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Received Nov 6, 2017; Accepted Jan 30, 2018
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1. Introduction
Altered body position influences the respiratory muscle strength and function in both healthy adults [1–5] and patients with cardiopulmonary dysfunction [6, 7]. A study by Costa et al. [1] reported significantly lower maximal inspiratory and expiratory mouth pressures in supine or semiupright sitting positions compared to the sitting position in healthy young adults. Similarly, Koulouris et al. [2] reported reduced respiratory muscle strength in the supine position compared to sitting position. Biomechanically, the length of the muscle affects the ability of a muscle fiber to develop active tension known as length-tension relationship [8]. Therefore, it is assumed that the changes in the ribcage may cause altered length-tension relationship of the respiratory muscles, such as diaphragm, resulting in reduced ability of these muscles to develop tension and consequently reducing the rate and depth of the breathing [1].
The measurement of the respiratory muscle strength is vital in the evaluation of therapeutic effects of various interventions for the respiratory muscle weakness or dysfunction [9]. Inspiratory muscle strength can be measured using a simple, reliable, and valid test known as sniff nasal inspiratory pressure (SNIP) [10–13]. The SNIP is a noninvasive, easy, and more acceptable technique compared to the static effort of the maximum inspiratory pressure [13] and has been an alternative [12, 14] to the measurement of the maximal inspiratory pressure.
The body position has a vital role in the cardiopulmonary physical therapy. Several positions, including sitting, supine, side lying, and semi-Fowler positions, have been adopted by the patients during the treatment sessions [1]. Nevertheless, these positions could influence the performance of the respiratory muscles during therapeutic interventions. This is especially applicable as the improvement of the inspiratory muscles’ strength in respiratory conditions, which are likely to become weak, is an essential outcome measure for physiotherapists [1]. The present study aimed to compare the effects of upright and slouched sitting postures on the respiratory muscle strength in healthy young males.
2. Methods
2.1. Subjects
A convenience sampling technique was used to recruit subjects from the College of...