<b>Dataset: Physical activity and skeletal muscle health in children with cancer undergoing chemotherapy</b>

<p dir="ltr">This dataset accompanies a cross-sectional study investigating the relationship between physical activity and skeletal muscle health among children with cancer undergoing chemotherapy.</p><p dir="ltr"><b>Study Design:</b> A total of 140 children with cancer undergoing intensive chemotherapy were recruited from the pediatric oncology departments of two Grade A tertiary hospitals in Guangzhou, China, between September 2023 and September 2024.</p><p dir="ltr"><b>Data Contents:</b> The dataset includes demographic and clinical characteristics (e.g., sex, age, residence, education, ethnicity, parental marital status, clinical diagnosis, tumor stage, age at diagnosis, relapse status), anthropometric and body composition measures (e.g., height, weight, BMI, total body water, total protein, minerals, body fat, skeletal muscle mass, skeletal muscle index (SMI)), and physical activity variables (sedentary behavior, light physical activity (LPA), moderate-to-vigorous physical activity (MVPA)).

Physical activity was assessed using the modified Children's Leisure Activities Study Survey (CLASS) questionnaire. Body composition was measured using the InBody 120 bioelectrical impedance analyzer.</p><p dir="ltr"><b>Data Availability and Ethics:</b> Data have been de-identified (names and hospital numbers removed). The study was approved by the Review Committee of Sun Yat-sen University (Ethical Clearance Reference Number: L2023SYSU-HL-025).