.000 for HR, and 0.034, 0.001 for LF/HF). The decrease in HR was greater after high intensity exercise than moderate intensity exercise (p= 0.025). Conclusion: Parasympathetic activity improves after moderate and high intensity exercise but improvement is more after high intensity exercise training. Therefore, high intensity exercise training is more beneficial than moderate intensity exercise training. J Bngladesh Soc Physiol 2021;16(1): 16-23

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