Introductionnowadays, with the increase of world obesity and the numbers of morbidly obese people, a concerning public health problem that is difficult to solve rises up. Objectiveto analyse the physiological responses after the 6-minute walk tests and maximum stress test in the arm cycle ergometer in morbidly obese pre-bariatric surgery women. Methodsfifteen level III obesity women aged 35.6±6.6 years took part in this experiment. Firstly, they went through an anamnesis and body composition analysis; secondly, they were submitted to a 6-minute walk test and a maximum stress test in arm cycle ergometer on alternate days. Resultspatients were able to perform the maximum stress test and showed better aerobic potentials in the arm cycle ergometer than in the 6-minute walk test. No significant differences were found between SPO2 and diastolic blood pressure between the moments of rest and after the tests, neither in the systolic blood pressure after the 6-minute walk test and the values of rest and post 5minutes in the maximum stress test. The main differences found were between the maximum systolic blood pressure in the cycle ergometer test and the other moments and the heart rate after the tests and the heart rate at rest. Conclusionthe maximum stress test in arm cycle ergometer is a safe method that allows greater requirement and control applied to the heart system than in the 6-minute walk test. In addition, it allows the development of a more individualized aerobic training and prescription of aerobic physical exercise program.