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--- a +++ b/jap/node12.html @@ -0,0 +1,121 @@ +<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"> +<!--Converted with LaTeX2HTML 96.1-h (September 30, 1996) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds --> +<HTML> +<HEAD> +<TITLE>Discussion</TITLE> +<META NAME="description" CONTENT="Discussion"> +<META NAME="keywords" CONTENT="gait-reprint"> +<META NAME="resource-type" CONTENT="document"> +<META NAME="distribution" CONTENT="global"> +<LINK REL=STYLESHEET HREF="gait-reprint.css"> +</HEAD> +<BODY LANG="EN" bgcolor="white"> + <A NAME="tex2html118" HREF="node13.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="/icons/latex2html/next_motif.png"></A> <A NAME="tex2html116" HREF="gait-reprint.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="/icons/latex2html/up_motif.png"></A> <A NAME="tex2html110" HREF="node11.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="/icons/latex2html/previous_motif.png"></A> <BR> +<B> Next:</B> <A NAME="tex2html119" HREF="node13.html">Footnotes</A> +<B>Up:</B> <A NAME="tex2html117" HREF="gait-reprint.html">Title Page</A> +<B> Previous:</B> <A NAME="tex2html111" HREF="node11.html">Relationship of Stride Dynamics </A> +<BR> <P> +<H1><A NAME="SECTION00050000000000000000">Discussion</A></H1> +<P> +This quantitative study of stride variability and dynamics reveals +several interesting new findings: 1) Stride to stride variations in gait cycle +duration are significantly larger in healthy 3 and 4 year old +children compared to 6 and 7 year old children and in 6 and 7 year old +children compared to children ages 11 to 14. 2) The temporal structure +of gait fluctuations is not fully developed in 7 year old +children, while in older children (11 to 14 year olds), stride dynamics +approach the values observed in adults. 3) Different features of stride +dynamics do not develop at the same time (Table 4). Thus, while +visual observation might suggest that the stride dynamics of +children are not different from that of adults, quantitative +measurement of gait dynamics indicates that stride-to-stride control +of walking is not fully mature even in 7 year olds. +<P> +A number of similarities have been reported in the gait pattern of children and elderly adults (5,6,23). This finding may reflect a +reappearance of primitive reflexes or simply diminished control of +balance (23). The present study +demonstrates that parallels also exist with respect to stride dynamics. +In older adults and persons with neurological +impairment, alterations of stride dynamics have been observed (3,4,7,8,10,14). +However, +while the stride dynamics of young children share some characteristics +of the unstable dynamics of older persons and those with +neurological impairment, there appear to be important differences as +well. For example, the present findings suggest that the fractal scaling +index changes monotonically throughout the lifespan (highest in +children, lower in adults and lowest in the elderly and persons with +neurological disease). In contrast, stride variability likely changes in a +U-shaped fashion (high in children, lower in adults, and higher with +disease and perhaps also in very advanced age). Thus, from the +perspective of stride time dynamics, the changes +in gait of older persons do not simply reflect a return to +an immature gait pattern. +<P> +The alterations of the dynamics of the stride time in the younger +children may be due to a number of factors. The increased variability +may in part be related to decreased walking velocity and decreased +postural stability at lower speeds (23). However, while adjustment +for height minimized the effects of age on velocity, the age-related +differences in both the magnitude of the variability and in the +dynamics persisted after controlling for height. A number of factors +also suggest that the observed age-related changes in the temporal +organization of stride dynamics are most likely not simply +attributable to reduced height, gait speed, change in concentration +during the walk, or increased stride-to-stride variability +(unsteadiness). For example, fractal scaling indices were similar in +the 3 and 4 year old children compared with the 6 and 7 years old +children, despite significant differences in stride-to-stride +variability, velocity, and height. Age-related differences in stride dynamics were evident +in dynamical measures even after detrending to minimize the effects of +changes in speed or local average stride time. Moreover, an age-related effect +was observed in the ratio of spectral balance, a measure that was derived +independently of stride to stride variability and very low frequency +changes likely to be associated with change of speed or loss of concentration. +<P> +Future study of children walking at different speeds may help +elucidate the role of velocity on stride dynamics in children. +In addition, studies that include assessment of +motor control and balance as well as other aspects of the locomotor +control system +may also help clarify the role of +potential contributing factors to the development of mature +gait dynamics. Perhaps, differences in motor control development +account for some of the observed heterogeneity in stride dynamics +within each age group (e.g., Figure 1). +An intriguing possibility is that these dynamical measures +may provide a means of quantifying the stage of maturational development. +In any case, it seems that 1) stride time +dynamics most likely depend on some aspect of the neuromuscular control system +that is not merely related to walking velocity or gait variability, +and 2) the immature gait dynamics in children may reflect the subtle +ongoing development of more than one component of motor control. +The dynamical action theory of motor +control postulates that locomotor function can be viewed as + a complex system with multiple degrees of freedom whose + collective behavior is governed in part by the principle of +self-organization (13,23,27). Therefore, perhaps mature locomotion dynamics +emerge only once all of the interacting individual components are +fully developed. The change in scaling exponents with age, +a measure associated with a non-equilibrium dynamical +system with multiple-degrees-of-freedom (1,22), may reflect +this emergent behavior. Candidate elements that could affect +stride dynamics include +biomechanical and neural properties that are +known to mature only in older children (e.g., electromyogram recruitment patterns +are more variable in children under 7 years of age) (15,23). +Additional studies will be needed to explain these complex age-related + changes in the magnitude and temporal +structure of stride dynamics. Nonetheless, the present findings have +potentially +important implications for the understanding and modeling of the +integrative control of locomotor function and neural development. Further, +the results suggest the possibility that quantitative measures +of stride dynamics may be useful in augmenting the early detection +and classification of gait disorders in children. +<P> +<HR><A NAME="tex2html118" HREF="node13.html"><IMG WIDTH=37 HEIGHT=24 ALIGN=BOTTOM ALT="next" SRC="/icons/latex2html/next_motif.png"></A> <A NAME="tex2html116" HREF="gait-reprint.html"><IMG WIDTH=26 HEIGHT=24 ALIGN=BOTTOM ALT="up" SRC="/icons/latex2html/up_motif.png"></A> <A NAME="tex2html110" HREF="node11.html"><IMG WIDTH=63 HEIGHT=24 ALIGN=BOTTOM ALT="previous" SRC="/icons/latex2html/previous_motif.png"></A> <BR> +<B> Next:</B> <A NAME="tex2html119" HREF="node13.html">Footnotes</A> +<B>Up:</B> <A NAME="tex2html117" HREF="gait-reprint.html">Title Page</A> +<B> Previous:</B> <A NAME="tex2html111" HREF="node11.html">Relationship of Stride Dynamics </A> +</BODY> +</HTML>