Effects of Age, Gender and Level of Co-contraction on Elbow and Shoulder Rotational Stiffness and Damping in the Impulsively End-Loaded Upper Extremity

摘要: Whether an arm will buckle under impulsive end-load should partly depend on the elastic and viscous properties of pretensed muscles. In measuring these we hypothesized that neither age, gender, nor muscle pre-contraction level would affect bilinear elbow or shoulder lumped rotational stiffness damping parameters in impulsively end-loaded upper extremity 38 healthy men women. Subjects were instructed to preactivate triceps either 25, 50 75% maximum myoelectric activity levels. Then a standardized was applied via 6-axis load cell wrist slightly flexed prone posture. Arm kinematic responses acquired at 280 Hz inverse dynamics analysis used estimate stiffnesses shoulder. The results show affected normalized joint coefficients (p < 0.02). Age initial for (p < 0.05), gender sagittal plane (p < 0.006). strength positively related elbow, but not We conclude each viscoelastic behavior adults.