Biomedical subjects

A Kranzl

Publications and source records attributed to A Kranzl.

5 recordsLinked to original sources

PubMed2000

Spinal posture during stooped walking under vertical space constraints.

STUDY DESIGN: Simultaneous spine kinematic variables in sewage workers were quantified using a two-dimensional video-based gait analysis system. OBJECTIVES: To identify patterns of spinal posture in a population of sewage workers pushing waste matter through tunnels while walking stooped under various height constraints. SUMMARY OF BACKGROUND DATA: Working with stooped postures is one of several occupational risk factors that have been associated with spinal disorders. However, the specific changes in spinal posture during stooped walking under various height constraints have not been documented. METHODS: A video-based gait analysis system was used to measure spinal posture in 22 sewage workers. Angles of the cervical, thoracic, and lumbar spine in the sagittal plane were assessed during walking with five levels of height constraint, from upright walking to stooped walking under a headroom restriction of 105 cm. Correlations among gait parameters, demographic data, and clinical results were determined. Linear regression analysis was performed to examine which variables have the largest impact on the posture resulting from a given vertical height constraint when age and body height are held constant. RESULTS: Mean angular values changed significantly with increasing headroom restrictions, with increases in cervical and thoracic extension as well as lumbar flexion. The cervical and thoracic angles were best correlated with height constraint, followed by lumbar angle and stride length. The inverse relation between cervical and thoracic angle during upright walking increased with increasing vertical space constraints, whereas the relation between the thoracic and lumbar angles decreased. Subjects with decreased abdominal muscle strength adopted a significantly more kyphotic thoracic posture when walking under headroom constraints than subjects with normal abdominal muscle strength. CONCLUSIONS: Combined walking and pushing under vertical space constraints was associated not only with the expected increased flexion of the lumbar spine, but also with greater extension (i.e., reduced kyphosis) of the thoracic spine.

Adult↗

PubMed2000

Load-dependence of fatigue related changes in tremor around 10 Hz.

OBJECTIVES: The aim of the study was to investigate the effects of different loads on tremor around 10 Hz during fatiguing contractions. METHODS: Eighteen healthy volunteers performed sustained isometric knee extensions at 30%, 50% and 70% maximum voluntary contraction (MVC). During the fatiguing contractions, mechanical recordings were made with a high-resolution force sensor. Tremor-power was calculated for the 6-20 Hz frequency window as a function of time normalized to endurance time. RESULTS: Initial tremor power was different between the high and low load tasks. Changes of tremor with contraction time differed between the three tasks, in that tremor of the 30% MVC contraction showed the least decrease throughout the sustained contraction, whilst that of the 50% and 70% MVC showed progressively higher decreases. At failure, all 3 contractions merged to the same tremor level. CONCLUSION: Load-dependent, fatigue-related 6-20 Hz tremor changes during sustained submaximum voluntary contractions seem mainly the consequence of recruitment of new units and fatigue-related properties of the high threshold motor units of muscles.

Adult↗

PubMed1998

[Clinical gait analysis--methods, limitations and possible applications].

Human gait is a complex and cyclic movement. Gait analysis of human walking can be done either without any technical support, or in combination with complex and expensive equipment. Modern gait analysis is based on the integration of multiple components to derive a complete analysis of gait. These methods may include observation, videotaping, electromyography, kinematics, kinetics and energetics. The results gained from these methods may then be used to determine the treatment course of a subject with gait abnormalities or to document the effects of therapeutical intervention. The purpose of this article is to provide an overview of the most common used methods in gait analysis. Emphasis will be placed on the type of information that can be derived from each component and how this information can be used clinically.

Electromyography↗

PubMed1997

Comparison of two insole materials using subjective parameters and pedobarography (pedar-system).

INTRODUCTION:: The objective of this trial was to investigate two commonly used insole materials prescribed for shock-absorption and cushioning concerning subjective and pedobarographic parameters. The design was prospective, controlled, randomized and single-blinded. MATERIAL AND METHODS:: A convenient sample of six healthy male adults without any history of leg or foot injury or pain wore -- in random order -- the custom-made insoles for one week. For both insoles the same base material (TEPEFON(R)) was used, insole 1 was covered with PLASTAZOTE(R) I, 3 mm, insole 2 with PPT, 3 mm. Both insoles had a metatarsal pad. After one week of wearing, in-shoe plantar pressures, measured at the same time of day and within the same type of indoor tennis shoes (sockliner removed), were obtained using the PEDAR-System(R) (Novel GmbH, Munich, Germany). Before each measurement the PEDAR-insoles were calibrated and the subject walked around for 5 minutes to get aquainted with the device. Three trials were performed for three different conditions and average values were determined: PEDAR-insole alone, with PLASTAZOTE(R) insole, with PPT(R) insole. Data were collected at self selected speed, gait velocity was determined using two optical switches on a 10 m walkway. Pressures were normalized to body weight. Main outcome parameters were 'Maximal Peak Pressure' (MPP) and 'Pressure Time Integral' (PTI). These parameters were determined for the whole footsole, medial and lateral heel, medial and lateral midfoot, medial, middle and lateral forefoot, hallux and toes II-V. Additionally the subjects filled in a questionnaire including: time wearing the insoles daily (in hours), sweating (visual analogue scale -- VAS), wearing comfort (VAS), perceived discomfort (location). Three months after the trial they were asked via telephone call whether they were still using the insoles. RESULTS:: 1. The overall MPP and PTI values did not differ significantly between the PEDAR-insole alone and the investigated inserts. There was a tendency for both insoles towards lower MPP and PTI values in all regions except for the toes, especially for the PPT(R) insole. 2. The questionaire showed a significantly higher wearing comfort for the PPT(R) insole in contrast to the PLASTAZOTE(R) insole, though all subjects sweated more with the PPT(R) material. Four of the six subjects experienced discomfort due to the metatarsal pad within the PLASTAZOTE(R) insole, only one within the PPT(R) insole. 3. None of the subjects continued to use the PLASTAZOTE(R) insole, but three continued to use the PPT(R) insoles. DISCUSSION:: Despite the significant differences in the subjective parameters, especially wearing comfort, no statistical significant difference for the overall MPP and PTI values between the PEDAR-insole alone and the investigated insoles or in between the insoles tested could be obtained. Yet there was a tendency for both insoles to lower MPP and PTI values in all regions except for the toes. This might be due to the thickness of the insoles and the reduced space within the toe box. The subjectively better tolerated PPT(R) insole tended to lower MPP and PTI more than the PLASTAZOTE(R) insole. CONCLUSION:: Wearing comfort and pedobarographic outcome measurements did not correlate significantly in this trial. Yet there was a tendency for the subjectively better tolerated PPT(R) insole to lower MPP and PTI more.

Journal Article↗

PubMed1997

Force distribution across the heel of the hand during simulated manual chest compression.

According to most published guidelines of cardiopulmonary resuscitation chest compression is performed on the lower half of the sternum by compressing the sternum with the heel of one hand and the other hand on top of the first. In all guidelines and during CPR training great importance is attributed to exact localisation of the so-called compression point. In a laboratory investigation we assessed the force distribution across the heel of the hand and defined the total breadth in contact with the sternum. In order to find out whether there is any difference in the force pattern with the right or the left hand in direct contact with the sternum we determined the resultant maximal force of that part of the heel of the hand exerting the maximal force. A total of 12 anaesthetists performed simulated chest compressions onto a flat surface covered with an integrated force sensor mat. The distance between the most ulnar part and the most radial part of the hand was determined to be 9.2 cm. Similar mean total forces were measured (right hand in contact: 644 N; left hand in contact: 621 N). In all except one anaesthetist the hypothenar part of the heel exerted a significantly higher force compared to the thenar part, independent of whether the right hand or the left hand was in contact. The distance between points of maximal force when the right hand or when the left hand in contact was 2.2 cm corresponding to the breadth of one and a half fingers. To reduce the potential risk of sternal fractures by chest compressions applied too far in a cephalad direction, we recommend use of the right hand in contact if the rescuer kneels at the right side of the patient and vice versa.

Adult↗