疲勞是一種組織損傷或身體能源短缺累積的結果。研究指出，促使疲勞的因子可與腸道菌相有關。諸多研究顯示益生菌具有平衡腸道菌相、改善身體機能的效果，因此應用益生菌舒緩運動引起之疲勞是有潛力的。故本研究評估約氏乳酸桿菌 (Lactobacillusjohnsonii) 菌株GKJ2 在抗運動疲勞與提升運動表現的效益。方法：試驗設計分為實驗組與對照組，實驗組給予6 週齡ICR 雄性小鼠 (N = 6) 食用乳酸菌L. johnsonii GKJ2 菌粉(200 mg/kg b.w./ day) 連續28 天後，紀錄其運動表現以及分析運動過程中與疲勞相關的血清生化指標，評估L. johnsonii 菌株GKJ2 舒緩運動疲勞的效果。結果：食用28 天乳酸菌 L. johnsonii GKJ2 菌粉後之小鼠，其游泳力竭運動時間較對照組提升約1.73 倍 (p< .001)。且GKJ2 組之小鼠在運動過程中能維持顯著較低的血乳酸鹽濃度，並在運動後相同休息時間內維持顯著較低的血尿素氮濃度。此外，分析小鼠肝臟 (p < .001) 及肌肉 (p< .01) 組織中的肝醣含量，發現皆較對照組明顯提高。結論：綜上實驗結果，L. johnsoniiGKJ2 具有提升運動能力表現與降低運動後肌肉疲勞的潛能。

Introduction: Fatigue is a cumulative result of tissue damage or an energy shortage in the body. Studies have shown that one factor causing fatigue may be related to the gut microbiota. Probiotics have mainly been studied to balance intestinal flora and improve physical function, so applying probiotics to ameliorate fatigue caused by exercise could be a potential solution. Therefore, this study evaluated the efficacy of Lactobacillus johnsonii strain GKJ2 in improving exercise performance and reducing fatigue caused by exercise. Methods: The experimental design comprised an experimental and a control group. The experimental group’s six-week-old male ICR mice (N = 6) were given lactic acid bacteria L. johnsonii GKJ2 powder (200 mg/kg body weight/day) for 28 consecutive days. The control group treated the same as the experimental group except no intervention of the strain GKJ2. Then, their exercise performance and the serum biochemical indicators related to fatigue were measured to evaluate the effects of L. johnsonii strain GKJ2 on ameliorating exercise fatigue. Results: The experimental group had 1.73-fold longer exhaustive swimming test times than the control mice (p < .001). In addition, the mice in the experimental group maintained significantly lower blood lactate concentrations during exercise and significantly lower blood urea nitrogen concentrations during the post-exercise rest than the control group. Moreover, the experimental group had significantly higher glycogen content in their liver (p < .001) and muscle (p < .01) tissues than the control group. Conclusion: L. johnsonii GKJ2 has the potential to improve exercise performance and reduce muscle fatigue after exercise.