Table 1.

Overview of the main human studies that investigated the association between fecal microbiota composition and gait speed.

First Author, Year	Study Design	Participants	Age	Type of Gait Assessment	Main Results	Taxa Correlated with Gait Speed
Scheperjans, 2015 [95]	Observational	72 patients with Parkinson’s disease; 72 controls	65 ± 6 (patients); 64 ± 7 (controls)	Clinical evaluation with UPDRS scale	Decreased abundance of Prevotellaceae in patients; Relative abundance of Enterobacteriaceae correlated with motor symptoms	Enterobacteriaceae
Barichella, 2019 [96]	Observational	193 patients with Parkinson’s disease; 22 patients with PSP; 22 patients with MSA; 113 controls	68 ± 10 (Parkinson); 71 ± 8 (PSP); 67 ± 7 (MSA); 66 ± 10 (controls)	Clinical evaluation with UPDRS scale	Decreased abundance of Lachnospiraceae in patients with PD; Abundance of three taxa associated with a worse clinical profile	Lachnospiraceae Lactobacillaceae Christensenellaceae
Morita, 2019 [97]	Non-randomized trial	32 sedentary women	70 ± 5	6-min walking distance test	Exercise intervention modified microbiota composition and improved 6-min walking distance test	Bacteroides
Román, 2019 [99]	Randomized controlled trial	36 patients with cirrhosis	65 ± 3	5-m walking test	Probiotic supplementation was associated with faster gait speed	None

UPDRS = Unified Parkinson’s Disease Rating Scale; PSP = Progressive Sopranuclear Palsy; MSA = Multisystemic Atrophy.