Inspiratory muscle training at 50% of MIP, the training load was set each 2 weeks to keep 50% of MIP.

Expiratory muscle training at 50% of MEP, following the same rules as HIT.

Respiratory training, performed through IMT, was carried out with a pressure threshold device (Treshold IMT, Philips-Respironics, Pittsburg, PA, USA). Threshold IMT offers a constant and specific pressure for strength and endurance training of the respiratory muscles, regardless of the strength or speed with which patient breathes. A flow-independent one-way valve ensures constant resistance and allows you to specifically adjust workload (in cmH2O). The training must be supervised by a healthcare professional. During the inspiration, a spring-loaded valve resists to stimulate the training of the respiratory muscles. Before training began, the participants and primary caregivers completed one-session familiarization with a specialist to know the operation of the device.

Adult people with acquired brain injury carried out the training program for 8 weeks, 1 session every day, 5 days a week. The participants performed 5 series of 1 minute with 1-minute rest between them.

It was measured using the maximum inspiratory pressure (MIP) with a pressure measurer (Elka PM-15, Laboliser, S.A., Barcelona, Spain), from residual volume and total lung capacity. Unit of measure, centimeter of water (cmH2O).

It was measured using the maximum expiratory pressure (MEP) with a pressure measurer (Elka PM-15, Laboliser, S.A., Barcelona, Spain), from residual volume and total lung capacity. Unit of measure, centimeter of water (cmH2O).

Forced expiratory volume in 1 second (FEV1). It was measured using the peak flow device (Asma-1, Vitalograph Ltd, Buckingham, England). Unit of measure, liters (L).