NAC Supplementation and Soccer Specific Performance

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

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.

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.

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

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.

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.

Participated in daily training sessions only and supplemented daily with N-acetylcysteine, orally in three daily dosages (morning-midday-evening),for seven consecutive days.

Participated in daily training sessions only and supplemented daily with Placebo, orally in three daily dosages (morning-midday-evening), for seven consecutive days.

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.

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.

High intensity running (i.e. > 14km/h) during the games was monitored by utilizing high time-resolution GPS devices.

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

Exercise Biochemistry Laboratory, School of Physical Education & Sports Sciences, University of Thessaly