Abstract Physical Insufficient levels of physical activity and sedentary behavior are highly prevalent worldwide and associated with cardiometabolic diseases and may vary according to gender and academic training. The objective was to investigate the association of sex and academic training with the level of physical activity and time spent in sedentary behavior in nursing students. It is a cross-sectional study with 286 nursing students from a public university. A sociodemographic and academic characterization instrument and an extended version of the International Physical Activity Questionnaire were applied. Data were analyzed descriptively and by Pearson's Chi-Square/Fisher's Exact test. The significance level was 5%. 65.7% of university students were active. Men were more active in leisure (p=0.000) and commuting (p=0.03). There was no association between sex and semester and total physical activity level. The prevalence of time in sedentary behavior ≥ 8 h/day for seven, five days, and weekends were 39.3%, 57.1%, and 21.4% for men and 55.0%, 65.1%, and 43.0% for women. A more significant proportion of women showed time in sedentary behavior ≥ 8 h/day on weekends (p=0.015) than men. A higher proportion between the 1st and 5th semesters remained ≥ 8 h/day in sedentary behavior on seven (p=0.024) and five days (p=0.001) week compared to those between the 6th and 10th semesters. The prevalence of insufficient physical activity levels and a long time in sedentary behavior were high and influenced by gender and training phase. Men were more active in commuting and leisure than women. Sedentary behavior is associated with gender and a training phase.