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Background: Skeletal muscle dysfunction is common in COPD. Ultrasound-derived rectus femoris cross-sectional area (RFCSA) is a radiation free, non-invasive measure of muscle bulk that relates to quadriceps strength in people with COPD. However, there are limited longitudinal data for RFCSA, and it is not known whether longitudinal change in RFCSA reflects change in quadricep strength, exercise capacity, lower limb function or muscle mass. We aimed to quantify longitudinal change in ultrasound-derived RFCSA and assess its relationship with change in quadriceps maximal voluntary contraction (QMVC), incremental shuttle walk test (ISWT), five-repetition sit-to-stand (5STS) and fat-free mass (FFM) over 12 months in people with COPD., Methods: We measured ultrasound-derived RFCSA, QMVC, ISWT, 5STS and FFM (measured by bioelectric impedance analysis) at baseline and 12 months in 169 people with stable COPD. Change was correlated using Pearson's or Spearman's coefficients., Results: Baseline characteristics: mean±sd age 70.4±9.4 years; FEV 1 53.3±18.9% predicted. Over the course of 12 months mean RFCSA change was -33.7 mm 2 (99% CI -62.6- -4.9 mm 2 ; p=0.003) representing a mean±sd percentage change of -1.8±33.5%. There was a weak correlation between change in RFCSA and FFM (r=0.205, p=0.009), but not with change in QMVC, ISWT or 5STS., Conclusion: There is a statistically significant decrease in ultrasound-derived RFCSA over 12 months in people with stable COPD, but this decrease does not correlate with change in quadriceps strength, exercise capacity, FFM or lower limb function., Competing Interests: Conflict of interest: T.O. Jenkins reports grants from the Royal Brompton and Harefield Hospital Charity, outside of the submitted work. T.O. Jenkins received funding from the National Institute for Health Research to undertake the submitted work. C.M. Nolan reports grants from the National Institute for Health and Care Research, Royal Brompton and Harefield Hospital Charities, and Brunel University London, outside of the submitted work. M. Maddocks reports grants from the National Institute for Health Research, the European Commission and UKRI Innovate UK, outside of the submitted work. M. Maddocks received funding from the National Institute for Health Research to undertake the submitted work. W.D-C. Man reports grants from the National Institute for Health Research, outside of the submitted work. W.D-C. Man received funding from the Medical Research Council to undertake the submitted work. W-D.C. Man is an Associate Editor of this journal. The remaining authors report no grants outside of the submitted work, or to undertake the submitted work., (Copyright ©The authors 2024.)

Rationale: Standing from a sitting position is an important activity of daily living. The five-repetition sit-to-stand test (5STS) is a simple physical performance test that measures the fastest time taken to stand five times from a chair with arms folded. It can be measured in most healthcare settings and at home, where traditional field walking tests may not be possible. The 5STS has been validated in community-dwelling older adults and people with chronic obstructive pulmonary disease, but data in idiopathic pulmonary fibrosis (IPF) are limited. Objectives: The aims of this cohort study were to establish the construct validity, responsiveness to pulmonary rehabilitation (PR), and minimal important difference (MID) of the 5STS in IPF. Methods: In 149 people with IPF, we compared the 5STS with measures of lung function, exercise capacity, quadriceps strength, breathlessness, and health-related quality of life. Responsiveness and effect sizes were determined by measuring the 5STS before and after PR. The MID was estimated using anchor- and distribution-based methods. Results: The 5STS correlated significantly with incremental shuttle walk test (ISW) ( r  = -0.55), isometric quadriceps maximum voluntary contraction (QMVC) ( r  = -0.45), Medical Research Council dyspnea scale score ( r  = 0.40), Chronic Respiratory Questionnaire-Total ( r  = -0.21), and King's Brief Interstitial Lung Disease Questionnaire-Total ( r  = -0.21) but not forced vital capacity percentage predicted or quadriceps one-repetition maximum (1RM). There was a significant but very weak correlation between change in 5STS and changes in Medical Research Council ( r  = 0.18), ISW ( r  = -0.21), and Chronic Respiratory Questionnaire-Total ( r  = -0.26) but no significant correlation with change in 1RM ( r  = -0.12) or QMVC ( r  = -0.18). 5STS time improved with PR (median [25th percentile, 75th percentile] change, -1.97 [-3.47, -0.62] s; P  < 0.001). The effect size for the 5STS was 0.66 and higher than quadriceps 1RM, QMVC, and ISW. The mean (range) MID estimate was -1.93 (-1.85 to -2.10) seconds. Conclusions: In people with IPF, the 5STS is a valid physical performance measure that is responsive to exercise-based interventions and suitable for use in most healthcare settings.

Background: Remote delivery may improve access to pulmonary rehabilitation (PR). Existing studies are largely limited to individuals with COPD, and the interventions have lacked codesign elements to reflect the needs and experiences of people with chronic respiratory disease, their carers/families and healthcare professionals. The aim of this study was, using experience-based codesign (EBCD), to collaborate with people with interstitial lung disease (ILD), their carers/families and healthcare professionals, to codesign a remote PR programme ready for testing in a future study., Methods: EBCD comprises interviews, stakeholder workshops and codesign meetings. One-to-one videorecorded interviews with purposively selected people with ILD with experience of PR, their carers/families and healthcare professionals, were edited into a 20 min film. The film was shown at three audiorecorded stakeholder feedback events to identify key themes and touchpoints, and short-list key programme components. The programme was finalised at two further codesign workshops., Results: Ten people with ILD, four carers/families and seven healthcare professionals were interviewed. Participants in the codesign workshops included service-user group: n=14 and healthcare professional group: n=11; joint event: n=21. Final refinements were made with small codesign teams, one comprising three people with ILD and one carer/family member, one with five healthcare professionals. The final codesigned model is a group based, supervised programme delivered by videoconference. Key elements of programme specific to ILD include recommendations to ensure participant safety in the context of desaturation risk, dedicated time for peer support and adaption of the education programme for ILD needs, including signposting to palliative care., Conclusion: In this EBCD project, a remote PR programme for people with ILD was codesigned by service-users, their carers/families and multidisciplinary healthcare professionals. Future research should explore the feasibility and acceptability of this intervention., Competing Interests: Competing interests: NS, JG-N, KAI and JH report no competing interests. LJB was funded by an ESRC Post-doctoral fellowship ES/X005259/1 and was supported by the NIHR Applied Research Collaboration South London (NIHR ARC South London) at King’s College Hospital NHS Foundation Trust. CMN reports funding from the Royal Brompton and Harefield Charity, National Institute for Health Research for Patient Benefit and Brunel University London BRIEF award. WD-CM reports grants from National Institute for Health Research, grants from British Lung Foundation, outside the submitted work., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY. Published by BMJ.)