Fig. 1.

Gut Lactobacillus relative abundance is negatively correlated with endurance performance in trained mice. (A) α-diversity analysis of bacterial communities in cecal content of control mice (sedentary; n = 6) and endurance trained mice (n = 12). Shannon index (richness and evenness) shows differences in diversity between control and endurance groups (p = 0.025) as determined by unpaired t test. Each mouse is represented by an independent point in the scatter dot plot. A bar represents the mean, and error is represented as S.E.M. (B) Average relative abundance of Firmicutes phylum at the family level in control (n = 6) mice and endurance mice (n = 12). (C) Relative abundance of Lactobacillaceae and Veillonellaceae families for control mice and endurance mice is shown (mean ± S.E.M.), and differences between groups were determined by unpaired t test. (D) Pearson correlation analysis indicates a negative correlation between Lactobacillaceae family abundance and percent variation for total distance in endurance-trained mice (n = 12). A nonsignificant positive correlation was found between Veillonellaceae family abundance and percent of variation in the same group of mice. (E) When post-training distance was considered, the Pearson correlation showed a nonsignificant negative association with Lactobacillaceae family relative abundance in endurance-trained mice (n = 12). In the case of Veillonellaceae family relative abundance, no correlation was found in the same group of mice. (F) At the genus level, Pearson correlation analysis showed a significant association between the genus Lactobacillus relative abundance and the percent variation for total distance in endurance-trained mice (n = 12). This association was not seen when the post-training total distance was analyzed for the same genus and the same group of mice. (G) For the assessment of endurance capacity, mice performed a 10-min warm-up at 15 cm/s and 10° slope. Then, at the same conditions established for the warm-up, speed was increased 5 cm/s every 3 min until reaching 40 cm/s. At this speed, the slope was increased from 10° to 15° and from 15° to 20° in 2 consecutive 3-min stages. After that, speed was increased again 5 cm/s every 3 min at 20° slope till exhaustion. Maximum speed (cm/s) and total time (s) were recorded, and total distance (m) was calculated as measurements of endurance capacity. (H) Total distance covered in pretraining and post-training tests. Eight-week-old male mice (n = 20) performed a pretraining maximal test before training intervention. After a progressive endurance training intervention of 5 days/week for 4 weeks, the same protocol was applied for post-training performance assessment. The before-after graph for distance (left Y-axis) shows each individual as an independent point. A box and whiskers (maximum to minimum) plot is also shown, where a bar represents the median; p < 0.0001 was obtained by Wilcoxon matched-pairs signed rank test. Percentage variation for total distance (calculated as: (post-training − pre-training) × 100/pre-training) is shown in the right Y-axis. The scatter box plot shows the mean and S.E.M. Each point represents 1 mouse.