EFFECT OF SODIUM-BICARBONATE INGESTION ON EXHAUSTIVE RESISTANCE EXERCISE PERFORMANCE

Six weight trained males were studied prior to, during, and in recover y from exhaustive resistance exercise, 105 min after ingesting 300 mg. kg-1 of either a placebo or NaHCO3. The exercise test consisted of fou r sets of 12 repetitions with a fifth set to volitional fatigue on a U niversal leg press machine at a resistance equaling approximately 70% of the subjects 1-repetition maximum. Arterialized venous blood was an alyzed for lactate concentration, blood ps, and acid-base parameters. The ingestion of NaHCO3 produced a significant increase in resting pH (739 to 7.46), HCO3- (22.9 to 28.3 mEq.l-1), and oxygenated base exces s (-1.3 to 4.4 mEq.l-1). With the completion of each exercise set, a p rogressive decline in the acid-base status of both groups was observed (pH set 1-5: NaHCO3, 7.40 to 7.31; placebo, 7.34 to 7.25; HCO3- set 1 -5: NaHCO3, 25.3 to 17.9; placebo, 21.7 to 15.3 mEq.l-1; base excess s et 1-5: NaHCO3, 3.7 to -7.1; placebo, -1.4 to -10.7 mEq.l-1); however, the NaHCO3 condition was significantly more alkaline than the placebo condition. Blood lactate concentration [La] progressively increased w ith the completion of each exercise set ([La] set 1-5: NaHCO3, 1.37 to 11.15; placebo, 1.31 to 9.81 mM); but were not significantly differen t between treatments. Repetitions performed in the final exercise set were not significantly different between groups (NaHCO3: 19.6 +/- 1.6, placebo: 18.2 +/- 1.1 repetitions). Whereas NaHCO3 has been shown to improve high-intensity running, cycling, and swimming performance, the se findings indicate that NaHCO3 does not necessarily enhance exhausti ve resistance exercise performance of the type typically used in stren gth training. However, additional experiments with a larger number of subjects and a more intense resistance exercise protocol appear to be warranted.