Association of Different Types of Physical Activity with Sarcopenia and its Parameters in Peritoneal Dialysis Patients: an Isotemporal Substitution Analysis

Hongyan Li^1,2Yuxin Xiong¹Xiaotian Zhang¹Yuanhua Zheng³Li Wei⁴Ruixue Bi^1,5Wei Luo⁶Xin Sun¹Xinyue Hou¹Gaoleer Yang¹Yaqing Zhang^2*

• ¹School of Nursing, Jiangxi Medical College, Nanchang University, Nanchang, China
• ²School of Nursing, Shanghai Jiao Tong University School of Medicine, Shanghai, China
• ³Peritoneal Dialysis Center, The First Affiliated Hospital of Nanchang University, Nanchang, China
• ⁴School of Nursing, College of Health and Education, Murdoch University, Murdoch, Australia
• ⁵Jiangxi Province Key Laboratory of Aging and Disease, Nanchang, China
• ⁶Department of Nursing, Jiangxi Provincial People's Hospital, Nanchang, China

Aim: The impact of different exercise modality on sarcopenia in peritoneal dialysis patients remain unclear. This study examined the association between physical activity and sarcopenia in peritoneal dialysis patients based on the Isotemporal Substitution Model and attempted to identify which specific exercise modality is more effective in patients with peritoneal dialysis. Methods: A cross-sectional analysis design was informed. From March 2023 to February 2024, patients undergoing peritoneal dialysis were recruited from the peritoneal dialysis centers of two general hospitals in China. Sarcopenia was diagnosed according to the 2019 criteria established by the Asian Working Group for Sarcopenia. physical activity levels were evaluated using the Chinese Low Physical Activity Questionnaire. Isotemporal Substitution Model were employed to examine the association between sarcopenia in peritoneal dialysis patients and four types of physical activity (walking, light physical activity, moderate-to-vigorous physical activity, and daytime inactivity). Results: A total of 643 patients were recruited in the study for data analysis. The prevalence of sarcopenia in peritoneal dialysis patients was 12.6%. Among the participants, 69.67% engaged in light physical activity, 15.86% in moderate physical activity, and only 0.93% in vigorous physical activity. Substituting 10 minutes of daytime inactivity with 10 minutes of light physical activity was associated with a significant increase in skeletal muscle index (β = 0.007, 95% CI: 0.001–0.013, P < 0.05), a significant improvement in handgrip strength (β = 0.118, 95% CI: 0.031–0.149, P < 0.001), and a reduction in five-time sit-to-stand test (β = -0.045, 95% CI: -0.078–-0.012, P < 0.01). Substituting 10 minutes of daytime inactivity with 10 minutes of walking was associated with a shorter five-time sit-to-stand test completion time (β = -0.077, 95% CI: -0.135–-0.019, P < 0.05). However, substituting 10 minutes of daytime inactivity with light physical activity, moderate-to-vigorous physical activity, or walking showed no significant change in the occurrence of sarcopenia. Conclusions: Based on the Isotemporal Substitution Model, this study found that substituting daytime inactivity with light physical activity was significantly associated with three parameters of sarcopenia. Substituting daytime inactivity with walking was significantly associated with the five-time sit-to-stand test.