Effect of induced alkalosis on exhaustive leg press performance.
OBJECTIVE
Fifteen males were studied before, during, and in recovery from exhaustive resistance exercise 105 min after ingesting 0.3 g.kg-1 of either a placebo (white flour) or sodium bicarbonate (NaHCO3).


METHODS
The exercise consisted of five maximal sets on a leg press machine, The load was adjusted to maintain the number of repetitions per set for each subject at approximately 12 repetitions. A significant (P < 0.05) increase in pH (7.40 to 7.47), oxygenated base excess (OxyBE) (-1.3 to 4.0 mEq.L-1), and bicarbonate concentration ([HCO3-]) (22.8 to 27.4 mM) was achieved before exercise with the ingestion of NaHCO3.


RESULTS
The exercise protocol produced significant changes in acid base status consistent with metabolic acidosis for both trials (pH sets 1-5: placebo, 7.4 to 7.26; NaHCO3, 7.47 to 7.33), (OxyBE sets 1-5: placebo, -1.3 to -12.3 mEq.L-1; NaHCO3, 4.0 to -6.9 mEq.L-1) and ([HCO3-] sets 1-5: placebo, 22.9 to 14.0 mM; NaHCO3, 27.4 to 17.6 mM). After every set; pH, OxyBE, and [HCO3-] were significantly higher in the NaHCO3 trial. Blood lactate concentration ([La-]) significantly increased throughout exercise for both trials ([La-] sets 1-5: placebo, 4.6 to 11.3 mM; NaHCO3, 4.8 to 13.4 mM). After sets 4 and 5, blood [La-] was significantly higher in the NaHCO3 trial. Bicarbonate ingestion did not improve performance (total repetitions: NaHCO3 = 59 +/- 3; placebo = 60 +/- 2).


CONCLUSIONS
This may be a result of a lower demand on the whole body metabolic system in comparison with that for other modes of exercise in which ergogenic effects have been found.
Portington
K J
KJ
Department of Health & Human Performance, Auburn University 36849-5323, USA.
Pascoe
D D
DD
Webster
M J
MJ
Anderson
L H
LH
Rutland
R R
RR
Gladden
L B
LB
D000328:Adult; D000471:Alkalosis / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D010807:Physical Endurance; D017693:Sodium Bicarbonate / Q000008:administration & dosage / Q000494:pharmacology*; D014891:Weight Lifting / Q000502:physiology*
D017693:Sodium Bicarbonate