Chronic Obstructive Pulmonary Disease (COPD) is characterized by chronic airflow limitation, a qualification of impairment of respiratory muscle function, including hyperinflation and muscle weakness. Thus, pulmonary rehabilitation is indicated for patients and is recommended for even the most severe cases. However some patients do not conclude conventional rehabilitation protocols, due to exercise intolerance, are then an electrical estimation and muscle training respiratory adjuvant treatments for patients. and little has been explored about the effects and methodologies of using TEDS in healthy subjects. The objective of this study on stage I is to evaluate the acute effect of transcutaneous electrical diaphragmatic stimulation on respiratory muscle strength, cardiac variability, thickness, resistance, mobility and diaphragmatic activation comparing different frequencies of electrical stimulation in healthy individuals.The objective of this study on stage II is to evaluate the effects of transcutaneous electrical diaphragmatic stimulation, compared to inspiratory muscle training on respiratory muscle strength, security of the technics, thickness and diaphragmatic function in healthy individuals.The objective of this study on stage III is to evaluate the effects of transcutaneous electrical diaphragmatic stimulation, compared to inspiratory muscle training on respiratory muscle strength, lung function, thickness and diaphragmatic function in patients with exacerbated chronic obstructive pulmonary disease. Methods: The Stage I is a cross-over Randomized Controlled Trial (RCT) in the first stage of this research, which will be performed at the Exercise Research Laboratory (LAPEX) of the School of Physical Education, Physiotherapy and Dance of the Universidade Federal do Rio Grande do Sul, the Stage II and is a randomized crossover clinical trial, to be performed at the Exercise Physiology Laboratory (LAFIEX) of Hospital de Clínicas de Porto Alegre (HCPA). Healthy individuals aged between 20 and 60 years, fully aware and cooperative, randomized into two groups will be included: one group that will perform TEDS and another that will perform IMT in a single session. TEDS will be applied with symmetrical biphasic pulsed current, frequency 30 Hertz (Hz), pulse width 0.5 ms, rise time of 1 second, sustain of 1s, descent of 2 s, maintaining respiratory rate of 15 rpm, intensity necessary to obtain muscle contraction visible, for 30 minutes or until muscle fatigue, daily. The IMT will be performed with the PowerBreath device with a charge of 50-60% of the PImax, for 30 breaths and Stage III will be an RCT, which will be performed at the Hospitalization Units of Hospital de Clinicas de Porto Alegre (HCPA). In the first stage only healthy individuals will be included, who will be randomized to TEDS, in the first day (group 1) the parameters will be with 30 hertz (Hz) frequency and the second day (group 2) will be with 80 Hz, with one-day interval between interventions. The TEDS will be applied with symmetrical biphasic pulsed current, pulse width 0.4 ms, rise time of 1 second (s), 1s lift, 2 s descent, maintaining respiratory rate of 15 breaths per minute, intensity required to obtain visible muscle contraction, for 20 minutes or until muscle fatigue. In this stage, heart rate variability, thickness and diaphragmatic mobility by ultrasonography, diaphragmatic activation by electromyography, inspiratory muscle endurance with powerbreath, and respiratory muscle strength by manovacuometry, before and at the end of treatment, the following variables will be measured. In the second stage patients with COPD (GOLD III and IV) hospitalized for exacerbation of the disease, who will be randomized into three groups: one group that will perform TEDS, another will perform IMT and a third group that will only perform conventional physiotherapy. The TEDS will be applied with symmetrical biphasic pulsed current, frequency 30 Hz, pulse width 0.4 ms, rise time of 1 second, sustain of 1s, decrease of 2 s, maintaining respiratory rate (RR) of 15 breaths per minute (rpm), intensity required to obtain visible muscle contraction for 20 minutes or even muscle fatigue daily. The IMT will be performed with the Power Breath device with load referring to 30-60% of PImax, during 30 breaths daily. Conventional physical therapy will be HCPA standard. In this stage, before and at the end of treatment, the following variables will be measured: respiratory muscle strength through manovacuometry, pulmonary function through spirometry, diaphragmatic thickness through echocardiography, diaphragmatic function through respiratory electroneuromyography, Body Mass-Index, Airflow Obstruction, Dyspnea and Exercise Capacity (BODE) Index with mass index (BMI), functional capacity through the six-minute walk test, dyspnoea by the Borg Scale and Medical Research Council (MRC) Scale, cardiovascular variables and time of hospitalization through the electronic medical record. The interventions will be carried out from the patient's hospitalization to the hospital discharge.