The impact of a 6000-meter endurance exercise test on acid-base balance parameters

Background and Study Aim. Physical exercise disrupts the body's homeostasis, particularly acid-base balance. These changes may influence athletic performance and recovery efficiency. This study aimed to evaluate the changes in acid-base and electrolyte balance parameters in response to a 6000-meter rowing ergometer test. It also examined their dynamics during the first hour of post-exercise recovery in highly trained athletes. Material and Methods. The study included 23 athletes (8 women and 15 men), all members of the Polish Youth National Rowing Team. All participants were university students. Participants completed a 6000-meter test on a Concept2 Model D rowing ergometer. Capillary blood samples were collected from the earlobe at three time points: at rest (T0), immediately after exercise (T1), and 60 minutes post-exercise (T2). Analyses were performed using a portable EPOC analyzer. Parameters assessed included acid-base balance (pH, pCO₂, pO₂, TCO₂, cHCO₃⁻, BE(ecf), BE(b)), electrolytes (Na⁺, K⁺, Ca²⁺, Cl⁻), hematological markers (Hct, cHgb), and energy metabolism (glucose, lactate). Renal indicators such as creatinine, urea, and their ratios (BUN/Creatinine, Urea/Creatinine) were also measured. Data were analyzed using repeated measures ANOVA to detect differences across time points and between sexes. Statistical significance was set at p < 0.05. Results. The exercise caused significant acid-base disturbances. At T1, pH, TCO₂, and cHCO₃⁻ levels decreased, with partial recovery at T2. Women showed consistently lower pCO₂ and base excess values than men, indicating sex-related differences in compensatory responses. In men, post-exercise sodium decreased and chloride increased. In women, potassium levels dropped significantly at T1. Calcium remained stable in both groups. Glucose and lactate levels increased after exercise and declined by T2. Lactate levels were higher in men. Creatinine increased after exercise and remained elevated at T2. In men, urea levels also increased during recovery. Hematocrit and hemoglobin rose after exercise and declined afterward, with women showing lower values throughout. Conclusions. Intense physical exertion leads to substantial disturbances in acid–base and electrolyte balance, with compensatory mechanisms failing to restore homeostasis within one hour post-exercise fully. Sex-specific differences in pCO₂, sodium, potassium, and metabolic responses suggest distinct physiological adaptation strategies. These findings highlight the importance of individualized recovery protocols and the consideration of sex-specific factors in training program design to enhance adaptation and accelerate the return to homeostasis. They also provide practical insights for physical education in university settings, supporting the development of evidence-based recovery strategies for student-athletes.