Stiffness of the hamstring muscles and its relationship to function in anterior cruciate ligament deficient individuals

Effects of Circumferential Ankle Pressure on Ankle Proprioception, Stiffness, and Postural Stability: A Preliminary Investigation

“…Passive stiffness arises from resistance of the passive muscle elements, tendons, ligaments, and joint capsules, whereas active muscle stiffness is derived from active or reflexmediated muscle contraction. [30][31][32]38,48,55,54,75,78 First, passive stiffness was computed from the ratio of applied static moment versus angular displacement. Three different moments (0 Nm, 6.13 Nm, and 9.19 Nm) were separately applied by loading the medial side of the platform with known weight plates while the subject stood symmetrically (Figure 1).…”

“…A ball was dropped with a constant velocity and magnitude to induce medial-rotational perturbation as it hit the lateral side of the platform. A second-order model of musculoskeletal dynamic was used to calculate stiffness (K A ) from the transientharmonic oscillations of ankle following each perturbation 55,54,62 :…”

“…K A can be calculated from the slope of the relationship between the external inertia applied to the platform and the inverse of the natural frequency 1/ n 2 recorded from the inversion-eversion motion following the perturbation. 55,54,62 Three separate levels of external inertia were applied (0.00, 0.07, and 0.14 kgm 2 ). Although this method provides accurate assessment of active muscle stiffness, this method (transient response) is limited in the presence of strong reflex behavior.…”

Differential effects of stimulus characteristics during knee joint perturbation on hamstring and quadriceps reflex responses

“…Isolated hamstring activation is recommended for ACL rehabilitation as it can directly counteract anterior tibial translation and thereby reduces ACL strain (McNair, Wood, & Marshall, 1992;Tsuda, Okamura, Otsuka, Komatsu, & Tokuya, 2001). However, the role of quadriceps activation for functional knee joint stability should not be neglected in connection with ACL injury.…”

Two Methods for Improvement of Short Hamstrings in Healthy Individuals

“…Short hamstrings can lead to posterior rotation of pelvis and flat back (3). Reduced hamstring extensibility is often associated with hip and knee joint movement dysfunction (4,5) and lumbosacral postural changes (6). This may be confirmed by induced hamstring shortening, which causes gait abnormalities in healthy people (7).…”