Abstract
Eight healthy males performed two rides to exhaustion at a work load corresponding
to 125 V̇O2 max, 1 h after ingesting either 0.2 g NaHCO3/kg body weight (E) or NaCI (C). Mean ± SE pre-exercise blood pH, HCO-
3, and base excess (BE) values were respectively 7.42 ± 0.01, 28.2 ± 1.5 mmol/l, and
2.02 ± 0.10 mmol/l for the E condition, and 7.39 ± 0.01, 24.4 ± 0.07 mmol/l, and -0.40
± 0.07 mmol/l for the C condition (P < 0.05 for all variables). Cycling time to exhaustion (E = 100.6 ± 6.1; C = 98.6
± 5.7 s) and total V̇O2 during recovery (E = 17.7 ± 0.9; C = 17.3 ± 0.8 I/30 min) did not differ significantly
between treatments. Blood pH, HCO-
3, and BE were significantly higher while the hydrogen ion to lactate ratio (nmol/mmol)
was significantly lower in E than in C during recovery. Blood LA levels were also
greater in E than in C during the latter part of recovery although peak individual
values were not significantly different between trials (E = 14.4 ± 0.4; C = 13.3 ±
0.0 mmol/l). In view of the insignificant differences in cycling time, peak individual
LA, and total recovery V̇O2, it is not likely that LA production was greater in E than in C. Rather it appears
that LA efflux was enhanced by the NaHCO3 feeding. Additionally, the return of the acid-base status in blood to resting conditions
was more rapid during alkalosis. Given this protocol, alkalosis does not help to sustain
an intense exercise bout. These data suggest, however, that NaHCO3 may be of benefit following repeated work bouts.
Key words
acid-base - alkalosis - exercise - recovery - performance
