The division of visual attention affects the transition point from level walking to stair descent in healthy, active older adults

Background: Stair descent is a frequent daily activity that poses great risks for injury due to falling. Very little is understood about the attentional demands of stair descent and their changes with aging. The present study compared combined locomotor and cognitive functioning during different phases of stair descent between healthy young and older individuals. Methods: Sixteen young and sixteen healthy older subjects walked down a 5-step staircase, performing a simultaneous visual Stroop task (i.e., a dual task) during the approach, transition or steady-state descent phases in some trials. Three dimensional kinematics of trunk and foot motion were recorded along with the accuracy and dual task costs (DTCs) for responses to the Stroop stimuli. Results: Dual tasking influenced both gait and cognitive performance for all subjects, and older adults generally walked slower with higher foot clearances and had greater DTCs. Specific age differences were found at stair transition where older adults showed more attentional effects. Conclusions: Healthy, active older adults showed changes to attention and planning due to normal aging specifically associated with a crucial point of fall risk during stair descent

Influence of the contact time on coupling time and a simple method to measure coupling time

International audienceThe enhancement of performance in stretch shortening cycle (SSC) exercises has been attributed to the recoil of elastic energy stored during the stretching phase and depends on the duration of the coupling time (T(coupling)) i.e., the duration of the isometric phase occurring between the stretch and the shortening of the muscle. However, instead of T(coupling), the contact time (T(contact))--i.e., the sum of T(coupling) plus the duration of the stretching and shortening phases that precede and follow T(coupling)--is more easily and often measured. The aim of this study was to investigate the T(coupling) changes within a large range of T(contact), in order to propose a possible relationship between T(coupling) and T(contact), thus allowing the accurate measurement of T(coupling )only from a tachometer and force data obtained classically in vertical jumps, jumps on sledge apparatus and running on force treadmills. Eleven subjects performed SSC exercises on a sledge apparatus with a large range of T(contact) (400, 700, 1,000, 1,500, 2,000 and 2,500 ms). The T(coupling) and T(contact) values were measured individually, from force platform recordings and the velocity of the carriage seat obtained by a tachometer. For the longest T(contact) (i.e., from 850 to 2,500 ms), we observed a significant linear relationship between T(contact) and T(coupling). This transition between T(contact) shorter or longer than about 850 ms seems to be important and to correspond to T(coupling) close to 300 ms. This limit observed in the present study could be explained physiologically due to a possible modification of the cross-bridges formation

ESMAC-SIAMOC 2001 Joint Congress: Gait Events in Hip Osteoarthritis and Total Hip Replaced Patients Evaluated by Two different Gait Analysis Systems

Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. One problem, however, is to ascertain that the computed parameters are correct and correspond to what could be measured by other, more complicated methods. A second point is to verify the feasibility of the measurement in pathologic cases. A third point is to understand the validity and the usefulness of the computed parameters to demonstrate the benefit for the clinical practice. In this study we describe an ambulatory system for temporal parameters estimation using gyroscopes. The accuracy of the measurement was assessed using a standard provided by an Elite system. To show the effectiveness of the method, gait parameters were obtained in patients with hip osteoarthrosis and after arthoplast

Gait Features Assessment in Hip Osteoarthritis and Total Hip Replaced Patients Based on an ambulatory System (Physilog)

Osteoarthritis is the most frequent joint pathology throughout the world. Obtaining objective, dynamic and quantified data allowing the evaluation of patients’ progress before and after hip arthroplasty is crucial. Gait analysis can be used for evaluating improvement in such patients, since walking is the principal human physical activity. Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. Recently, we have proposed a new ambulatory system for gait analysis (Physilog) and validated its performances for normal and abnormal walking (Aminian et al., 2002). The aim of this study is to show the efficacy of Physilog system for clinical gait analysis in orthopaedic

Evaluation of an ambulatory system for gait analysis in hip osteoarthritis and after total hip replacement.

Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. A new gait analysis system is proposed which consists of (a) an ambulatory device (Physilog®) including a set of miniature gyroscopes and a portable datalogger, and (b) an algorithm for gait analysis. The aim of this study was the validation of this system, for accuracy and clinical applicability. Eleven patients with coxarthrosis, eight patients with total hip arthroplasty and nine control subjects were studied using this portable system and also a reference motion analyzer and force plate. The small differences in the stance period (19 ± 31 ms), stride length and velocity (0.4 ± 9.6 cm and 2.5 ± 8.3 cm/s, respectively), as well as thigh and shank rotations (2.4 ± 4.3◦ and 0.3 ± 3.3◦, respectively), confirmed good agreement of the proposed system with the reference system. In addition, nearly the same accuracy was obtained for all three groups. Gait analysis based on Physilog® was also in agreement with their Harris Hip Scores (HHS): the subjects with lower scores had a greater limp, a slower walking speed and a shorter stride. This ambulatory gait analysis system provides an easy, reproducible and objective method of quantifying changes in gait after joint replacement surgery for coxarthrosis