Fleming Braden C, Ohlén Goran, Renström Per A, Peura Glenn D, Beynnon Bruce D, Badger Gary J
McClure Musculoskeletal Research Center, Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, Vermont, USA.
Am J Sports Med. 2003 Sep-Oct;31(5):701-7. doi: 10.1177/03635465030310051101.
High graft strains incurred during rehabilitation after anterior cruciate ligament reconstruction may be minimized if an external compressive load is simultaneously applied to the joint during closed kinetic chain exercises.
Peak anterior cruciate ligament strains will 1). increase with an increase in resistance torque during an exercise that involves concentric contraction of the extensor mechanism, 2). decrease with an increase in resistance torque during an exercise that involves concentric contraction of the flexors, and 3). decrease when an external compressive load is applied to the knee during both exercises relative to the no external compressive load condition.
Controlled laboratory study.
Strains in the anteromedial bundle were measured in 10 subjects with normal ligaments. Flexor and extensor exercises were performed against controlled resistance torques with and without a compressive load applied to the foot.
An increase in resistance produced an increase in peak anterior cruciate ligament strain for the extensor exercise with no compressive load applied. During the flexor exercise without a compressive load, an increase in resistance produced a decrease in peak strains. During the extensor exercise, the peak anterior cruciate ligament strain was not reduced with the application of the external compressive force.
Extensor and flexor exercises that incorporate an external compressive load do not shield the anterior cruciate ligament from strain. However, no additional increase in strain occurs with an increase in resistance when the external compressive load is applied. Thus, it may be possible to increase the activity of the quadriceps muscles without increasing the strain by applying a compressive load (as with closed kinetic chain exercises).
如果在闭链运动期间同时对关节施加外部压缩负荷，前交叉韧带重建术后康复过程中产生的高移植应变可能会降至最低。
1）在前交叉韧带峰值应变在涉及伸肌机制向心收缩的运动中，会随着阻力扭矩的增加而增加；2）在涉及屈肌向心收缩的运动中，会随着阻力扭矩的增加而降低；3）在两种运动中，相对于无外部压缩负荷的情况，当对膝盖施加外部压缩负荷时，峰值应变会降低。
对照实验室研究。
对10名韧带正常的受试者测量其前内侧束的应变。在有和没有对足部施加压缩负荷的情况下，针对受控阻力扭矩进行屈伸运动。
在未施加压缩负荷的伸肌运动中，阻力增加会导致前交叉韧带峰值应变增加。在未施加压缩负荷的屈肌运动中，阻力增加会导致峰值应变降低。在伸肌运动中，施加外部压缩力并未降低前交叉韧带的峰值应变。
包含外部压缩负荷的屈伸运动并不能保护前交叉韧带免受应变。然而，当施加外部压缩负荷时，随着阻力增加，应变不会进一步增加。因此，通过施加压缩负荷（如闭链运动），有可能在不增加应变的情况下增加股四头肌的活动。
