Effect of Lactobacillus Plantarum GKK1 Supplementation on Anti-fatigue Health Effects

Title: Effect of Lactobacillus plantarum GKK1 Supplementation on Anti-Fatigue Health Effects: A Randomized, Double-Blind, Placebo-Controlled Trial

This study aims to investigate the effects of Lactobacillus plantarum GKK1 supplementation on fatigue reduction and physical performance enhancement in healthy adults. Probiotics are known to modulate gut microbiota and may influence exercise-induced fatigue and recovery.

A total of 48 healthy adults aged 18-35 years will be randomly assigned to either the probiotic group (Lactobacillus plantarum GKK1, 100 billion CFU/day) or the placebo group, with supplementation for 28 consecutive days. On Day 29, participants will perform an exhaustive exercise test, and their anaerobic power, explosive power, isometric muscle strength, and stress hormone levels (cortisol, catecholamines, GH, testosterone, hs-CRP) will be evaluated before and after exercise.

The primary objective is to assess whether probiotic supplementation can reduce exercise-induced fatigue and muscle damage while improving recovery performance. Blood biochemical markers, muscle damage indicators, and subjective fatigue perception will also be analyzed.

This study is conducted at National Taiwan Sport University, under ethical approval from Landseed Hospital IRB (IRB-24-034-A2).

Probiotic supplementation has garnered increasing interest in sports science due to its potential effects on gut microbiota modulation, systemic inflammation, and exercise recovery. Lactobacillus plantarum GKK1, a strain isolated from fermented plant sources, exhibits promising antioxidative and anti-inflammatory properties, making it a candidate for supporting physical resilience and fatigue recovery in active individuals.

This study is designed as a randomized, double-blind, placebo-controlled clinical trial aiming to evaluate whether supplementation with L. plantarum GKK1 can attenuate physiological stress responses and muscle damage following exhaustive exercise in healthy adults. The probiotic intervention lasts for 28 consecutive days, during which participants maintain habitual dietary and lifestyle behaviors, except for the avoidance of other functional supplements.

The experimental exercise model includes a structured fatigue-inducing protocol involving repetitive plyometric movements. This model was selected to simulate high-intensity sport-like conditions while reliably inducing measurable muscle stress. Following this challenge, blood and urine samples are collected at predefined time points to monitor temporal changes in selected biochemical markers.

The trial incorporates both objective and subjective metrics, including validated physical performance tests and standardized fatigue perception scales. Biochemical assessments are conducted using automated clinical analyzers and immunoassay techniques under Good Laboratory Practice conditions. The core hypothesis posits that probiotic intervention will result in lower elevations in stress hormones and muscle damage biomarkers, along with improved physical performance maintenance compared to placebo.

All procedures are conducted at the National Taiwan Sport University under IRB approval (IRB-24-034-A2). This trial may provide evidence for the application of probiotic supplementation as a supportive strategy for fatigue management and exercise recovery enhancement in recreationally active populations.

Eligibility Criteria:
Inclusion Criteria:

* Healthy adults aged 18 to 35 years
* Non-smokers and non-alcohol drinkers
* No history of chronic disease (e.g., cardiovascular disease, diabetes, asthma, metabolic disorders)
* No musculoskeletal injuries in the past 6 months
* Not taking anti-inflammatory or pain-relief medication in the past month
* No history of gastrointestinal surgery (excluding hernia or polyp removal)
* No allergies to dairy or probiotics

Exclusion Criteria:

* Diagnosed with cardiovascular, metabolic, or neurological disorders
* Regular consumption of probiotics within the last three months
* Pregnant or lactating women
* Individuals taking medication affecting hormonal balance or immune response
* Use of corticosteroids, NSAIDs, or muscle relaxants in the past month
* Participating in another clinical trial within the last three months