Biomedical subjects

J W Feuerbach

Publications and source records attributed to J W Feuerbach.

5 recordsLinked to original sources

PubMed1996

Measures of paraspinal muscle performance do not predict initial trunk kinematics after tripping.

The ability to limit the trunk flexion associated with an anteriorly directed trip is a determinant of successful recovery of recovering postural stability and is subservient to rapidly detecting and correcting the imposed trunk flexion in the available time. This experiment tested the hypothesis that subjects demonstrating greater eccentric trunk/hip extension strength, faster voluntary reaction times, shorter automatic response latencies, and larger automatic activation amplitudes of the paraspinal muscles, would demonstrate less trunk flexion following a trip. An isokinetic protocol was used to obtain measures of trunk extension strength, response latencies, and activation amplitudes. Motion analysis methods were used to quantify trunk kinematics during the positioning phase of recovery following an induced trip. Statistically significant and functionally meaningful relationships between eccentric strength of the trunk/hip extensors, voluntary-reaction time, automatic reaction time, activation amplitudes and trunk kinematics failed to emerge. Thus, although automatic and voluntary paraspinal muscle responses have the potential to limit trunk flexion during the positioning phase of recovery, the task may be achieved through intersegmental factors or other muscular sources such as the gluteus maximus and hamstrings.

Accidental Falls↗

PubMed1995

Visual guidance to force plates does not influence ground reaction force variability.

Gait analysis methods commonly require the subject to avoid visual guidance, that is, targeting, the force plate upon which a foot-strike is necessary. The putative rationale underlying the preference for not using targeting is the unsubstantiated contention that gait is altered. This study evaluated the influence of force plate targeting on the variability of ground reaction forces (GRF) in 15 normal subjects. Secondary factors of single vs multiple steps to the force plate and whether or not subjects were informed of the study's primary purpose were also examined. ANOVA main effects revealed that targeting did not significantly affect GRF variability (p > 0.05). A significant main effect of the number of steps required to reach the force plate on AP force variability was found (p = 0.002). Prior knowledge of the purpose of the study did not significantly affect GRF variability (p > 0.05). It was concluded that the variability of ground reaction forces is not significantly affected by targeting the force plate. Thus, targeting would not be expected to influence the variability of calculated kinetic variables that are subservient to GRF.

Adult↗

PubMed1993

Converting Chattecx Balance System vertical reaction force measurements to center of pressure excursion measurements.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the precision with which the postural stability data generated by the Chattecx Balance System could be converted to center of pressure displacement measurements. SUBJECTS: Two men and one woman were selected to represent a broad range of body sizes (age = 23-33 years, height = 154-175 cm, weight = 45-80 kg). METHODS: The Balance System load cells were placed on a force plate, and data were collected simultaneously from the Balance System and the force plate while the subjects performed standardized postural tasks. Linear regression analysis was used to characterize the relationship between the estimated center of pressure from the Balance System and the calculated center of pressure from the force plate. RESULTS: Significant linear relationships between the center of pressure estimated from the Balance System and the center of pressure calculated from the force plate were determined (all R2 values = > .90). CONCLUSION AND DISCUSSION: System data can be converted, and the methods recommended for use with the Balance System are described.

Adult↗

PubMed1993

Effect of the aircast on unilateral postural control: amplitude and frequency variables.

Little objective data exist regarding the effect of the Aircast Air-Stirrup on motor performance. Thus, the effect of the Aircast on the amplitude and frequency of postural sway during unilateral stance was evaluated for 15 uninjured male subjects. Postural sway during static and dynamic tests was measured using the Chattecx Balance System. Use of the Aircast improved unilateral postural control as evidenced by decreases in some of the components of postural sway. Previously, a link was made between a large amplitude of unilateral sway and a high probability of ankle injury (14). Thus, since Aircast use was found to decrease the amplitude of unilateral sway, it may also be beneficial in reducing the probability of injury. Although the scope of this study did not allow for differentiation among the complex systems involved in postural control, the possibility of the Aircast enhancing afferent feedback was proposed. The restricted inversion-eversion range of motion associated with the Aircast, in conjunction with the present observation that unilateral stability was enhanced with its use, suggests that the Aircast may provide a valuable prophylactic role in helping to reduce the incidence of ankle injuries.

Adult↗

PubMedDate not supplied

Effect of an ankle orthosis and ankle ligament anesthesia on ankle joint proprioception.

The purposes of this study were to determine the effect of a rigid ankle orthosis (Aircast Air-Stirrup) and lateral ankle ligament anesthesia on ankle joint proprioception. Twelve noninjured subjects attempted to match nine reference ankle joint positions with their eyes closed before and after application of the ankle brace and before and after one or two of the lateral ankle ligaments (anterior talofibular and calcaneofibular) were anesthetized. Three-dimensional ankle joint orientations were recorded with a Motion Analysis system. No significant differences in the constant, variable, or absolute error were seen between subjects in the non-anesthetized and anesthetized conditions (P > 0.05), regardless of whether one or two ligaments were anesthetized. Thus, it appears that ligament mechanoreceptors contributed little to ankle joint proprioception, and that the afferent feedback from skin, muscle, and other joint receptors was adequate for the positioning task of the present study. Both the variable and absolute error in matching the reference positions were significantly less with the orthosis than without (P < 0.05). Application of an orthosis may increase the afferent feedback from cutaneous receptors in the foot and shank, which may in turn lead to an improved ankle joint position sense.

Adult↗