Forms of forward quadrupedal locomotion. III. A comparison of posture, hindlimb kinematics, and motor patterns for downslope and level walking
Forms of forward quadrupedal locomotion. III. A comparison of posture, hindlimb kinematics, and motor patterns for downslope and level walking
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DOI：
10.1152/jn.1998.79.4.1702
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发表时间：
1998-04-01
影响因子：
2.5
通讯作者：
Trank, TV
中科院分区：
文献类型：
--
作者：
Smith, JL;Carlson-Kuhta, P;Trank, TV
为了进一步了解不同形式的四足行走的神经机制，对从 25%（14 度坡度）到 100%（45 度）的四个等级的下坡行走的姿势定向、后肢运动学和运动模式的数据进行了评估，并与跑步机（0.6 m/s）上五个等级（5-25%）的水平和下坡行走的数据进行了比较。通过数字化电影胶片获得运动学数据，并从 13 个不同的后肢肌肉中获取与运动学记录同步的肌电图 (EMG)。在 25% 至 75% 的坡度处，周期周期相似，但在最陡的坡度处，周期较短，因为站立阶段缩短。所有坡度的爪子接触顺序都与横向顺序行走一致，但步伐行走通常发生在最陡的坡度上。猫在陡峭的坡度上蹲伏，并且蹲伏与前肢和后肢方向的变化有关，这与站立期间制动力的增加和推进力的减少一致。除臀部外，后肢关节的平均运动范围在两个最陡的斜坡上通常是不同的。在摆动过程中，膝关节和踝关节的屈曲范围减小，踝关节的伸展范围和持续时间增加，以降低爪子向下接触。站立期间，踝关节屈曲范围增大，膝关节和跖趾关节伸展范围减小。下坡行走也与一些肌肉的肌电图变化有关。站立时髋部伸肌不活跃；相反，髋部屈肌活跃，可能是为了减慢髋部伸展的速度。尽管踝关节伸肌在站立期间处于活动状态，但其爆发持续时间被缩短并集中在爪子接触附近。在需要开始摆动之前，在陡峭斜坡的中间位置之后，踝关节屈肌是活跃的，而屈指肌和伸指肌在整个站立过程中都是协同活动的。总体而言，站立期间姿势、后肢运动学和后肢肌肉活动模式的变化反映了抵消会加速某些关节角位移的外力的需要。通过使用当前步行神经控制模型来讨论这些变化的影响。
To gain further insight into the neural mechanisms for different forms of quadrupedal walking, data on postural orientation, hindlimb kinematics, and motor patterns were assessed for four grades of downslope walking, from 25% (14 degrees slope) to 100% (45 degrees), and compared with data from level and downslope walking at five grades (5-25%) on the treadmill (0.6 m/s). Kinematic data were obtained by digitizing cine film, and electromyograms (EMGs) synchronized with kinematic records were taken from 13 different hindlimb muscles. At grades from 25 to 75%, cycle periods were similar, but at the steepest grade the cycle was shorter because of a reduced stance phase. Paw-contact sequences at all grades were consistent with lateral-sequence walking, but pace walking often occurred at the steepest grades. The cats crouched at the steeper grades, and crouching was associated with changes in fore-and hindlimb orientation that were consistent with increasing braking forces and decreasing propulsive forces during stance. The average ranges of motion at the hindlimb joints, except at the hip, were often different at the two steepest slopes. During swing, the range of knee- and ankle-joint flexion decreased, and the range and duration of extension increased at the ankle joint to lower the paw downward for contact. During stance the range of flexion during yield increased at the ankle joint, and the range of extension decreased at the knee and metatarsophalangeal joints. Downslope walking was also associated with EMG changes for several muscles. The hip extensors were not active during stance; instead, hip flexors were active, presumably to slow the rate of hip extension. Although ankle extensors were active during stance, their burst durations were truncated and centered around paw contact. Ankle flexors were active after midstance at the steeper slopes before the need to initiate swing, whereas flexor and extensor digit muscles were coactive throughout stance. Overall the changes in posture, hindlimb kinematics, and activity patterns of hindlimb muscles during stance reflected a need to counteract external forces that would accelerate angular displacements at some joints. Implications of these changes are discussed by using current models for the neural control of walking.