Respiratory Muscle Training in Patients With Spinal Muscular Atrophy (SMA).

The goal of this clinical trial is to study respiratory muscle training in patients with Spinal Muscular Atrophy (SMA). The main questions it aims to answer are:Is a home-based individualized training program for the inspiratory and expiratory muscles feasible (good adherence and good acceptability)?Can a home-based individualized training program for the inspiratory and expiratory muscles increase the strength of these muscles? Participants will be asked to perform 10 training sessions per week, spread out over 5-7 days. Each training session consists of 30 breathing cycles through the inspiratory muscle trainer and 30 breathing cycles trough the expiratory muscle trainer.In the first four months of the study researchers will compare two groups to see if a higher trainings load is more effective.One group will start at a trainings load of 10% of their maximal inspiratory and expiratory muscle strength.The other group will start at a trainings load of 30% of their maximal inspiratory and expiratory muscle strength. This group also need to adjust the trainings load based on their perceived exertion.After four months all participants will train on a trainings load of 30% of their maximal inspiratory and expiratory muscle strength and adjust the trainings load based on their perceived exertion.The participants will come to the hospital for lung function tests every four months for 12 months.

Inclusion Criteria:Age ≥ 8 years;Respiratory muscle weakness (PImax ≤80 cmH2O (31));Maintenance dose (≥2 months) Spinraza® or (≥2 months) Risdiplam or no treatment;Given oral and written informed consent when ≥18 years old and additional informed consent by the parents or legal representative if the participant is <16 years old.Exclusion Criteria:Inability to perform respiratory and/or lung-function testing;Inability to understand Dutch or English;A history of pneumothorax or symptomatic low cardiac output syndrome;Treatment period < 2 months of Spinraza® or Risdiplam