The purpose of this study was to compare the postural sway profiles of 20 boys with and without Developmental Coordination Disorder (DCD) on two conditions of a quiet standing task: eyes open and eyes closed. Anterior-posterior (AP) sway, medio-lateral sway (LAT), area of sway, total path length, and Romberg’s quotient were analyzed. When visual information was available, there was no difference between groups in LAT sway or path length. However, boys with DCD demonstrated more AP sway (p < .01) and greater area of sway (p < .03), which resulted in pronounced excursions closer to their stability limits. Analysis of Romberg’s quotient indicated that boys with DCD did not over-rely on visual information.
Control of Stance and Developmental Coordination Disorder: The Role of Visual Information
Eryk P. Przysucha and M. Jane Taylor
The Nature and Control of Postural Adaptations of Boys with and Without Developmental Coordination Disorder
Eryk P. Przysucha, M. Jane Taylor, and Douglas Weber
This study compared the nature of postural adaptations and control tendencies, between 7 (n = 9) and 11-year-old boys (n = 10) with Developmental Coordination Disorder (DCD) and age-matched, younger (n = 10) and older (n = 9) peers in a leaning task. Examination of anterior-posterior, medio-lateral, maximum and mean area of sway, and path length revealed one significant interaction as older, unaffected boys swayed more than all other groups (p < .01). As a group, boys with DCD displayed smaller anterior-posterior (p < .01) and area of sway (p < .01). Analysis of relative time spent in the corrective phase (p < .002) revealed that boys with DCD spent 54% under feedback control while boys without DCD spent 78%. This was attributed to reduced proprioceptive sensitivity, as confirmed by significant differences between the groups (p < .009) in spectral analysis of peak frequency of sway.
Molecular Characteristics of Aged Muscle Reflect an Altered Ability to Respond to Exercise
Alison C. Jozsi, Esther E. Dupont-Versteegden, Jane M. Taylor-Jones, William J. Evans, Todd A. Trappe, Wayne W. Campbell, and Charlotte A. Peterson
Studies have been performed in humans to identify changes in gene expression that may account for the relatively weak and variable response of aged muscle to resistance exercise. The gene expression profile of skeletal muscle from elderly (62–75 years old) compared to younger (20–30 years old) men demonstrated elevated expression of genes typical of a stress or damage response. The expression of the majority of these genes was unaffected by a single bout of high-intensity resistance exercise in elderly subjects but was altered acutely by exercise in younger subjects so as to approach the pre-exercise levels observed in older subjects. The inability of muscle from elderly subjects to respond to resistance exercise was also apparent in the expression of inflammatory response genes, which increased within 24 hours of the exercise bout only in younger subjects. Other genes with potentially important roles in the adaptation of muscle to exercise, showed a similar or even more robust response in older compared to younger subjects. Taken together, these results may help to explain the variable hypertrophic response of muscle from older individuals to resistance training.