Home-based respiratory muscle training on quality of life and exercise tolerance in long-term post-COVID-19: Randomized controlled trial.
Tamara Del Corral, Raúl Fabero-Garrido, Gustavo Plaza-Manzano and 3 others
PMID 36191860WHAT IT FOUND
Eight weeks of home breathing-muscle training improved quality of life only in the group training both inspiratory and expiratory muscles, not in the group training inspiratory muscles alone, and did not improve exercise tolerance.
Inspiratory strength, endurance and leg strength improved in both real-training groups.
Key findings
01Quality of life improved in only one comparison: at eight weeks the combined inspiratory/expiratory training group scored higher than its matched sham group on the EQ-5D index by 0.151 points (95% CI 0.029 to 0.273, a large effect). No other between-group quality-of-life comparison was significant, and the authors note the combined group did not differ significantly from the inspiratory sham group.
02Exercise tolerance did not improve: there was no significant group-by-time interaction and no between-group difference at either time point. Only the combined training group improved relative to its own baseline value (p = 0.047).
03Both real training groups gained inspiratory muscle strength and endurance and lower-limb strength compared with their sham groups, while only the combined group gained expiratory muscle strength and peak expiratory flow.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 22 people per group and a single eight-week block of training; the authors themselves say the results should be extrapolated to clinical practice with caution. The quality-of-life gain rested on one comparison against the matched sham group, and combined training did not differ significantly from the inspiratory sham group. Exercise tolerance was measured with a field test (the Ruffier test), not full cardiopulmonary exercise testing. Breathlessness and fatigue were recorded only as present or absent, so the study cannot show whether the size of any effect depends on how severe those symptoms were. There was no follow-up beyond the end of the eight weeks, so nothing is known about whether any gains lasted, and no medium- or long-term outcomes were measured. Participants were mostly middle-aged women (average age around 46) with preserved lung function, and almost none had needed intensive care; the results may not transfer to people who were ventilated or who have residual lung damage. Participants and the therapist could tell which muscles were being trained, so expectation effects on the self-reported outcomes cannot be fully ruled out. Only respiratory muscle training was tested; the authors suggest larger studies should examine it added to another exercise programme such as aerobic training.
Declared interests
The authors declare they have no known competing financial interests or personal relationships that could have influenced the work. The supplied text does not say who funded the study or whether any funder had a role in it.
The easy way to misread this
Do not read this as proof that combined breathing training improves quality of life in long COVID. That result rested on one comparison against the matched sham group, and the combined-training group did not differ significantly from the inspiratory sham group. Each group had only 22 people and there was no follow-up after the eight weeks ended, so nothing is known about whether any gain lasted.
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