The utility of heart rate and minute ventilation as predictors of whole-body metabolic rate during occupational simulations involving load carriage

Ergonomics ◽  
2015 ◽  
Vol 58 (10) ◽  
pp. 1671-1681 ◽  
Author(s):  
Sean R. Notley ◽  
Gregory E. Peoples ◽  
Nigel A.S. Taylor
Keyword(s):  
Heart Rate ◽  
Metabolic Rate ◽  
Minute Ventilation ◽  
Load Carriage ◽  
Whole Body

scholarly journals Effects of a Wearable Carriage Aid on Whole-Body Physiological Measures and Balance

2020 ◽  
Vol 10 (22) ◽  
pp. 8076
Author(s):  
Saad A. Alabdulkarim ◽  
Abdulsalam M. Farhan ◽  
Mohamed Z. Ramadan
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Minute Ventilation ◽  
Aid Effectiveness ◽  
Whole Body ◽  
Physiological Measures ◽  
Future Studies ◽  
Lower Back ◽  
The Impact ◽  
Load Mass

Carriage tasks are common and can lead to shoulder and lower back injuries. Wearable carriage aids have shown mixed effects on local physical demand measures. This study examined the impact of a wearable carriage aid on whole-body physiological measures (normalized oxygen consumption, minute ventilation, respiratory rate, and heart rate) to obtain a more comprehensive assessment regarding aid effectiveness. Additionally, this study investigated the effect of wearing the device on perceived balance. The potential moderating effect of carried load mass was considered. The examination was conducted while walking on a treadmill at a constant speed (2 km/h) for 5 min and was completed by 16 participants. Wearing the device reduced normalized oxygen consumption (~14%), minute ventilation (~7%), and heart rate (~3%), while substantially improving perceived balance (~61%). These effects were consistent across examined carried load levels. Although this study highlighted the potential for the developed aid, future studies are required for more diverse and realistic testing conditions.

scholarly journals Tyrosine kinase inhibitors modulate the ventilatory response to hypoxia in the conscious rat

1999 ◽  
Vol 87 (1) ◽  
pp. 363-369 ◽  
Author(s):  
Marc A. Czapla ◽  
Narong Simakajornboon ◽  
Gregory A. Holt ◽  
David Gozal
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Brain Stem ◽  
Tyrosine Phosphorylation ◽  
Minute Ventilation ◽  
Whole Body ◽  
Control Mechanisms ◽  
Conscious Rat ◽  
Adult Rats

Tyrosine kinases (TKs) exert multiple regulatory roles in neuronal activity and synaptic plasticity and could be involved in modulation of cardiovascular and respiratory control mechanisms within the dorsocaudal brain stem. To study this issue, the cardioventilatory responses to 1-μl microinjection within the dorsocaudal brain stem of either vehicle (Veh), the inactive TK inhibitor analog tyrphostin A1 (A1; 1 mM), or the active TK inhibitors genistein (Gen; 10 mM) and tyrphostin A25 (A25; 1 mM) were assessed by whole body plethysmography in unrestrained Sprague-Dawley adult rats. No changes in minute ventilation, heart rate, or mean arterial pressure occurred with Veh, A1, Gen, or A25 during room air breathing ( P not significant). However, Gen and A25 attenuated the peak hypoxic ventilatory responses (HVR) to 10% O2( P < 0.006 vs. Veh), whereas A1 did not modify HVR ( P not significant). HVR reductions by Gen and A25 were primarily due to diminished respiratory frequency enhancements ( P< 0.002). No changes in heart rate or mean arterial pressure responses occurred during hypoxia with TK inhibition. In addition, increases in tyrosine phosphorylation of the NR2A/B subunits, but not of the NR2C subunit, of the N-methyl-d-aspartate receptor occurred at 5, 30, and 60 min of hypoxia in the dorsocaudal brain stem and returned to baseline values at 120 min. We conclude that hypoxia induces tyrosine phosphorylation of the N-methyl-d-aspartate glutamate receptor, and TK inhibition within the dorsocaudal brain stem attenuates components of HVR in conscious rats.

Ergonomic Considerations of Fin Size for Working Divers

1982 ◽  
Vol 26 (6) ◽  
pp. 525-529 ◽  
Author(s):  
I. B. Mekjavic ◽  
P. A. Rowe ◽  
J. B. Morrison
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Cardiovascular System ◽  
Surface Area ◽  
Minute Ventilation ◽  
Metabolic Cost ◽  
Breathing Frequency ◽  
Work Period ◽  
Ventilatory Volume

Four divers conducted two identical work protocols, consisting of swimming against a graded resistance on an underwater ergometer at a depth of ten feet. In one protocol the divers used fins each having a surface area of 540 cm2 and in the second protocol they used fins whose surface area was 940 cm2. Oxygen consumption, heart rate, ventilation, breathing frequency and kick rate were monitored throughout the twenty minute work period. The 540 cm2 fins demanded a siqnificantly higher metabolic rate than the 940 cm2 fins (50.85 ± 1.54 compared to 46.99 ± 1.52 ml.min.-1.kg-1). The smaller fins also elicited higher heart rates (171.8 ± 4.3 min.-1) than the larger fins (142.5 ± 8.7 min.-1) and induced a higher kicking frequency than was required with the larger fins (43 ± 4 min.-1 and 32 ± 1 min.-1 respectively). Ventilatory volume at the end of the final workload was 128.6 ± 7 1/min. with small fins and 111.1 ± 6.5 1/min. with large fins. These data suggest that the larger fins are more economical in terms of minute ventilation and metabolic cost and are less demanding on the cardiovascular system. Subjectively, the larger fins were perceived as less fatiguing than the smaller fins.

scholarly journals Estradiol Protects Against Cardiorespiratory Dysfunctions and Oxidative Stress in Intermittent Hypoxia

SLEEP ◽  
2017 ◽  
Vol 40 (8) ◽  
Author(s):  
Sofien Laouafa ◽  
Alexandra Ribon-Demars ◽  
François Marcouiller ◽  
Damien Roussel ◽  
Aida Bairam ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Metabolic Rate ◽  
Intermittent Hypoxia ◽  
Minute Ventilation ◽  
Female Rats ◽  
Whole Body ◽  
Sprague Dawley ◽  
Ventilatory Responses ◽  
Reduced Body ◽  
And Oxidative Stress

Abstract Study Objectives We tested the hypothesis that estradiol (E2) protects against cardiorespiratory disorders and oxidative stress induced by chronic intermittent hypoxia (CIH) in adult female rats. Methods Sprague-Dawley female rats (230–250 g) were ovariectomized and implanted with osmotic pumps delivering vehicle or E2 (0.5 mg/kg/d). After 14 days of recovery, the rats were exposed to CIH (21%–10% O2: 8 h/d, 10 cycles per hour) or room air (RA). After 7 days of CIH or RA exposure, we measured arterial pressures (tail cuff), metabolic rate (indirect calorimetry), minute ventilation, the frequency of sighs and apneas at rest, and ventilatory responses to hypoxia and hypercapnia (whole body plethysmography). We collected the cerebral cortex, brainstem, and adrenal glands to measure the activity of NADPH and xanthine oxidase (pro-oxidant enzymes), glutathione peroxidase, and the mitochondrial and cytosolic superoxide dismutase (antioxidant enzymes) and measured lipid peroxidation and advanced oxidation protein products (markers of oxidative stress). Results CIH increased arterial pressure, the frequency of apnea at rest, and the hypoxic and hypercapnic ventilatory responses and reduced metabolic rate. CIH also increased oxidant enzyme activities and decreased antioxidant activity in the cortex. E2 treatment reduced body weight and prevented the effects of CIH. Conclusions E2 prevents cardiorespiratory disorders and oxidative stress induced by CIH. These observations may help to better understand the underlying mechanisms linking menopause and occurrence of sleep apnea in women and highlight a potential advantage of hormone therapy.

Skin Cooling on Breath-Hold Duration and Predicted Emergency Air Supply Duration During Immersion

2020 ◽  
Vol 91 (7) ◽  
pp. 578-585
Author(s):  
Victory C. Madu ◽  
Heather Carnahan ◽  
Robert Brown ◽  
Kerri-Ann Ennis ◽  
Kaitlyn S. Tymko ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Hold Time ◽  
Whole Body ◽  
Breath Hold ◽  
Endurance Time ◽  
Skin Exposure ◽  
Breathing Apparatus ◽  
Air Supply ◽  
Skin Cooling ◽  
Breath Hold Duration

PURPOSE: This study was intended to determine the effect of skin cooling on breath-hold duration and predicted emergency air supply duration during immersion.METHODS: While wearing a helicopter transport suit with a dive mask, 12 subjects (29 ± 10 yr, 78 ± 14 kg, 177 ± 7 cm, 2 women) were studied in 8 and 20°C water. Subjects performed a maximum breath-hold, then breathed for 90 s (through a mouthpiece connected to room air) in five skin-exposure conditions. The first trial was out of water for Control (suit zipped, hood on, mask off). Four submersion conditions included exposure of the: Partial Face (hood and mask on); Face (hood on, mask off); Head (hood and mask off); and Whole Body (suit unzipped, hood and mask off).RESULTS: Decreasing temperature and increasing skin exposure reduced breath-hold time (to as low as 10 ± 4 s), generally increased minute ventilation (up to 40 ± 15 L · min−1), and decreased predicted endurance time (PET) of a 55-L helicopter underwater emergency breathing apparatus. In 8°C water, PET decreased from 2 min 39 s (Partial Face) to 1 min 11 s (Whole Body).CONCLUSION: The most significant factor increasing breath-hold and predicted survival time was zipping up the suit. Face masks and suit hoods increased thermal comfort. Therefore, wearing the suits zipped with hoods on and, if possible, donning the dive mask prior to crashing, may increase survivability. The results have important applications for the education and preparation of helicopter occupants. Thermal protective suits and dive masks should be provided.Madu VC, Carnahan H, Brown R, Ennis K-A, Tymko KS, Hurrie DMG, McDonald GK, Cornish SM, Giesbrecht GG. Skin cooling on breath-hold duration and predicted emergency air supply duration during immersion. Aerosp Med Hum Perform. 2020; 91(7):578–585.

Some consequences of body size

1984 ◽  
Vol 247 (4) ◽  
pp. H495-H507 ◽  
Author(s):  
L. E. Ford
Keyword(s):  
Heart Rate ◽  
Body Weight ◽  
Metabolic Rate ◽  
Muscle Power ◽  
Weight Ratio ◽  
Single Species ◽  
Hill Climbing ◽  
Proper Size ◽  
Higher Power ◽  
Metabolic Indices

The question of the proper size denominator for metabolic indices is addressed. Metabolic rate among different species is proportional to the 3/4 power of body weight, not surface area. Muscle power also varies with the 3/4 power of weight, suggesting that metabolic rate is determined mainly by muscle power. Power-to-weight ratio, specific metabolic rate, and a number of metabolic periods, including heart rate, all vary inversely with the 1/4 power of body weight. Thus the relative times required for physiological and pathological processes in different species may be estimated from the average resting heart rate for the species. There are not many small humans among athletic record holders in events involving acceleration and hill climbing, as would be expected if they had higher power-to-weight ratios. Thus the relationship between size and metabolic rate in different species should not be applied within the single species of humans. Evidence is reviewed showing that basal metabolic rate in humans is determined mainly by lean body mass.

Respiratory Metabolism During Pregnancy in the Guinea Pig

1957 ◽  
Vol 190 (3) ◽  
pp. 425-428 ◽  
Author(s):  
Richard M. Hoar ◽  
William C. Young
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Guinea Pig ◽  
Metabolic Rate ◽  
Adrenal Cortex ◽  
Guinea Pigs ◽  
Sharp Decrease ◽  
Zona Fasciculata ◽  
Respiratory Metabolism ◽  
Morphological Differences

Oxygen consumption and heart rate during pregnancy were measured in untreated, thyroxin-injected and thyroidectomized guinea pigs given I131. From impregnation until parturition, oxygen consumption increased 7.9% in untreated females. The increase continued until 5 days postpartum when a sharp decrease occurred. The increase is not accounted for by growth of the fetal mass. Comparable increases occurred in thyroxin-injected (16.2%) and thyroidectomized (11.9%) females, although the levels throughout were higher and lower, respectively, than in intact females. Heart rate did not increase. On the contrary, statistically significant decreases occurred in the untreated and thyroxin-injected females. Although the mechanism associated with the increased metabolic rate is not known, the possibility of thyroid participation would seem to be excluded. Involvement of the adrenal cortex is suggested by morphological differences in the cells of the zona fasciculata in pregnant and nonpregnant females and by evidence cited from other studies.

Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation

2021 ◽  
pp. 1-16
Author(s):  
Alexander Yang Hui Xiang ◽  
Prashanna Khwaounjoo ◽  
Yusuf Ozgur Cakmak
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Visual Stimulation ◽  
Pupil Diameter ◽  
Parasympathetic Activity ◽  
Whole Body ◽  
Vagal Activity ◽  
Eyes Closed ◽  
Visual Flow ◽  
Visual Interactions

BACKGROUND: Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated. OBJECTIVE: This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter. METHODS: Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset. RESULTS: CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed. CONCLUSIONS: Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

Regulation of ventilation and oxygen consumption by delta- and mu-opioid receptor agonists

1985 ◽  
Vol 59 (3) ◽  
pp. 959-968 ◽  
Author(s):  
J. I. Schaeffer ◽  
G. G. Haddad
Keyword(s):  
Metabolic Rate ◽  
Minute Ventilation ◽  
Periodic Breathing ◽  
Receptor Agonists ◽  
Shallow Breathing ◽  
Stressful Stimulation ◽  
Alveolar Hypoventilation ◽  
Dose Dependent Decrease ◽  
Mu Agonists ◽  
Delta Receptor

To study the effect of endorphins on metabolic rate and on the relationship between O2 consumption (VO2) and ventilation, we administered enkephalin analogues (relatively selective delta-receptor agonists) and a morphiceptin analogue (a highly selective mu-receptor agonist) intracisternally in nine unanesthetized chronically instrumented adult dogs. Both delta- and mu-agonists decreased VO2 by 40–60%. delta-Agonists induced a dose-dependent decrease in mean instantaneous minute ventilation (VT/TT) associated with periodic breathing. The decrease in VT/TT started and resolved prior to the decrease and returned to baseline of VO2, respectively. In contrast, the mu-agonists induced an increase in VT/TT associated with rapid shallow breathing. Arterial PCO2 increased and arterial PO2 decreased after both delta- and mu-agonists. Low doses of intracisternal naloxone (0.002–2.0 micrograms/kg) reversed the opioid effect on VT/TT but not on VO2; higher doses of naloxone (5–25 micrograms/kg) reversed both. Naloxone administered alone had no effect on VT/TT or VO2. These data suggest that 1) both delta- and mu-agonists induce alveolar hypoventilation despite a decrease in VO2, 2) this hypoventilation results from a decrease in VT/TT after delta-agonists but an increase in dead space ventilation after mu-agonists, and 3) endorphins do not modulate ventilation and metabolic rate tonically, but we speculate that they may do so in response to stressful stimulation.

scholarly journals Heat Stress and Cardiovascular, Hormonal, and Heat Shock Proteins in Humans

2012 ◽  
Vol 47 (2) ◽  
pp. 184-190 ◽  
Author(s):  
Masaki Iguchi ◽  
Andrew E. Littmann ◽  
Shuo-Hsiu Chang ◽  
Lydia A. Wester ◽  
Jane S. Knipper ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heat Stress ◽  
Heat Shock ◽  
Body Temperature ◽  
Controlled Trial ◽  
Whole Body ◽  
Cord Injury ◽  
Whole Body Heat Stress ◽  
Body Heat

Context: Conditions such as osteoarthritis, obesity, and spinal cord injury limit the ability of patients to exercise, preventing them from experiencing many well-documented physiologic stressors. Recent evidence indicates that some of these stressors might derive from exercise-induced body temperature increases. Objective: To determine whether whole-body heat stress without exercise triggers cardiovascular, hormonal, and extra-cellular protein responses of exercise. Design: Randomized controlled trial. Setting: University research laboratory. Patients or Other Participants: Twenty-five young, healthy adults (13 men, 12 women; age = 22.1 ± 2.4 years, height = 175.2 ± 11.6 cm, mass = 69.4 ± 14.8 kg, body mass index = 22.6 ± 4.0) volunteered. Intervention(s): Participants sat in a heat stress chamber with heat (73°C) and without heat (26°C) stress for 30 minutes on separate days. We obtained blood samples from a subset of 13 participants (7 men, 6 women) before and after exposure to heat stress. Main Outcome Measure(s): Extracellular heat shock protein (HSP72) and catecholamine plasma concentration, heart rate, blood pressure, and heat perception. Results: After 30 minutes of heat stress, body temperature measured via rectal sensor increased by 0.8°C. Heart rate increased linearly to 131.4 ± 22.4 beats per minute (F6,24 = 186, P &lt; .001) and systolic and diastolic blood pressure decreased by 16 mm Hg (F6,24 = 10.1, P &lt; .001) and 5 mm Hg (F6,24 = 5.4, P &lt; .001), respectively. Norepinephrine (F1,12 = 12.1, P = .004) and prolactin (F1,12 = 30.2, P &lt; .001) increased in the plasma (58% and 285%, respectively) (P &lt; .05). The HSP72 (F1,12 = 44.7, P &lt; .001) level increased with heat stress by 48.7% ± 53.9%. No cardiovascular or blood variables showed changes during the control trials (quiet sitting in the heat chamber with no heat stress), resulting in differences between heat and control trials. Conclusions: We found that whole-body heat stress triggers some of the physiologic responses observed with exercise. Future studies are necessary to investigate whether carefully prescribed heat stress constitutes a method to augment or supplement exercise.

Sign in / Sign up

Export Citation Format

Share Document