We defined respiratory sarcopenia as a coexistence of respiratory muscle weakness and decreased respiratory muscle mass. Although respiratory muscle function is indispensable for life support, its evaluation has not been included in the regular assessment of respiratory function or adequately evaluated in clinical practice. Considering this situation, we prepared a position paper outlining basic knowledge, diagnostic and assessment methods, mechanisms, involvement in respiratory diseases, intervention and treatment methods, and future perspectives on respiratory sarcopenia, and summarized the current consensus on respiratory sarcopenia. Respiratory sarcopenia is diagnosed when respiratory muscle weakness and decreased respiratory muscle mass are observed. If respiratory muscle mass is difficult to measure, we can use appendicular skeletal muscle mass as a surrogate. Probable respiratory sarcopenia is defined when respiratory muscle weakness and decreased appendicular skeletal muscle mass are observed. If only respiratory muscle strength is decreased without a decrease in respiratory function, the patient is diagnosed with possible respiratory sarcopenia. Respiratory muscle strength is assessed using maximum inspiratory pressure and maximum expiratory pressure. Ultrasonography and computed tomography are commonly used to assess respiratory muscle mass; however, there are insufficient data to propose the cutoff values for defining decreased respiratory muscle mass. It was jointly prepared by the representative authors and authorized by the Japanese Society for Respiratory Care and Rehabilitation, Japanese Association on Sarcopenia and Frailty, Japanese Society of Respiratory Physical Therapy and Japanese Association of Rehabilitation Nutrition. Geriatr Gerontol Int 2023; 23: 5–15.

Background Idiopathic pulmonary fibrosis (IPF) is characterised by worsening dyspnoea and exercise intolerance. Research question Does a long-term pulmonary rehabilitation improve exercise tolerance in patients with IPF treated with standard antifibrotic drugs, which are expected to reduce disease progression? Methods This open-label randomised controlled trial was performed at 19 institutions. Stable patients receiving nintedanib were randomised into pulmonary rehabilitation and control groups (1:1). The pulmonary rehabilitation group underwent initial rehabilitation which included twice-weekly sessions of monitored exercise training for 12 weeks, followed by an at-home rehabilitation programme for 40 weeks. The control group received usual care only, without pulmonary rehabilitation. Both groups continued to receive nintedanib. The primary and main secondary outcomes were change in 6 min walking distance (6MWD) and change in endurance time (using cycle ergometry) at week 52. Results Eighty-eight patients were randomised into pulmonary rehabilitation (n=45) and control (n=43) groups. Changes in 6MWD were −33 m (95% CI −65 to −1) and −53 m (95% CI −86 to −21) in the pulmonary rehabilitation and control groups, respectively, with no statistically significant difference (mean difference, 21 m (95% CI −25 to 66), p=0.38). Changes in endurance time were significantly better in the pulmonary rehabilitation (64 s, 95% CI −42.3 to 171)) than in the control (−123 s (95% CI −232 to −13)) group (mean difference, 187 s (95% CI 34 to 153), p=0.019). Interpretation Although pulmonary rehabilitation in patients taking nintedanib did not improve 6MWD in the long term, it led to prolonged improvement in endurance time. Trial registration number UMIN000026376.

There have been no reviews describing the efficacy of the combination of both rehabilitation and nutritional treatments. This systematic review aimed to assess the effects of nutritional therapy on patients with an acute and critical illness undergoing rehabilitation. Online searches using PubMed (MEDLINE), Cochrane Central Register of Controlled Trials, EMBASE (ELSEVIER), and Ichu-shi Web databases identified 986 articles, and 16 additional articles were found through other sources. Each trial assessed for the risk of bias using the Cochrane Collaboration’s tool, and the quality of the body of evidence with The Grading of Recommendations Assessment, Development and Evaluation approach. Two randomized controlled trials were included in this review. Jones et al reported that with an enhanced rehabilitation program, there was no effect of nutritional intervention on quality of life (standardized mean difference [SMD] 0.55, 95% confidence intervals [CI] -0.05 to 1.15; P = 0.12). However, Hegerova et al reported positive effects of physical therapy and oral supplements on muscle mass (0.65; 95% CI, 0.36 to 0.93; P < 0.00001) and activities of daily living (SMD 0.28, 95% CI 0.00 to 0.56; P = 0.05). Strengthened nutritional intervention with enhanced rehabilitation treatment for patients with acute and critical illness may possibly be effective for increasing muscle mass, as well as for improving activities of daily living within a short period after discharge.

Interoception is the sensing function of physiological conditions and is crucial in self-regulation and decision-making. We examined the association of heartbeat tracking task performance, an indicator of interoceptive accuracy, with the degree of improvement in exercise tolerance in patients undergoing home-based cardiac rehabilitation. Participants underwent baseline peak oxygen uptake (VO₂) measurements and a heartbeat tracking task. The heartbeat tracking task score varies between 0 and 1, with higher scores indicating a better heartbeat perception. After 6 months of home-based exercise training, peak VO₂ was measured again, and the percentage change (%Δ peak VO₂) relative to the peak VO₂ at baseline was calculated. Univariate regression analysis was performed to examine the association between %Δ peak VO₂ and the heartbeat tracking task score. Multiple regression analysis was performed to determine the predictors of %Δ peak VO₂. Of 120 participants, 100 patients (age, 65.9 ± 11.9 years; 86% male) were included. There was a significant positive association between %Δ peak VO₂ and the heartbeat tracking task score at baseline (R² = 0.236, P < 0.001). In multiple regression analysis, the percentage of measured peak VO₂ to the predicted value (%predicted peak VO₂) (β = -0.248, P = 0.002), exercise adherence (β = 0.364, P < 0.001), and heartbeat tracking task score at baseline (β = 0.372, P < 0.001) were significantly associated with %Δ peak VO₂. Heartbeat tracking task performance, an indicator of interoceptive accuracy, at baseline is associated with the degree of improvement in exercise tolerance.