Abstract
Five cases (4 males, 1 female) with ACL insufficiency were evaluated by frequency analysis of surface EMG. Subjects ranged in age from 17 to 41 years (mean 27 years). Surface EMG was recorded from above the quadriceps musle during sustained (30s) isometric contraction. The recorded EMG was computerized by spectrum analyzer. Results were as follows. Double peaks were seen in the frequency distribution in the range of 20-40Hz and 70-90Hz. Mean power frequency in the normal side gradually decreased, but no change was seen in the uninjured side. The higher (>81Hz) frequency zone in injured side decreased in comparison with the normal side. We concluded that type II fibres of knee extensors were dysfunctiond in patients with ACL insufficiency.
