Study aim: to develop and estimate the validity of non-exercise methods to predict VO2max among young male conscripts entering military service in order to divide them into the different physical training groups.

Material and methods: fifty males (age 19.7 ± 0.3 years) reported their physical activity before military service by IPAQ and SIVAQ questionnaires. Furthermore, Jackson’s non-exercise method was used to estimate VO2max. Body mass and height were measured, body mass index calculated and VO2max measured directly in a maximal treadmill test. Subjects were randomly divided into two groups. The results of the Group 1 (N = 25) were used to develop a regression equation to estimate VO2max. The results of the Group 2 (N = 25) were used to evaluate the validity of the developed non-exercise methods and Jackson’s non-exercise methods to estimate VO2max by Bland and Altman plot. The validity was further evaluated by comparing the results to 12-minute running test performed by 877 male conscripts (age 19.6 ± 0.2 years).

Results: the developed models explained 68–74% of the variation in VO2max. Mean difference between directly measured and estimated VO2max was not significant, while Jackson’s method overestimated VO2max (p < 0.001). Both developed models were equally valid to divide conscripts into tertile group of fitness. However, 5% of the conscripts were classified into the highest fitness group based on both methods, but they were actually in the lowest fitness group based on a running test.

Conclusion: in practice, these findings suggest that developed methods can be used as a tool to divide conscripts into different fitness groups in the very beginning of their military service.