Beta-alanine is a dietary supplement that increases skeletal muscle carnosine concentration and may enhance the muscle's ability to buffer hydrogen ions produced during high-intensity exercise. This buffering effect could potentially delay fatigue and improve exercise performance, particularly under conditions that increase metabolic stress, such as hypoxia. However, previous studies examining the effects of beta-alanine supplementation on repeated sprint performance under hypoxic conditions have produced inconsistent findings.

The purpose of this study is to determine whether four weeks of beta-alanine supplementation improves repeated high-intensity cycling performance and influences markers of acid-base balance in trained male cyclists exercising under normoxic and hypoxic conditions. Participants will perform repeated Wingate anaerobic cycling tests before and after a four-week supplementation period with either beta-alanine or placebo.

Mechanical performance outcomes, including peak power, mean power, total work, and fatigue indices, will be assessed alongside physiological measures of metabolic stress, including blood lactate concentration, pH, bicarbonate concentration, and base excess. Performance and physiological responses will be compared between supplementation groups and environmental conditions.

The findings of this study may contribute to a better understanding of the ergogenic potential of beta-alanine supplementation during repeated high-intensity exercise and provide practical information for athletes and practitioners regarding the effectiveness of beta-alanine under conditions of reduced oxygen availability.

Beta-alanine is a non-essential amino acid and the rate-limiting precursor for the synthesis of carnosine, an intracellular dipeptide found in high concentrations within skeletal muscle. Carnosine contributes to intracellular acid-base regulation by buffering hydrogen ions (H+) produced during high-intensity exercise. Supplementation with beta-alanine has consistently been shown to increase muscle carnosine concentrations, potentially enhancing buffering capacity and delaying the onset of fatigue during exercise characterized by substantial glycolytic energy production.

The ergogenic potential of beta-alanine has been extensively investigated in a variety of exercise modalities. Previous studies and meta-analyses suggest that supplementation may improve performance during high-intensity exercise lasting approximately one to four minutes, where metabolic acidosis is considered an important contributor to fatigue. However, findings remain inconsistent, particularly in exercise protocols involving repeated maximal efforts and in environmental conditions that alter oxygen availability.

Exercise performed in hypoxic environments is associated with reduced oxygen delivery to working muscles, increased reliance on anaerobic glycolysis, accelerated accumulation of hydrogen ions and lactate, and greater disturbance of acid-base homeostasis. Consequently, hypoxic exercise may increase the physiological importance of buffering mechanisms and potentially enhance the relevance of interventions aimed at improving buffering capacity. Despite this theoretical rationale, limited information is available regarding the effectiveness of beta-alanine supplementation during repeated supramaximal exercise performed under hypoxic conditions.

The purpose of this study is to evaluate the effects of four weeks of beta-alanine supplementation on repeated high-intensity cycling performance and physiological responses associated with metabolic acidosis in trained male cyclists. The study utilizes a randomized, double-blind, placebo-controlled design. Participants complete repeated laboratory testing sessions under both normoxic and normobaric hypoxic conditions before and after the supplementation period.

Exercise performance is assessed using a repeated Wingate anaerobic cycling protocol consisting of three consecutive 30-second maximal efforts separated by standardized recovery intervals. The protocol was selected because it induces substantial anaerobic energy production and metabolic stress, allowing evaluation of both performance outcomes and buffering-related physiological responses. Testing is conducted under normoxic conditions and under normobaric hypoxia corresponding to an altitude of approximately 2500 meters above sea level.

Physiological measurements include assessments of blood lactate concentration and indicators of acid-base balance collected in conjunction with the exercise protocol. These measurements are intended to characterize the metabolic and buffering responses to repeated supramaximal exercise and to determine whether beta-alanine supplementation modifies these responses.

The study is designed to improve understanding of the role of beta-alanine supplementation in athletes performing repeated high-intensity exercise under conditions of normal and reduced oxygen availability. The findings may contribute to the evidence base regarding nutritional strategies intended to support performance during repeated maximal efforts and may help clarify whether environmental stressors such as hypoxia influence the ergogenic effectiveness of beta-alanine supplementation.

Inclusion Criteria:

• Healthy male participants aged 20-50 years
• Regularly riding a bike (min. 5000 km on the bike in the last year)
• Willingness to maintain habitual dietary and physical activity patterns throughout the study.
• Willingness to refrain from consuming dietary supplements other than those provided as part of the study.

Exclusion Criteria:

• Prevalence of chronic diseases
• β-alanine supplementation within the previous six months
• Use of other dietary supplements, except carbohydrate and whey protein supplements
• Adherence to a vegetarian or vegan diet
• Participation in another clinical trial within the previous 3 months.

Anonymised data will be available upon reasonable request.