Association Between Serum α-Klotho Levels and Habitual Physical Activity in Hemodialysis Patients: A Pilot Clinical Study.

<b>Background/Objectives:</b> Chronic kidney disease (CKD) is characterized by accelerated aging and functional decline. Serum α-Klotho levels, an anti-aging biomarker predominantly associated with renal function, have emerged as potential indicators of biological aging and cardiovascular risk. To investigate the association between serum α-Klotho levels and habitual physical activity in hemodialysis patients. <b>Methods:</b> This study combined (1) a prospective case analysis of high-intensity interval training (HIIT) in a hemodialysis patient and (2) a cross-sectional analysis of 24 hemodialysis patients and 18 healthy controls. Serum α-Klotho levels were measured using ELISA, and their association with habitual physical activity was evaluated. <b>Results:</b> Serum α-Klotho levels were significantly lower in hemodialysis patients than in healthy controls (<i>p</i> < 0.001). In hemodialysis patients, physical activity was moderately correlated with serum α-Klotho levels (r = 0.52, <i>p</i> = 0.02), whereas no significant association was observed in healthy controls. The case analysis demonstrated marked improvement in physical function following HIIT. These findings suggest that serum α-Klotho levels may be associated with physical activity status in hemodialysis patients. <b>Conclusions:</b> Serum α-Klotho levels were associated with habitual physical activity in hemodialysis patients and may represent a potential molecular indicator related to physical function and rehabilitation status. These findings support further investigation of biomarker-informed approaches in renal rehabilitation.