Comparison of three methods to assess muscular strength in individuals with spinal cord injury

The aim of the project was to compare three methods for measuring muscle strength in individuals with SCI: the manual muscle test (MMT), the hand-held myometry and the isokinetic dynamometry (Cybex). Thirty-eight (38) subjects, 31 men and seven women (age range = 14-63; lesion from C5 to L3) were included in this project. Muscle strength assessment of upper limbs was performed at admittance and discharge using MMT and myometry for the left and right side, and using Cybex dynamometer for the stronger side. The testing sessions were at least a day apart and performed by a single evaluator (trained physiotherapist). Significant and non-significant differences of myometry mean strength values were observed between consecutive levels of MMT. However, the range of myometry scores within each MMT grade led to significant overlaps between two adjacent MMT grades of each muscle group. Variables correlations were observed between the strength values measured by MMT and myometry with paraplegia (0.26 < or = r < or = 0.67) and tetraplegia (0.50 < or = r < or = 0.95). Similar results were observed when compared MMT and Cybex with the stronger side. Moderate to strong correlations were observed between the strength values measured by myometry and Cybex with paraplegia (0.70 < or = r < or = 0.90) and tetraplegia (0.57 < or = r < or = 0.96). These results suggest that the MMT method does not seem to be sufficiently sensitive to assess muscle strength, at least for grade 4 and higher and to detect small or moderate increases of strength over the course of rehabilitation. Since outcome measures is an important issue in rehabilitation, objective measurements of strength should be used in clinical settings. Considering cost and assessment time, the myometry technique seems to be highly valuable.