S-Acetyl Glutathione and Performance Recovery in Soccer

Official title

Pharmacodynamics & Pharmacokinetics Study of S-Acetyl Glutathione in Highly Trained Soccer Players

Overview

Soccer players display elevated inflammatory and oxidative stress markers combined with reduced soccer specific performance over a 72-hour period. However, in modern soccer, players participate very often in 2 or 3 matches within a week, with a recovery period of 72 hours between successive matches, that is insufficient to restore skeletal muscle homeostasis and performance. Of note, reduced glutathione (GSH) levels, a tripeptide consisting of the amino acids cysteine, glycine and glutamic acid, are substantially reduced during the 72-hour recovery period after a match because of the trauma-related acute inflammatory and oxidative stress response. GSH availability is a crucial regulator of cellular redox status, affecting numerous intracellular and physiological processes such as redox signalling, immunoregulation and muscle metabolism. Indeed, enhanced GSH availability following muscle damaging exercise has been shown to be beneficial for skeletal muscle and performance recovery by mitigating the inflammatory and oxidative stress response. Thus, the enhancement of GSH availability through dietary interventions would be a promising strategy to accelerate skeletal muscle and performance recovery following a soccer game. S-Acetyl Glutathione (SAG) is a glutathione precursor with enhanced absorption kinetics due to chemical S-acetylation of the thiol group on the cysteinyl amino acid of GSH and oral administration of SAG has been shown to be more effective in restoring intracellular glutathione levels compared to oral glutathione. The aim of this study is to (i) perform a pharmacokinetic assessment of 200 mg/day vs 500 mg/day of SAG during a 7-day supplementation period (pre-loading) and (ii) to establish the pharmacodynamic effect of the two dosages at 24, 48 and 72h following a 90-minute official soccer match.

Detailed description

Following baseline testing \[including assessment of anthropometrics, body composition (via DXA instrumentation) and physical performance (cardiorespiratory fitness, drop jump and countermovement jump performance, repeated sprint anility, isokinetic peak torque)\], 20 well-trained, soccer players will participate in three trials, receiving daily (i) 200 mg SAG, (ii) 500 mg SAG or (iii) Placebo, according to a randomized, double-blind, crossover, repeated-measures design. The duration of each trial will be 11 days, including a 7-day pre-loading period (days 1 -7), a match day (day 8) and 3 consecutive recovery days after the match (days 9-11). Between trials a 3-week washout period will be implemented.

Pre-loading period: During the 7-day pre-loading period players will participate daily in training sessions according to a soccer-specific weekly training schedule, while receiving the respective supplement. Blood samples will be collected on day 1 and day 7 while daily nutrient intake (via 7-day diet recalls), physical activity level (via accelerometry) and training load (via global positioning system instrumentation during training sessions) will be monitored daily.

Match day: On match day, players will participate in an official 90-min soccer match. Field activity (total distance, average and maximum speed, high intensity running, high speed running, accelerations, decelerations) and heart rate (mean and maximum heart rate) will be continuously monitored using global positioning system (GPS) and heart rate monitors, respectively.

Recovery days: During the 3-day recovery period after the match, players will participate daily in (i) morning testing sessions and (ii) training sessions in the evening. Testing sessions will include blood sampling and performance measurements including drop jump and countermovement jump performance, repeated sprint anility, isokinetic peak torque and muscle soreness (DOMS). Dietary intake (via a 3-day diet recalls), physical activity level (via accelerometry) and training load (via GPS instrumentation during training sessions) will be monitored daily.

Interventions

• Dietary supplement 200 mg S-Acetyl Glutathione
  Participants will be supplemented daily with 200 mg of S-acetyl glutathione, orally, over the 11-day experimental period.
• Dietary supplement 500 mg S-Acetyl Glutathione
  Participants will be supplemented daily with 500 mg of S-acetyl glutathione, orally, over the 11-day experimental period.
• Dietary supplement Placebo Supplementation
  Participants will be supplemented daily with placebo, orally, over the 11-day experimental period.

Primary outcome measures

• Change in creatine kinase levels [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in myoglobin levels [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in reduced glutathione [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in oxidized glutathione [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in glutathione reductase activity [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in glutathione peroxidase activity [Time frame: Day 1, day 7, day 9, day 10 and day 11.]
• Change in catalase activity [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in superoxide dismutase activity [Time frame: Day 1, day 7, day 9, day 10 and day 11]
• Change in maximal voluntary isometric contraction [Time frame: Day 1, day 9, day 10 and day 11]
• Change in maximal peak torque [Time frame: Day 1, day 9, day 10 and day 11]

Secondary outcome measures (10)

• Change in total distance covered [Time frame: Daily throughout the 11-day experimental period]
• Change in internal load [Time frame: Daily throughout the 11-day experimental period]
• Change in dietary intake [Time frame: Daily throughout the 11-day experimental period]
• Change in time spent in moderate-to-vigorous physical activity [Time frame: Daily throughout the 11-day experimental period]
• Change in distance covered with high-intensity running [Time frame: Daily throughout the 11-day experimental period]
• Change in distance covered with sprinting [Time frame: Daily throughout the 11-day experimental period]
• Change in accelerations [Time frame: Daily throughout the 11-day experimental period]
• Change in decelerations [Time frame: Daily throughout the 11-day experimental period]
• Change in total step count [Time frame: Daily throughout the 11-day experimental period]
• Change in physical activity-related energy expenditure [Time frame: Daily throughout the 11-day experimental period]

Eligibility criteria

Inclusion criteria

• participation at elite (top three division leagues) for ≥ 4 years
• no recent history of febrile illness, musculoskeletal problems and metabolic diseases
• no consumption of medications and performance-enhancing supplements (including anti-inflammatory, antioxidants, vitamins and multivitamin supplements) for at least 6 months prior to the study
• participation in at least 5 training sessions and 1 match per week
• non-smokers

Exclusion criteria

• musculoskeletal injury
• consumption of medication and performance-enhancing supplements
• illness during the course of the study
• loss of follow-up measurements

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Crossover

Masking

Triple blind

Primary purpose

Other

Study locations

Greece · 1 center

• Department of Physical Education and Sport Science, University of Thessaly — Trikala

Identifiers

NCT: NCT07690124 · UTH-06/13.02.2026

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗