The effect of metabolic alkalosis on fibre-specific maximal force production and rates of force development (RFD) has been previously investigated in animal models, with evidence suggesting an improved capacity to rapidly develop force in fast- compared to slow-twitch muscle. To date, the fibre-type dependent findings related to pH and rapid force generation have not been replicated in the exercising human. PURPOSE: To model in vivo the fatigue profile of voluntary and involuntary maximal force and rate of force development in the triceps’ surae and brachii after sodium bicarbonate (NaHCO3) ingestion. METHODS: In a double-blind, 3-way repeated measures design participants (n=10) ingested either 0.3 g·kg-1 NaHCO3 (ALK) or equivalent calcium carbonate (PLA) prior to 2-min of continuous (1Hz) supramaximal stimulation (300ms at 40Hz) of the triceps’ surae or brachii, with maximal voluntary efforts (MVT) coupled with direct muscle stimulation also measured at baseline, 1-min and 2-min. RESULTS: Metabolic alkalosis was achieved in both ALK trials but was not different between muscle groups. Regardless of condition, involuntary torque declined nearly 60% in the triceps brachii (p < 0.001) and ~ 30% in the triceps surae (p < 0.001). In all trials there was a significant decline in normalised involuntary RFD (p < 0.05). MVT declined nearly 28% but was not different between conditions (p < 0.01), and although declining nearly 21% in voluntary RFD (p < 0.05) there was no difference between PLA and ALK in either muscle group (p = 0.93). CONCLUSION: NaHCO3 exhibited no effect on the fatigue observed between representative fibre-type muscle groups on maximal voluntary and involuntary torque or rates of torque development during and after 2-min of tetanic stimulation.