All subjects (sixty men) will perform spirometry, measure of inspiratory capacity (IC) and maximal inspiratory and expiratory pressures (MIP and MEP). Baseline blood pressure (BP), respiratory rate (RR), heart rate (HR), sensation of dyspnea (Borg Scale) and oxygen saturation (pulse oximetry, SpO2) will be collected prior to the performance of pulmonary function tests.
The electrical activity of the scalene (ESC), sternocleidomastoid (SCM) and external intercostal muscles (INTER) will be measured by surface electromyography (sEMG) at rest and during the maneuvers of IC, MIP and MEP.
Control group: The control group will perform isotonic concentric contraction of the biceps (two sets of five push-ups elbow in both arms) with the individual sitting in a chair with back support.
Intervention group: The contract-relax method of proprioceptive neuromuscular facilitation (PNF) technique will be used for stretching of ESC, ECM and external intercostals muscles. The contraction of agonist muscles against the resistance imposed by the physiotherapist (isometric contraction) is maintained for 6 seconds. After that, the patient will be asked to relax the muscles for 6 seconds without losing range of motion, and then the muscle will be lengthened. This procedure is repeated until the maximum amplitude of motion of the neck and upper limb is reached. The stretching will be performed on the right and left sides of the body.
Statistical analysis will be carried out with the Statistical Package for the Social Sciences, version 18.0 (SPSS Inc., Chicago, IL, USA). Normality of data distribution will be assessed by the Shapiro-Wilk test.
Values will be presented as mean ± standard deviation (SD) or median (25-75%). To compare the differences between the baseline characteristics between the groups the t test for independent samples will be used. The effect of the intervention will be evaluated by paired t test. For the analysis of the electromyographic signal will be use the Wilcoxon T test. Statistical significance is accepted at p \< 0.05.
