| Sumario: | 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 lilting 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.
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