Zhang S N, Bates B T, Dufek J S
Exercise Science Unit, Biomechanics/Sports Medicine Laboratory, The University of Tennessee, Knoxville 37996, USA.
Med Sci Sports Exerc. 2000 Apr;32(4):812-9. doi: 10.1097/00005768-200004000-00014.
The purpose of the study was to investigate changes in lower extremity joint energy absorption for different landing heights and landing techniques.
Nine healthy, active male subjects volunteered to perform step-off landings from three different heights (0.32 m, 2.5 m(-s); 0.62 m, 3.5 m(-s); and 1.03 m, 4.5 m(-s)) using three different landing techniques (soft, SFL; normal, NML; and stiff landing, STL). Each subject initially performed five NML trials at 0.62 m to serve as a baseline condition and subsequently executed five trials in each of the nine test conditions (3 heights x 3 techniques).
The results demonstrated general increases in peak ground reaction forces, peak joint moments, and powers with increases in landing height and stiffness. The mean eccentric work was 0.52, 0.74, and 0.87 J x kg(-1) by the ankle muscles, and 0.94, 1.31, and 2.15 J x kg(-1) by the hip extensors, at 0.32, 0.62, and 1.03 m, respectively. The average eccentric work performed by the knee extensors was 1.21, 1.63, and 2.26 J x kg(-1) for the same three heights.
The knee joint extensors were consistent contributors to energy dissipation. The ankle plantarflexors contributed more in the STL landings, whereas the hip extensors were greater contributors during the SFL landings. Also a shift from ankle to hip strategy was observed as landing height increased.
本研究旨在调查不同着陆高度和着陆技术下下肢关节能量吸收的变化。
九名健康、活跃的男性受试者自愿使用三种不同的着陆技术（软着陆，SFL；正常着陆，NML；硬着陆，STL）从三个不同高度（0.32米，2.5米/秒；0.62米，3.5米/秒；1.03米，4.5米/秒）进行跳下着陆。每位受试者最初在0.62米高度进行五次NML试验作为基线条件，随后在九个测试条件（3个高度×3种技术）中的每一个条件下执行五次试验。
结果表明，随着着陆高度和刚度的增加，地面峰值反作用力、峰值关节力矩和功率普遍增加。在0.32米、0.62米和1.03米高度时，踝关节肌肉的平均离心功分别为0.52、0.74和0.87焦耳/千克，髋部伸肌的平均离心功分别为0.94、1.31和2.15焦耳/千克。对于相同的三个高度，膝关节伸肌的平均离心功分别为1.21、1.63和2.26焦耳/千克。
膝关节伸肌是能量耗散的持续贡献者。在硬着陆中，踝关节跖屈肌的贡献更大，而在软着陆中，髋部伸肌的贡献更大。随着着陆高度的增加，还观察到从踝关节策略向髋部策略的转变。
