The wrist and finger extensors play a crucial role in the muscle coordination during grasping tasks. Nevertheless, few data are available regarding their force-generating capacities. The objective of this study was to provide a model of the force-length-activation relationships of the hand extensors using non-invasive methods. The extensor carpi radialis (ECR) and the extensor digitorum communis (EDC) were studied as representative of wrist and finger extensors. Ten participants performed isometric extension force-varying contractions in different postures on an ergometer recording resultant moment. The joint angle, the myotendinous junction displacement and activation were synchronously tracked using motion capture, ultrasound and electromyography. Muscle force was estimated via a musculoskeletal model using the measured joint angle and moment. The force-length-activation relationship was then obtained by fitting a force-length model at different activation levels to the measured data. The obtained relationships agreed with previously reported data regarding muscle architecture, sarcomere length and activation-dependent shift of optimal length. Muscle forces estimated from kinematics and electromyography using the force-length-activation relationships were comparable, below 15% differences, to those estimated from moment via the musculoskeletal model. The obtained quantitative data provides a new insight into the different muscle mechanics of finger and wrist extensors.

在抓紧任务期间，腕部和手指伸肌在肌肉协调中起着至关重要的作用。然而，关于其力量生成能力的数据很少。这项研究的目的是提供一种使用非侵入性方法的手伸肌力-长度-激活关系模型。研究了腕car伸肌（ECR）和指指伸肌（EDC）作为腕部和手指伸肌的代表。十名参与者在测功计上以不同的姿势进行了等轴测伸展力变化的收缩，记录了结果力矩。使用运动捕获，超声和肌电图同步跟踪关节角度，肌腱结位移和激活。使用测得的关节角度和力矩通过肌肉骨骼模型估算肌肉力量。然后通过将不同激活级别的力长模型拟合到测量数据中来获得力长激活关系。所获得的关系与先前报道的有关肌肉结构，肌节长度和最佳长度的激活依赖性变化的数据一致。根据运动学和肌电图使用力-长度-激活关系估算出的肌肉力与通过肌肉骨骼模型从瞬间估算出的力相当，低于15％。获得的定量数据为手指和腕部伸肌的不同肌肉力学提供了新的见解。所获得的关系与先前报道的有关肌肉结构，肌节长度和最佳长度的激活依赖性变化的数据一致。根据运动学和肌电图使用力-长度-激活关系估算出的肌肉力与通过肌肉骨骼模型从瞬间估算出的力相当，低于15％。获得的定量数据为手指和腕部伸肌的不同肌肉力学提供了新的见解。所获得的关系与先前报道的有关肌肉结构，肌节长度和最佳长度的激活依赖性变化的数据一致。根据运动学和肌电图使用力-长度-激活关系估算出的肌肉力与通过肌肉骨骼模型从瞬间估算出的力相当，低于15％。获得的定量数据为手指和腕部伸肌的不同肌肉力学提供了新的见解。