Development of a kinematic coordination pattern in toddler locomotion: planar covariation

Abstract

The purpose of this study is to analyze the coordination patterns of the elevation angles of lower limb segments following the onset of unsupported walking in children and to look for the existence of a planar covariation rule as previously described in adult human locomotion. The kinematic patterns of locomotion were recorded in 21 children (11-144 months of age) and 19 adults. In 4 children we monitored the very first unsupported steps. The extent to which the covariation of thigh, shank, and foot angles was constrained on a plane in 3D space was assessed by means of orthogonal regression and statistically quantified by means of principal component analysis. The orientation of the covariation plane of the children was compared with the mean value of the adults' plane. Trunk stability with respect to the vertical was assessed in both the frontal (roll) and sagittal (pitch) planes. The evolution with walking experience of the plane orientation and trunk oscillations demonstrated biexponential profiles with a relatively fast time constant (<6 months after the onset of unsupported locomotion) followed by a much slower progression toward adult values. The initial fast changes of these walking parameters did not parallel the slow, monotonic maturation of anthropometric parameters. The early emergence of the covariation plane orientation and its correlation with trunk vertical stability reflect the dynamic integration of postural equilibrium and forward propulsion in a gravity-centered frame. The results support the view that the planar covariation reflects a coordinated, centrally controlled behavior, in addition to biomechanical constraints. The refinement of the planar covariation while morphological variables drastically change as the child grows implies a continuous update of the neural command.

Development of human locomotion

“…Unsupported walking is jerky and variable, with poor balance over the single support leg (while swinging the contralateral leg), the arms raised above the waist (as balance poles), legs splayed wide apart, and short variable steps [5 , 25,[54][55][56][57][58][59]. Double support is relatively prolonged, while swing is brief.…”

“…These changes occur rapidly over the first 6 months after the onset of independent walking. Afterwards, gait continues to develop more slowly until 8-10 years of age, as shown by changes in several parameters, such as stride length, cadence, coordination timing, and energy recovery [5 , 54,59]. …”

Optimal walking speed following changes in limb geometry

“…The temporal gait cycle events, namely heel strike (HS) and toe off (TO), were determined using SMART310 analysis software (BTS), from the kinematics of the LM (anterior-posterior maximum) and the MT (anterior-posterior minimum) markers, respectively. The same software was used to compute the elevation angles of the thigh (GT-LE), shank (LE-LM) and foot (LM-MT) segments relative to the vertical (Cheron et al, 2001).…”

Distinct multi-joint control strategies in spastic diplegia associated with prematurity or Angelman syndrome

“…In whole-body movements, the level of trunk stability is a distinctive feature of mature vs. immature (Ledebt et al, 1995;Cheron et al, 2001), skilled vs. unskilled movement (Mouchnino et al, 1992), and treated vs. untreated movement disorder (Grasso et al, 1999). As discussed before, thè as fast as possible' requirement used in this study implies high signal controls, and therefore a high level of signaldependent biological noise, which should result in increasing kinetic variation, and therefore postural instability, with increasing speed of movement.…”