Search results for "Respiratory minute volume"
showing 10 items of 21 documents
Influence of ultra-long-term fatigue on the oxygen cost of two types of locomotion.
2000
The aim of this study was to examine the effects of fatigue induced by a 65-km ultramarathon on the oxygen cost of running (Cr) and cycling (Ccycl). The day before and immediately after the race, a group of nine well-trained male subjects performed two sub-maximal 4-min exercise bouts: one cycling at a power corresponding to 1.5 W · kg−1 body mass on an electromagnetically braked ergometer, and one running at 11 km · h−1 on a flat asphalt roadway. Before oxygen cost determinations, the subjects performed 12 “ankle” jumps at a given frequency that was fixed by an electronic metronome (2.5 Hz). From the non-fatigued to the fatigued condition, there was a significant increase in minute ventila…
Thyrotropin-releasing hormone has stimulatory effects on ventilation in humans
1991
Thyrotropin-releasing hormone (TRH) stimulates pituitary thyrotropin synthesis and release and also regulates autonomic nervous system functions by acting as a neuromodulator and neurotransmitter. In experimental animals a stimulation of ventilation by thyrotropin-releasing hormone was shown when applied at central nervous system sites that affect respiratory motor output. It was the goal of our study to investigate the respiratory properties of thyrotropin-releasing hormone on basal and stimulated (i.e. CO2-rebreathing) conditions following systemic thyrotropin-releasing hormone application in healthy humans. Thyrotropin-releasing hormone (200 micrograms, 400 micrograms intravenous) initia…
Hybrid Functional Electrical Stimulation Exercise Training Alters the Relationship Between Spinal Cord Injury Level and Aerobic Capacity
2014
Objective To test the hypothesis that hybrid functional electrical stimulation (FES) row training would improve aerobic capacity but that it would remain strongly linked to level of spinal cord lesion because of limited maximal ventilation. Design Longitudinal before–after trial of 6 months of FES row training. Setting Exercise for persons with disabilities program in a hospitaL. Participants Volunteers (N=14; age range, 21–63y) with complete spinal cord injury (SCI) (T3-11) who are >2 years postinjury. Intervention Six months of FES row training preceded by a variable period of FES strength training. Main Outcome Measures Peak aerobic capacity and peak exercise ventilation before and after…
Effect of pedalling rates on physiological response during endurance cycling
2001
International audience; This study was undertaken to examine the effect of different pedalling cadences upon various physiological responses during endurance cycling exercise. Eight well-trained triathletes cycled three times for 30 min each at an intensity corresponding to 80% of their maximal aerobic power output. The first test was performed at a freely chosen cadence (FCC); two others at FCC-20% and FCC +20%, which corresponded approximately to the range of cadences habitually used by road racing cyclists. The mean (SD) FCC, FCC-20% and FCC + 20% were equal to 86 (4), 69 (3) and 103 (5) rpm respectively. Heart rate (HR), oxygen uptake (VO2), minute ventilation (VE) and respiratory excha…
Human corticotropin-releasing factor (hCRF) is a potent respiratory analeptic. Physiological and clinical aspects.
1986
During intravenous corticotropin-releasing factor stimulation tests we observed a deepening of the tidal volume in 35 patients. To investigate this presumed respiratory stimulation we measured respiratory parameters in 12 healthy male volunteers in a single-blind placebo-controlled trial. The intravenous 60-s infusion of 100 micrograms of human corticotropin-releasing factor induced a very potent respiratory stimulation in every subject: respiratory minute volume (mean +/- S.D.) increased by 81% from 6.319 +/- 0.577 to 11.464 +/- 1.264 liters per min (P less than 0.001), whereas there was only a slight rise in the mean respiratory rate from 12.4 +/- 3.0 to 14.7 +/- 2.7 breaths per min (P le…
Human Corticotropin-Releasing Hormone in Man: Dose-Response of Minute Ventilation and End-Tidal Partial Pressures of Carbon Dioxide and Oxygen*
1987
The respiratory stimulant properties of iv injections of 33, 67, and 100 micrograms synthetic human corticotropin-releasing hormone (hCRH) were studied in 12 normal men in a single blind, placebo-controlled trial. All doses of hCRH induced a respiratory stimulation in every subject, and the stimulation was dose dependent. The onset of respiratory stimulation occurred within 15-30 sec after hCRH infusion was started. Initially, there was an increase in tidal volume (VT), followed by an increase in respiratory rate. The maximum minute ventilation (VE) occurred 60-120 sec after starting the injection. The 33-micrograms hCRH dose induced a 35% increase in VE from 6.3 +/- 0.6 (+/- SD) to 9.7 +/-…
Information domain analysis of respiratory sinus arrhythmia mechanisms.
2019
Ventilation related heart rate oscillations – respiratory sinus arrhythmia (RSA) – originate in human from several mechanisms. Two most important of them – the central mechanism (direct communication between respiratory and cardiomotor centers), and the peripheral mechanism (ventilation-associated blood pressure changes transferred to heart rate via baroreflex) have been described in previous studies. The major aim of this study was to compare the importance of these mechanisms in the generation of RSA non-invasively during various states by quantifying the strength of the directed interactions between heart rate, systolic blood pressure and respiratory volume signals. Seventy-eight healthy…
Cardiorespiratory Changes During Prolonged Downhill Versus Uphill Treadmill Exercise
2020
AbstractOxygen uptake (V̇O2), heart rate (HR), energy cost (EC) and oxygen pulse are lower during downhill compared to level or uphill locomotion. However, a change in oxygen pulse and EC during prolonged grade exercise is not well documented. This study investigated changes in cardiorespiratory responses and EC during 45-min grade exercises. Nine male healthy volunteers randomly ran at 75% HR reserve during 45-min exercise in a level (+1%), uphill (+15%) or downhill (−15%) condition. V̇O2 , minute ventilation (V̇E ) and end-tidal carbon dioxide (PetCO2) were recorded continuously with 5-min averaging between the 10th and 15th min (T1) and 40th and 45th min (T2). For a similar HR (157±3 bpm…
Accuracy of delivered versus preset minute ventilation of portable emergency ventilators.
1989
The accuracy of delivered minute volume (VE) ventilation of portable emergency ventilators (PEV) was evaluated. Five PEV from three manufacturers were adapted to an artificial lung for varying compliance and resistance. Each PEV was tested in the "no airmix" (pure oxygen) and "airmix" (approximately 60% oxygen) setting at different frequencies and VE. Measurement of delivered VE (VEdel) was made using a pneumotachograph and digital integration of the flow values greater than 1 min (maximal error +/- 2%). Maximal inspiratory pressure (Pinsp) was measured with a transducer. Two PEV from one manufacturer produced severe hyperventilation when used at low VE (i.e., in children). Two other PEV fr…
Towards understanding the complexity of cardiovascular oscillations: Insights from information theory.
2018
Abstract Cardiovascular complexity is a feature of healthy physiological regulation, which stems from the simultaneous activity of several cardiovascular reflexes and other non-reflex physiological mechanisms. It is manifested in the rich dynamics characterizing the spontaneous heart rate and blood pressure variability (HRV and BPV). The present study faces the challenge of disclosing the origin of short-term HRV and BPV from the statistical perspective offered by information theory. To dissect the physiological mechanisms giving rise to cardiovascular complexity in different conditions, measures of predictive information, information storage, information transfer and information modificati…