Impact of Sarcopenia, Dynapenia, and Obesity on Muscle Strength and Quality in Chronic Kidney Disease Patients: A Sex-Specific Study.

Sex-specific differences in the prevalence of sarcopenia, dynapenia, and the impact of obesity on muscle strength and quality in patients with chronic kidney disease (CKD) remain underexplored. Background/Objectives: In this cross-sectional study, 78 adults with stage 5 CKD undergoing thrice-weekly maintenance hemodialysis in Brazil (44 men, 34 women; mean ± SD age = 57.55 ± 4.06 years) were assessed. Anthropometry (BMI, waist circumference, waist-to-height ratio), dual-energy X-ray absorptiometry, circulating IL-6, Timed Up and Go, handgrip strength (Jamar ^® dynamometer), and muscle quality index (MQI = handgrip/BMI) were obtained. Dynapenia (handgrip < 27 kg men and < 16 kg women) and sarcopenia (1.0 kg/kg for men and 0.56 kg/kg for women) were classified using EWGSOP2-2018 and FNIH thresholds. Results: Compared with reference values, men showed markedly reduced muscle strength and muscle quality (men: handgrip 21.3 ± 5.1 kg; MQI 0.80 ± 0.23 AU) than women. Also, men were 5.1 times more likely to present with dynapenia (88.6%; 95% CI 2.28-11.60) and 3.15 times more likely to present with sarcopenia (75.0%; 95% CI 1.88-5.30) than women. Waist circumference, waist-to-height ratio, BMI, and body fat % correlated inversely with MQI in both sexes (p ≤ 0.01) and with handgrip strength in men (p ≤ 0.01) but not in women. Conclusions: Among hemodialysis patients, men exhibit a substantially higher burden of dynapenia and sarcopenia than women and excess adiposity is independently associated with poorer muscle quality in both sexes. These findings highlight the need for sex-specific screening cut-offs and integrated strategies targeting both muscle dysfunction and central obesity in CKD management.