This study investigated whether acutely consuming a large dose of a highly acidic beverage (orange juice) affects blood pH, muscle oxygenation or exercise performance in young active men. Thirteen participants completed two experimental phases. In Phase A, subjects ingested either orange juice with added sodium bicarbonate (pH 6.72±0.32; placebo) or orange juice (pH 3.50±0.99), randomly assigned. Blood pH and muscle oxygenation were monitored over 40 minutes following the ingestion of both beverages to identify any beverage-induced changed in blood pH and muscle oxygenation to guide sampling times for Phase B. In Phase B, participants consumed the same beverage as in Phase A, followed by assessments of anaerobic (Wingate test) and aerobic (peak oxygen consumption) performances, along with continuous muscle oxygenation monitoring. Results showed no significant differences (p>0.05) between treatments in blood pH, aerobic or anaerobic performance, or muscle oxygenation parameters. The acute ingestion of a highly acidic beverage like orange juice does not disrupt acid–base regulatory mechanisms or impair physiological or performance outcomes in healthy active men. These findings highlight the robustness of the body’s acid–base regulatory mechanisms and offer direct empirical evidence countering publicly circulated claims that normal dietary acidity impairs physiological function or exercise performance.