Causes of variation in intrinsic ankle stiffness and the consequences for standing

Sakanaka, Tania Emi (2017). Causes of variation in intrinsic ankle stiffness and the consequences for standing. University of Birmingham. Ph.D.

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Abstract

Previous studies have shown that the intrinsic mechanical stiffness of the ankles is less than necessary to fully stabilize the body in the upright position (Loram and Lakie, 2002a; Morasso and Schieppati, 1999; Morasso and Sanguineti, 2002; Casadio et al., 2005). Following these studies, research about the controlling mechanisms of standing (the maintenance of an upright posture by a combination of intrinsic and active mechanisms) has developed considerably (Lakie et al., 2003; Loram et al., 2005a,b, 2011; Masani et al., 2006; Maurer and Peterka, 2005; Peterka, 2002). However, very little attention was given to the intrinsic mechanisms themselves. Here I tackled this issue by manipulating the ankle (and its surrounding tissues) in various ways. The objective was to investigate ankle stiffness dependency on mechanical properties that are particular to muscles and tendons. Within-individual differences were confirmed in various conditions. I have shown that in standing, intrinsic ankle stiffness is affected by movement amplitude and history of movement, as well as active ankle torque and passive tendon stretch. I have found no dependency of ankle stiffness on localized cooling. With regards to the effect that differences in intrinsic ankle stiffness may cause to standing sway, a between-individual analysis showed an inverse correlation between ankle stiffness and sway magnitude.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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