Electromyographic activity to keep a lower limb in a raised position in healthy subjects and subjects with multiple sclerosis

The objective of this work was to assess the activation of the stabilization muscles used to keep one lower limb raised from a supine position, in healthy subjects and in subjects with multiple sclerosis ( MS) in two different conditions. The test required subjects to keep the right lower limb at 45 from the supine position on a horizontal bed plane, with the knee extended. The position was reached in two ways: by raising the right limb ( A), and by resting the left lower limb on the bed after both limbs had been raised ( B). During the test, pelvis and hip kinematics and the surface electromyographic ( sEMG) activity were acquired. Fourteen healthy subjects and 14 subjects with multiple sclerosis were included in the study. Results showed that in the A condition, healthy subjects had a greater activation of the biceps femoris than the abdominal muscles, while in the B condition the difference between the two muscles decreased. In the MS group there was no difference in muscular activation for the two conditions. The data show that in the MS subjects there is an alteration of the stabilization muscles with regard the quality of the activation. Starting from these data new exercises of motor rehabilitation in subjects with multiple sclerosis could be recommended.