Effect of unstable surface during loaded-inspiratory task on diaphragm and trunk muscle activity in stroke patients.
Fang Liu, Alice Y M Jones, Raymond C C Tsang et al.
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In 30 seconds
This randomized controlled study examined whether seating surface affects respiratory and trunk muscle activity during loaded inspiratory efforts in 41 people after stroke. Participants performed 10 breaths at 50% of maximal inspiratory pressure while seated on a chair, with and without a balance pad. Compared with stable sitting, the unstable surface increased diaphragm thickening fraction by 20% on the non-affected side and 16% on the hemiplegic side (p < 0.001). Sternocleidomastoid activity decreased bilaterally, erector spinae activity increased, and abdominal muscle activity did not change significantly.
Key findings
- Diaphragm thickening fraction increased by 20% on the non-affected side and 16% on the hemiplegic side with unstable versus stable sitting (p < 0.001).
- Sternocleidomastoid activity decreased by nearly 10% bilaterally during loaded inspiration on the unstable surface.
- Erector spinae activity increased by 7% on both sides; abdominal muscle activity showed no significant change.
Why it matters
The findings suggest that adding a postural challenge during loaded inspiration can alter recruitment of the diaphragm and trunk muscles in people after stroke. This may be relevant when considering how inspiratory training tasks engage both breathing and balance-related musculature, although the study measured immediate muscle activity rather than longer-term respiratory or functional outcomes.
What to keep in mind
The study assessed muscle activity during 10 breaths in two seating conditions; it did not establish long-term effects on inspiratory function.