Effects of inspiratory muscle training on thoracoabdominal volume regulation in older adults: a randomised controlled trial

James Manifield*, Charikleia Alexiou, Dimitrios Megaritis, Katherine Baker, Nicola Adams, Gill Barry, Ioannis Vogiatzis*

*Corresponding author for this work

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Abstract

Objectives
We investigated the effect of inspiratory muscle training (IMT) on inspiratory muscle strength, functional capacity and respiratory muscle kinematics during exercise in healthy older adults.

Methods
24 adults were randomised into an IMT or SHAM-IMT group. Both groups performed 30 breaths, twice daily, for 8 weeks, at intensities of ~50% maximal inspiratory pressure (PImax; IMT) or <15% PImax (SHAM-IMT). Measurements of PImax, breathing discomfort during a bout of IMT, six-minute walk distance, physical activity levels, and balance were assessed pre- and post-intervention. Respiratory muscle kinematics were assessed via optoelectronic plethysmography (OEP) during constant work rate cycling.

Results
PImax was significantly improved (by 20.0±11.9 cmH2O; p=0.001) in the IMT group only. Breathing discomfort ratings during IMT significantly decreased (from 3.5±0.9 to 1.7±0.8). Daily sedentary time was decreased (by 28.0±39.8 min; p=0.042), and reactive balance significantly improved (by 1.2±0.8; p<0.001) in the IMT group only. OEP measures showed a significantly greater contribution of the pulmonary and abdominal rib cage compartments to total tidal volume expansion post-IMT.

Conclusions
IMT significantly improves inspiratory muscle strength and breathing discomfort in this population. IMT induces greater rib cage expansion and diaphragm descent during exercise, thereby suggesting a less restrictive effect on thoracic expansion and increased diaphragmatic power generation.
Original languageEnglish
Article number104278
JournalRespiratory Physiology & Neurobiology
Early online date10 May 2024
DOIs
Publication statusE-pub ahead of print - 10 May 2024

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