Today's lifestyle has created a large proportion of obese people and thus obesity has become one of the world's leading public health problems. Obesity is originally a health problem associated with a number of cardiovascular and other diseases and is a common cause of shorter life expectancy. Regular physical activity eliminates visceral fat and reduces the risk of diseases associated to obesity. Any physical activity requires immediate adaptation of the body and response of the cardiovascular system to the changed load. Accordingly, heart rate and cardiac cycle are closely related to the level of physical activity. The mentioned heart values are the best indicator of the condition of the heart muscle and its ability to withstand physical effort. In other words, it is the best indicator of cardio-respiratory endurance. The main goal of this research is to examine the effect of physical activity on cardiac cycle values in obese people. The necessary measurements were carried out using a modified Harvard step test, which the subjects performed before and after 48 training sessions. The sample consists of seventeen subjects, 10 female and 7 male, with a body mass index (BMI) greater than 29.9 〖kg/m〗^2, which according to the guidelines represents the limit of obesity. By statistical calculation using the Student's test, the results of the research showed that physical activity, which was carried out through 48 training sessions over a period of six months, reduced the score of the heart cycle in obese people.