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NCT Number: NCT07690124

S-Acetyl Glutathione and Performance Recovery in Soccer

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.

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Key information

Conditions

Performance Recovery Exercise-induced Inflammation Exercise-induced Oxidative Stress

Age range

19 year–29 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

200 mg S-Acetyl Glutathione

Dietary Supplement

Participants will be supplemented daily with 200 mg of S-acetyl glutathione, orally, over the 11-day experimental period.

500 mg S-Acetyl Glutathione

Dietary Supplement

Participants will be supplemented daily with 500 mg of S-acetyl glutathione, orally, over the 11-day experimental period.

Placebo supplementation

Dietary Supplement

Participants will be supplemented daily with placebo, orally, over the 11-day experimental period.

Primary outcomes

  1. Change in creatine kinase levels

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Creatine kinase concentration will be measured in serum using a Clinical Chemistry Analyzer

  2. Change in myoglobin levels

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Myoglobin concentration will be measured in serum using a Clinical Chemistry Analyzer

  3. Change in reduced glutathione

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Reduced glutathione will be photometrically determined in red blood cell lysates using a spectrophotometer

  4. Change in oxidized glutathione

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Oxidized glutathione will be photometrically determined in red blood cell lysates using a spectrophotometer

  5. Change in glutathione reductase activity

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Glutathione reductase activity will be photometrically determined in red blood cell lysates using a spectrophotometer

  6. Change in glutathione peroxidase activity

    Time frame: Day 1, day 7, day 9, day 10 and day 11.

    Glutathione peroxidase activity will be photometrically determined in red blood cell lysates using a spectrophotometer

  7. Change in catalase activity

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Catalase activity will be photometrically determined in red blood cell lysates using a spectrophotometer

  8. Change in superoxide dismutase activity

    Time frame: Day 1, day 7, day 9, day 10 and day 11

    Superoxide dismutase activity will be photometrically determined in red blood cell lysates using a spectrophotometer

  9. Change in maximal voluntary isometric contraction

    Time frame: Day 1, day 9, day 10 and day 11

    Maximal voluntary isometric contraction will be assessed at a 60o knee joint angle, in both dominant and non-dominant limb, using an isokinetic dynamometer

  10. Change in maximal peak torque

    Time frame: Day 1, day 9, day 10 and day 11

    Maximal concentric and eccentric peak torque at 60o/s of the knee extensors and flexors in both dominant and non-dominant limb, will be assessed on an isokinetic dynamometer

  11. Change in jumping performance

    Time frame: Day 1, day 9, day 10 and day11

    Countermovement jump and drop jump performance will be tested using an optical measurement system consisting of a transmitting and receiving bar

  12. Change in repeated sprint ability

    Time frame: Day 1, day 9, day 10 and day 11

    Repeated sprint ability will be assessed by performing 5x25 m sprints interspersed by a 25-seconds recovery period using infrared photocells

  13. Change in delayed onset muscle soreness (DOMS)

    Time frame: Day 1, day 9, day 10 and day 11

    DOMS will be assessed using a 10-scale visual analogue scale

Secondary outcomes

  1. Change in total distance covered

    Time frame: Daily throughout the 11-day experimental period

    Total distance (km) covered during training and match play will be monitored using Global Positioning System (GPS)

  2. Change in internal load

    Time frame: Daily throughout the 11-day experimental period

    Heart rate during training sessions and the match will be monitored using heart rate monitors

  3. Change in dietary intake

    Time frame: Daily throughout the 11-day experimental period

    Dietary intake will be assessed using diet recalls

  4. Change in time spent in moderate-to-vigorous physical activity

    Time frame: Daily throughout the 11-day experimental period

    The time (minutes) spent in moderate-to-vigorous physical activity on a daily basis will be monitored using accelerometers

  5. Change in distance covered with high-intensity running

    Time frame: Daily throughout the 11-day experimental period

    Distance (km) covered with high-intensity running during training and match play will be monitored using Global Positioning System (GPS)

  6. Change in distance covered with sprinting

    Time frame: Daily throughout the 11-day experimental period

    Distance (km) covered with high-intensity sprinting during training and match play will be monitored using Global Positioning System (GPS)

  7. Change in accelerations

    Time frame: Daily throughout the 11-day experimental period

    The number of accelerations performed during training and match play will be monitored using Global Positioning System (GPS)

  8. Change in decelerations

    Time frame: Daily throughout the 11-day experimental period

    The number of decelerations performed during training and match play will be monitored using Global Positioning System (GPS)

  9. Change in total step count

    Time frame: Daily throughout the 11-day experimental period

    The total number of steps performed daily will be monitored using accelerometers

  10. Change in physical activity-related energy expenditure

    Time frame: Daily throughout the 11-day experimental period

    Energy expenditure (kcal) related to habitual physical activity will be assessed using accelerometers

Study contacts

Contact information is provided by the study sponsor or research team.

Athanasios Poulios, PhD

CONTACT

[email protected]

+30 2431047053

Dimitrios Draganidis, PhD

CONTACT

[email protected]

+30 2431047078

Sponsors and collaborators

Lead sponsor

University of Thessaly

Other

Collaborators

  • Lesaffre International

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2026
Study completion
2027
First posted
Jul 8, 2026
Registry last updated
Jul 8, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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