Concurrent cognitive task modulates coordination dynamics.

Does a concurrent cognitive task affect the dynamics of bimanual rhythmic coordination? In-phase coordination was performed under manipulations of phase detuning and movement frequency and either singly or in combination with an arithmetic task. Predicted direction-specific shifts in stable relative phase from 0° due to detuning and movement frequency were amplified by the cognitive task. Nonlinear cross-recurrence analysis suggested that this cognitive influence on the locations of the stable points or attractors of coordination entailed a magnification of attractor noise without a reduction in attractor strength. An approximation to these findings was achieved through parameter changes in a motion equation in relative phase. Results are discussed in terms of dual-task performance as limited resources, dynamics rather than chronometrics, and reparameterization rather than degradation.

Postural sway increases with attentional demands of concurrent cognitive task.

The purpose of the present project was to determine whether postural sway varied with the difficulty of a concurrent unrelated cognitive task. Participants stood on a compliant surface under four conditions of varied attentional demand. Information reduction tasks (digit reversal, digit classification, counting backward by 3s) were used to quantify the attentional demands of the cognitive activity. Results showed attentional demands of the cognitive task impacted postural sway, with the most difficult cognitive task having the greatest influence.

Reliability and concurrent validity of the figure-of-eight method of measuring hand size in patients with hand pathology.

STUDY DESIGN: Methodological study using correlational methods. OBJECTIVE: To determine the intratester and intertester reliability and concurrent validity of the figure-of-eight method of measuring hand size in patients with hand pathology. BACKGROUND: Measuring edema is an important component of the physical examination of patients with conditions affecting the hand. The figure-of-eight method of measuring hand size has been suggested as an alternative to volumetry. The reliability and concurrent validity of the figure-of-eight method has been established in individuals without hand pathology, but not in patients with conditions involving the hand. METHODS AND MEASURES: Participants were 24 patients with conditions affecting the hand, 9 with bilateral involvement. Two testers performed 3 figure-of-eight measurements of hand size each. A third tester performed 2 volumetric measurements. Intraclass correlation coefficient (ICC3,1) was used to determine intratester reliability of both measurement procedures. ICC2,3 was used to examine intertester reliability of the figure-of-eight method. Pearson product moment correlation coefficients examining the association between the 2 methods were used to establish concurrent validity of the figure-of-eight technique. RESULTS: Intratester ICCs for figure-of-eight and volumetric methods were 0.98 to 0.99. The intertester ICC for the figure-of-eight method was 0.99. Pearson correlation coefficients examining the relationship between the 2 methods were 0.92 to 0.94. CONCLUSION: The figure-of-eight method is a reliable and valid measure of hand size in individuals with conditions affecting the hand.

Qualitative analysis of lumbar stabilization using point light and normal video displays.

Professionals in many fields use qualitative analysis to improve human movement. In previous research examining the reliability of physical therapists' qualitative assessments of lumbar stabilization, three experienced observers showed substantial agreement when viewing point light displays, but only moderate agreement when observing normal video displays. Replication of these findings in a larger group of less experienced observers would strengthen the notion that point light displays enhance qualitative analysis. The present study examined the reliability of qualitative assessments of lumbar stabilization when novice observers made judgments from two types of video displays. 50 fourth-year physical therapy students viewed either normal or point light video displays to judge lumbar stabilization of individuals performing a floor to waist lift. Multirater kappa coefficients for assessments made from normal displays and point light displays were .30 and .46, indicating fair and moderate agreement, respectively. These results suggest that point light displays may enhance observers' visual perception of human movement.

The influence of concurrent cognitive tasks on postural sway in children.

PURPOSE: The purpose of this study was to examine the influence of concurrent tasks on postural sway in children. METHODS: Nineteen fourth-grade students, while standing on a balance platform, were asked to stand still, count backward, and read second-grade level sentences. The AMTI Accusway System was used to calculate the length of center of pressure path (LCOP), sway range (SR), and variability (SV) in mediolateral (ML) and anteroposterior (AP) directions of sway. RESULTS: Analysis of variance revealed a main effect of cognitive task condition for SR-AP, SR-ML, SV-AP, and SV-ML. Post hoc comparisons revealed lower values of those four dependent measures for the counting backward task than for the standing still task and lower SV-AP for the counting backward task than for the reading task. In addition, there was a trend toward greater LCOP when performing a concurrent cognitive task. CONCLUSIONS: The demands of concurrent cognitive tasks while standing affect postural sway in children. The findings of this study contribute to our understanding of postural control in children and may explain why improvements in postural skills attained in clinical settings may not transfer to improved performance in other settings.

Figure-of-eight method of measuring hand size: reliability and concurrent validity.

The purpose of this study was to examine reliability and validity of a new method of measuring hand size in which a tape measure is wrapped around the hand in a figure-of-eight pattern. In the first experiment, two testers measured hand size in 60 individuals with no recent history of injury or surgery. Intraclass correlation coefficients of 0.99 and 0.97 indicated high intratester and intertester reliability. In the second experiment, concurrent validity of the figure-of-eight method was examined using volumetry as the criterion measure. Right hand size of 25 individuals with no recent history of injury or surgery was measured using the figure-of-eight method and volumetry. Pearson correlation coefficients of 0.94 indicated high concurrent validity. This study demonstrated reliability and validity of the figure-of-eight method of measuring hand size. To establish clinical usefulness, these findings must be replicated in individuals undergoing hand rehabilitation.