Fatigability in patients with multiple sclerosis during maximal concentric contractions

Publication date: Available online 25 January 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Sophie Hameau, Djamel Bensmail, Nicolas Roche, Raphael Zory
ObjectiveTo compare quadriceps fatigability during maximal concentric contractions in persons with MS and healthy subjects (HS).DesignObservational study.SettingHospital rehabilitation departmentParticipantsThirty eight persons with MS and fourteen HS were included. Torque of the knee flexor and extensor muscles and fatigability of the knee extensor muscles were evaluated using an isokinetic device. Surface electromyographic activity of rectus femoris, vastus lateralis, biceps femoris, and semi tendinosus was recorded.InterventionsNone.Main outcome measuresMuscle fatigability (torque fatigue index)ResultsThe torque fatigue index was lower in persons with MS than in HS, but when the torque is normalized to maximal isometric peak torque, persons with MS and HS finished the fatigue protocol at exactly the same level of relative strength (50% of maximal isometric peak torque). Moreover, the reduction in torque was primarily due to a reduction in neuromuscular efficiency with no changes of coactivation of antagonist muscles.ConclusionAlthough fatigue is a disabling symptom of multiple sclerosis, persons with MS develop less muscle fatigue than HS during repeated maximal concentric contractions but they end up at the same level of relative strength.



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