1st Joint ESMAC-GCMAS Meeting - Análise de Marcha
1st Joint ESMAC-GCMAS Meeting - Análise de Marcha
1st Joint ESMAC-GCMAS Meeting - Análise de Marcha
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Results<br />
At all speeds, the net influence of stance-si<strong>de</strong> muscles was to slow forward progression during<br />
loading response and early single-limb support, and to propel the body forward during late<br />
single-limb support and preswing (Fig. 1). Braking<br />
and propulsion by stance-si<strong>de</strong> muscles increased<br />
with walking speed. Individual muscle<br />
contributions to progression reflected this trend<br />
(Fig. 2).<br />
Discussion<br />
We generated subject-specific, muscle-actuated,<br />
3D simulations of a child walking at three speeds.<br />
Increased walking speed arose from greater<br />
propulsion by hip flexors and ankle plantarflexors<br />
during late single-limb support and preswing. A<br />
Figure 1. Average fore-aft induced<br />
counterintuitive finding was that knee extensors generated<br />
accelerations from stance-si<strong>de</strong> muscles.<br />
larger braking effects at higher speeds. The braking<br />
effects of dorsiflexors at the slowest and fastest walking<br />
speed were similar, suggesting unusually high dorsiflexor forces during slow walking. This<br />
finding is consistent with a prolonged internal dorsiflexion moment computed from the<br />
subject’s experimental data during slow walking.<br />
These results suggest that therapies aimed at increasing hip flexor and plantarflexor strength<br />
may be beneficial for patients with limited walking speed, since these two muscle groups are<br />
primarily responsible for increasing gait speed.<br />
Figure 2. Major muscle contributors to braking<br />
and propulsion. Top panel: Vasti and<br />
dorsiflexors were the primary sources of braking<br />
during loading response. Second panel: Vasti,<br />
gastrocnemius, and soleus provi<strong>de</strong>d braking<br />
during early single-limb support, with some<br />
assistance from rectus femoris (not shown).<br />
Third panel: Gastrocnemius and iliopsoas<br />
propelled the body forward during late singlelimb<br />
support. Smaller contributions from gluteus<br />
minimus, medial hamstrings, peroneal muscles<br />
(not shown), soleus, and dorsiflexors also<br />
assisted in propulsion, but were inconsistent<br />
across walking speeds. Bottom panel:<br />
Gastrocnemius, soleus, and iliopsoas provi<strong>de</strong>d<br />
propulsion during preswing, with smaller<br />
contributions from medial hamstrings and<br />
peroneal muscles that were inconsistent across<br />
walking speeds.<br />
References<br />
[1] <strong>de</strong>n Otter, et al, (2004), Gait Posture, 19, 270-278<br />
[2] Neptune et al, (2004), Gait Posture, 19, 194-205<br />
[3] Liu et al, (in press), J Biomech<br />
[4] Thelen and An<strong>de</strong>rson, (2006), J Biomech, 39, 6, 1107-1115<br />
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