This study aims to investigate the effects of four-week astaxanthin supplementation on soccer-specific performance under fatigue in soccer players. Using a randomized, double-blind, placebo-controlled design, participants were assigned to receive either astaxanthin or placebo for 4 weeks. After the supplementation period, participants completed an exhaustive exercise protocol followed by assessments of soccer-specific performance, neuromuscular function, and fatigue-related responses. The study is designed to determine whether astaxanthin supplementation can attenuate fatigue-related declines in performance and improve recovery-related outcomes in soccer players.

Soccer is characterized by repeated high-intensity efforts, rapid changes of direction, technical execution, and decision-making under physically demanding conditions. Fatigue induced by exhaustive exercise may impair neuromuscular performance, technical skills, and cognitive function. Astaxanthin is a carotenoid with antioxidant properties and has been suggested to help reduce exercise-related oxidative stress and fatigue. However, evidence regarding its effects on soccer-specific performance under fatigue remains limited.

The purpose of this study was to examine the effects of four-week astaxanthin supplementation on soccer-specific performance, neuromuscular function, and fatigue-related biomarkers under exhaustive exercise conditions in soccer players. This study used a randomized, double-blind, placebo-controlled parallel design. Eligible soccer players were assigned to either an astaxanthin supplementation group or a placebo group for 4 weeks.

After the intervention period, participants completed a standardized exhaustive exercise protocol to induce fatigue. Outcome assessments were then performed to evaluate soccer-specific performance and fatigue-related responses. The primary objective was to determine whether astaxanthin supplementation could reduce fatigue-related performance decline. Secondary objectives were to examine its effects on neuromuscular function and selected fatigue-related physiological responses.

The findings of this study may help clarify the potential role of astaxanthin supplementation as a nutritional strategy to support performance maintenance under fatigue in soccer players.

Inclusion Criteria:

• - Male soccer players aged 18 to 25 years.
• Healthy collegiate soccer players with regular soccer training experience.
• Participated in systematic soccer training for at least 3 years and regular training at least 3 times per week during the previous 6 months.
• Able to complete the supplementation protocol, exhaustive exercise protocol, and all performance assessments.
• Provided written informed consent before participation.

Exclusion Criteria:

• - Current musculoskeletal injury, pain, or illness affecting exercise performance or test participation.
• History of cardiovascular, metabolic, neurological, or other medical disorders that could affect study safety or outcomes.
• Use of antioxidant, ergogenic, or nutritional supplements that could influence study outcomes within 4 weeks before enrollment.
• Known allergy or intolerance to astaxanthin or capsule ingredients.
• Smoking, excessive alcohol consumption, or use of medications that could affect fatigue, performance, or physiological responses.
• Failure to comply with study procedures or intervention requirements.

This study used a double-blind, placebo-controlled design. Participants, investigators, and outcome assessors were blinded to group assignment. Astaxanthin and placebo capsules were identical in appearance, packaging, and administration schedule throughout the intervention period.