Effect of induced alkalosis on the power-duration relationship of "all-out" exercise.
OBJECTIVE
We tested the hypotheses that sodium bicarbonate (NaHCO3) ingestion would result in no alteration in critical power (CP) but would improve performance in a 3-min all-out cycling test by increasing the total amount of work done above CP (W').


METHODS
Eight habitually active subjects completed 3-min all-out sprints against fixed resistance in a blind randomized design after a dose of 0.3 g.kg body mass of NaHCO3 and 0.045 g.kg body mass of sodium chloride (placebo; PL trial). Blood acid-base status was assessed from arterialized fingertip blood samples before and after exercise. The CP was calculated as the mean power output during the final 30 s of the test, and the W' was estimated as the power-time integral >CP.


RESULTS
The NaHCO3 dose was effective in inducing preexercise alkalosis as indicated by changes in blood pH (PL = 7.40 +/- 0.02 vs NaHCO3 = 7.46 +/- 0.01, P < 0.001), [bicarbonate] (PL = 21.9 +/- 3.0 vs NaHCO3 = 29.0 +/- 3.8 mM, P < 0.05), and base excess (PL = -1.9 +/- 2.5 vs NaHCO3 = 5.0 +/- 3.0 mM, P < 0.05). There were no significant differences in the total work done (PL = 62.8 +/- 10.1 vs NaHCO3 = 62.7 +/- 10.1 kJ), the CP (PL = 248 +/- 50 vs NaHCO3 = 251 +/- 51 W), or the W' (PL = 18.2 +/- 6.4 vs NaHCO3 = 17.5 +/- 6.0 kJ) estimates between treatments.


CONCLUSIONS
Despite notably enhanced blood-buffering capacity, NaHCO3 ingestion had no effect on the W', the CP, or the overall performance during 3 min of all-out cycling. It is concluded that preexercise blood alkalosis had no influence on the power-duration relationship for all-out exercise.
Vanhatalo
Anni
A
School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Exeter, UK. a.vanhatalo@exeter.ac.uk
McNaughton
Lars R
LR
Siegler
Jason
J
Jones
Andrew M
AM
D000328:Adult; D000471:Alkalosis / Q000139:chemically induced / Q000503:physiopathology*; D001642:Bicycling / Q000502:physiology; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000187:drug effects*; D005082:Physical Exertion / Q000187:drug effects*; D017693:Sodium Bicarbonate / Q000008:administration & dosage* / Q000494:pharmacology; D055815:Young Adult
D017693:Sodium Bicarbonate