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Evaluation of Gait Stability Based on Variability of Medio-Lateral Motion of the Center of Mass
Abstract
The purpose of this study was to investigate an index based on the trajectory of the center of mass (COM) to determine whether it could distinguish between stable and unstable gaits. Eleven healthy males volunteered for this study. To generate an unstable gait condition, we used a separated-belt treadmill. The treadmill belt could be driven at the same speed (stable condition) and at different speeds (unstable condition). In the stable condition, the subjects walked at slow (1.0 km/h), normal (2.5 km/h), and fast (5.0 km/h) rates. In the unstable condition, the subjects were perturbed by randomly decelerating and accelerating one side of the walking belt (0.1 km/h - 5.0 km/h). Lateral sway of COM and stride time were calculated from the trajectory of COM in the frontal plane, and these values were compared between the stable and unstable gait conditions. The result was that coefficient of variation and standard deviation of lateral sway and stride time increased significantly only in the unstable gait condition, while the values were not influenced by gait speed changes between the three stable gait conditions. The results suggest that the trajectory of COM could be used to indicate the stability of the gait, in terms of both spatial and temporal factors.
... The CoM lateral displacement was calculated as the parameter of gait stability. The CoM lateral displacement has been reported to be a useful parameter for evaluating the gait stability (Iida and Yamamuro, 1987;Shinoda et al., 2008). For the CoM lateral displacement, we calculated the difference between the maximum and minimum values of the lateral motion of the third lumbar vertebra in each gait cycle and then averaged them over 20 gait cycles. ...
As humans, we constantly change our movement strategies to adapt to changes in physical functions and the external environment. We have to walk very slowly in situations with a high risk of falling, such as walking on slippery ice, carrying an overflowing cup of water, or muscle weakness owing to aging or motor deficit. However, previous studies have shown that a normal gait pattern at low speeds results in reduced efficiency and stability in comparison with those at a normal speed. Another possible strategy is to change the gait pattern from normal to step-to gait, in which the other foot is aligned with the first swing foot. However, the efficiency and stability of the step-to gait pattern at low speeds have not been investigated yet. Therefore, in this study, we compared the efficiency and stability of the normal and step-to gait patterns at intermediate, low, and very low speeds. Eleven healthy participants were asked to walk with a normal gait and step-to gait on a treadmill at five different speeds (i.e., 10, 20, 30, 40, and 60 m/min), ranging from very low to normal walking speed. The efficiency parameters (percent recovery and walk ratio) and stability parameters (center of mass lateral displacement) were analyzed from the motion capture data and then compared for the two gait patterns. The results suggested that step-to gait had a more efficient gait pattern at very low speeds of 10–30 m/min, with a larger percent recovery, and was more stable at 10–60 m/min in comparison with a normal gait. However, the efficiency of the normal gait was better than that of the step-to gait pattern at 60 m/min. Therefore, step-to gait is effective in improving gait efficiency and stability when faced with situations that force us to walk slowly or hinder quick walking because of muscle weakness owing to aging or motor deficit along with a high risk of falling.
... Each deviation is approximately 2 cm (up and to each side) 11) . On the other hand, when subjects walked on a treadmill at 2.5 km/h with both arms crossed, the trajectory of the center of mass in the frontal plane swayed transversely by approximately 3% of height 12) . If the subject's height is 160 cm, 3% is 4.8 cm. ...
[Purpose] This study investigated the reliability of an automated sphygmomanometer based on an oscillometric method, when used during exercise. [Subjects and Methods] Ten healthy subjects were included. Blood pressure (BP) was measured with an automated sphygmomanometer based on a cuff-oscillometric method. The experiment consisted of five tests: sitting posture at rest, walking with swinging the upper limbs, walking without swinging the upper limbs, walking on a treadmill, and riding a bicycle ergometer. Right and left brachial artery BP was measured twice at the same times. If the difference in systolic BP on bilateral testing was less than 15 mmHg, it was judged to be accurate, and accurate measurement rates were calculated. [Results] BP could not be measured in most limbs on walking with swinging the upper limbs, walking without swinging the upper limbs, or walking on a treadmill. The accurate measurement rates in bilateral limbs were 95.0% in sitting posture at rest, 0.0% on walking with swinging upper limbs, 5.0% on walking without swinging upper limbs, 15.0% on walking on a treadmill, and 65.0% on riding a bicycle ergometer. [Conclusion] An automated sphygmomanometer based on an oscillometric method was useful for BP measurement only at rest.
In this study, we quantify the center of pressure （COP） trajectory oscillation as the difference between the measured COP trajectory and approximate curve during walking. Further, we determine the relationship between the COP trajectory oscillation and center of gravity oscillation of each body part during walking to examine its effectiveness as an index of walking. The subjects were 10 young males who walked at free speed along a 10-m walking path. We measured the COP position and displacement of 22 markers in the whole body in the left-right direction during walking and calculated the amount of oscillation of the center of foot pressure trajectory and the center of mass of 14 segments. The results showed that the amount of oscillation of COP trajectory substantially differed among walking periods; it was larger during heel-ground contact and landing, which were considered unstable during walking. In addition, it was related to the center of mass oscillation among the right forearm, right upper arm, left upper arm, head, and torso parts. These results indicate that COP trajectory oscillation can be an index to evaluate the sway and posture control of each body part.
[Purpose] This study aimed to clarify the relationship between gait independence and the functional assessment for control of trunk (FACT) in community-dwelling elderly people who need support or care. [Participants and Methods] The subjects were 100 elderly people requiring support or care who used gait at home as their means of locomotion. Their degree of independence was classified according to the functional independence measure (FIM) of gait function (gait FIM). The relationships between gait FIM, grip strength, the timed up and go (TUG) test, maximum walking speed, CS30, one-leg standing time, and FACT were investigated. The relationships between gait FIM and FACT subordinate items were also examined. [Results] The results revealed that gait FIM was associated with TUG in females, and TUG and FACT in males. In addition, the degree of independence of gait and the subordinate items of FACT were related to question 5 (move the buttocks from the seat surface for 3 seconds or more) and question 8 (walking forward and backward) for both males and females. [Conclusion] FACT is associated with gait independence in males, and the trunk function associated with gait independence was lateral shift of the center of gravity.
House flooring materials may be one of the main causes lead to the high fall incidents among the elderly. The main objective of this study is to investigate the effects of different flooring materials on the walking motion of the elderly. 18 men （age, 70.8±3.2 years） without any walking impediments were recruited. The experiment conditions are common Japanese house flooring materials, namely wood, carpet and tatami. The participants walked on the flooring materials in randomized order and the walking motion was recorded by a three-dimensional motion analysis system. The stride length was significantly longer for tatami compared to that for wood. Foot clearance was significantly larger for carpet and tatami than that for wood. Subsequently, the initial contact hip joint and foot sole angles were significantly larger for tatami compared to that for wood and carpet. Additionally, range of hip joint, knee joint and foot sole angles were significantly larger for carpet and tatami than that for wood. The results suggest tatami may reduce the abnormal short stepped and shuffling gait often found among the elderly.
In the clinical, it is difficult to carry out the motion analysis because it requires a large place. The purpose of this study is to examine the gait analysis method by one direction frontal video that can be easily measured in clinical. The subjects were five healthy persons attached four markers at both shoulders and both anterior superior iliac spine (ASIS). The walking motion of each subject toward a camera was analyzed. Body trunk tilt and centroid sway of the upper body part were calculated and compared with the results of three-dimensional gait analysis methods. The result showed the same tendency of the body trunk tilt and the centroid sway changes based on each method. The result suggested that the gait analysis by one direction frontal video could evaluate the large abnormal gait. Further, authors evaluated OA knee joint thrust using one direction frontal video. The change of the knee joint alignment and the distance between the loading axis of lower extremity and knee joint center were calculated as knee joint thrust. Results showed that knee adduction angle and distance of knee joint center from lower limb loading axis of OA patient were increased. The result suggested that this method could evaluate the knee joint thrust of OA patient.
The main challenges of designing devices for paraplegic walking can be summarized into three groups, stability and comfort, high efficiency or low energy consumption, dimensions and weight. A new economical device for people with paraplegia which tackles all problems of the three groups is introduced in this paper. The main idea of this device is based on HALO mechanism. HALO is compact passive medial hip joint orthosis with contralateral hip and ankle linkage, which keeps the feet always parallel to the ground and assists swinging the leg. The medial hip joint is equipped with one actuator in the new design and the new orthosis is called @halo. Due to this update, we can achieve more stable and smoother walking patterns with decreased energy consumption of the users, yet maintain its compact and lightweight features. It is proven by the results from preliminary experiments with able-bodied subjects during which the same device with and without actuator was evaluated. Waddling and excessive vertical elevation of the center of gravity were decreased by 40% with significantly smaller standard deviations in case of the active orthosis. There was 52% less energy spent by the user wearing @halo which was calculated from the vertical excursion difference. There was measured 38.5% bigger impulse in crutches while using passive orthosis. The new @halo device is the first active orthosis for lower limbs with just one actuated degree of freedom for users with paraplegia.
This paper shows the dynamic measurement system of the body swing in jogging by acceleration sensor on the waist. This system is wearable sensing system. That can measure the body swing in jogging at indoor and outdoor. This system is composed of acceleration sensor, micro processor and memory. This is small and simple structure. This system measures the acceleration of the waist. The body swing in jogging is detected by the acceleration of the waist. The increase body swing in jogging was confirmed by this system on the experimental results.
To know load unbalance of body is an important concern for us to keep our physical health. The measurement of load unbalance of human body standing at a point is well known. But, on the other hand, it is more important to know the load unbalance in dairy life. This paper describes the system and method to measure load unbalance of human body to left or right side in walking. The load unbalance is estimated by an inclination angle of body. The inclination angle is calculated by acceleration information from acceleration sensor attached on waist. As the measurement system is constructed as a portable and wearable unit, it is used indoor and outdoor.
The aim of this study was to examine the effect of aging on body reactions to perturbation during walking. The subject group comprised 15 young and 15 elderly individuals. Perturbation was produced by abruptly decelerating one side of the walking-belt of a two-belt treadmill for 500 ms during walking. Each subject received 30 perturbations during a 10-minute walking period. Muscle activity in the lower limb muscles and acceleration at the pelvis were recorded using surface electromyographs and accelerometers. Peak values of acceleration following perturbation were significantly greater than in normal walking. Posterior peak values of acceleration appeared prior to anterior peak values of acceleration following perturbation. These outcomes seem to demonstrate that external forces by perturbations act on the center of gravity of the whole body and that external forces work from the rear to the front. In addition, the tibialis anterior muscles demonstrated bilaterally reduced latency of muscle reactions. Latency of the tibialis anterior on the stimulation side was significantly shorter than that on the non-stimulation side. This suggests that perturbation in one leg triggers a righting reaction of that leg within the first 120 ms, facilitating the subsequent stepping reaction of the contralateral leg. Comparisons according to age demonstrated that both the appearance of anterior peak values of acceleration and latency of the tibialis anterior on the non-stimulation side were significantly delayed after perturbation for older subjects. These results suggest that the capacity for postural adjustment during stepping might be deteriorated in elderly individuals.
Momentum must be controlled in stable locomotor activities, including sit-to-stand and gait. The relationship of momentum control and balance maintenance in elders or in a balance-impaired population has not been studied. Although decreased locomotor speed has long been reported among elders, the literature is lacunar concerning the mechanical mechanisms underlying this slowing. The purpose of this study was to describe the whole body and upper body linear and angular momentum for healthy elders during sit-to-stand and gait and compare them to a group of balance-impaired elders who have bilateral vestibular hypofunction (BVH).
Ten elders with BVH were matched to 10 healthy elders aged 67-90. Linear and angular momentum were calculated for sit-to-stand and for free speed and paced gait. Means and 95% confidence intervals were used to compare groups.
Elders with BVH used significantly less linear and angular momentum to rise from a chair than healthy elders and showed excessive lateral momentum during gait, despite walking at a slower velocity.
Healthy elders limit momentum generation by decreasing gait velocity, apparently because they lack sufficient strength or balance control to safely dissipate the momentum that a faster, less controlled gait engenders. Elders with BVH further limit momentum in locomotor activities to decrease their risk of falling, but are apparently unable to control lateral momentum during gait. Excessive lateral momentum in gait among balance-impaired elders leads to loss of balance, a frequent occurrence in this patient population.
In clinical practice, visual gait observation is often used to determine gait disorders and to evaluate treatment. Several reliability studies on observational gait analysis have been described in the literature and generally showed moderate reliability. However, patients with orthopedic disorders have received little attention. The objective of this study is to determine the reliability levels of visual observation of gait in patients with orthopedic disorders.
The gait of thirty patients referred to a physical therapist for gait treatment was videotaped. Ten raters, 4 experienced, 4 inexperienced and 2 experts, individually evaluated these videotaped gait patterns of the patients twice, by using a structured gait analysis form. Reliability levels were established by calculating the Intraclass Correlation Coefficient (ICC), using a two-way random design and based on absolute agreement.
The inter-rater reliability among experienced raters (ICC = 0.42; 95%CI: 0.38-0.46) was comparable to that of the inexperienced raters (ICC = 0.40; 95%CI: 0.36-0.44). The expert raters reached a higher inter-rater reliability level (ICC = 0.54; 95%CI: 0.48-0.60). The average intra-rater reliability of the experienced raters was 0.63 (ICCs ranging from 0.57 to 0.70). The inexperienced raters reached an average intra-rater reliability of 0.57 (ICCs ranging from 0.52 to 0.62). The two expert raters attained ICC values of 0.70 and 0.74 respectively.
Structured visual gait observation by use of a gait analysis form as described in this study was found to be moderately reliable. Clinical experience appears to increase the reliability of visual gait analysis.
The purpose of this study was to determine the effect (if any) of significant sensory loss on the long-range correlations normally observed in the stride intervals of human gait. Fourteen patients with severe peripheral neuropathy and 12 gender-, age-, height-, and weight-matched nondiabetic controls participated. Subjects walked around an approximately 200-m open-level walkway for 10 min at their comfortable pace. Continuous knee joint kinematics were recorded and used to calculate a stride interval time series for each subject. Power spectral density and detrended fluctuation analyses were used to determine whether these stride intervals exhibited long-range correlations. If the loss of long-range correlations indicates deterioration of the central control of gait, then changes in peripheral sensation should have no effect. If instead the loss of long-range correlations is a consequence of a general inability to regulate gait cycle timing, then a similar loss should occur in patients with peripheral locomotor disorders. Both power spectral density analyses and detrended fluctuation analyses showed that temporal correlations in the stride times of neuropathic and control subjects were statistically identical (P = 0.954 and P = 0.974, respectively), despite slower gait speeds (P = 0.008) and increased stride time variability (P = 0.036) among the neuropathy patients. All subjects in both groups exhibited long-range correlations. These findings demonstrate that the normal long-range correlation structure of stride intervals is unaltered by significant peripheral sensory loss. This further supports the hypothesis that the central nervous system is involved in the regulation of long-range correlations.
In this study, we analyzed optimal walk and fastest walk using the gait analysis system, GAITRite, and investigated the reliability of different measurement methods as well as characteristics of gender, the dominant leg and non-dominant leg. The results of gait analysis of 42 subjects (18 male, 24 female, average age 22.1 years) gave high reproducibility with an intra-class correlation coefficient greater than 0.9 in both optimal walk and fastest walk for step width, step time, walking speed and walking rate. No differences for gender were found in optimal walk, however at fastest walk significant differences were found in all indices other than step time and walking rate. With regard to the dominant leg and the non-dominant leg, no significant differences were found in any of the measurement values. These results suggest that whichever of optimal walk or fastest walk is used for gait analysis in clinical practice, a highly reproducible value will be obtained, however, in order to more accurately elaborate individual gait performance, fastest walk is superior to optimal walk.
In order to investigate the influence of subjects' height in stabilization of body sway, postural EMG reactions were analysed following perturbation of posture during stance on a force measuring platform. Perturbing momenta of different strengths were unexpectedly applied at the back (level of the center of gravity) after being matched to the body weight of each subject. EMG activity of the antagonistic leg muscles and head, hip and ankle joint movements were recorded. There was a close correlation between displacement amplitude at the ankle joint and height of the subject, with the largest displacements in small subjects. The consequence of this relationship was that 1) The compensatory reactions consisted of larger gastrocnemius responses and a stronger coactivation of the tibialis anterior; 2) Momenta of increasing strength resulted in a larger increment of both ankle joint displacement and gastrocnemius EMG responses in small compared to larger subjects. In analogy to tip-toeing movements, it is concluded that the coactivation pattern is typical for stance conditions with a restricted area of support in order to reduce body sway. On the basis of latency measurements it is suggested that the response pattern is induced by proprioceptive information from the impact site of the momentum.
The aim of this study was to determine a gait profile of two groups of elderly adults: one with a history of falls and one without a history of falls. The following gait characteristics were identified: step frequency, stance time, swing time, double support time, step length, heel width, heel height, toe height, and hip, knee, and ankle angular excursion. The history of falls group was composed of 25 subjects (seven men and 18 women), and the no history of falls group was composed of 30 subjects (12 men and 18 women). Two 16-mm Locam cameras were used to film the subjects. Each subject was filmed while walking on a motorized treadmill at 4 km/h and 6 km/h. The film data were digitized on a sonic digitizer interfaced to a VAX computer. The ANOVA statistic indicated significant (p less than .05) difference between the two independent variables for heel width. There appears to be no significant relationship between the studied gait characteristics (other than heel width) and falls in apparently healthy elderly individuals.
The kinetics of the body's center of gravity during level walking were analyzed in 50 normal subjects and 47 patients. The three-dimensional displacements of the center of gravity were computed by the integration of force plate data. The energy levels and the power requirements of the center of gravity were also calculated, and the average and standard deviation of these variables were determined for normal and pathological gaits. The sex-related variation in normal gait, as suggested by previous force plate studies, was clearly demonstrated in our study. The parameters obtained from the displacements and the energy variations of the center of gravity are considered useful in the evaluation of stability and efficiency for pathological gaits.
Most hip fractures result from falls. However, the role of fall-related factors has seldom been examined. Comparison of the predictive value of these factors with that of bone mineral density (BMD) has important implications for the prevention of hip fractures.
We assessed femoral-neck BMD by dual-photon X-ray absorptiometry and potential fall-related risk factors, which included self-reported physical capacity, neuromuscular function, mobility, visual function, and use of medication in 7575 women, aged 75 years or older, with no history of hip fracture recruited at five centres in France. We followed up these women every 4 months to record incident hip fractures. During an average of 1.9 years of follow-up 154 women suffered a first hip fracture.
In age-adjusted multivariate analyses, we found four independent fall-related predictors of hip fracture: slower gait speed (relative risk = 1 . 4 for 1 SD decrease [95% Cl 1.1-1.6)]; difficulty in doing a tandem (heel-to-toe) walk (1.2 for 1 point on the difficulty score [1.0-1.5]); reduced visual acuity (2.0 for acuity < or = 2/10 [1.1-3.7]); and small calf circumference (1.5 [1.0-2.2]). After adjustment for femoral-neck BMD, neuromuscular impairment--gait speed, tandem walk--and poor vision remained significantly associated with an increased risk of subsequent hip fracture. With high risk defined as the top quartile of risk, the rate of hip fracture among women classified as high risk based on both a high fall-risk status and low BMD was 29 per 1000 women-years, compared with 11 per 1000 for women classified as high risk by either a high fall-risk status or low BMD; for women classified as low risk based on both criteria the rate was five per 1000.
We conclude that neuromuscular and visual impairments, as well as femoral-neck BMD, are significant and independent predictors of the risk of hip fracture in elderly mobile women, and that their combined assessment improves the prediction of hip fractures.
To test the hypothesis that quantitative measures of gait unsteadiness are increased in community-dwelling elderly fallers.
Retrospective, case-control study.
General community.
Thirty-five community-dwelling elderly subjects older than 70 years of age who were capable of ambulating independently for 6 minutes were categorized as fallers (age, 82.2 +/- 4.9 yrs [mean +/- SD]; n = 18) and nonfallers (age, 76.5 +/- 4.0 yrs; n = 17) based on history; 22 young (age, 24.6 +/- 1.9 yrs), healthy subjects also participated as a second reference group.
Stride-to-stride variability (standard deviation and coefficient of variation) of stride time, stance time, swing time, and percent stance time measured during a 6-minute walk.
All measures of gait variability were significantly greater in the elderly fallers compared with both the elderly nonfallers and the young subjects (p < .0002). In contrast, walking speed of the elderly fallers was similar to that of the nonfallers. There were little or no differences in the variability measures of the elderly nonfallers compared with the young subjects.
Stride-to-stride temporal variations of gait are relatively unchanged in community-dwelling elderly nonfallers, but are significantly increased in elderly fallers. Quantitative measurement of gait unsteadiness may be useful in assessing fall risk in the elderly.
Since falling is one of the main causes of morbidity and mortality among the elderly, attention should be paid to prevention. The purpose of the present study was to investigate the risk factors for falls among the elderly by a 5-year longitudinal observation.
The subjects were the elderly aged 65 years and over living in a rural community in the eastern part of Honshu, Japan. Of the 852 eligible subjects, 685 persons (278 males and 407 females) received the multidimensional medical examination including physical performance as the baseline of TMIG-LISA (Tokyo Metropolitan Institute of Gerontology, Longitudinal and Interdisciplinary Study on Aging) in 1992.
From baseline medical examinations, the following variables were adopted to investigate risk factors for falls (2 or more times during the 5-year follow-up): self-rated health, experience of falling, TMIG-index of competence, visual deficit, anthropometric measurements (height, weight, BMI, total skinfold thickness), lumbar bone mineral density, and physical performance tests (grip strength, finger-tapping rate, one leg standing time with eyes open or closed, preferred and maximum speed walking for 5 meters).
A total of 108 subjects experienced falls two or more times during the 5-year follow-up period (43 men and 65 women). There were significant differences in grip strength, preferred and maximum walking speeds between those who fell and those who did not. Multiple logistic regression analysis controled for age, sex and other variables adopted in this study revealed the following variables were significantly and independently related to falling: experience of falling within one year preceding the baseline survey (directly, p<0.0001), preferred walking speed (inversely, p<0.005) and total skinfold thickness (inversely, p<0.01). These results suggest that the walking test as well as the experience of falling have discriminant and predictive validity for assessing the future occurrence of falls among the elderly.
To determine if joint kinetic gait alterations in fallers persist when they attempt to walk at a faster speed that is more comparable with nonfallers' comfortable walking speed.
Retrospective, case-control study. Stereophotogrammetric and force platform data were collected.
A gait laboratory.
Sixteen elderly subjects who had at least 2 falls in the last 6 months from an unclear cause and 23 elderly subjects with no history of repeated falls.
Differences in all major peak joint kinetic (moment and power) values during the gait cycle between elderly nonfallers walking at comfortable speed and elderly fallers walking at (1) comfortable and (2) fast speed.
Statistically significant differences present at both comfortable and fast walking speeds were present in 4 sagittal plane parameters. There was an increase in peak external hip flexion moment in stance, a reduction in peak hip extension moment, a reduction in knee flexion moment in preswing, and a reduction in knee power absorption in preswing.
The presence and persistence of 4 specific alterations in sagittal plane joint kinetics at both comfortable and fast walking speeds imply specific intrinsic pattern differences and allow for new insights into the mechanics of gait in elderly people who fall. The presence of these alterations also suggests they may serve as potential identifiable markers to detect those who may be at risk for falls.
We measured variability of foot placement during gait to test whether lateral balance must be actively controlled against dynamic instability. The hypothesis was developed using a simple dynamical model that can walk down a slight incline with a periodic gait resembling that of humans. This gait is entirely passive except that it requires active control for a single unstable mode, confined mainly to lateral motion. An especially efficient means of controlling this instability is to adjust lateral foot placement. We hypothesized that similar active feedback control is performed by humans, with fore-aft dynamics stabilized either passively or by very low-level control. The model predicts that uncertainty within the active feedback loop should result in variability in foot placement that is larger laterally than fore-aft. In addition, loss of sensory information such as by closing the eyes should result in larger increases in lateral variability. The control model also predicts a slight coupling between step width and length. We tested 15 young normal human subjects and found that lateral variability was 79% larger than fore-aft variability with eyes open, and a larger increase in lateral variability (53% vs. 21%) with eyes closed, consistent with the model's predictions. We also found that the coupling between lateral and fore-aft foot placements was consistent with a value of 0.13 predicted by the control model. Our results imply that humans may harness passive dynamic properties of the limbs in the sagittal plane, but must provide significant active control in order to stabilize lateral motion.
This study examined the sensitivity and specificity of the Timed Up & Go Test (TUG) under single-task versus dual-task conditions for identifying elderly individuals who are prone to falling.
Fifteen older adults with no history of falls (mean age=78 years, SD=6, range=65-85) and 15 older adults with a history of 2 or more falls in the previous 6 months (mean age=86.2 years, SD=6, range=76-95) participated.
Time taken to complete the TUG under 3 conditions (TUG, TUG with a subtraction task [TUGcognitive], and TUG while carrying a full cup of water [TUGmanual]) was measured. A multivariate analysis of variance and discriminant function and logistic regression analyses were performed.
The TUG was found to be a sensitive (sensitivity=87%) and specific (specificity=87%) measure for identifying elderly individuals who are prone to falls. For both groups of older adults, simultaneous performance of an additional task increased the time taken to complete the TUG, with the greatest effect in the older adults with a history of falls. The TUG scores with or without an additional task (cognitive or manual) were equivalent with respect to identifying fallers and nonfallers.
The results suggest that the TUG is a sensitive and specific measure for identifying community-dwelling adults who are at risk for falls. The ability to predict falls is not enhanced by adding a secondary task when performing the TUG.
To determine whether there is an increase in energy use for able-bodied subjects with their arm and/or knee immobilized, while walking on a level surface at comfortable walking speed (CWS).
Prospective, quantitative, with randomly sequenced experimental trials.
Rehabilitation center.
Ten healthy subjects, none of whom had gait abnormality.
Subjects walked on a treadmill at CWS under 4 conditions: (1) without an arm or knee immobilized (N); (2) with an arm immobilized (AI); (3) with a knee immobilized (KI); and (4) with both arm and ipsilateral knee immobilized (KAI).
Breath-by-breath oxygen cost; differences in energy consumption in trials during which constraints were used were compared with energy consumed under the N condition and the percentage of change was calculated.
Mean oxygen cost increased by 22.7% with a knee immobilized compared with N values (mean difference,.044 mL x kg(-1) x m(-1), p <.0001), and increased by 24.7% with a knee and arm immobilized (mean difference,.048 mL x kg(-1) x m(-1), p <.0001). However, no significant differences existed in oxygen cost with AI compared with N, or with KAI compared with KI. The differences in CWS between the stages followed a similar pattern.
Arm immobilization does not increase energy expenditure during level walking at CWS, and does not further increase energy expenditure when the ipsilateral knee also is immobilized.
It has been suggested that sequential movements in patients with Parkinson's disease (PD) might be improved by the effects of external rhythmic cues. We studied spatiotemporal gait parameters and temporal gait variability in patients with PD and control subjects under different walking conditions in order to investigate whether rhythmic auditory cues could improve temporal variability. A total of 30 subjects were recruited, comprising 15 patients with idiopathic PD and 15 control subjects with no history of neurological disorder. As an indicator for temporal stability, we used the coefficient of variability (CV=standard deviation/mean X 100) of recorded intervals between two consecutive steps (gait variability). After control values were obtained, subjects underwent a Physical Rehabilitation Programme (PRP) consisting of a variety of motor tasks performed in combination with rhythmic sounds with different cadences. Sessions lasted 1h/day, five times a week for a period of four consecutive weeks. At the end of the PRP subjects were evaluated again. Following completion of the programme the patients' coefficients of variability improved significantly for the preferred gait (gait: t=2.950, p=0.011) but were not significantly different from those obtained in control subjects (gait: t=3.873, p=0.391). These results are consistent with and extend prior studies of rhythmic auditory facilitation in PD and suggest a valuable method of improving gait timing in these patients.
Variability of gait may be regarded as a sign of adaptability and thus a requirement for successful locomotion, or as a sign of impaired balance control. In this study we examined the role of step width variability (SWV) and interstride trunk acceleration variability in two groups of fit and frail old people. We investigated the association of these measures and how they differentiated the two groups. We examined 33 fit older adults (mean age 73 years, S.D. 3.3 years) and 32 frail old people (mean age 80 years, S.D. 4.0 years). Subjects performed timed walking at different speeds ranging from very slow to very fast. SWV was measured from footprints. Trunk accelerations were registered by a triaxial accelerometer and interstride trunk acceleration variability assessed by an unbiased autocorrelation procedure. All measures were normalized to a walking speed of 0.9 m/s to avoid the confounding effect of gait speed on speed dependent gait parameters. SWV demonstrated low association with the trunk variability measures, and did not differ between groups. The frail group had lower mediolateral (P=0.015), but higher vertical (P=0.015) and anteroposterior (P<0.02) trunk variability than the fit group. Trunk variability classified 80% of the subjects correctly into their respective group (sensitivity=0.75, specificity=0.85). The findings are compatible with a notion that mediolateral interstride trunk variability represents a different aspect of motor control than variability in the direction of propulsion.
The movement of the center of mass (COM) during human walking has been hypothesized to follow a sinusoidal pattern in the vertical and mediolateral directions. The vertical COM displacement has been shown to increase with velocity, but little is known about the mediolateral movement of the COM. In our evaluation of the mediolateral COM displacement at several walking speeds, 10 normal subjects walked at their self-selected speed and then at 0.7, 1.0, 1.2, and 1.6 m/s in random order. We calculated COM location from a 15-segment, full-body kinematic model using segmental analysis. Mediolateral COM displacement was 6.99 +/- 1.34 cm at the slowest walking speed and decreased to 3.85 +/- 1.41 cm at the fastest speed (p < 0.05). Vertical COM excursion increased from 2.74 +/- 0.52 at the slowest speed to 4.83 +/- 0.92 at the fastest speed (p < 0.05). The data suggest that the relationship between the vertical and mediolateral COM excursions changes substantially with walking speed. Clinicians who use observational gait analysis to assess walking problems should be aware that even normal individuals show significant mediolateral COM displacement at slow speeds. Excessive vertical COM displacement that is obvious at moderate walking speeds may be masked at slow walking speeds.
To define a parameter that quantifies balance control during gait and better identifies elderly people who are at a higher risk of falling.
Controlled study.
University research laboratory.
Twelve elderly patients (mean age, 76.9+/-6y) with complaints of imbalance during walking, or with a history of falls, and 12 matched healthy elderly adults.
Not applicable.
Temporal-distance gait parameters (gait velocity, stride length, step width); and sagittal and frontal center of mass (COM) and center of pressure (COP) inclination angles.
Elderly patients demonstrated a significantly greater medial, but a significantly smaller anterior, inclination angle than their matched controls during both unobstructed and obstructed gait. The medial COM-COP inclination angle was not affected by the gait velocity in the healthy elderly. When the 2 groups were compared at a similar gait velocity ( approximately 1m/s), the elderly patients still had a significantly greater medial COM-COP inclination angle than did the controls.
Instantaneous COM-COP inclination angles during walking provide information about the ability to control COM position in relation to the corresponding COP. The medial COM-COP inclination angle may be a sensitive measure of gait stability in the elderly.
Kinetic alterations independent of walking speed
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The timed "up & go" test is a useful predictor of falls in community-dwelling older people
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