Renal responses to exercise-induced lactic acidosis

Area of Science:

• Exercise Physiology
• Renal Physiology
• Sports Medicine

Background:

• Intense exercise induces significant metabolic and physiological changes.
• Understanding renal responses to maximal exertion is crucial for athlete health and performance.
• Lactate accumulation and acid-base balance are key concerns during and after strenuous activity.

Purpose of the Study:

• To investigate the impact of maximal exercise on glomerular filtration rate (GFR).
• To analyze changes in renal electrolyte and lactate excretion post-exercise.
• To determine the relationship between urine chloride and lactate concentrations during recovery.

Main Methods:

• Five healthy males underwent four 30-second maximal exercise bouts on an isokinetic cycle ergometer.
• Arterial blood and urine samples were collected at rest, immediately post-exercise, and during 90 minutes of recovery.
• Glomerular filtration rate (GFR) was measured using continuous inulin infusion.

Main Results:

• A significant decrease in GFR was observed post-exercise and during recovery.
• Plasma lactate concentration ([Lac-]) increased significantly, while renal sodium (Na+) and potassium (K+) excretion decreased.
• Urine chloride ([Cl-]) excretion decreased significantly, correlating inversely with increased urine lactate, potentially buffering pH changes.

Conclusions:

• Maximal exercise acutely reduces GFR and alters renal ion handling.
• Reduced renal chloride excretion plays a role in mitigating the fall in urine pH associated with exercise-induced lactate accumulation.
• The majority of lactate produced during maximal exercise is metabolized rather than excreted renally.