Leg joint function during walking acceleration and deceleration

Modulation of leg joint function to produce emulated acceleration during walking and running in humans

“…Qiao & Jindrich [27] studied human leg joint function during constant-velocity and accelerative walking by characterizing each joint's function in these tasks with functional indexes. These indexes described joint function as being relatively more spring-like, motor-like, strut-like or damper-like with a normalized value for each mechanical function.…”

“…This approach may be particularly useful for understanding what components a prosthetic or assistive device might need to incorporate. However, Qiao & Jindrich's [27] purpose was only to examine the stance phase of walking. Previous analyses of constant-speed walking have identified sub-phases of the gait cycle incorporating leg swing when the hip stores and returns energy like a spring [28] and when the knee joint exhibits energy absorption/dissipation like a damper [29], the latter inspiring an energy-harvesting knee device [29].…”

“…Previous analyses of constant-speed walking have identified sub-phases of the gait cycle incorporating leg swing when the hip stores and returns energy like a spring [28] and when the knee joint exhibits energy absorption/dissipation like a damper [29], the latter inspiring an energy-harvesting knee device [29]. Thus, it would be useful to extend the analyses of [27] to incorporate the swing phase of constant-speed and accelerative walking and to include running. Whole leg [22] and leg joint mechanics [24] have been studied for accelerative running, but not in terms of the indexes presented by Qiao & Jindrich [27].…”

Modulation of upper limb joint work and power during sculling while ballasted with varying loads

“…Our results therefore suggest a transversal motor strategy of power modulation across physical environments, limbs and tasks, regardless of whether or not they demand net positive work. Previous findings of proximal redistribution of work and power output that occurred when accelerating (Qiao and Jindrich, 2016), sprinting (Schache et al, 2015) and incline running (Roberts and Belliveau, 2005) might thus have been confounded by postural constraints altering muscle effective mechanical advantage, rather than reflecting an actual neuromuscular response. This is further exemplified by the work of Farris and Sawicki (2012a) on the distribution of lower limb joint work during hopping across various frequencies.…”

“…During level walking and running up to ∼7 m s -1 , demands for increased positive work per stride are achieved by increasing in parallel the work done by all lower limb muscle groups (Farris and Sawicki, 2012b;Schache et al, 2015). By contrast, sprinting, accelerating and incline running necessitate a different control strategy, as they involve a redistribution of work and power output proximally to the hip (Qiao and Jindrich, 2016;Roberts and Belliveau, 2005;Schache et al, 2015). However, unlike level steady-speed locomotion, these tasks have the peculiarity that they are associated with a net positive work requirement and/or a change in limb posture that requires the hip muscles to do greater work (Roberts and Belliveau, 2005); hence the suggestion that task net work requirement might be an important indicator of how humans meet overall mechanical demands (Farris and Sawicki, 2012b).…”