This work describes a simple and fast electrochemical method to evaluate the level of physical stress in athletes by monitoring total proteins in saliva. The proposed system is based on FIA with multiple pulse amperometric detection (FIA/MPA) using gold as the working electrode and 0.1 mol L À1 NaOH as the unique reagent. The proposed method is economical, fast (110 injections per hour) and allows the analysis of a small amount of saliva (~32 mL) with no sample treatment (just dilution). The results obtained by FIA/MPA were compared with the reference spectrophotometric method (Bradford) and a good agreement was found (r = 0.967; p < 0.05). In order to investigate a portable system to determinate physical stress, the electrodes were adapted to a batch injection analysis system (BIA) and the current signals of total proteins in saliva were obtained, similar to FIA.