Abstract Introduction: Several tests can predict the maximum weight an individual can lift using submaximal weights, which has been widely used in resistance training and clinical rehabilitation, but the reliability of these tests is not well documented. Objective: To analyze the test relative and absolute reliability of 10 maximum repetitions in the supine vertical bench press and leg extension machines. Method: Twenty-three healthy, untrained, and sedentary adults participated in the study. The test and retest evaluations were performed on the supine vertical press and leg extension machines. The retest was performed seven, 14 or 21 days after the test. Results: Intra-class correlation coefficient (ICC) was classified as very high (0.99) for upper limbs and (0.98) for lower limbs. The results for minimum detectable change (MDC) for the bench press resulted in a total of 2.77 kgf of actual change between test and retest, with an MDC% of 11.46%. For the leg extension, we found 3.15 kgf with MDC% of 8.94%. In both exercises, we obtained an MDC% below 30%, therefore acceptable. Conclusion: The 10RM test with the supine vertical press and leg extension has a very high relative reliability and an MDC acceptable for young, untrained and sedentary adults.