Trunk Flexor and Extensor Muscle Strength Capacity in Healthy Individuals

Objective: Generating reference values of trunk muscle strength is of value for specific age groups and gender in every society. The aim of this study was to define flexor and extensor muscle strength of the trunk and the flexion/extension ratio in healthy individuals. Materials and Methods: Hundred and two healthy individuals were included in this study. Isokinetic concentric strength of trunk flexor (Flex) and extensor (Ext) muscles of the participants were measured via an isokinetic dynamometer. Tests were performed at speeds of 60°/s and 180°/s. Maximum strength was characterized with peak torque (PT) (Flex abs , Ext abs ; N·m), peak torque normalized to body weight (PTNBW) (Flex norm , Ext norm ; N·m·kg bw -1 ), and Flex abs /Ext abs ratio. Results: For angular velocity of 60 0 /s, PT and PTNBW of flex and ext strength were higher in men; while for angular velocity of 180 0 /s, PTNBW of flex and ext strength were higher in women (p<0.05). Extensor strength for 60 0 /s and 180 0 /s angular velocities yielded lower values than flexor strength in both genders. The Flex abs /Ext abs ratios were 1.67±0.62 for 60 0 /s and 4.93±4.60 for 180 0 /s. Conclusion: Trunk extensor strength was higher than flexor strength in men and women at 60 0 /s and 180 0 /s angular velocities. In this study, the ratio of Flex abs /Ext abs was not within the accepted range in non-active adults and there was no difference between men and women, indicating that muscle strength is not sufficient in this population. The data of this study can be used as a comparison parameter in future studies to get normative data, or common values in healthy individuals aged 18-30.