Uremic toxins levels from the gut microbiota seem not to be altered by physical exercise in hemodialysis patients

Regular physical exercise may result in many benefits to patients with chronic kidney disease (CKD) on hemodialysis (HD), including gut microbiota modulation and solute removal. The study aimed to evaluate the effects of two programs of intradialytic exercises on uremic toxins plasma levels in HD patients. In experiment 1, twenty HD patients [12 men, 44.1 ± 8.9 years, BMI of 23.4 ± 2.4 kg/m2] were randomized into two groups: Aerobic exercise group (AEG, n = 11) that performed aerobic exercise on an adapted exercise bike three times a week for three months (36 sessions) and Control group (CG, n = 9). In experiment 2, twenty-six HD patients [19 men, 47.6 ± 11.0 years, BMI of 25.9 ± 3.6 kg/m2] were randomized into Resistance exercise group (REG, n = 14) that performed a resistance exercise program (using elastic bands and ankle cuffs with both lower limbs) monitored three times a week, during six months (72 sessions) and CG (n = 12). P-cresyl sulfate (p-CS), indoxyl sulfate (IS), and indol-3-acetic acid (IAA) plasma levels were determined by high-performance liquid chromatography (HPLC) with fluorescent detection. The uremic toxins plasma levels did not reduce in both exercise programs, aerobic exercise (IS: 32.7 ± 14.0 vs 33.0 ± 15.4 mg/L, p = 0.86; p-CS: 59.9 ± 39.3 vs 60.0 ± 41.2 mg/L, p = 0.99; IAA: 2233 [1488–2848] vs 2227 [1275–2824] µg/L, p = 0.72) and resistance exercise (IS: 28.3 ± 11.3 vs 29.1 ± 9.7 mg/L, p = 0.77; p-CS: 31.4 ± 21.3 vs 34.2 ± 19.8 mg/L, p = 0.63; IAA: 1628 [1330–3530] vs 2000 [971–3085] µg/L, p = 0.35) in HD patients. According to our findings, physical exercise does not appear to alter the levels of uremic toxins produced by the gut microbiota in HD patients.