BACKGROUND: Trunk muscles fatigue is one of the risk factors in workplaces and daily activities. Loads would be redistributed among active and passive tissues in a non-optimal manner in fatigue conditions. Therefore, a single tissue might be overloaded with minimal loads and as a result the risk of injury would increase.
OBJECTIVE: The goal of this paper was to assess the electromyographic response of trunk extensor and abdominal muscles after trunk extensor muscles fatigue induced by cyclic lifting task.
METHODS: This was an experimental study that twenty healthy women participated. For assessing automatic response of trunk extensor and abdominal muscles before and after the fatigue task, electromyographic activities of 6 muscles: thorasic erector spine (TES), lumbar erector spine (LES), lumbar multifidus (LMF), transverse abdominis/ internal oblique (TrA/IO), rectus
abdominis (RA) and external oblique (EO) were recorded in standing position with
no load and symmetric axial loads equal to 25% of their body weights.
RESULTS: Statistical analysis showed that all the abdominal muscles activity decreased
with axial loads after performing fatigue task but trunk extensor activity remained constant.
CONCLUSIONS: Results of the current study indicated that muscle recruitment strategies changed with muscle fatigue and load bearing, therefore risks of tissue injury may increase in fatigue conditions.
