Introduction: Nonspecific low back pain has been associated with the presence of low endurance and strength of the trunk muscles, especially in people who are exposed to the constant handling of loads.Objetives: The objective of the present study was to determine the anterior, lateral and posterior muscular endurance in operators of a specialized transport company of merchandise.Materials and methods: For this, 22 operators who performed work of manipulation, transfer and merchandise storage, all healthy at the time of the application of the tests, which were as follows: Sorensen's test for posterior resistance, 60 ° bending test for the anterior resistance and left and right lateral bridges for lateral resistance. Subsequently a descriptive analysis of the results for each of the variables was performed, and the force ratios between the anterior and posterior planes were determined between both the lateral planes and between the posterior and lateral planes.Results: It was established the presence of low muscle resistance of the trunk in the operators in relation to the normative data of McGill.Conclusions: There are muscular imbalances in the lateral ratios and the right ratio posteriorlateral, fact that supports a possible risk of low back pain in the study subjects.