Probiotic Lactobacillus rhamnosus GKLC1 enhances endurance and metabolism in mice with low exercise capacity.

OBJECTIVE: Individuals with intrinsically low exercise capacity are at increased risk of metabolic dysfunction and reduced endurance performance. This study investigated whether supplementation with Lactobacillus rhamnosus GKLC1 improves exercise performance and energy metabolism in a mouse model selectively bred for instrinsic low aerobic exercise capacity (i-LAEC). RESULTS: Male i-LAEC ICR mice were orally administered L. rhamnosus GKLC1 (0.021 g/kg/day) or sterile water (n = 6/group) for six weeks. GKLC1 supplementation significantly prolonged treadmill running time to exhaustion compared with controls. During swimming challenge tests, treated mice exhibited lower serum lactate and blood urea nitrogen levels, indicating improved fatigue recovery. GKLC1 also reduced epididymal fat mass and increased glycogen content in liver and skeletal muscle. No significant differences were observed in body weight, food intake, or serum AST and ALT levels between groups. These findings demonstrate that GKLC1 enhances endurance performance and modulates energy-related metabolism without detectable adverse effects in i-LAEC mice.