Studies of the prevalence of risk behaviors in different population sat the beginning of the last decade were common only in countries of the northern hemisphere, because epidemiological surveillance do not focus solely on the aspects of mortality and morbidity [1] . Currently, the centralization of studies on risk behavior of populations focuses primarily on chronic on-communicable diseases, with the premise warning about epidemics resulting from risk factors caused by negative lifestyle of populations, associated with the leading causes of death [2] [3] .

Several studies have demonstrated the correlation between a sedentary lifestyle [3] , smoking and overweight affects people’s health negatively, leading to lower levels of quality of life and increasing the incidence of diseases [4] [5] . Data published by Brazil’s Ministry of Health at the beginning of the last decade indicated that a sedentary lifestyle, smoking, and poor nutrition were responsible for over 50% of the total risk of developing any type of chronic disease [6] .

Engaging in regular physical activity is recognized as one of the main elements that contribute toward the prevention of risk factors for health [7] . A study conducted in Northeast and Southeast Brazilin the 1990s found that the percentage of physical inactivity (defined as less than 150 minutes per week of moderate physical activity or 60 minutes a week of vigorous physical activity during leisure time) had already reached 96.7% [8] . Currently, the percentage of physical inactivity during leisure time in Brazil’s adult population differs according to the region, 52% [9] in southern cities, 65.4% [10] in the Southeast, 47.5% [11] in the Midwest region, and 57.6% [12] in the Northeast. This analysis indicates that society does not engage in the minimum recommended levels of physical activity recommended by the American University of Sports Medicine, which would enable individuals to improve their fitness levels and thus contribute to a better quality of life.

The term quality of life is associated with abstract and everyday perceptions about the life style of each individual [13] [14] . However, its interrelationship with the area of health sciences emphasizes that the daily practice of physical exercise is essential to the creation of positive habits that provide a change of lifestyle, thus acting as one of the main factors that contribute toward improved health [15] - [17] . Among young Brazilian university students, the literature describe students of physical education [17] , psychology [18] , law [19] , nursing [12] [16] [20] , and medicine [19] [21] . These studies have shown that regular physical activity helps reduce risk factors and increases the level of quality of life, especially among engineering students, where we can see a shortage of studies.

The correlations between the quality of life domains and physical activity levels are strong and positive for both genders, concluding that the domains of quality of life and physical activity level differ between the genders and show positive strong relationships in undergraduate students [17] . Thus, this work involved an investigation of the level of quality of life and physical activity, and their correlation with the behavioral risk factors of young mechanical engineering students.

This is a cross-sectional study with a descriptive probabilistic sign conducted with mechanical engineering students enrolled at the Federal University of Paraná―UFPR. The study population consisted of 536 students of both sexes, arranged in ten periods. To calculate the sample, a sampling error of 4% and a confidence level of 95% were adopted, making a total of 296 participants in the study.

Intervening variables (sex, daily use of tobacco) were used as control, as well as the level of physical activity (International Physical Activity Questionnaire-IPAQ, short version) [22] , the level of quality of life (Quality of Life Questionnaire of the World Health-WHOQOL-bref) [14] , and nutritional status, also adopting the criteria of the World Health Organization (WHO) [13] , which verifies the overall level of quality of life, plus four domains: physical, psychological, social and environmental. Considering a BMI of <24.9 kg/m² as the limit between normal weight and overweight. Height and total body mass measurements were obtained from self-reported information, whose validity is described in several studies [23] .

All the individuals of the sample were informed about the procedures through a Free Prior and Informed Consent Form, describing the procedures and purpose of the research, according to the “Guidelines and Standards Regulating Research Involving Human Beings” (196/96), published by the National Health Commission and approved by the Research Ethics Committee of Ponta Grossa State University―UEPG.

The statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS, version 14.0) for Windows. The Kolmogorov-Smirnov test was used to check data normality. Due to this test, nonparametric inferences were used for some variables (Mann-Whitney, Kruskal-Wallis tests), and central tendency measures were used in the descriptive analysis of the data, adopting a value of p < 0.05.

With regard to the total number of participants, it was found that the average age of the population was 20.6 years, with ages ranging from 17 to 30 years, most of them, 77.7%, males, 98.6% single, 14.1% smokers and 26.3% classified as overweight.

When asked “How would you rate your quality of life?” 45.9% answered “good” (fourth point on a five-point Likert scale). The average level of quality of life “general” is analyzed based on the WHOQOL-bref syntax, which results in a scale of (0 - 100 points) and on which a good quality of life should be indicated by a result of close to 100. Based on this syntax, this study found a general health value of 71.4 points.

Table 1 lists the mean values and standard deviations of the overall level of quality of life of the participants, subdivided into its respective domains (Physical Domain―PhD, Psychological Domain―PsD, Social Relationships Domain―SRD and Environment Domain―ED), resulting from the evaluation using the WHOQOL-bref syntax, as well as the frequency of the level of physical activity based on the IPAQ classification.

The level of physical activity obtained with the IPAQ indicates that the highest