EFFECTS OF NAHCO3 LOADING ON ACID-BASE-BALANCE, LACTATE CONCENTRATION, AND PERFORMANCE IN RACING GREYHOUNDS

This investigation examined the effects of NaHCO3 loading on lactate c oncentration ([La]), acid-base balance, and performance for a 603.5-m sprint task. Ten greyhounds completed a NaHCO3 (300 mg/kg body weight) and control trial in a crossover design. Results are expressed as mea ns +/- SE. Presprint differences (P < 0.05) were found for NaHCO3 vs. control, respectively, for blood pH (7.47 +/- 0.01 vs. 7.42 +/- 0.01), HCO3- (28.4 +/- 0.4 vs. 23.5 +/- 0.3 meq/l), and base excess (5.0 +/- 0.3 vs. 0.2 +/- 0.3 meq/l). Peak blood [La] increased (P < 0.05) in N aHCO3 vs. control (20.4 +/- 1.6 vs. 16.9 +/- 1.3 mM, respectively). Re lative to control, NaHCO3 produced a greater (P < 0.05) reduction in b lood base excess (-18.5 +/- 1.4 vs. -14.1 +/- 0.8 meq/l) and HCO3- (-1 7.4 +/- 1.2 vs. -12.8 +/- 0.7 meq/l) from presprint to postexercise. P ostexercise peak muscle H+ concentration ([H+]) was higher (P < 0.05) in NaHCO3 vs. control (158.8 +/- 8.8 vs. 137.0 +/- 5.3 nM, respectivel y). Muscle [H+] recovery half-time (7.2 +/- 1.6 vs. 11.3 +/- 1.6 min) and time to predose values (22.2 +/- 2.4 vs. 32.9 +/- 4.0 min) were re duced (P < 0.05) in NaHCO3 vs. control, respectively. No differences w ere found in blood [H+] or blood [La] recovery curves or performance t imes. NaHCO3 increased postexercise blood [La] but did not reduce the muscle or blood acid-base disturbance associated with a 603.5-m sprint or significantly affect performance.