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G18R FREE COMMUNICATION/POSTER SKELETAL MUSCLE III

INFLUENCE OF INCOMPLETE SPINAL CORD INJURY ON LOWER EXTREMITY MUSCLE MASS

Bickel, C S.1; Dudley, G A. FACSM1

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Medicine & Science in Sports & Exercise: May 2001 - Volume 33 - Issue 5 - p S295
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Weight bearing activities are essential to the maintenance of muscle mass. In accord with this concept, complete spinal cord injury (SCI) causes rapid atrophy that can be extensive. The atrophic response is muscle specific, reflecting relative differences in unloading among muscles. Individuals with incomplete SCI are often community ambulators, but frequently present with reduced strength in one or both lower limbs. This pilot study examined incomplete SCI patients to determine if apparent differences in loading were refelected in muscle size of the involved and non-involved lower limb. Four subjects (37 ± 8 yr, 79 ± 7 kg, mean ± SE) at least one year post an incomplete SCI participated. Magnetic resonance (MR) images of the thigh and leg were taken to asses muscle cross sectional area. Subjects verbally indicated which of their lower limbs was involved. This was confirmed by determining the 1 repetition maximum for each knee extensor muscle group. In all subjects, the involved limb had a lower 1 RM than its non-involved counterpart. On average, the quadriceps femoris (p < 0.001), adductor (p < 0.025), and hamstring (p < 0.001) muscle groups of the non-involved thigh were 5 to 8% larger than those of the involved extremity. The m. gastrocnemius, soleus and tibialis anterior of the leg did not show differences between limbs (p > 0.05). These preliminary results suggest relatively less loading of the involved thigh in chronic, incomplete SCI. This may reflect the general impression that most of the ambulation these patients perform is over level ground, thereby emphasizing use of the calf. In contrast, when they do ascend stairs, for example, they apparently favor their non-involved thigh. Supported by the Foundation for physical Therapy (CSB)

©2001The American College of Sports Medicine