Abstract
ObjectivesIntervention studies do not account for high within-individual variation potentially compromising the magnitude of an effect. Repeat administration of a treatment allows quantification of individual responses and determination of the consistency of responses. We determined the consistency of metabolic and exercise responses following repeated administration of sodium bicarbonate (SB).Design and Methods15 physically active males (age 25±4 y; body mass 76.0±7.3 kg; height 1.77±0.05 m) completed six cycling capacity tests at 110% of maximum power output (CCT110%) following ingestion of either 0.3 g∙kg-1BM of SB (4 trials) or placebo (PL, 2 trials). Blood pH, bicarbonate, base excess and lactate were determined at baseline, pre-exercise, post-exercise and 5-min post-exercise. Total work done (TWD) was recorded as the exercise outcome.ResultsSB supplementation increased blood pH, bicarbonate and base excess prior to every trial (all p ≤ 0.001); absolute changes in pH, bicarbonate and base excess from baseline to pre-exercise were similar in all SB trials (all p > 0.05). Blood lactate was elevated following exercise in all trials (p ≤ 0.001), and was higher in some, but not all, SB trials compared to PL. TWD was not significantly improved with SB vs. PL in any trial (SB1: +3.6%; SB2 +0.3%; SB3: +2.1%; SB4: +6.7%; all p > 0.05), although magnitude-based inferences suggested a 93% likely improvement in SB4. Individual analysis showed ten participants improved in at least one SB trial above the normal variation of the test although five improved in none.ConclusionsThe mechanism for improved exercise with SB was consistently in place prior to exercise, although this only resulted in a likely improvement in one trial. SB does not consistently improve high intensity cycling capacity, with results suggesting that caution should be taken when interpreting the results from single trials as to the efficacy of SB supplementation.Trial RegistrationClinicalTrials.gov NCT02474628
Highlights
The effects of sodium bicarbonate (SB) on exercise have been extensively investigated with a meta-analysis indicating that a 0.3 gÁkg-1BM dose of SB results in a 1.7 ± 2.0% improvement in exercise performance [1]
The mechanism for improved exercise with SB was consistently in place prior to exercise, this only resulted in a likely improvement in one trial
SB does not consistently improve high intensity cycling capacity, with results suggesting that caution should be taken when interpreting the results from single trials as to the efficacy of SB supplementation
Summary
The effects of sodium bicarbonate (SB) on exercise have been extensively investigated with a meta-analysis indicating that a 0.3 gÁkg-1BM dose of SB results in a 1.7 ± 2.0% improvement in exercise performance [1]. It has recently been suggested that the way in which intervention studies are analysed (i.e. using mean differences between groups or trials) does not account for the potentially high variation within individuals compromising the magnitude of effect of the intervention [8]. The relationship between dose and the degree of blood alkalosis following SB ingestion has long been suggested to be weak [10] and the large variability in individual blood pH and bicarbonate responses to supplementation may result in the purported mechanism underlying a potential ergogenic effect of SB not always being present in all individuals which may have contributed to the inconsistent exercise results reported. The majority of studies have investigated the effect of SB during a solitary trial and not during multiple trials at the same intensity to determine group and individual consistencies in blood and exercise responses
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
