Daniel Blanke

Age and gender effects on postural control measures

OBJECTIVE Identifying age-related changes in the postural control system is an important first step towards understanding the risk for falls in older adults. The purpose of this study was to determine whether age or gender had any effects on six relatively new postural control measures. DESIGN Cross-sectional, 2 x 2 factorial design, representing two ages (younger [20 to 35 years], and older [60 to 75 years]) and both sexes. SETTING University campus. PARTICIPANTS Twenty-four community dwelling healthy adults (12 women, 12 men) participated in each of the younger and older groups. MAIN OUTCOME MEASURES Outcome measures included five force platform measures and functional reach (cm). The force platform measures, obtained using the Balance Master system, included movement time and path length to targets, and sway area under conditions of eyes open, eyes closed, and with visual feedback. RESULTS Although gender was not significant for any outcome measure, age was significant in all six outcome measures. Older adults demonstrated larger areas of sway regardless of condition (eyes open, eyes closed or with visual feedback). Older adults had longer movement times, longer path lengths, and shorter distances of functional reach when compared with younger adults. CONCLUSIONS The results suggest that the measures studied are sensitive to age-related changes in healthy elderly.

Comparison of Gait of Young Women and Elderly Women

The purpose of our study was to describe and compare free-speed gait patterns of healthy young women with healthy elderly women. The evaluation was completed with high-speed cinematography using synchronized front and side views of 26 healthy volunteers. One group was composed of 13 subjects 20 to 35 years of age, and the other group was composed of 13 subjects 60 to 84 years of age. Each subject participated in one test session consisting of three filmed trials of free-speed ambulation down a 14-m walkway. The processed film was analyzed for 10 gait characteristics. Differences in gait characteristics between the two groups were examined using a correlated t test (p less than .01). The elderly women demonstrated significantly smaller values of step length, stride length, ankle range of motion, pelvic obliquity, and velocity when compared with the younger women. The results of our study suggest that the physical therapist should not establish similar expectations for young women and elderly women during gait rehabilitation.

Comparison of Gait Patterns between Young and Elderly Women: An Examination of Coordination:

This study investigated intralimb coordination during walking in young and elderly women using the theoretical model of dynamical systems. 20 women, 10 Young (M age = 24.6 yr., SD = 3.2 yr.) and 10 Elderly (M age = 73.7 yr., SD = 4.9 yr.), were videotaped during free speed gait and gait perturbed by an ankle weight. Two parameters, one describing the phasing relationship between segments (mean absolute relative phase) and the other the variability of this relationship (deviation in phase), were calculated from the kinematics. Two-way analysis of variance (age and weight) with repeated measures on weight indicated that during the braking period the weight increased the mean absolute relative phase between the shank and the thigh and decreased it between the foot and the shank. The Elderly women had significant smaller values for the mean absolute relative phase between the shank and the thigh during the braking period. For the same period, deviation in phase increased for the segmental relationship between the shank and the thigh. The findings suggest that changes in intralimb coordination take place with asymmetrical weighting and the aging process. These changes are most clearly present during the braking period.

Intralimb coordination following obstacle clearance during running: the effect of obstacle height

The purpose of this study was to investigate the different coordination strategies used following obstacle clearance during running. Ten subjects ran over a level surface and over obstacles of six different heights (10, 12.5, 15, 17.5, 20 and 22.5% of their standing height). Analysis based upon the dynamical systems theory (DST) was used and the phasing relationships between lower extremity segments were examined. The results demonstrated that the increasing obstacle height elicited behavioral changes. The foot and the leg became more independent in their actions, while the leg and the thigh strengthened their already stable relationship. The 15% obstacle height seems to be a critical height for the observed changes.

Methods to Improve the Reliability of the Functional Reach Test in Children and Adolescents With Typical Development

Purpose: Test-retest reliability of the Functional Reach Test was examined in children with typical development by comparing standard and alternate methods. Methods: Eighty subjects ages seven to 16 years were tested and 69 retested for four methods of Functional Reach Test (ie, one-arm finger-to-finger, two-arm finger-to-finger, one-arm toe-to-finger, and two-arm toe-to-finger). Intraclass correlation coefficients and limits of agreement were calculated. Results: Intraclass correlation coefficients were high in toe-to-finger measurement methods (0.97–0.98) for the entire group and specific age groups (00.83–0.93). Toe-to-finger methods were more reliable than finger-to-finger methods. The two-arm toe-to-finger method had the best limis of agreement with approximately ±5 cm indicated by the 95% confidence interval. Conclusions: Test-retest reliability using a toe-to-finger method of measuring is stronger than previously reported when using traditional methods. Limits of agreement analyses imply a change of 5 cm or more is likely to represent a true clinical difference when using the two-arm toe-to-finger method.

Development of Upper Body Coordination During Sitting in Typically Developing Infants

Our goal was to determine how the actions of the thorax and the pelvis are organized and coordinated to achieve independent sitting posture in typically developing infants. The participants were 10 typically developing infants who were evaluated longitudinally from first onset of sitting until sitting independence. Each infant underwent nine testing sessions. The first session included motor evaluation with the Peabody test. The other eight sessions occurred over a period of 4 mo where sitting behavior was evaluated by angular kinematics of the thorax and the pelvis. A physical therapist evaluated sitting behavior in each session and categorized it according to five stages. The phasing relationship of the thorax and the pelvis was calculated and evaluated longitudinally using a one-way analysis of variance. With development, the infants progressed from an in-phase (moving in the same direction) to an out-of-phase (moving in an opposite direction) coordinative relationship between the thorax and the pelvis segments. This change was significant for both sagittal and frontal planes of motion. Clinically, this relationship is important because it provides a method to quantify infant sitting postural development, and can be used to assess efficacy of early interventions for pediatric populations with developmental motor delays.

Do lower-extremity joint dynamics change when stair negotiation is initiated with a self-selected comfortable gait speed?

Previous research on the biomechanics of stair negotiation has ignored the effect of the approaching speed. We examined if initiating stair ascent with a comfortable self-selected speed can affect the lower-extremity joint moments and powers as compared to initiating stair ascent directly in front of the stairs. Healthy young adults ascended a custom-built staircase instrumented with force platforms. Kinematics and kinetics data were collected simultaneously for two conditions: starting from farther away and starting in front of the stairs and analyzed at the first and second ipsilateral steps. Results showed that for the first step, participants produced greater peak knee extensor moment, peak hip extensor and flexor moments and peak hip positive power while starting from farther away. Also, for both the conditions combined, participants generated lesser peak ankle plantiflexor, greater peak knee flexor moment, lesser peak ankle negative power and greater peak hip negative power while encountering the first step. These results identify the importance of the starting position in experiments dealing with biomechanics of stair negotiation. Further, these findings have important implications for studying stair ascent characteristics of other populations such as older adults.

Spanning set defines variability in locomotive patterns.

The purpose of the investigation was to use the spanning set methodology to quantify variability in locomotive patterns and to compare this method with traditional measures of variability. Subjects ran on a treadmill while sagittal plane kinematic data were collected with a high-speed (180 Hz) camera. Changes in variability were evaluated as the subject ran barefoot and in shoes. Mean ensemble curves for the knee angle during the stance period were created for each condition. From these curves, traditional measures of variability were calculated using the coefficients of variation (CVs), and the mean deviation (MD). Spanning set vectors were defined from the coefficients of polynomials that were fitted to the respective standard deviation curves. The magnitude of the spanning set was determined by calculating the norm of the difference between the two vectors. The normalised difference between the two conditions was 6.6%, 6.9% and 98%, for the MD, CV and spanning sets, respectively. The results indicated that the spanning set was capable of statistically (p<0.05) determining differences in variability between the two conditions. CV and MD measures were unable to detect statistical differences (p>0.05) between the two conditions. The spanning set provides an alternative, and sensitive measure for evaluating differences in variability from the mean ensemble curve.

Foot strike patterns after obstacle clearance during running

PURPOSE Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights. METHODS Ten heel strike subjects ran at their self-selected pace under seven different conditions: unperturbed running (no obstacle) and over obstacles of six different heights (10%, 12.5%, 15%, 17.5%, 20%, and 22.5% of their standing height). The obstacle was placed directly before a Kistler force platform. Repeated measures ANOVAs were performed on the subject means of selected kinetic parameters. RESULTS The statistical analysis revealed significant differences (P < 0.004) for all of the parameters analyzed. The evaluation of the center of pressure and the ground reaction forces indicated that the foot strike patterns were affected by the increased obstacle height. Between the 12.5% and 15% obstacle conditions, the group response changed from a heel strike to a forefoot strike pattern. CONCLUSIONS At height > 15%, the pattern was more closely related to the foot strike patterns found in jumping activities. This strategy change may represent a gait transition effected as a mechanism to protect against increased impact forces. Greater involvement of the ankle and the calf muscles could have assisted in attenuating the increased impact forces while maintaining speed after clearing the obstacle.

Factors affecting functional reach scores in youth with typical development

Purpose: Functional Reach Test scores were examined for the effects of traditional and alternate methods and subject characteristics. Methods: Eighty subjects aged 7 to 16 years were tested. Effects of measurement method (from finger-to-finger or from toe-to-finger) and style of reach (1 or 2 arms) were investigated. Five subject variables were analyzed for interactions among the methods and groups defined by subject characteristics. Results: Measurement method and style of reach showed a significant interaction. Interaction of method with subject characteristics was significant for age, height, and base of support only. Height groups by quartile were significantly different and scores increased with height, especially in toes-to-finger methods. Conclusions: Functional Reach Test scores were affected by method of reach and method of measurement. Height categories may be more useful when using the test for discriminative purposes, especially with toes-to-finger methods.