Department of Anatomical Sciences, Stony Brook University, NY 11794-8081, USA.
Am J Phys Anthropol. 2010 Feb;141(2):222-34. doi: 10.1002/ajpa.21138.
Nonprimate terrestrial mammals may use digitigrade postures to help moderate distal limb joint moments and metapodial stresses that may arise during high-speed locomotion with high-ground reaction forces (GRF). This study evaluates the relationships between speed, GRFs, and distal forelimb kinematics in order to evaluate if primates also adopt digitigrade hand postures during terrestrial locomotion for these same reasons. Three cercopithecine monkey species (Papio anubis, Macaca mulatta, Erythrocebus patas) were videotaped moving unrestrained along a horizontal runway instrumented with a force platform. Three-dimensional forelimb kinematics and GRFs were measured when the vertical force component reached its peak. Hand posture was measured as the angle between the metacarpal segment and the ground (MGA). As predicted, digitigrade hand postures (larger MGA) are associated with shorter GRF moment arms and lower wrist joint moments. Contrary to expectations, individuals used more palmigrade-like (i.e. less digitigrade) hand postures (smaller MGA) when the forelimb was subjected to higher forces (at faster speeds) resulting in potentially larger wrist joint moments. Accordingly, these primates may not use their ability to alter their hand postures to reduce rising joint moments at faster speeds. Digitigrady at slow speeds may improve the mechanical advantage of antigravity muscles crossing the wrist joint. At faster speeds, greater palmigrady is likely caused by joint collapse, but this posture may be suited to distribute higher GRFs over a larger surface area to lower stresses throughout the hand. Thus, a digitigrade hand posture is not a cursorial (i.e. high speed) adaptation in primates and differs from that of other mammals.
非灵长类陆地哺乳动物可能会采用趾行姿势来帮助适度减轻高速运动时产生的远端肢体关节力矩和副跖骨的应力，因为此时会产生高地面反作用力（GRF）。本研究评估了速度、GRF 和远端前肢运动学之间的关系，以评估灵长类动物是否也出于同样的原因在陆地运动中采用趾行手姿势。我们对三种长尾猴物种（Papio anubis、Macaca mulatta、Erythrocebus patas）进行了录像，这些猴子在安装了力台的水平跑道上自由移动。当垂直力分量达到峰值时，测量了三维前肢运动学和 GRF。手姿势通过测量掌骨段与地面的夹角（MGA）来确定。正如预测的那样，趾行手姿势（更大的 MGA）与较短的 GRF 力矩臂和较低的腕关节力矩有关。与预期相反，当前肢受到更大的力（更快的速度）时，个体采用了更类似掌行的（即，更少趾行）手姿势（更小的 MGA），这可能导致更大的腕关节力矩。因此，这些灵长类动物可能不会利用改变手姿势的能力来降低高速时关节力矩的上升。低速时的趾行可能会提高穿过腕关节的抗重力肌肉的机械优势。在更高的速度下，更大的掌行很可能是由于关节塌陷造成的，但这种姿势可能更适合将更高的 GRF 分布在更大的表面积上，以降低整个手部的应力。因此，趾行手姿势不是灵长类动物的奔袭（即高速）适应特征，与其他哺乳动物的适应特征不同。
