Investigating the role of dietary probiotics on athletic performance and health via lactate and SCFA metabolism
Exercise performance and metabolism
The study will be a 2-month double-blind, randomised, placebo-controlled crossover intervention trial in endurance-trained males. All participants will complete the treatment (probiotic supplement) and control (placebo supplement) conditions of the study, the order of which will be randomly assigned using simple randomisation at the site of manufacture by the industry partner. Both the probiotic and placebo will be taken for 14 days in capsule form. A minimum of 2 weeks' wash-out will be completed between conditions. Supplementation of probiotics: 3B Propionibacterium; 1 B Lactobacillus rhamnosus LC-705 for the first 12 days of the 14-day supplementation period (in 1 capsule/day), and 15B Propionibacterium; 5B Lactobacillus rhamnosus LC-705 for the last 2 days of the 14-day supplementation period (in 5 capsules/day). Supplementation of placebo (taste and appearance matched): Capsule containing maltodextrin powder (1 capsule per day for days 1-12, followed by 5 capsules per day for days 13 and 14). Pre and post supplementation periods, participants will visit the laboratory where they will complete a submaximal exercise test (speed lactate test) and an exercise performance trial (self-paced 5km time trial), both on a motorised treadmill. During the exercise tests, lactate concentration, heart rate, rating of perceived effort (RPE), and gastrointestinal (GI) symptoms will be recorded. The submaximal exercise test will proceed until the Onset of Blood Lactate Accumulation (OBLA; blood lactate concentration of 4mmol/L). At rest (pre), following the submaximal exercise test (during), and following the exercise performance trial (post), saliva (salivary IgA, cortisol) and venous blood samples (venous propionate, intestinal-fatty acid binding protein [I-FABP], lipopolysaccharide binding protein [LBP], testosterone) will be taken. Participants will also provide a stool sample pre and post supplementation period for the assessment of gut microbiome composition via DN
1. Male 2. Aged between 20-40 years 3. Physically active and defined as “trained” in line with McKay et al. (2022) 4. Have a 5km time trial personal best of <21 minutes within the last three months
1. Routine consumption of ω-3 PUFA supplements and/or supplements with antioxidants 2. Routine consumption of prebiotic, and/or probiotic supplements 3. Routine consumption of collagen-based supplements 4. Use of antibiotics in the past 3 months 5. Milk allergy or lactose intolerance 6. Take a daily dose of aspirin or other NSAIDs 7. Intake of drugs which affect gastrointestinal mobility/laxatives in the 4 weeks before the study 8. Previously diagnosed with COPD, emphysema, chronic bronchitis or similar respiratory illness 9. History of heart failure, pulmonary hypertension, embolism, or other pulmonary heart disease 10. History of recurrent chest infections 11. Smoker 12. Acute infection within the last four weeks 13. Major operation within the past four months 14. History of gastrointestinal drug reaction 15. History or current evidence of gastrointestinal disease, e.g. chronic constipation, diarrhoea, irritable bowel syndrome, Crohn’s Disease