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Aging and Coordination from the Dynamic Pattern Perspective

1996; Elsevier BV; Linguagem: Inglês

10.1016/s0166-4115(96)80007-0

2543-1056

Laurence S. Greene, Harriet G. Williams,

Balance, Gait, and Falls Prevention

Movement scientists have extensively described aging effects on speeded unilateral and uniarticular movements; in contrast, little is known about how aging affects the coordination of multi-degree of freedom actions. In this chapter we review studies on motor coordination (defined in terms of the spatio-temporal patterning among multiple elements of motor systems) in older adults. In addition, we present our application of the principles and research strategy of 'dynamic pattern theory' (Kelso & Schöner, 1988) to the study of aging and coordination. Findings on the older mover's ability to coordinate intra- and inter-limb movements are equivocal. Older subjects exhibit (a) loose spatio-temporal coupling of muscle synergies during postural responses and (b) temporal asynchrony in discrete bimanual reaching. However, locomotor coordination (based on temporal relative phasing between the legs) appears to be well-maintained with age. We observed similar bimanual phasing relationships in 23-78 year olds during cyclical in-phase (IP) and anti-phase (AP) movements. In a phase shift experiment, where movement frequency was systematically increased, older subjects exhibited abrupt transitions from AP to IP cycling at significantly lower frequencies than young counterparts. We present findings which suggest that older subjects experience critical fluctuation and phase shifts at lower frequencies than young subjects due to fundamental deficiencies in coordination. We also present evidence for a deficiency in the speed at which older subjects execute voluntary changes from IP to AP movements. An explanation for age-related incoordination may be the relative strengthening of intrinsic dynamics. We discuss our findings in relation to conceptualizations of aging as a thermodynamic process whereby constraints are altered in ways that reduce behavioral stability and the ability to adapt to environmental challenges (Yates, 1988).