Principles underlying the organization of movement initiation from quiet stance

The role of the ipsilesional side in the rehabilitation of post-stroke subjects

“…Similarly to what was observed during the first phase of sit-to-stand and stand-tosit, stereotyped activity patterns have been demonstrated during the first phase of gait initiation (Brunt et al, 1991;Brunt et al, 1999;Crenna et al, 1991;Elble et al, 1994;Fiolkowski et al, 2002;Shapiro et al, 1981). The inhibition of the tonically active soleus followed by the activation of the tibialis anterior early in gait initiation (Crenna et al, 1991;Elble et al, 1994;Jian et al, 1993) enable the backward displacement of the centre of pressure (Brunt et al, 1991;Crenna et al, 1991), contributing to postural stability (Massion, 1992;McIlroy et al, 1999), as well as the optimum generation of momentum at the end of the first step to reach the steady-state gait (Lepers et al, 1995).…”

Gait initiation in lower limb amputees

“…The trailing limb normally produces the major part of the anterior GRF in the first step [11,[22][23][24][25]. Peak anterior GRF was predominantly decreased in the trailing prosthetic limb, which corresponded with the absent COP shift in the leading non-affected limb condition.…”

“…As a result, the ground reaction force (GRF) in the anterior direction increases, thereby generating a forward momentum [3,10]. Simultaneously, abductor muscles in the leading limb shift the COP toward this limb [3,11]. Prior to heel-rise of the leading limb the COM is shifted toward the trailing limb, which unloads the leading limb and creates a stable base for balance control in single-limb stance [12].…”

Influence of temporal pressure constraint on the biomechanical organization of gait initiation made with or without an obstacle to clear

“…Gait was initiated in a condition with or without a temporal pressure constraint and with or without an environmental constraint in the form of an obstacle to be cleared placed in front of the participants. The presence of an obstacle to be cleared has been shown to increase the duration of the execution phase of gait initiation (Brunt et al 1999(Brunt et al , 2005Kim and Brunt 2009) and stepping initiation in reaction to rapid surface translation ("compensatory stepping initiation"; Zettel et al 2002a, b), thereby potentially increasing mediolateral instability. In the present study, the condition with an obstacle to be cleared was thus used to further challenge the postural balance system, especially in the condition with a high temporal pressure.…”

“…In the present study, the condition with an obstacle to be cleared was thus used to further challenge the postural balance system, especially in the condition with a high temporal pressure. To date, very few studies focused on the effect of an obstacle to be cleared on the gait initiation process (Brunt et al 1999(Brunt et al , 2005Kim and Brunt 2009). Brunt et al (1999) showed that the duration of APA and the peak of anteroposterior ground reaction forces applied to the stance leg (this peak was reached at swing toe-off) were reduced in the obstacle condition compared to the no-obstacle condition.…”