The relationship between sarcopenia and respiratory muscle weakness undergoing phase 2 cardiac rehabilitation in elder patients

Background Exercise capacity improvement is known as a part of effectiveness of cardiac rehabilitation (CR), however cardiovascular disease patients with sarcopenia have more difficulty not only in regaining but also maintenance physical function1). As sarcopenia is a systemic disease, it is likely that age-related loss of muscle mass plus low muscle strength also causes weakness in the respiratory muscles such as the diaphragm and intercostal muscles2). The relationship between respiratory muscle weakness and sarcopenia may provide a clue to the mechanism of sarcopenia development. Objective To investigate the relationship between sarcopenia and respiratory muscle weakness in elder patients undergoing CR and to conduct an exploratory study to reduce respiratory muscle weakness. Methods 50 patients enrolled CR (Age 77.7 ± 6.0) were assessed sarcopenia by Asian Working Group for Sarcopenia 2 criteria (AWGS2)3) and respiratory sarcopenia by a position paper by four professional organizations4). Exclusion criteria were as follows: those with a history of respiratory diseases, those with serious orthopedic diseases that would interfere with measurements, those with metal implants in the body such as cardiac pacemakers or artificial joints, and those with a diagnosis of dementia. The patients were classified into the "robust group (n=17)" if they had neither sarcopenia nor respiratory muscle weakness, "sarcopenia group (n=16)" if they had sarcopenia, "respiratory muscle weakness group (n=10)" if they had respiratory muscle weakness, and "respiratory sarcopenia group (n=7)" if they had both sarcopenia and respiratory muscle weakness. During phase 2 CR program, exercise stress test: peak VO2, peak WR, VE/VCO2, nutrition: geriatric nutritional risk index (GNRI), cardiac function: LVEF, E/e’, renal function: eGFR, anemia: Hb were observed. The outcome measures were compared among the four groups using the one-way factorial analysis of variance. A post-hoc Bonferroni test was used to perform multiple comparisons between groups. Results No significant differences in any parameters within VE/VCO2, cardiac function and renal function, anemia between four groups, but peak VO2 decline (p<0.05), peak WR decline (p<0.05), GNRI decline (p<0.01) were significantly observed in respiratory sarcopenia group than robust group. Conclusion This study is the first to investigate the interrelationship between sarcopenia and respiratory muscle weakness undergoing phase 2 cardiac rehabilitation in elder patients. In patients with baseline comorbidity of respiratory sarcopenia, exercise capacity and nutritional status were suggested to be lower than those in the robust group. These findings suggest importance of more personal and intensive intervention to improve respiratory sarcopenia with appropriate CR program.exercise stress test geriatric nutritional risk index