Sodium bicarbonate (NaHCO3) is a pre-exercise alkalotic buffering agent that is ingested to alleviate accumulation of hydrogen anions during exercise. As such, this supplement has been extensively used in scientific literature to assess NaHCO3 ergogenic properties during high intensity exercise. These ergogenic properties are likely to be apparent when exercise perturbs the acid-base balance with excessive H+ accumulation; therefore, the lowest intensity at which NaHCO3 may exert an ergogenic effect is during exercise performed within the severe intensity domain. The physiological characteristics of severe intensity exercise include exacerbated rise in [bla], and therefore acid-base perturbations, until the termination of exercise. The environmental conditions can also have an additive physiological stress to exercise; indeed, acute hypoxia increases the relative energy contribution of anaerobic glycolysis. The resultant effect is an exacerbated rise in H+ during exercise, which may, at least in part, contribute to the ergolytic effect of acute hypoxia on exercise performance and capacity. As such, severe intensity exercise performed in acute hypoxic conditions may benefit from NaHCO3 ingestion to alleviate acidic stress and mitigate for the ergolytic effect of acute hypoxia. The purpose of this thesis was to evaluate the effect of NaHCO3 on severe intensity exercise performed in acute hypoxic conditions. Furthermore, this effect was evaluated through the parameter of the powerduration relationship (i.e. CP and !") during all-out, intermittent and constant load exercise to exhaustion. Together, this series of investigations are the first to demonstrate that NaHCO3 may be an effective ergogenic aid in acute moderate hypoxic conditions. In particular, this effect was observed during exercise in the severe intensity domain, with NaHCO3 enhancing the capacity of !" during all-out and constant load exercise; along with increasing volume of work that can be performed at this intensity during intermittent exercise. Indeed, Chapter six demonstrated that NaHCO3 may accelerate the rate of !" recovery during intermittent exercise when applied to the !#$% " model. Interestingly, this thesis is the first to identify the presence of an intensity dependant effect, with the magnitude of NaHCO3 ergogenicity diminishing as exercise intensity rises from the severe intensity domain to supra-maximal intensities. Further research should consider testing these hypotheses in alternative ambient conditions to determine the efficacy of NaHCO3 (e.g. in normoxic conditions or in combined extreme environmental conditions).
|Date of Award||18 Oct 2018|
|Supervisor||LARS MCNAUGHTON (Director of Studies) & Andy Sparks (Supervisor)|