Is physical performance (in mice) increased by Veillonella atypica or decreased by Lactobacillus bulgaricus?

Regular exercise induces changes in the overall diversity and in the relative abundance of certain gut microbiota phyla and families, both in humans and animal models. This relationship has attracted a great deal of interest, being one of the mechanisms that could potentially determine the health benefits of regular exercise and influence performance. Recently, Scheiman et al. proposed that the administration of Veillonella atypica in non-trained mice improves performance through its impact in lactate metabolism. These authors observed an acute increase in the relative abundance of this genus in human stool samples after marathon. From these data they decided to administrate Veillonella atypica (isolated from runners' samples) to non-trained mice. A performance improvement in a run-to-exhaustion test was observed, compared to Lactobacillus bulgaricus-gavaged mice, used as control. Focusing on the approach with animal models, here we provide data confirming that Lactobacillaceae family relative abundance, and more specifically, the genus Lactobacillus, is negatively associated with endurance capacity performance in trained mice. This suggests that the use of Lactobacillus bulgaricus as control by Scheiman et al., without considering its potential effect on performance and in the absence of a vehicle-treated group, can lead to misinterpretation of the results about the impact of Veillonella on performance.