A Randomized, Double-Blind Study to Assess the Effect of a Postbiotic on Oxidative Stress and Exercise Performance

Serum malondialdehyde (MDA) concentration will be measured to assess the effect of the postbiotic blend on lipid peroxidation and oxidative stress. Higher MDA levels indicate increased oxidative stress.

Urinary 8-OHdG, a biomarker for oxidative DNA damage, will be measured to evaluate oxidative stress. Values reflect the total oxidative stress experienced by participants.

Serum oxidized LDL will be measured as an indicator of oxidative modification in lipids, associated with cardiovascular risk. Higher levels represent increased lipid oxidation.

Glutathione peroxidase levels, a measure of antioxidant enzyme activity, will be assessed in serum. Higher activity indicates greater antioxidant defense.

Urinary 8-isoprostane, a marker for lipid peroxidation, will be measured to assess oxidative stress. Higher values indicate greater oxidative damage to lipids.

Total Antioxidant Status (TAS) in serum will be measured to gauge overall antioxidant capacity. Higher levels indicate a stronger antioxidant defense.

Serum superoxide dismutase (SOD) activity, an antioxidant enzyme, will be measured to assess the body's defense against superoxide radicals. Higher activity levels indicate greater antioxidative defense.

Serum protein carbonyls, markers of oxidative damage to proteins, will be measured. Higher levels indicate increased protein oxidation and cellular stress.

Serum uric acid will be measured as an indicator of purine metabolism and antioxidant activity, where higher levels may indicate greater antioxidant activity or metabolic changes.

Immunoglobulin A (IgA) levels in serum will be measured to assess immune function, with higher levels indicating a robust immune response

Immunoglobulin M (IgM) levels in serum will be measured to assess immune function, with higher levels indicating a robust immune response

Immunoglobulin G (IgG) levels in serum will be measured to assess immune function, with higher levels indicating a robust immune response

Serum creatine kinase (CK), a marker of muscle damage, will be measured. Higher CK levels indicate greater muscle stress or damage.

Delayed onset muscle soreness (DOMS) will be self-rated using a 10-point visual analog scale (VAS), where 0 indicates no soreness and 10 represents extreme soreness.

Recovery will be self-rated by participants on a 10-point VAS, where 0 represents no recovery and 10 represents full recovery.

Perceived muscle soreness in the quadriceps will be assessed using a digital algometer, which applies consistent pressure to measure pain threshold and discomfort. Higher readings indicate higher resistance to soreness, while lower values indicate increased perceived soreness.

Participants will complete a daily diary to self-report any symptoms related to upper respiratory tract infections (URTI) and gastrointestinal (GI) health throughout the 8-week supplementation period. This diary will track symptom type, severity, and duration.

The Gastrointestinal Symptoms Rating Scale (GSRS) will assess GI symptoms across multiple dimensions, including abdominal pain, reflux, indigestion, diarrhea, and constipation. Scores range from 1 (no discomfort) to 7 (severe discomfort) on each dimension, with higher scores indicating greater symptom severity.

The GAD-7, a 7-item self-report questionnaire, will assess anxiety levels. Scores range from 0 to 21, with higher scores indicating greater anxiety severity. The questionnaire will be completed by participants before and after supplementation.

Perceived restfulness will be assessed using a 10-point Visual Analog Scale (VAS), where 0 represents no restfulness and 10 represents feeling fully rested. Participants will complete the scale at baseline and at the end of the supplementation period.

Perceived sleep quality will be rated on a 10-point Visual Analog Scale (VAS), with 0 indicating poor sleep quality and 10 indicating excellent sleep quality. Participants will complete the scale at baseline and after the supplementation period.

The Pittsburgh Sleep Quality Index (PSQI), a self-rated questionnaire, assesses overall sleep quality and disturbances over a 1-month period. Scores range from 0 to 21, with higher scores indicating worse sleep quality. The PSQI will be completed at baseline and after the supplementation period.

The total distance in miles covered during a 10-minute running time trial will be measured to assess exercise performance. Greater distance covered indicates improved aerobic capacity and endurance.

Heart rate, measured in beats per minute (bpm), will be assessed throughout treadmill running to monitor cardiovascular response. Lower heart rates at a set intensity indicate improved cardiovascular efficiency.

RPE will be recorded using the Borg scale (6-20), where higher values indicate greater perceived effort. Lower RPE values at a fixed intensity suggest improved endurance and perceived ease of exercise.

Blood lactate, measured in mmol/L, will be assessed as a marker of metabolic stress, with lower levels indicating improved lactate clearance and aerobic efficiency.

Blood glucose, measured in mg/dL, will be monitored to assess energy utilization. Stable or lower levels may indicate improved metabolic flexibility.

Fat oxidation rate, measured in grams per minute (g/min), will be assessed to evaluate substrate utilization, with higher rates suggesting greater reliance on fat as an energy source.

Carbohydrate oxidation rate, measured in grams per minute (g/min), will be assessed to evaluate energy source utilization, with lower rates indicating improved fat utilization at moderate intensities.

Participants will complete a daily self-report diary to record any adverse events (AEs) experienced, detailing the type, severity, duration, and any related symptoms. This log will help monitor the safety and tolerability of the supplementation over the study period.

Shotgun metagenomic sequencing will analyze the composition and diversity of the gut microbiome in fecal samples. This measure provides insights into microbiome changes related to supplementation and exercise, with results expressed as relative abundance and diversity of microbial species.

Fecal metabolomic analysis will assess the profile of metabolites produced by the gut microbiota, providing insights into metabolic changes. Metabolite concentrations will be reported, with changes potentially reflecting shifts in gut microbial activity and metabolic byproducts.