The RESISTANT study (Respiratory Muscle Training in Patients with Spinal Muscular Atrophy): results of a randomized controlled trial.

OBJECTIVES

To investigate the efficacy and feasibility of respiratory muscle training (RMT) in patients with spinal muscular atrophy (SMA) and respiratory muscle weakness.

DESIGN

A 4-month, single-blinded RCT, followed by an 8-month extension phase.

SETTING

The outpatient clinic of the Neurology department and the Child Development and Exercise Center at the University Medical Center Utrecht, The Netherlands.

PARTICIPANTS

30 participants, ≥eight years, SMA type 1 to 4, and respiratory muscle weakness.

INTERVENTIONS: The training group started RMT at 30% of their maximum inspiratory (PImax) and expiratory pressure (PEmax) and adjusted their training intensity based on perceived exertion. The control group started and continued RMT at 10% of PImax and PEmax. After four months, the control group received the same RMT as the training group.

MAIN OUTCOME MEASURES: The primary outcome was the between-group difference in PImax after the RCT phase. Additionally, we explored the association between training volume (i.e., number of training sessions x training intensity) and increase in PImax over 1 year.

RESULTS

25 participants completed the study. Mean PImax after four months (corrected for baseline value) training group: 61.1 cmH2O, control group: 54.3 cmH2O, mean difference in PImax: 6.8 cmH2O [95% CI: -2.0 to 15.6]. Despite the study being underpowered, we did find an association between training volume and increase in PImax (R2 = 0.531).

CONCLUSION

There was a small between-group difference in PImax after the RCT phase. The training was safe, but the feasibility of the training needs further improvement.

CLINICAL TRIAL REGISTRATION NUMBER: NL73280.041.20. CONTRIBUTION OF THE PAPER.