Objectives The aim of this study was to evaluate the acute effects of different inspiratory loads and different interfaces on the breathing pattern and activity of the respiratory muscles. Methods Twenty healthy adults were recruited and assigned to two groups (20 and 40% of the Maximal Inspiratory Pressure) by way of randomized crossover allocation. Subjects were evaluated during quiet breathing, breathing against inspiratory load, and recovery. The measurements were repeated using two different interfaces (nasal and oral). Chest wall volumes and respiratory muscle activity were assessed with optoelectronic plethysmography and surface electromyography, respectively. Results During the application of inspiratory load, significant changes were observed in the respiratory rate ( p < 0.04), inspiratory time ( p < 0.02), minute ventilation ( p < 0.04), tidal volume ( p < 0.01), end-inspiratory volume ( p < 0.04), end-expiratory volume ( p < 0.03), and in the activity of the scalene, sternocleiomastoid, and parasternal portion of the intercostal muscles (RMS values, p < 0.01) when compared to quiet breathing, regardless of the load level or the interface applied. Inspiratory load application yielded significant differences between using nasal and oral interfaces with an increase in the tidal volume ( p < 0.01), end-inspiratory volume ( p < 0.01), and electrical activity of the scalene and sternocleiomastoid muscles ( p < 0.01) seen with using the nasal interface. Conclusion The addition of an inspiratory load has a significant effect on the breathing pattern and respiratory muscle electrical activity, and the effects are greater when the nasal interface is applied.

AimThe aim of this study was to evaluate the acute effects of different inspiratory resistance devices and intensity of loads via nasal airway on the breathing pattern and activity of respiratory muscles in children with mouth breathing syndrome.MethodsChildren with mouth breathing syndrome (MBS) were randomized into two groups based on inspiratory load intensity (20% and 40% of the Maximal Inspiratory Pressure). These subjects were assessed during quiet breathing, breathing against inspiratory load via nasal airway and recovery. The measurements were repeated using two different devices (pressure threshold (PT) and flow resistance (FR)). Chest wall volumes and respiratory muscle activity were evaluated by optoelectronic plethysmography and surface electromyography, respectively.ResultsDuring the application of inspiratory load, there was a significant reduction in respiratory rate (p<0.04) and an increase in inspiratory time (p<0.02), total time of respiratory cycle (p<0.02), minute volume (p<0.03), tidal volume (p<0.01) and scalene and sternocleidomastoid muscles activity (RMS values, p<0.01) when compared to quiet spontaneous breathing and recovery, regardless of load level or device applied. The application of inspiratory load using the FR device showed an increase in the tidal volume (p<0.02) and end-inspiratory volume (p<0.02).ConclusionFor both devices, the addition of inspiratory loads using a nasal interface had a positive effect on the breathing pattern. However, the FR device was more effective in generating volume and, therefore, has advantages compared to PT.

BACKGROUND: Advanced stages of Duchenne muscular dystrophy (DMD) result in muscle weakness and the inability to generate an effective cough. Several factors influence the effectiveness of cough in patients with DMD. The aim of this study was to assess whether differences in positioning affect cough peak flow (CPF) and muscular electromyographic activation in subjects with DMD compared with paired healthy subjects. METHODS: Optoelectronic plethysmography and surface electromyography were used to assess chest wall volumes, chest wall inspiratory capacity, CPF, breathing pattern, and electromyographic activity of sternocleidomastoid, scalene, rectus abdominis, and external oblique muscles during inspiratory and expiratory cough phases in the supine position, supine position with headrest raised at 45 , and sitting with back support at 80 in 12 subjects with DMD and 12 healthy subjects. RESULTS: Subjects with DMD had lower CPF (P < .01) in comparison to control subjects in all positions; the DMD group also exhibited lower CPF (P 5 .045) in the supine position versus 80. Moreover, the relative volume contributions of the rib cage and abdominal compartments to tidal volume modified significantly with posture. The electromyographic activity during inspiratory and expiratory cough phases was lower in subjects with DMD compared to healthy subjects for all evaluated muscles (P < .05), but no significant differences were observed with posture change. CONCLUSIONS: In subjects with DMD, posture influenced CPF and the relative contribution of the rib cage and abdominal compartments to tidal volume. However, muscular electromyographic activation was not influenced by posture in subjects with DMD and healthy subjects.

Introdução: Obesidade infantil, inatividade física e baixo nível de aptidão física geram consequências precoces na saúde cardiovascular e metabólica. Objetivos: Comparar o nível de atividade física (IPAQ versão curta) com aptidão cardiorrespiratória (shuttle run test) em escolares com sobrepeso/obesos. Métodos: Realizou-se estudo da prevalência de sobrepeso/obesidade em 334 escolares, divididos posteriormente em dois grupos: G1, com sobrepeso/obesos (n=39), e G2, eutróficos (n=39), para a aplicação do IPAQ versão curta e shuttle run test. Resultados: Classificaram-se 261 escolares como eutróficos; 56 como obesos/com sobrepeso; e 17 com desnutrição/desnutrição severa. Não houve diferença significativa no IPAQ versão curta (p

BACKGROUND: We sought to evaluate the acute effects of different inspiratory loads using nasal and oral interfaces on the volumes of the chest wall and its compartments, breathing pattern, and respiratory muscle activation in children with mouth-breathing syndrome. METHODS: Children with mouth-breathing syndrome were randomized into 2 groups, one with an inspiratory load intensity 20% of maximum inspiratory pressure (n 5 14), and the other with an inspiratory load intensity 40% of maximum inspiratory pressure (n 5 15). The chest wall volumes and electromyography of sternocleidomastoid, rectus abdominis, scalene, and internal intercostal muscles were used to analyze respiration against the 2 load intensities and using 2 interfaces (ie, nasal and oral). RESULTS: A total of 72 children with mouth-breathing syndrome were recruited, and 29 were evaluated in this study. The use of inspiratory load promoted improvement in the components of the breathing pattern: breathing frequency (P 5 .039), inspiratory time (P 5 .03), and total respiratory time (P 5 .043); and increases in tidal volume (P < .001), end-inspiratory volume (P < .001), and electrical activity of scalene muscles and sternocleidomastoid muscles (P < .001) when compared to quiet breathing. The load imposed via a nasal interface versus an oral interface provided an increase in tidal volume (P 5 .030), endinspiratory volume (P 5 .02), and electrical activity of scalene muscles (P < .001) and sternocleidomastoid muscles (P 5 .02). CONCLUSIONS: The use of acute inspiratory loads improved the breathing pattern and increased lung volume and electrical activity of inspiratory muscles. This work brings new perspective to the investigation of using nasal interfaces during the application of inspiratory loads. The nasal interface was more effective compared to the oral interface commonly used in clinical practice.

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