The condition of O2 in the morning is different from the night because the process of photosynthesis occurs in plants. Plants absorb CO2 in the morning and release CO2 at night. Exercise affects the frequency of breathing which results in an increase in the mass of accessory muscles of respiration so that the uptake of O2 in the lungs increases. O2 is taken up by the blood through the lungs and binds to Hb. O2 that diffuses into the lungs and binds to Hb, affects the value of the body's oxygen saturation (SpO2). This study aims to compare the acute response of morning and evening outdoor exercise to oxygen saturation (SpO2) after aerobic activity. This type of research is a quasiexperimental pretest-posttest with a cross-over design. The subjects were 32 athletes who were divided into 2 groups. Measurement of oxygen saturation using a pulse oximeter. The data analysis technique used the statistical package for social science (SPSS 16.0). The results of the oxygen saturation analysis before morning and evening outdoor exercise showed no significant difference (p>0.05). Oxygen saturation after morning and evening outdoor exercise showed no significant difference (p>0.05). The results of this study concluded that there is no difference in oxygen saturation before outdoor exercise in the morning and evening. There is no difference in oxygen saturation after morning and evening outdoor exercise.

oxygen saturation

morning outdoor exercise

evening outdoor exercise

aerobic activity