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Abstract Background It has been reported that the way we breathe (whether through the nose or mouth) can influence many aspects of our health and to some extent, sport performance. The purpose of this study was to evaluate the acute effects of different breathing regimens on muscular endurance and physiological variables. Methods A randomized experiment to verify the acute effect of different breathing regimens (NN– inhaling and exhaling through the nose; NM– inhaling through the nose, exhaling through the mouth; MM– inhaling and exhaling through the mouth) on the muscular endurance performance was conducted. 107 physically active college students (68 males, 39 females) performed repeated bench press testing protocol (repetitions to failure (RTF) with 60% of body weight for males (BP60), respectively 40% of body weight for females (BP40)) with various breathing regimens (NN, NM, MM) in random order. Heart rate (HR), blood oxygen saturation (SpO2) and perceived exertion by Borg scale (RPE) were measured as well. A short questionnaire, given after the testing protocol and observation during familiarization, was used to detect each subject’s normal breathing approach during resistance training. Results In both genders, no significant differences in RTF, RPE and SpO2 were found. No individual case of deviation of arterial oxygen saturation outside the physiological norm was recorded. ​​In the male group, significantly lower HR values were found during the NN trials, compared to during the NM (p = 0.033) and MM (p = 0.047) trials with no significant differences in females. The HR differences in the males demonstrated a small effect size (NN

Background: It has been reported that the way we breathe (whether through the nose or mouth) can influence many aspects of our health and to some extent, sport performance. The purpose of this study was to evaluate the acute effects of different breathing regimens on muscular endurance and physiological variables. Methods: A randomized experiment to verify the acute effect of different breathing regimens (NN– inhaling and exhaling through the nose; NM– inhaling through the nose, exhaling through the mouth; MM– inhaling and exhaling through the mouth) on the muscular endurance performance was conducted. 107 physically active college students (68 males, 39 females) performed repeated bench press testing protocol (repetitions to failure (RTF) with 60% of body weight for males (BP60), respectively 40% of body weight for females (BP40)) with various breathing regimens (NN, NM, MM) in random order. Heart rate (HR), blood oxygen saturation (SpO2) and perceived exertion by Borg scale (RPE) were measured as well. A short questionnaire, given after the testing protocol and observation during familiarization, was used to detect each subject's normal breathing approach during resistance training. Results: In both genders, no significant differences in RTF, RPE and SpO2 were found. No individual case of deviation of arterial oxygen saturation outside the physiological norm was recorded. ​​In the male group, significantly lower HR values were found during the NN trials, compared to during the NM (p = 0.033) and MM (p = 0.047) trials with no significant differences in females. The HR differences in the males demonstrated a small effect size (NN < NM, d = 0.32; NN < MM, d = 0.30). Questionnaire results suggest that 80% of our participants use NM breathing, 15% use MM breathing and 5% use NN breathing during resistance training. Conclusion: It seems, that various breathing regimens have none or only minor effect on muscular endurance performance and selected physiological parameters. NN seems to be as efficient as other two regimens, which are mostly used in practice (NM, MM). [ABSTRACT FROM AUTHOR]

Oronasal breathing may adversely impact obstructive sleep apnea (OSA) patients either by increasing upper airway collapsibility or by influencing continuous positive airway pressure (CPAP) treatment outcomes. Predicting a preferential breathing route would be helpful to guide CPAP interface prescription. We hypothesized that anthropometric measurements but not self-reported oronasal breathing are predictors of objectively measured oronasal breathing. Seventeen OSA patients and nine healthy subjects underwent overnight polysomnography with an oronasal mask with two sealed compartments attached to independent pneumotacographs. Subjects answered questionnaires about nasal symptoms and perceived breathing route. Oronasal breathing was more common (P = <0.001) among OSA patients than controls while awake (62 ± 44 vs. 5 ± 6%) and during sleep (59 ± 39 vs. 25 ± 21%, respectively). Oronasal breathing was associated with OSA severity (P = 0.009), age (P = 0.005), body mass index (P = 0.044), and neck circumference (P = 0.004). There was no agreement between objective measurement and self-reported breathing route among OSA patients while awake (κ = -0.12) and asleep (κ = -0.02). The breathing route remained unchanged after 92% of obstructive apneas. These results suggest that oronasal breathing is more common among OSA patients than controls during both wakefulness and sleep and is associated with OSA severity and anthropometric measures. Self-reporting is not a reliable predictor of oronasal breathing and should not be considered an indication for oronasal CPAP. [ABSTRACT FROM AUTHOR]

Injuries due to inhalation of hot gas are commonly encountered when dealing with fire and combustible material, which is harmful and threatens human life. In the literature, various studies have been conducted to investigate heat and mass transfer characteristics in the human respiratory tract (HRT). This study focuses on assessing the injury taking place in the upper human respiratory tract and identifying acute tissue damage, based on level of exposure. A three-dimensional heat transfer simulation is performed using Computational Fluid Dynamics (CFD) software to study the temperature profile through the upper HRT consisting of the nasal cavity, oral cavity, trachea, and the first two generations of bronchi. The model developed is for the simultaneous oronasal breathing during the inspiration phase with a high volumetric flow rate of 90 liters/minute and the inspired air temperature of 100 degrees Celsius. The geometric model depicting the upper HRT is generated based on the data available and literature cited. The results of the simulation give the temperature distribution along the center and the surface tissue of the respiratory tract. This temperature distribution will help to assess the level of damage induced in the upper respiratory tract and appropriate treatment for the damage. A comparison of nasal breathing, oral breathing, and oronasal breathing is performed. Temperature distribution can be utilized in the design of the respirator systems where inlet temperature is regulated favoring the human body conditions.

Background: Since nasal respiration is physiologically important, many studies have been conducted to find factors necessitating a change from nasal breathing into oronasal breathing during exercise. The present study tried to understand the role of anterior nasal resistance in this switching. Methods: Twelve young, healthy, non-athletic and non-smoker male volunteers with normal body mass index (BMI) were selected after medical examinations. Following anterior rhinomanometry at rest, the subjects participated in an exercise protocol during which ventilation, workload and oronasal switching point (OSP) were measured. The protocol involved a 25 watt increase in workload per minute until the OSP was reached. Findings: There were significant correlations between anterior nasal resistance and OSP, workload, and ventilation difference to OSP ratio (P < 0.05). Conclusion: Anterior nasal resistance can be considered as an effective factor on OSP occurrence. In addition, by reducing nasal resistance, one can tolerate longer periods of nasal respiration during exercise.

In plutonium (Pu) handling facilities, there is a potential for internal exposure of radiation workers along with external exposure. Nasal swabs (NS) taken rapidly, on site, help in not only providing an early estimate of internal dose due to inhalation of Pu but also in decision making for medical intervention. However, the Committed Effective Dose (CED) computed based on the observed NS activity and that estimated from bioassay measurements of individuals may vary significantly. One of the reasons would be the use of default particle size (5 μm) for computing the CED based on the activity on NS. Other parameters like breathing pattern and levels of exercise would also influence the NS reference activity level and hence their impact needs to be assessed. This study indicated that observed NS reference levels had a direct dependence on all these parameters and use of default parameters for evaluation of internal dose based on NS activity would result in large uncertainties in the dose assessment. [ABSTRACT FROM AUTHOR]

Background: Since nasal respiration is physiologically important, many studies have been conducted to find factors necessitating a change from nasal breathing into oronasal breathing during exercise. The present study tried to understand the role of anterior nasal resistance in this switching. Methods: Twelve young, healthy, non-athletic and non-smoker male volunteers with normal body mass index (BMI) were selected after medical examinations. Following anterior rhinomanometry at rest, the subjects participated in an exercise protocol during which ventilation, workload and oronasal switching point (OSP) were measured. The protocol involved a 25 watt increase in workload per minute until the OSP was reached. Findings: There were significant correlations between anterior nasal resistance and OSP, workload, and ventilation difference to OSP ratio (P < 0.05). Conclusion: Anterior nasal resistance can be considered as an effective factor on OSP occurrence. In addition, by reducing nasal resistance, one can tolerate longer periods of nasal respiration during exercise. [ABSTRACT FROM AUTHOR]

Background and Objective: Breathing through the nose and mouth is one of the controversial issues during exercise. The present study was scheduled to investigate a quantitative approach to habitual versus the obligatory switching point from nasal to oronasal breathing during exercise as well as coincidence of soft palate movement as the main aims of this study, that has not been studied previously. Materials and Methods: In this experimental study, twenty-five young adult volunteers (12 males and 13 females) participated in the study. An incremental exercise protocol was incorporated in three protocols for determination of switching point from nasal to oronasal breathing during habitual, obligatory conditions, and determination of change in soft palate position. In two latter conditions, subjects were advised to breathe via nasal route as long as they could. Switching point from nasal to oronasal breathing was determined by a CO2 2]: sensor. ed nasal breathing. Obligatory opening of mouth and change in soft palate position were coincident. Ventilation increment at habitual shift from nasal to oronasal respiration was lower than obligatory one. Switching time to oronasal breathing correlated either with ventilation increment or exercise workload. Rate of ventilation was higher in females but switching time was significantly longer in males in three mentioned conditions. In the last two protocols, ventilation incrimination was significantly lower in females. Conclusion: In conclusion, duration of tolerated nasal breathing was longer than habitual one and changes in the position of soft palate occurs simultaneously. [ABSTRACT FROM AUTHOR]

We measured the partitioning of airflow between nasal and oral circuits in five species of lizards before, during and after exercise. Expired gases were measured separately from the mouth and nose circuits in order to estimate the relative contribution of each circuit to ventilatory airflow. Nasal breathing dominates before exercise; however, during exercise the breathing pattern switched to oronasal expiration. Airflow averaged 30% oral expiration across all species during and after exercise. These results have important implications for the design of appropriate masks for respirometry in lizards. In order to ensure that all gases are captured, it is critically important that both the nose and mouth circuits are sampled. [ABSTRACT FROM AUTHOR]

We examined oronasal flow partitioning in 27 volunteers with normal or slightly increased nasal resistance (mean ± SD, 0.24±0.19 kPa/l/s). Mean percentage of inspiratory nasal flow contribution was measured during spontaneous oronasal breathing. The averaged nasal admixture of airflow differed considerably within and between all subjects (mean ± SD, 20.9%±16.5%; range 1%-70%), showing no correlation to nasal resistance. Five of 27 subjects with a history of habitual mouth breathing had a significantly lower nasal admixture as compared with controls (2.5%±1.7% vs 25.1%±15.4%; P<0.005), but with no statistical difference in nasal resistance. To evaluate the hypothesis that velopharyngeal narrowing is due to an increased tone of the soft palate, measurements were also performed under positive nasal pressure, inspiratory resistive loading at the mouth, and during breath-holding. There was no significant difference of airflow distribution between these modifications and unloaded breathing in either group. These data suggest, therefore, that (a) oronasal flow distribution is due to active positioning of the soft palate, and that (b) habitual mouth breathing without any nasal obstruction may be associated with closure of the velopharyngeal isthmus as a consequence of disturbed neural control mechanisms. [ABSTRACT FROM AUTHOR]