NAC Supplementation and Soccer Specific Performance

Study Overview
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Brief Summary
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In this investigation the investigators utilized NAC supplementation to boost GSH availability during an one-week-microcycle consisting of three soccer games, in order to test the hypotheses that: i) antioxidant supplementation may enhance the recovery of performance and physiological stress variables following multiple match-plays and ii) redox status perturbations are critical in regulating the inflammatory response and repair in skeletal muscle, following repetitive exercise-induced muscle injuries.

Detailed Description
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After exercise-induced muscle microtrauma the thiol/disulfide couple of reduced (GSH) and oxidized glutathione (GSSG) is a key regulator of important transcriptional pathways that control the inflammatory response and recovery of skeletal muscle. The objective was to examine how thiol-based antioxidant supplementation affects the muscle damage, oxidative stress, inflammatory and immune responses, as well as the level of post-game fatigue and muscle's recovery kinetics in response to three soccer games within a week. Participants were randomly assigned to one of four groups: i) Experimental-NAC [EXP-NAC, N=10, participated in daily training sessions and three games and received NAC (20 mg/kg/day)], ii) Experimental-Placebo (EXP-Pla, N=10, participated in daily training sessions and three games and received Placebo), iii) Control-NAC [CON-NAC, N=10, participated in daily training sessions only and received NAC(20 mg/kg/day)] and iv) Control-Placebo (CON-Pla, N=10, participated in daily training sessions only and received Placebo). Blood samples were collected at baseline, post-games and daily during recovery. Performance was assessed at baseline and daily during recovery.

Official Title
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Effects of NAC Supplementation on Immune Function, Inflammatory and Performance Responses of Elite Soccer Players Participated in Three Repetitive Games.

Conditions
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Skeletal Muscle Damage, Exercise-induced Aseptic Inflammation, Skeletal Muscle Performance, Antioxidant Status

Intervention / Treatment
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* Dietary Supplement: N-acetylcysteine
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participation at elite level (top three division leagues) of soccer competition for at least five years Abstained from consumption of performance-enhancing supplements, antioxidant supplements and medications (for at least 6 months before and during the study) Participation in at least six two-hour training sessions and one match per week Non-smokers Exclusion Criteria: A known NAC intolerance or allergy A recent febrile illness History of muscle lesion Lower limb trauma Metabolic diseases

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 28 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: EXP-NAC<br>Participated in daily training sessions and three games, and supplemented daily with N-acetylcysteine, orally in three daily dosages (morning-midday-evening),for seven consecutive days. | Dietary Supplement: N-acetylcysteine<br>* Orally in three daily dosages (morning-midday-evening), at 20 mg/kg/day, for seven consecutive days.<br>* Other names: NAC;|
| Experimental: EXP-Pla<br>Participated in daily training sessions and three games, and supplemented daily with Placebo, orally in three daily dosages (morning-midday-evening), for seven consecutive days. | Dietary Supplement: Placebo<br>* 500 mL drink that contained water (375 mL), sugar-free cordial (125 ml), and 2 g of low-calorie glucose/dextrose powder. Orally in three daily dosages (morning-midday-evening), for seven consecutive days.<br>|
| Active Comparator: CON-NAC<br>Participated in daily training sessions only and supplemented daily with N-acetylcysteine, orally in three daily dosages (morning-midday-evening),for seven consecutive days. | Dietary Supplement: N-acetylcysteine<br>* Orally in three daily dosages (morning-midday-evening), at 20 mg/kg/day, for seven consecutive days.<br>* Other names: NAC;|
| Active Comparator: CON-Pla<br>Participated in daily training sessions only and supplemented daily with Placebo, orally in three daily dosages (morning-midday-evening), for seven consecutive days. | Dietary Supplement: Placebo<br>* 500 mL drink that contained water (375 mL), sugar-free cordial (125 ml), and 2 g of low-calorie glucose/dextrose powder. Orally in three daily dosages (morning-midday-evening), for seven consecutive days.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in total antioxidant capacity in serum |  | At baseline and daily throughout the study, up to 11 days | 
| Change in protein carbonyls in serum |  | At baseline and daily throughout the study, up to 11 days | 
| Change in thiobarbituric acid reactive substances in serum |  | At baseline and daily throughout the study, up to 11 days | 
| Change in reduced glutathione in red blood cells |  | At baseline and daily throughout the study, up to 11 days | 
| Change in oxidized glutathione in red blood cells |  | At baseline and daily throughout the study, up to 11 days | 
| Change in creatine kinase in activity in plasma |  | At baseline and daily throughout the study, up to 11 days | 
| Change in white blood cell count in blood |  | At baseline and daily throughout the study, up to 11 days | 
| Change in repeated sprint ability | Players' repeated sprint ability was assessed via a repeared sprint test. Each player performed 5 x 30 meters sprints interspersed by 25 seconds of active recovery. Sprint time was recorded by using infrared photoelectrical gates. | At baseline and daily throughout the study, up to 11 days | 
| Change in high intensity running during the game | High intensity running (i.e. > 14km/h) during the games was monitored by utilizing high time-resolution GPS devices. | During games 1, 2 and 3 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in blood lactate concentration during the game |  | During games 1, 2 and 3 | 
| Change in average heart rate during the game |  | During games 1, 2 and 3 |