**3. Results**

#### *3.1. Study Population*

Of a total of 45 eligible subjects, 1 declined to participate. The remaining 44 were randomized to the study groups (22 in each group), but 1 subject assigned to the placebo group did not receive the assigned intervention and was lost to follow-up. The final study sample included 22 subjects in the probiotic group (25.3 ± 7.2 years) and 21 (27.1 ± 8.4 years) in the placebo group (Figure 1). Baseline BMI was 23.6 (2.6) kg/m2) and VO2 max 51.1 (8.8) mL/kg/min. Significant differences after randomization were not observed.

#### **Figure 1.** Flow chart of the study population.

#### *3.2. Lipid, Protein, and DNA-Related Oxidative Stress Biomarkers and Antioxidative Enzymes*

The oxidative stress model based on the performance of high intensity exercise and duration (test 1) produced statistically significant increases in biomarkers of oxidative stress and enzymes.

As shown in Table 1, urinary isoprostanes increased significantly in both groups after tests #1 and #2 as compared with baseline, but the difference between tests #1 and #2 (Δ mean difference) and between-group differences were not significant. Serum MDA showed a significant Δ mean difference of −207 ng/mL (95% CI −349.1 to 66.1) (*p* < 0.05) in the

probiotic group only, with between-group differences also statistically significant (*p* < 0.05). Serum Ox-LDL showed a significant Δ mean difference of −122.5 pg/mL (95% CI −240 to −4.5) (*p* < 0.05) in the probiotic group only, but between-group differences almost reached statistical significance (*p* = 0.063). Urinary 8-OHdG increased significantly in both groups after tests #1 and #2, although the Δ mean difference (−10.9 pg/day, 95% CI −14.5 to −7.3; *p* < 0.001) was only significant in the probiotic group; moreover, between-group differences were also significant (*p* < 0.001). Serum protein carbonyl increased significantly after test #1 and test #2 in both groups, but neither Δ mean difference nor between-group differences were statistically significant. Serum GPx increased significantly in both groups after test #1 and in the placebo group only after test #2; however, neither Δ mean difference nor betweengroup differences were statistically significant. Serum SOD increased significantly in both groups after test #2, but again neither Δ mean difference nor between-group differences were statistically significant.

**Table 1.** Results of lipid, protein, and DNA-related oxidative stress biomarkers and antioxidative enzymes.


protein


**Table 1.** *Cont.*

SE: standard error; CI: confidence interval; MDA: malondialdehyde; Ox-LDL: oxidized low-density lipoprotein; GPx: glutathione peroxidase; SOD: superoxide dismutase; F: F-Snedecor.
