S10 The effect of inspiratory muscle training in older adults: a randomised-controlled trial

J Manifield,K Baker,N Adams,D Megaritis,G Barry,C Alexiou,I Vogiatzis

doi:10.1136/thorax-2022-btsabstracts.16

Abstract

<h3>Objectives</h3> We investigated the effect of inspiratory muscle training (IMT) on inspiratory muscle strength, functional capacity and respiratory muscle kinematics during exercise in older adults. <h3>Methods</h3> 24 older adults (age: 68.3±2.5 years) were evenly randomised into an experimental (IMT) or control (SHAM-IMT) group. Both groups performed 30 breaths, twice daily, for 8 weeks, with the IMT group training at an intensity of ~50% maximal inspiratory pressure (PImax) and the SHAM-IMT group training at an intensity of <15% PImax. Measurements of PImax, breathing discomfort (Borg scale ratings) during a bout of IMT at 50% PImax, 6MWT, accelerometry-assessed physical activity levels, and balance (mini-BEST), were assessed pre- and post-intervention. Furthermore, respiratory muscle kinematics were assessed via optoelectronic plethysmography (OEP) during constant work rate cycling at the same absolute intensity (75% predicted peak work rate) before and after training. Participant views towards the intervention were explored via interviews. <h3>Results</h3> Inspiratory muscle strength (reflected by an increased PImax) was significantly improved in the IMT group (by 20.0±11.9 cmH<sub>2</sub>O; p=0.001) but not in the SHAM-IMT group (by 2.24±9.3 cmH<sub>2</sub>O). Breathing discomfort ratings significantly decreased (from 3.5±0.9 to 1.7±0.8) following IMT but did not change (3.6±1.0 to 3.3±1.2) in SHAM-IMT. The 6MWD increased by 18.8±28.4 m (p=0.042) in the IMT group with no change (-0.4±29.0 m) in SHAM-IMT. Sedentary time was decreased following IMT (by 28.0±39.8 min; p=0.042), and the reactive component within the mini-BEST balance was 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 the total tidal volume (V<sub>T</sub>) expansion only in the IMT group. Older adults reported positive experiences with IMT, highlighting facilitators such as ease of use and sessions not being time-consuming. <h3>Conclusions</h3> IMT significantly improved inspiratory muscle strength, IMT-induced breathing discomfort, and functional capacity in this population. Observations of respiratory muscle kinematics during exercise suggest greater expansion of the rib cage compartment following IMT, potentially due to a greater contribution of intercostal muscles and the diaphragm. Qualitative measures revealed that IMT is well-tolerated in healthy older adults.

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