Inspiratory Muscle Training Speeds Up COVID-19 Recovery

Liam Davenport

September 10, 2021

The rate of recovery from COVID-19 infection can be significantly increased by home-based inspiratory muscle training (IMT) as part of a patient’s rehabilitation programme, suggest early results from a UK trial.

Melitta McNarry, professor, sport and exercise sciences, Swansea University, and colleagues randomised COVID-19 patients whose primary symptom was breathlessness to an 8-week IMT or control arm.

Results in the first 87 participants showed that the intervention, which was delivered via video call, significantly improved not only breathing measures but also fitness and fatigue.

The findings were presented at the European Respiratory Society International Congress (ERS) 2021 on September 5.

IMT "significantly accelerated" recovery from COVID-19, said Professor McNarry, and is an "acceptable and feasible home-based rehabilitation tool".

Consequently, it "should be considered for wider implementation as part of COVID-19 recovery strategies".

Promising Initial Results

Dr Daniel Langer, secretary of the European Respiratory Society’s Assembly for Allied Respiratory Professionals, said the study has "promising initial results".

However, he told Medscape News UK that the "absence" of a proper control group in the current data "means that we need to be cautious to formulate strong conclusions regarding the effects of this intervention".

Dr Langer, who is assistant professor at the Department of Rehabilitation Sciences, Respiratory Rehabilitation Group at KU Leuven, Belgium, added that "substantial spontaneous recovery" is to be expected in these patients.

Consequently, more data "will be needed in the future to validate these initial findings" and to determine in which COVID-19 patients respiratory muscle weakness is the "most prevalent" feature.

If those hurdles can be overcome, Dr Langer believes that "in patients with pronounced weakness, IMT might be a useful intervention".

Breathlessness

Professor McNarry noted that previous research has shown COVID-19 infection is associated with high rates of breathlessness, in around 70% of patients in the acute phase and approximately 40% during follow-up.

Increasing breathlessness forms a vicious cycle, as it leads to reduced activity, which reinforces social isolation and increases depression, which in turn increases breathlessness further, she said.

Physical deconditioning can then result. Combined with hypoxia, chronic inflammation, medication exposure, and poor nutrition due to chronic lung disease, this can lead to peripheral muscle dysfunction and, eventually, disability.

As recent meta-analyses have suggested that IMT leads to clinically meaningful decreases in breathlessness and increases in functional capacity, as well as improvements in quality of life, the team examined whether it could help in post COVID-19 rehabilitation.

They randomised adults recovering from self-reported COVID-19 infection who had a primary symptom of shortness of breath to an 8-week IMT programme or a control arm, with a ratio of 4:1 intervention to control participants.

The intervention consisted of three sessions per week at 80% maximal capacity, delivered remotely via Zoom.

At baseline and following the intervention, participants completed the King’s Brief Interstitial Lung Disease Questionnaire (KBILD) and the Chester Step Test to determine overall fitness. They also wore a device to examine physical activity levels.

Study Results

Two hundred and fifty adults, with an average age of 48 years and of whom 84% were female, were included. Complete data is currently available for the first 87 participants, which includes 68 assigned to IMT.

The intervention improved all domains of the KBILD, with breathlessness reduced by a significant 33% (p<0.001), or twice the minimally clinical important difference.

IMT was associated with a significant improvement in maximal inspiratory pressure (IMP), from 75 cm H2O at baseline to 117 cm H2O at follow-up (p<0.001). Sustained IMP also improved significantly, from 420 pressure-time units to 575 pressure-time units (p<0.001).

The fatigue index also increased significantly with IMT, from 17 au at baseline to 23 au at follow-up (p<0.001), while fitness rose from 36 ml/kg/min to 44 ml/kg/min (p<0.001).

While participants in both the intervention and control arms improved over time, the magnitude of improvement with IMT was two to 14 times greater than that seen with controls.

The intervention was, however, not associated with changes in overall physical activity.

No funding declared.

No relevant financial relationships declared.

European Respiratory Society International Congress 2021: Abstract 169. Presented 5 September

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