| Summary: | 碩士 === 國立臺灣大學 === 物理治療學研究所 === 94 === Background: The important role of cervical multifidus has been demonstrated by anatomical, morphological and biomechanical models. However, fewer studies have investigated the dynamic function of cervical multifidus which might be disturbed by the present of chronic pain. Purpose: The present study was to investigate the thickness changes of cervical multifidus during contraction and relaxation; and to compare the differences in activation patterns of cervical multifidus between participants with and without cervical symptoms. Method: Thirty participants (29.1±5.3 years old, 15 women and 15 men; 29.4±6.4 years old, 16 women and 13 men) were recruited to investigate the multifidus activation patterns during retraction against a fixed strain gauge (U3B1- 50K- B, Minebea Co., Ltd., Singapore). This force recording system was synchronized with ultrasonographic system (HDI 5000, ATL, USA). The mathematical relationship of instantaneous force (x) and changes of muscle thickness (y) during contraction (and relaxation) was estimated by quadratic models and the R2 values were calculated. Mixed models were used to examine the interaction and main effect of group (symptomatic and asymptomatic), contraction (contraction and relaxation) and levels (C4-C6). Results: Muscle thickness at resting condition showed no significantly smaller in participants with cervical symptom than those without symptoms. Muscle thickness, as well as the change from resting to maximal contraction, were significantly smaller than those of asymptomatic one (p<0.05). The best estimation equations during contraction and relaxation between the thickness-force relationship in asymptomatic participants (y=ax2+bx+c, a: range from -0.0018 to -.0033; b: from 0.41 to 0.51; c: from 1.05 to 14.09) showed significant curvilinear relationship (R2: 0.28-0.98). Compared to those of the asymptomatic participants, the symptomatic ones (y=ax2+bx+c, a: from -0.00005 to-.0031; b: from 0.22 to 0.41; c: range 1.33 to 13.35, R2: 0.25 -0.98) showed significantly smaller absolute value of a (p<0.05) and b values (p<0.05). Significant smaller c was observed during contraction than relaxation. Conclusion: Inability of increasing muscle thickness during maximal head retraction resistance was observed in symptomatic participants. Furthermore, the curvature of the thickness-force curve during contraction of the symptomatic participants was different from the asymptomatic participants, indicating the change of contraction in low load and high load condition was not consistent. Clinical application of this approaching might involve in early diagnosis and monitoring treatment effect of exercise.
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