The Utilization of Body Composition to Predict Cardiorespiratory Fitness and Determine Association with CKD Stage in Individuals with Mid-Spectrum CKD: A Pilot Study

Body composition (BC), a measure of body fat mass (FM), lean body mass (LBM), and bone mineral content (BMC), can be used as a predictor of cardiorespiratory fitness (CRF). Prior studies have established a relationship between BC and VO2max in healthy individuals over 35 years of age. However, this relationship is poorly understood in chronic disease populations. The focus of the study was to assess the relationship between BC, cardiorespiratory fitness, and chronic kidney disease (CKD). A cross-sectional analysis was conducted among 24 (9 males and 15 females) individuals diagnosed with mid-spectrum CKD (stages G2–G3b) who completed a health screening, dual-energy X-ray absorptiometry (DEXA) scan, and underwent a VO2max exercise test. Normality tests, descriptive statistics, Pearson’s correlations, t-tests, and ANOVAs were conducted in SAS v.9.4. The average percent body fat (%BF) was 36.28 ± 8.47%, LBM was 109.4 ± 29.1 lb, BMC was 2308.7 ± 735.1 g, and VO2max was 20.13 ± 5.04 mL/kg/min−1. BC was able to predict CRF via VO2max (R2 = 0.721, p < 0.001) and CKD stage (R2 = 0.390, p < 0.017). Positive correlations were observed in LBM (r = 0.750, p < 0.0018) and BMC (r = 0.647, p < 0.001), and negative correlations were observed with FM (r = −0.384, p < 0.032) and %BF (r = −0.802, p < 0.0001). BC was able to predict both CRF and CKD stages, with significant associations observed between BC, VO2max, and CKD stage. The progression of the CKD stage was associated with lower LBM, BMC, and VO2max values, indicating a graded effect of BC on CRF and CKD stage.