Objectives: To examine the effect of the method on inspiratory and expiratory muscle strength and on the chest expansion of sedentary patients. Specific objectives: to explain the Isostretching technique, to classify inspiratory and expiratory muscle strength, to measure chest expansion at the axillary level, the xiphoid process and the basal region of the study population, and to discuss the data obtained before and after the Isostretching method intervention. Methodology: It is characterized as an exploratory research, where 5 sedentary volunteers were evaluated through the manovacuometer and the cirtometry and performed 20 sessions of the Isostretching method. Results: In relation to MIP values. 41.7% and 25.7% of MEP increased, while values for chest expansion were 39% at axillary level, 43.9% at xiphoid and 48.8% at baseline . Conclusion: In the study presented on Isostretching, the technique applied in sedentary patients during 20 sessions, obtained relevant data on respiratory mechanics.