Leg stiffness primarily depends on ankle stiffness during human hopping

Farley, Claire T.; Morgenroth, David C.

doi:10.1016/s0021-9290(98)00170-5

Cited by 405 publications

(390 citation statements)

References 25 publications

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“…This may be because eccentric activity reflects the integrated response of both feedforward and feedback activity to prepare for and absorb impact forces, providing a truer reflection of overall movement control. The strong relationship between changes in eccentric muscle activity of the SOL and CoMd and the observation that the short-latency stretch-reflex significantly increased in the SOL, support the suggestion that leg stiffness is primarily determined by stiffness of the ankle and not the knee (Farley and Morgenroth 1999;Kuitunen et al 2011).…”

Section: Discussionsupporting

confidence: 62%

“…Hopping was performed for 10 s, with the 10 consecutive hops with most consistent frequency used for further analysis (Oliver and Smith 2010). Double-integration of the force-time data allowed calculation of CoM displacement during ground contact, leg stiffness was then calculated as peak ground reaction force (GRF) divided by peak CoM discplacment (Farley and Morgenroth, 1999). Spring-like behaviour was confirmed where the relationship between CoM displacement and GRF were r > 0.8 (Padua et al 2005).…”

Section: Leg Stiffnessmentioning

confidence: 99%

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Altered neuromuscular control of leg stiffness following soccer-specific exercise

et al. 2014

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2 AbstractPurpose: To examine changes to neuromuscular control of leg stiffness following 42-min of soccer-specific exercise. Methods: Ten youth soccer players aged 15.8  0.4 hopped on a force plate at a self selected frequency before and after simulated soccer exercise performed on a non-motorised treadmill. During hopping muscle activity was measured using surface EMG from four lower limb muscles and analysed to determine feedforward and feedback mediated activity, as well as co-contraction. Results: There was no change in stiffness following the soccer-specific exercise (26.6  10.6 versus 24.0  7.0 kN·m -1 , p > 0.05), with half the group increasing and half decreasing their stiffness. Changes in stiffness were significantly related to changes in CoM displacement (r = 0.90, p < 0.01) but not changes in peak GRF (r = 0.58, p > 0.05). A number of significant relationships were observed between changes in stiffness and CoM displacement with changes in feedforward, feedback and eccentric muscle activity of the soleus and vastus lateralis muscles following the soccer exercise (r = 0.64-0.98, p < 0.05), but not with changes in co-contraction around the knee and ankle (r = 0.11-0.55, p > 0.05). Conclusions:Following soccer-specific exercise individual changes in extensor muscle activity modulate changes in CoM displacement and leg stiffness. Individuals who reduce preactivation, braking activity and consequently leg stiffness with fatigue may be at a greater risk of injury.

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Section: Discussionsupporting

confidence: 62%

Section: Leg Stiffnessmentioning

confidence: 99%

Altered neuromuscular control of leg stiffness following soccer-specific exercise

et al. 2014

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“…the resistance of the leg to compression (flexion of hip, knee and ankle joints) during landing. Leg stiffness refers to the stiffness of the leg when modelled as a single linear spring and is calculated as the ratio of the change in vertical GRF to the change in vertical displacement of the centre of gravity (CG) between ground contact and maximum vertical GRF (Farley and Morgenroth 1999). Knee joint stiffness refers to the torsional stiffness of the knee joint when modelled as a spring and is calculated as the ratio of the change in knee joint moment to the change in knee flexion angular displacement between ground contact and maximum knee joint moment (Farley and Morgenroth 1999).…”

mentioning

confidence: 99%

“…Furthermore, previous studies (Granata, Padua, and Wilson 2002;Farley and Morgenroth 1999) only report absolute leg stiffness without normalising for body weight and height. Since leg stiffness is the combined effect of the stiffness in the hip, knee and ankle joints, the lower leg stiffness in females compared to males reported by Granata, Padua, and Wilson (2002) may be due, at least in part to reduced stiffness of one or more of the hip, knee and ankle joints in females compared to males.…”

mentioning

confidence: 99%

Lower Limb Coordination and Stiffness During Landing from Volleyball Block Jumps

Hughes

Watkins

2008

Research in Sports Medicine

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Abstract.The aim of the study was to investigate lower limb coordination and stiffness in five male and five female university volleyball players performing block jump landings. Coordination was assessed using angle -angle plots of the hip -knee, knee -ankle and hip -ankle joint couplings and discrete relative phase (DRP) of right -left joint couplings (i.e. left knee coupled with right knee). Leg stiffness was calculated as the ratio of the change in vertical ground reaction force (GRF) to the change in vertical displacement of the centre of gravity between ground contact and maximum vertical GRF. Knee stiffness was calculated as the ratio of the change in knee joint moment to the change in knee flexion angular displacement between ground contact and maximum knee joint moment. Comparison of the DRP angles between left and right legs indicated reduced symmetry between the left and right legs in females compared to males which may indicate greater likelihood of ligament strain in females compared to males. Furthermore, females exhibited reduced stability in the coordination between the left and right knee joints than males. Males exhibited significantly greater absolute and normalised leg stiffness and significantly greater absolute and normalised knee joint stiffness during landing compared to females. In conjunction with the coordination data, this may indicate reduced dynamic stability of the leg in females compared to males which may contribute to the greater incidence of ACL injury in females compared to males.

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“…Testing consisted of two two-legged hopping trials of 30 seconds duration at each test frequency with one foot on each FP and during quiet standing. The two-legged hopping movement was similar to that performed by Farley and Morgenroth (1999) and Hobara et al (2010), where the two feet were positioned hip width apart and both legs jumped simultaneously in place. FP X and Y axes were aligned to the ML and AP directions respectively.…”

Section: Data Acquisitionmentioning

confidence: 99%

A motion analysis marker-based method of determining centre of pressure during two-legged hopping

Furlong

Harrison

2014

Journal of Biomechanics

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Citation: FURLONG, L-A. and HARRISON, A.J., 2014. A motion analysis marker-based method of determining centre of pressure during two-legged hopping. Journal of Biomechanics, 47(8), pp. 1904Biomechanics, 47(8), pp. -1908 Additional Information:• This paper was accepted for publication in the journal Journal of The smallest difference in calculated sagittal plane ankle moment and timing of maximum moment was during 3.0 Hz hopping, and largest at 1.5 Hz. Results indicate the marker-based method of determining CoP may be a suitable alternative to a force plate to determine CoP position during a two-legged hopping task at frequencies greater than 1.5 Hz.

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Leg stiffness primarily depends on ankle stiffness during human hopping

Cited by 405 publications

References 25 publications

Altered neuromuscular control of leg stiffness following soccer-specific exercise

Altered neuromuscular control of leg stiffness following soccer-specific exercise

Lower Limb Coordination and Stiffness During Landing from Volleyball Block Jumps

A motion analysis marker-based method of determining centre of pressure during two-legged hopping

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