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

Spinal muscular atrophy often weakens the breathing muscles, and physiotherapists have long wondered whether targeted respiratory muscle training can meaningfully strengthen them. This trial compared a higher-intensity training protocol, starting at 30% of a person's maximum inspiratory and expiratory pressure, against a low-intensity version started and held at 10%, in people aged eight and older with SMA types 1 to 4. After four months, the higher-intensity group showed a somewhat higher average inspiratory pressure than the control group, but the difference was small and the confidence interval crossed zero, meaning the trial did not detect a statistically significant between-group difference. An exploratory analysis did find that people who trained more, combining more sessions with higher intensity, tended to gain more inspiratory strength over the full year, though this association does not prove the training caused the improvement.

The training was reported as safe, but the authors note the approach still needs refinement to be practically feasible, and this was a small trial of 30 enrolled participants, with 25 completing it.

If you or someone you care for has spinal muscular atrophy, breathing muscle weakness is a common concern, and researchers wanted to know whether practicing breathing exercises at a higher effort level helps those muscles grow stronger compared with a much easier version of the same exercises. In this study, one group trained at a higher starting intensity while another trained at a very low intensity for four months, after which the low-intensity group switched to the higher-intensity program too. After four months, the higher-intensity group showed a slightly stronger inspiratory muscle measurement on average, but the difference between the two groups was small and not statistically meaningful, so the study cannot say for sure that the higher-intensity training made a real difference.

Interestingly, people who trained more often and harder over the full year tended to show bigger improvements, though this pattern doesn't prove the training caused it. The training did not cause safety problems in this study.

This was a small trial, so these findings are preliminary, and the researchers themselves said the training approach needs further refinement before it becomes more practical to use.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This randomised controlled trial addresses a specific clinical question: does increasing the intensity of respiratory muscle training, from 10% to 30% of maximum inspiratory and expiratory pressure, produce a meaningfully greater strength gain in people with SMA who have respiratory muscle weakness, compared with ongoing low-intensity training. After four months, the primary outcome, maximum inspiratory pressure, was somewhat higher in the training group (61.1 cmH2O versus 54.3 cmH2O, adjusted mean difference 6.8 cmH2O, 95% CI -2.0 to 15.6), but the confidence interval crossing zero means no statistically significant between-group difference was detected. An exploratory secondary analysis found an association between cumulative training volume (sessions times intensity) and inspiratory pressure gains over the full year (R2 = 0.531), which is a correlational finding within a small, likely underpowered sample and should not be read as proof that higher training volume causes greater strength gain.

The control group eventually received the same higher-intensity protocol after month four, so the extension phase does not add an independent control comparison. For practice, this study offers preliminary signal that training intensity and volume may matter for respiratory muscle training in SMA, but it does not establish clinical benefit from higher-intensity protocols, and the authors themselves flag that feasibility of the approach needs improvement. With 30 enrolled and 25 completing, and no statistically significant primary result, this evidence should inform discussion of respiratory training approaches cautiously rather than change standard practice.