Towards the importance of minimum toe clearance in level ground walking in a healthy elderly population

doi:10.1016/j.gaitpost.2014.07.016

Gait & Posture

Volume 40, Issue 4, September 2014, Pages 727-729

https://doi.org/10.1016/j.gaitpost.2014.07.016 Get rights and content

Highlights

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Minimum toe clearance can be seen as a task-relevant parameter to prevent trips.
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We explored dual-task costs of variability of minimum toe clearance.
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Other gait parameters’ variability does increase in a dual-task situation.
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Minimum toe clearance variability does not increase in a dual-task situation.
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Its assessment might depict an effective tool for fall risk estimation.

Abstract

Tripping is presumed to be the principal cause for falls during walking. At minimum toe clearance, the potential for trip-related falls is considered to be highest. Thus, controlling minimum toe clearance is essential for walking without tripping. In theory, the central nervous system should therefore give priority to accurate control of the variability in minimum toe clearance, as compared to other gait parameters, since people tend to only modify variability in any given task if it interferes with the task performance. The aim of this study was to determine whether elderly individuals show less increase in variability of minimum toe clearance during a dual-task condition (where an increase of gait variability is provoked), while allowing a larger range of variability in the other gait parameters. Forty elderly participants walked back and forth on a 25 m long track for five minutes. They then walked a second time performing an additional cognitive task. The variability in stride time, stride length and minimum toe clearance as well as dual-task costs of each gait parameter were calculated for each walk. The variability in minimum toe clearance did not change during dual task-walking, whereas the variability of stride length and stride time increased, showing dual-task costs of about 66% and 84%, respectively. To avoid additional detrimental load on the central nervous system, the modification of task-irrelevant variability may be tolerated during dual-task conditions, whereas minimum toe clearance is controlled with high priority.

Introduction

Falls in the elderly population represent a major cost to the public health system [1], [2]. Tripping while walking is presumed to be the principal cause of falls [3], and at minimum toe clearance (MTC), the potential for a trip-related fall is considered to be highest [4]. Extreme levels of variability in human walking have been reported to be a predictor of risk of falling [5] and constitute a key neuromuscular deficit in elderly people [6]. However, according to the minimum intervention principle, humans tend to only modify this variability if it interferes with task performance [7], since the additional control of task-irrelevant variability would constitute additional detrimental load on the central nervous system [8]. Controlling the swing phases of gait, and consequently MTC, is considered a precise-end-point control task [4], [9]. From a falls perspective, controlling MTC in level-ground walking could be the task-relevant variable, whereas the control of other gait parameters may be less important for goal-directed task performance (e.g. walking without tripping). If this is true, an efficient central nervous system should give high priority to accurate control of MTC as compared to other gait parameters. In plain terms, the central nervous system may allow a greater degree of variability in the less important (task-irrelevant) variables, while minimising variability in task-relevant parameters of human walking [8]. If that assumption is true, dual-task costs (defined as a percentage increase in gait variability) would be lower in MTC variability than in the other spatial or temporal gait parameters’ variability to prevent trips. The aim of the current study was to explore whether the central nervous system of healthy elderly individuals minimises variability in MTC when an increase of gait variability is experimentally provoked (with a cognitive dual task) while allowing an increase in variability in other spatial or temporal gait parameters. We hypothesised that in healthy elderly individuals, the variability in MTC would increase much less than that of other gait parameters when a dual task is introduced, as compared to normal level walking.

Section snippets

Methods

From a larger study (study protocol of the local ethics committee: 22|12), we recruited 40 elderly (age: 67.6 ± 3.4 years) participants who were not suffering from orthopaedic or neurological complaints (mini-mental state examination performance above 28 points). After they signed written informed consent, the subjects were asked to walk back and forth along a 25 m track at their preferred walking speed for five minutes. Thereafter, participants were allowed five minutes rest. After the break,

Results

Our data show that the walking speeds and mean gait parameters (Table 1) differed between the trials (p = .000) and that the variability of stride length and stride time (Table 2) in cognitive dual-task walking was significantly higher as compared to normal walking (p-value for each test = .000). The dual-task costs for the variability of stride length, and stride time were 65.9% and 84.2%, respectively. However, the variability of MTC did not change (p = .090) and the dual-task cost was −7.1%. Note

Discussion

This is the first study to explore the origins of changes of variability in task-relevant and task-irrelevant gait parameters from normal walking to cognitive dual-task walking. We believe that older adults adopt a preferential lower increase in MTC variability even during a dual-task paradigm. At MTC, the potential for a trip-related fall is considered to be highest [4] and should be controlled with the highest priority in all situations. Hence, we expected a smaller increase in the

Acknowledgement

No external sources of support have to be declared.
Conflict of interest

There is no conflict of interests.

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Tripping is one of the main causes of falls in older adults and has an important association with minimum toe clearance (MTC). MTC variability while performing alternating (ADT) or concurrent (CDT) dual-task activities may be a useful gait parameter to differentiate once-only fallers from non-faller older adults.
Is the MTC variability influenced by ADT and CDT in once-only faller community-dwelling older adults?
Twenty-two community-dwelling older adults with a self-report of up to one fall in the last 12 months were allocated to the fallers group and 38 to the non-fallers group. Gait data were collected by two foot-worn inertial sensors (Physilog® 5, GaitUp, Lausanne, Switzerland). MTC mean magnitude and variability, as well as the stride-to-stride variability, stride time and length, lower limb peak angular velocity, and foot forward linear speed at the MTC instant, were calculated across approximately 50 gait cycles for each participant and condition using the GaitUp Analyzer software (GaitUp, Lausanne, Switzerland). The statistical analyzes were performed in the Statistical Package for the Social Sciences (SPSS), v.22.0, using generalized mixed linear models, adopting an alpha of 5%.
No interaction effect was observed; however, faller participants reduced the MTC variability (standard deviation) [(mean difference, MD = −0.099 cm; confidence interval, 95%CI = −0.183 to −0.015)], regardless of the condition. CDT compared to a single task (only gait) reduced the mean magnitude of the foot forward linear speed (MD=−0.264 m/s; 95%CI=−0.462 to −0.067), peak angular velocity (MD = −25.205 degrees/s; 95%CI = −45.507 to −4.904), and gait speed (MD = −0.104 m/s; 95%CI = −0.179 to −0.029), regardless of the group. These results suggest that MTC variability, regardless of condition, may be a promising gait parameter to differentiate once-only faller community-dwelling older adults from non-fallers.
Compensation of stochastic time-continuous perturbations during walking in healthy young adults: An analysis of the structure of gait variability
2020, Gait and Posture
Citation Excerpt :
Recent investigations applying the TNC method on gait movements considered the position of the center of mass (CoM) during the stance phase as a result parameter and the lower extremity joint kinematics as execution parameters [12,13]. During the swing phase, the minimum toe clearance (MTC) can be used as result parameter given its high relevance for stable gait [7,14,15]. The MTC is affected by the CoM height and the joint kinematics.
During everyday locomotion, we cope with various internal or external perturbations (e.g. uneven surface). Uncertainty exists on how unpredictable external perturbations increase noise within the motor system and if they are compensated by employing covariation of the limb joints or rather due to decreased sensitivity of an altered posture.
Do continuous stochastic perturbations affect the structure of gait variability in young and healthy adults?
In a cross-over study, gait kinematics of 21 healthy young sports students were registered during treadmill walking with and without continuous stochastic perturbations. Using the TNC method, the following aspects were analyzed: (a) the sensitivity of body posture to perturbations (‘tolerance’) decreasing gait variability, (b) the unstructured motor ‘noise’ increasing gait variability and (c) the amount of ‘covariation’ of the limb joints.
Compared to normal walking, gait variability was significantly increased (p < .001) during walking with perturbations. The negative effect of noise was partly compensated by improved ‘covariation’ of leg joints (p < .001). The aspect ‘tolerance’ had a small effect on increasing gait variability during stance phase (p < .001) and decreasing gait variability during swing phase (p < .001).
Increased motor noise due to external perturbations is partly compensated by improved covariation of the limb joints. However, the effect of an altered posture slightly affects gait variability. Further studies should focus on different populations (e.g. older participants) to see if they use the same mechanism (improved covariation) to compensate for stochastic perturbations.
Characterizing cognitive-motor impairments in patients with myotonic dystrophy type 1
2020, Neuromuscular Disorders
Myotonic Dystrophy Type 1 (DM1) is the most frequent hereditary, adult-onset muscular dystrophy. Nevertheless, DM1-associated cognitive-motor impairments have not been fully characterized so far. This study aimed at profiling cognitive and locomotor dysfunctions in these patients. In addition, cognitive-motor interactions were assessed using a dual-task paradigm. Comprehensive cognitive-motor impairment profiles were generated for 19 patients with DM1 and 19 healthy subjects by thorough clinical, biomechanical and neuropsychological examinations. Detailed gait analysis was performed using a 3D motion capture system, whereas cognitive function was assessed using a standardized neuropsychological test battery. Patients with DM1 showed impaired functional mobility, gait velocity and endurance. DM1-related gait pathology was mainly characterized by enhanced dynamic instability, gait variability, and restricted ankle dorsiflexion. Patients’ cognitive impairments particularly concerned attentional functions. Dual-task conditions induced gait deviations that slightly differed between patients and controls. DM1-associated cognitive impairments correlated with reduced functional mobility and impaired ankle dorsiflexion. Patients with DM1 revealed significant impairments of walking function, balance and cognitive performance. Differential cognitive-motor interference and significant interactions between cognitive and motor dysfunctions point towards a prominent role of cognition in gait performance of patients with DM1.
Joint movements associated with minimum toe clearance variability in older adults during level overground walking
2020, Gait and Posture
Approximately one-third of falls are caused by the swing foot contacting an object or the ground, resulting in a trip. The increased incidence of trip-related falls among older adults may be explained by greater within-person minimum toe clearance (MTC) variability.
Will kinematic variability at any of the 6 major joints in the lower limbs, individually or in combination, be associated with MTC variability?
This cross-sectional study investigated whether single or multiple joint movements best explained MTC variability in older adults. Twenty healthy older adults (7 males, 13 females; mean age = 71.3 ± 7.2 years) were recruited. Participants were fitted with a modified Cleveland Clinic marker set and walked for 50 trials at self-selected speeds over a 7-meter walkway (with a rest at 25 trials) while 6 infrared cameras recorded kinematics.
Seven joint movements were evaluated, and swing hip flexion-extension variability was the only joint movement significantly associated with MTC variability (r = 0.577, p = 0.008) and explained 29.6% (adjusted R²) of the variance of MTC variability in older adults (F (1, 18) = 8.897, p = 0.008).
Identifying the joint movement/s associated with inconsistencies in toe clearance will improve our understanding of endpoint control in older adults and may lead to the development of effective trip prevention strategies.
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2019, Gait and Posture
Tripping is a common event leading to falls amongst elderly. Minimum foot clearance (MFC) is a critical swing phase control factor associated with tripping and falls.
Are there differences in MFC characteristics among three age groups of women and are there association between MFC and lower limb kinematics?
Cross-sectional observational study. Three-dimensional gait analysis of 55 healthy women. ANOVA was used to compare (p<0.05) MFC characteristics among young, middle-aged and elderly groups. Multiple Linear Regression Analysis was used to test prediction over MFC.
Elderly women walked slower, with lower MFC and lower maximum foot velocity during swing (MFV) than young and middle-aged women. There were more hip flexion and less ankle dorsiflexion during MFC among elderly. There is a strong positive relationship between dorsiflexion and MFC. And ankle dorsiflexion was the most predictive variable over MFC.
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CMI should be assessed in MS with a standardised dual task such as the Verbal Fluency task while walking, with measurements of the double support time and the effect on the cognitive task. The clinical usefulness of CMI in the assessment of patients with MS is discussed.

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Short CommunicationTowards the importance of minimum toe clearance in level ground walking in a healthy elderly population

Highlights

Abstract

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgement

Gait Posture

Gait Posture

Gait Posture

Brain Res

J Biomech

Gait Posture

Cost of falls in old age: a systematic review

Osteoporos Int

Short Communication
Towards the importance of minimum toe clearance in level ground walking in a healthy elderly population