BACKGROUND AND OBJECTIVE: Thixotropy conditioning of inspiratory muscles changes the end-expiratory position of the respiratory system during resting breathing. We examined the immediate effects of thixotropy conditioning of inspiratory muscles on chest wall inflation induced by CPAP. METHODS: A cross-over design study was performed in 13 healthy men. Operating chest ...

This study examined the patterning of acute affective responses to prescribed and self-selected exercise intensities in a young adolescent population. Twenty-two young adolescents (13.3 +/- .33 years) completed a maximal exercise test to identify ventilatory threshold (VT). Participants then completed two prescribed intensities (one set above and one below the ...

The prevalence of activity-related breathlessness increases with age, particularly in women, but the specific underlying mechanisms have not been studied. This novel cross-sectional study was undertaken to examine the effects of age and sex, and their interaction, on the perceptual and ventilatory responses to incremental treadmill exercise in 73 healthy ...

The objective of these studies was to assess the reproducibility of (i) short-term food intake (FI) and subjective appetite following a glucose preload, (ii) ventilation threshold (VT) and subjective appetite after short-duration exercise, and (iii) body composition assessed by bioelectrical impedance (BIA). On two separate weekend mornings, boys (n = ...

In cardiac arrest due to ventricular fibrillation (VF), moderate hypothermia (MH, 33 degrees C) has been shown to improve defibrillation success compared with normothermia (NR, 37 degrees C) and severe hypothermia (SH, 30 degrees C). The underlying mechanisms remain unclear. We hypothesized that MH might prevent reentrant excitations rotating around ...

The concept of ventilatory thresholds (VTs) has been shown to be particularly useful to prescribe exercise intensities, yet, to date no study has examined the effects of previous submaximal exercise (i.e. a simulated training session) on the subsequent occurrence of VTs. We designed the present study to test the hypothesis ...

BACKGROUND: Nuclear respiratory factor 1 (NRF-1) is a critical component of the energy-sensing mechanism in mammalian cells, and translates physiological signals (particularly those induced by exercise) into increased capacity for mitochondrial biogenesis and oxidative phosphorylation. OBJECTIVE: To study the possible association between rs2402970, rs6949152 and rs10500120 NRF-1 genotypes and several ...

PURPOSE: Correlative data have suggested that the Talk Test (TT) may be a surrogate of the ventilatory threshold (VT). This study examined manipulations of either the VT or exercise protocol to test the hypothesis that the TT and VT are related in a robust way, adequate for exercise prescription. METHODS: ...

The objective of the present study was to evaluate breathing pattern, thoracoabdominal motion and muscular activity during three breathing exercises: diaphragmatic breathing (DB), flow-oriented (Triflo II) incentive spirometry and volume-oriented (Voldyne) incentive spirometry. Seventeen healthy subjects (12 females, 5 males) aged 23 +/- 5 years (mean +/- SD) were studied. ...

In cardiac rehabilitation, different endurance exercises such as walking and cycling are often performed. The training intensity for these modes is determined from a single treadmill or bicycle test by ventilatory threshold (VT). In this study, differences of VT between walking and cycling and agreement of VT between training modes ...

PURPOSE: The purpose of the study was to compare affective responses for two bouts of cycle ergometry with differing duration and intensity, but equal total work in kilocalories. METHODS: Thirty-seven participants (20 male, 17 female, mean age 23.9 yr) completed a multistage cycle ergometer protocol to determine ventilatory threshold (VT) ...

This study investigated 1) whether ventilatory and lactic thresholds (VT and LT, respectively) are different in sickle cell trait carriers (SCTc) and subjects with normal hemoglobin (control group), and 2) whether the first LT and VT and the second LT and VT are respectively coincident in the two populations. Seven ...

The periaqueductal gray (PAG) is a central neural region essential for defense behavior and coordination of accompanying autonomic responses. Activation of rostral versus caudal dorsal (dPAG) regions mediates different cardiovascular response patterns. Stimulation of the dPAG also elicits increased respiratory activity, however, it is unknown if there is a regional ...

Air flow rate through filters and face masks is one important determinant of the final protection factor of a respiratory protective device in use. Respiratory minute volumes and instantaneous breath flow rates were measured in eight subjects during treadmill work using three types of filtering respirators and one control breathing ...

Expiratory muscle loading results in increased perception of respiratory effort; this response is mediated by non-vagal reflexes originating in the chest wall. Furosemide, due to its vagal effect, might not affect the perception of respiratory effort during expiratory flow-limited incremental exercise. In this study, we compared in nine healthy subjects ...

BACKGROUND: Central hypercapnic chemosensitivity (Chemo) influences the enhanced ventilatory and sympathetic responses in heart failure patients; however, its influence on these responses in Fontan patients is unknown. OBJECTIVES: To measure Chemo and compare the results with rest and exercise ventilatory characteristics in Fontan patients. METHODS AND RESULTS: We measured Chemo ...

Behçet's disease (BD) has well-defined pulmonary complications, but cardiopulmonary exercise testing and the strength of the respiratory muscles have not been studied in detail. We aimed to investigate the pulmonary functions tests, inspiratory and expiratory muscle strength and endurance, cardiopulmonary exercise test response, and the relationship of these parameters in ...

OBJECTIVE: We compared the levels of ventilatory threshold (VT) and exercise habits in subjects with metabolic syndrome with those in age, sex-matched subjects without metabolic syndrome. METHODS: We used data of 155 Japanese men (47.1+/-9.2 years) with metabolic syndrome; the diagnosis was given by the definition and the diagnostic standard ...

PURPOSE: To study the sensitivity for detection of activation for multiple vs. single inversion time (TI) pulsed arterial spin labeling (PASL). MATERIALS AND METHODS: The number of activated voxels and the mean t-statistic over activated voxels was measured by means of multiple and single TI PASL sequences in five volunteers ...

We investigated the effect of 4 week of inspiratory (IMT) or expiratory muscle training (EMT), as well as the effect of a subsequent 6 week period of combined IMT/EMT on rowing performance in club-level oarsmen. Seventeen male rowers were allocated to either an IMT (n = 10) or EMT (n ...

The self-contained breathing apparatus (SCBA) increases the expiratory pressure required to maintain high rates of ventilation, suggesting that the expiratory work of breathing (WOB) is increased; however, this has never been reported. The objective of this study, therefore, was to determine if the WOB is increased with the SCBA regulator ...

PURPOSE: To determine whether changes in lung function are associated with exercise-related transient abdominal pain (ETAP). METHODS: Twenty-eight subjects susceptible to ETAP performed a flow-volume loop before (pre) and after (post) treadmill exercise. Fourteen of the subjects developed symptoms of ETAP during the exercise and completed the flow-volume loop while ...

The aim of this study was to assess the within subject reproducibility of cardioventilatory measurements and the maximum permitted 'normal' variability over time at rest and exercise using the respiratory mass spectrometer (RMS). Ten subjects underwent an incremental exercise test on three separate occasions utilising rebreathing (RB) and helium dilution ...

Inspiratory muscle conditioning at a lower or higher lung volume based on the principles of muscle thixotropy causes acute changes in end-expiratory chest wall and lung volumes. The present study aimed to demonstrate the time course of effects of this conditioning on both end-expiratory chest wall volume and thoracoabdominal synchrony. ...

We investigated whether the inspiratory muscles affect maximal incremental exercise performance using a placebo-controlled, crossover design. Six cyclists each performed six incremental exercise tests. For three trials, subjects exercised with proportional assist ventilation (PAV). For the remaining three trials, subjects underwent sham respiratory muscle unloading (placebo). Inspiratory muscle pressure (P(mus)) ...

BACKGROUND: Current discrimination algorithms do not completely avoid inappropriate tachycardia detection. OBJECTIVES: This study analyzes the discrimination capability of the changes of the first postpacing interval (FPPI) after successive bursts of anti-tachycardia pacing (ATP) trains in implantable cardioverter-defibrillator (ICD)-recorded tachycardias. METHODS: We included 50 ICD patients in this prospective study. ...

INTRODUCTION: Length-tension and force-velocity characteristics of respiratory muscles and hyperinflation are the likely determinants of dyspnea in subjects exercising under hyperbaric conditions. We hypothesize that hyperinflation plays a minor role and that the reduced velocity of shortening of the respiratory muscles modulates dyspnea for any given pleural pressure. METHODS: We ...

To study the relationship between the onset of an increase in dyspnea and ventilatory threshold (VT) in children with congenital heart impairment, sixteen young subjects underwent a cardiopulmonary exercise test with dyspnea perception and ventilatory gas exchange assessments. Dyspnea score was measured from a visual analogical scale at rest and ...

Developmental changes in the respiratory activity and its modulation by substance P (SP) were studied in the neonatal rat brainstem-spinal cord preparation from the day of birth to day 3 (P0-P3). The respiratory network activity in the ventrolateral medulla was represented by two types of bursts: basic regular bursts with ...

The purpose of this study was to determine the effects of inspiratory muscle training (IMT) on exercise in hypoxia (H) and normoxia (N). A 4-week IMT program was implemented with 12 healthy subjects using an inspiratory muscle trainer set at either 15% (C; n=5) or 50% (IMT; n=7) maximal inspiratory ...

Anaerobic threshold (AT) has been considered the optimal exercise intensity for type 2 diabetes mellitus (DM 2) patients, but there is little information about the comparison between lactate (LT) and ventilatory (VT) thresholds in this population, particularly during treadmill exercise. Therefore, we evaluated DM 2 women in order to compare ...

PURPOSE: The work rate (WR) corresponding to ventilatory threshold (VT) is an appropriate intensity for regenerative and low-intensity training sessions. During incremental ramp exercise, VO(2) increase lags behind WR increase. Traditionally, a VO(2) time delay (t(d)) of 45 seconds is used to calculate the WR at VT from such tests. ...

Dyspnea, a leading respiratory symptom, shares many clinical, physiological, and psychological features with pain. Both activate similar brain areas. The neural mechanisms of dyspnea are less well described than those of pain. The present research tested the hypothesis of common pathways between the two sensations. Six healthy men (age 30-40 ...

We evaluated the sensation of dyspnea induced by hypercapnia alone and a combination of hypercapnia and flow-resistive loading by the use of visual analogue scale (VAS) and the use of 13 listed descriptors in 23 healthy subjects. Hypercapnia alone caused a modest degree of dyspnea characterized by both air hunger ...

The effects of inspiratory muscle (IM) warm-up on the maximum dynamic IM function and the maximum repetitions of 20-m shuttle run (Ex) in the Yo-Yo intermittent recovery test were examined. Ten men were recruited to perform identical IM function test and exercise test in three different trials randomly. The control ...

Physical exercise inhibits cardiac vagal activity. To study the relationship between heart rate (HR) and respiratory pattern, we applied the 4-s exercise test (4sET) and measured cardiac vagal index (CVI) in 30 healthy subjects who served as their own controls, using the standard plus three additional variations, essentially respiratory, of ...

To analyze the influence of step-duration protocol (1 vs. 3 min) on breathing strategy according to the physical fitness of healthy elderly subjects, this study compared the ventilatory responses and exercise tidal flow-volume loops (ETFVL) at the first and second ventilatory thresholds (VT(1) and VT(2)). Nineteen master athletes (mean age ...

Respiratory-related variabilities in stroke volume and arterial pulse pressure (Delta%Pp) are proposed to predict fluid responsiveness. We investigated the influence of tidal volume (Vt) and adrenergic tone on these variables in mechanically ventilated patients. Cyclic changes in aortic velocity-time integrals (Delta%VTI(Ao), echocardiography) and Delta%Pp (catheter) were measured simultaneously before and ...

PURPOSE: To analyze the limits of agreement between exercise ventilatory threshold values (VT1 and VT2) estimated from a combination of pulmonary gas exchange and ventilatory variables (cardiopulmonary exercise testing) and those derived from an alternative approach based on the ventilatory response only (V(E), ventilometry). METHODS: Forty-two nontrained subjects (24 males, ...

We determined the effects of augmented expiratory intrathoracic pressure (P(ITP)) production on cardiac output (Q(TOT)) and blood flow distribution in healthy dogs and dogs with chronic heart failure (CHF). From a control expiratory P(ITP) excursion of 7 +/- 2 cmH2O, the application of 5, 10, or 15 cmH2O expiratory threshold ...

BACKGROUND AND PURPOSE: Previous investigations have demonstrated that a regimen of high-intensity inspiratory muscle training (IMT) resulted in changes in ventilatory function and exercise capacity in patients with chronic lung disease, although the effect of high-intensity IMT in subjects who are healthy is yet to be determined. The purpose of ...

The recruitment of expiratory muscles during exercise might be altered by the application of negative expiratory pressure (NEP) inducing a feature of expiratory flow limitation (EFL) called muscle EFL. To check this hypothesis EFL and expiratory muscle EMG (ExpEMG) were measured at rest and during exercise in eight healthy subjects. ...

Introduction: Fusion exercises have been used in the management of intermittent exotropia (X(T)) for over one hundred years. The opinions regarding their efficacy are controversial. Patients and Method: Dynamics of binocular status were investigated retrospectively in ninety-six patients with X(T). Forty-eight subjects had specific orthoptic treatment (treatment group). Forty-eight had ...

OBJECTIVES/HYPOTHESIS: To assess the diagnostic feasibility and patient acceptance of a new developed diagnostic test for exercise induced upper airway flow limitation. STUDY DESIGN: Clinical case control study including evaluation of contemporary ergo-spirometry and laryngoscopy continuously performed during exercise. METHODS: Twelve nonsymptomatic controls and four young females with documented dyspnea ...

Self-inflating manual resuscitators (SIMRs) can mislead caregivers because the bag, unlike a Mapleson-type device, reinflates even without patient exhalation. We added a whistle as an audible indicator to the exhalation port of a SIMR. In randomized order, each participant provided two sets of breaths via mask ventilation with a SIMR, ...

This study evaluates the effects of training with noninvasive ventilatory support in patients with chronic obstructive pulmonary disease in a randomised, controlled, observer-blinded trial. Twenty-nine patients with chronic obstructive pulmonary disease and with a ventilatory limited exercise capacity (forced expiratory volume in one second < 60% predicted, breathing reserve at ...

OBJECTIVE: The purpose of this study was to quantify the acoustic output of clinical ultrasound instruments, as expressed by the thermal index (TI) and mechanical index (MI), during routine obstetric examinations. METHODS: A prospective, observational study was conducted. Sonographers were unaware of the data being sought. Data were collected regarding ...

The purpose of this study was to establish an objective method for identifying the heart-rate threshold (HRT) in cyclists. Fifty-six male cyclists were tested on a cycle ergometer to volitional fatigue. Identification of the HRT used a heart-rate increase above a logarithmic regression line of best fit, coupled with the ...

The aim of this study was to assess respiratory muscles deoxygenation and to determine ventilatory threshold using near infrared spectroscopy (NIRS) in children during incremental cardiopulmonary exercise. Fourteen healthy children with a mean +/- SD age of 12.8 +/- 1.4 yrs performed an incremental exercise test on a cycle ergometer. ...

We studied mechanical ventilatory constraints in 13 aerobically trained (Tr) and 11 untrained (UT) prepubescent children by plotting the exercise flow-volume (F-V) loops within the maximal F-V loop (MFVL) measured at rest. The MFVL allowed to determine forced vital capacity (FVC) and maximal expiratory flows. Expiratory and inspiratory reserve volumes ...