Induced metabolic alkalosis affects muscle metabolism and repeated-sprint ability.
OBJECTIVE
The purpose of this study was to assess the effects of induced metabolic alkalosis, via sodium bicarbonate (NaHCO3) ingestion, on muscle metabolism and power output during repeated short-duration cycle sprints.


METHODS
: Ten active females (mean +/- SD: age = 19 +/- 2 yr, VO2max = 41.0 +/- 8.8 mL x kg x min ) ingested either 0.3 g x kg NaHCO3 or 0.207 g x kg of NaCl (CON), in a double-blind, random, counterbalanced order, 90 min before performing a repeated-sprint ability (RSA) test (5 x 6-s all-out cycle sprints every 30 s).


RESULTS
Compared with CON, there was a significant increase in resting blood bicarbonate concentration [HCO3] (23.6 +/- 1.1 vs 30.0 +/- 3.0 mmol x L ) and pH (7.42 +/- 0.02 vs 7.50 +/- 0.04), but no significant difference in resting lactate concentration [La] (0.8 +/- 0.2 vs 0.8 +/- 0.3 mmol x L ) during the NaHCO3 trial. Muscle biopsies revealed no significant difference in resting muscle [La], pH, or buffer capacity (beta(in vitro)) between trials (P > 0.05). Compared with CON, the NaHCO3 trial resulted in a significant increase in total work (15.7 +/- 3.0 vs 16.5 +/- 3.1 kJ) and a significant improvement in work and power output in sprints 3, 4, and 5. Despite no significant difference in posttest muscle pH between conditions, the NaHCO3 trial resulted in significantly greater posttest muscle [La].


CONCLUSIONS
As NaHCO3 ingestion does not increase resting muscle pH or beta(in vitro), it is likely that the improved performance is a result of the greater extracellular buffer concentration increasing H efflux from the muscles into the blood. The significant increase in posttest muscle [La] in NaHCO3 suggests that an increased anaerobic energy contribution is one mechanism by which NaHCO3 ingestion improved RSA.
Bishop
David
D
Team Sport Research Group, School of Human Movement and Exercise Science, The University of Western Australia, Crawley, WA, Australia. dbishop@cyllene.uwa.edu.au
Edge
Johann
J
Davis
Cindy
C
Goodman
Carmel
C
D000328:Adult; D000471:Alkalosis / Q000503:physiopathology*; D000704:Analysis of Variance; D001642:Bicycling / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D011659:Pulmonary Gas Exchange; D017693:Sodium Bicarbonate / Q000008:administration & dosage / Q000494:pharmacology
D007773:Lactates; D017693:Sodium Bicarbonate