Evaluation of blood pH has been widely used in exercise physiology as an indirect way to assessing muscle acidosis. However, collecting venous or arterial blood in athletes in field condition is not an easy and secure method. Capillary blood is an alternate technique that is not so invasive and, in opposition to venipuncture, much more acceptable to athletes and coaches. So, the aim of this study was analyze the capillary blood pH alterations in response to incremental exercise on a cycle ergometer as an alternative method to traditional blood collection. In a pre-experimental design approved by the ethics committee of the University of Pernambuco/Recife-PE/Brazil, nine trained male cyclists (24±2 years; 71±7 kg; 170±4 cm; 47±9 mL/kg/min; 4.1±0.6 W/kg) underwent to an incremental exercise on a cycle ergometer, started at 10%Wmax (maximal output in Watts), determined by a previous (7-days before) peak power output test which included respiratory gas analysis (CPX, Cortex, Germany), which the load was increased incrementally by 10% each three minutes until volitional exhaustion. Capillary blood samples (25μL) from a finger were homogenized in 1% NaF (50μL) and the pH was immediately measured in a digital pH meter (Spear, USA) at rest, at the end of each 3-minute increment of exercise and at 3, 6, 9, 15, 30 and 60 minutes after exercise (passive recovery). A one-way repeated measures analysis of variance ANOVA (rest vs. exercise/recovery) and regression analysis were performed and the level of significance was set at p<0.05. The results showed that pH at rest was 7.7±0.08 and the lowest value was 7.08±0.22, obtained at third minute during recovery. Capillary pH showed a decrease in response to exercise, being significant different from resting values from the intensity equivalent to 70%Wmax, returning to baseline only after 60 minutes, F(15, 124)=14.710; p<0.001 (Fig. 1). The cubic trend was strong and statistically significant, where average capillary pH was correlated with the exercise intensity (%Wmax), (pH=7.752 – 0.076Wmax + 0.014Wmax2 – 0.001Wmax3; F=117.9; R2adjusted=0.975; S.E.=0.023; p<0.001). In conclusion, the capillary blood pH of cyclists declined with increasing intensity of exercise on a cycle ergometer. The proposed model suggests that (i) pH determined in capillary blood is a sensitive method to evaluate exercise intensity (ii) and can be used as a low cost alternative for exercise intensity determination.