The impact of malnutrition on the effectiveness of intradialytic exercise in hemodialysis patients: amulticenter cohort study

Purpose Low physical function can be effectively improved via intradialytic exercise. However, the association between the effects of intradialytic exercise on physical function and malnutrition severity has not been studied extensively. This study aimed to investigate the impact of nutritional status severity on physical function in patients undergoing hemodialysis with low physical function to whom intradialytic exercise was prescribed. Methods The participants were patients with decreased mobility [walking speed < 1.0 m/s and/or Short Physical Performance Battery (SPPB) < 12] who had been undergoing hemodialysis thrice a week for 6 months and performing intradialytic exercise program. Patients were divided into groups based on the Geriatric Nutritional Risk Index (GNRI) [Non-malnutrition group (GNRI > 98), Gentle/slim malnutrition group (GNRI ≤ 98, GNRI ≥ 92), Mild malnutrition group (GNRI < 92, GNRI ≥ 82), Severe malnutrition group (GNRI < 82)]. The primary outcomes were Grip strength, isometric knee extension strength (IKES), SPPB, and 10-m walking speed measured at baseline and at 6 months. Statistical analyses were performed using a linear mixed-effects model with the intention-to-treat analysis, including within-group analysis and between-group comparison. Results A total of 805 participants were included in the study. Within-group comparisons showed significantly improved IKES, 10-m walking speed, and SPPB improved, except in the Severe malnutrition group. Grip strength significantly improved in the Gentle/slim and mild malnutrition groups. Between-group comparison with controls showed that the improvement in Grip strength was significantly bigger in the Gentle/slim malnutrition group [0.98 (0.15 to 1.82) kg] than in the non-malnutrition group. However, IKES in the Severe malnutrition group [− 5.14 (− 9.18 to − 1.10) %] less significantly improve than that in the non-malnutrition group. No significant differences were found in the other indices. Conclusion In patients with severe malnutrition, the changes in IKES scores resulting from Intradialytic exercise were significantly smaller than those observed in non-malnourished patients. Therefore, it is necessary to initiate suitable nutritional and exercise therapy based on the severity of malnutrition.