Effects of Aging on the Obstacle Negotiation Strategy while Stepping over Multiple Obstacles (original) (raw)
Related papers
Strategies for obstacle crossing in older adults with high and low risk of falling
Journal of Physical Therapy Science, 2016
Tripping is a frequent cause of falls among aging adults. Appropriate limb movements while negotiating obstacles are critical to trip avoidance. The aim of our study was to investigate the mechanics of obstacle crossing in older adults at low or high risk of falling. [Subjects and Methods] Twenty community-dwelling adults aged ≥55 years, were evaluated with the Tinetti Balance and Gait scale and classified as being at high or low risk of falling. Between-group comparisons of kinematics were evaluated for obstacle heights of 10%, 20%, and 30% of leg length. [Results] The high-risk group demonstrated greater toe-obstacle clearance of the leading leg. Increasing obstacle height led to increased maximal toe-obstacle clearance, toe-obstacle distance, and shortened swing phase of the leading limb. Adaptation of clearance height was greater for the trailing leg. Individuals at high risk of falling demonstrated less symmetry between the leading and trailing legs and a narrower step width, features that increase the likelihood of tripping. [Conclusion] Kinematic parameters of obstacle clearance, including the symmetry index described in our study, could provide clinicians with a quick screening tool to identify patients at risk of falling and to evaluate outcomes of training programs.
Age-associated changes in obstacle negotiation strategies: Does size and timing matter?
Gait & posture, 2018
Tripping over an obstacle is one of the most common causes of falls among older adults. However, the effects of aging, obstacle height and anticipation time on negotiation strategies have not been systematically evaluated. Twenty older adults (ages: 77.7±3.4years; 50% women) and twenty young adults (age: 29.3±3.8years; 50% women) walked through an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 25mm and 75mm. Kinect cameras captured the: (1) distance of the subject's trailing foot before the obstacles, (2) distance of the leading foot after the obstacles, (3) clearance of the leading foot above the obstacles, and (4) clearance of the trailing foot above the obstacles. Linear-mix models assessed changes between groups and conditions. Older adults placed their leading foot closer to the obstacle after landing, compared to young adults (p<0.001). This pattern was enhanced in high obstacles (group*height interaction, p=0.033). Older adults ...
Age effects on strategies used to avoid obstacles
Gait & Posture, 1994
found that the rates of success which 24 healthy younger and 24 healthy older adults achieved in not stepping on fixed and suddenly appearing virtual obstacles was adversely affected by reducing their available response time. This paper reports the gait strategies used by those 48 subjects in avoiding the obstacles and the factors associated with falls by four of the subjects. Differences among gait parameters were analysed with respect to age, gender, available response time, and avoidance strategy. Both short-and long-step strategies were used to avoid stepping on the obstacles, but age differences in strategy choice were not significant. The shortstep strategy was used more often with shorter available response times. To avoid a fixed obstacle gait was seldom adjusted more than two steps before reaching it; the older adults, however, adjusted their stepping pattern one step earlier than did the younger adults. As the available response time was shortened, the results suggest that older adults had more difficulty than did younger adults in employing the long-step strategy. Although the short-step strategy is easier to employ at short available response times, it becomes a highly risky strategy when combined with a fast walking speed and resulted in actual falls. The results show that in both young and old healthy adults, tripping does not necessarily originate from contacts with a physical obstacle; it can be self initiated.
Gait & Posture, 2004
Previous research suggests that older adults may have difficulty attending to simultaneous tasks. This study was conducted to determine how concurrent performance of a secondary cognitive task influences walking and stepping over an obstacle in community dwelling older adults. Twenty-one men and women with a mean age of 73.4 years (S.D. = 5.3) participated in the study. Subjects performed a gait task both alone (single-task condition) and in combination with a cognitive task that involved reciting numbers (dual-task condition). In the gait task, each subject walked at his/her fastest speed along a 10-m walkway and stepped over an obstacle designed to simulate a door threshold. Paired t-tests were used to compare gait parameters (10 m gait speed, gait speed during obstacle approach and negotiation, medial-lateral center of pressure excursion and velocity during obstacle negotiation, foot clearance over the obstacle, step length and foot position relative to the obstacle) and cognitive task performance under single and dual-task conditions. Toe-obstacle distance was greater and obstacle-heel distance was reduced under dual-task conditions. Performance of the remaining gait parameters did not change with the addition of a secondary cognitive task. Cognitive task performance decreased under dual-task conditions. These community dwelling older adults demonstrated minimal or no change in measured gait parameters during simultaneous performance of a cognitive task. The observed decrement in cognitive task performance suggests that subjects may have placed a higher priority on gait performance.
Age-related changes in avoidance strategies when negotiating single and multiple obstacles
Experimental Brain Research, 2007
The aim of this research was to describe agerelated changes in locomotor adjustments during obstructed gait and expand and build from the current body of literature describing single obstacle avoidance strategies by including trials in which the subjects stepped over two identical obstacles placed in series. We observed young adults (YA: N = 8; aged 23.1 § 2.0 years) and older adults (OA: N = 8; aged 76.1 § 4.3 years) as they walked along a 5 m long instrumented pathway (GAITRite) and stepped over one or two obstacles that were scaled to their lower leg length. Infrared markers, tracked using the Optotrak motion analysis system (60 Hz; Northern Digital Inc, Canada), were Wxed to subjects' trunk and feet, and several anatomical landmarks were digitized for each segment (e.g. toes). Data analyses included lead and trail toe clearance values, take-oV and landing distance, step time, length, width and velocity, and three-dimensional trunk angles. Both age groups were able to successfully complete the obstacle avoidance task, and the presence of a second obstacle did not aVect clearance strategies of either OA or YA. OA crossed the obstacles with a reduced step velocity and stepped closer to the trailing edge, although take-oV distances were not diVerent between the age groups. Additionally, OA used similar ranges of trunk motion as YA when crossing the obstacle, but did so while using smaller step lengths and step widths compared to YA, eVectively, using a narrower base of support. Together, these Wndings suggest that older adults adopted a more cautious crossing strategy in that they reduced their crossing step velocity. However, other aspects of the avoidance strategy used by the older adults, speciWcally the shortened landing distances and the use of similar ranges of trunk motion within a narrowed BOS, could potentially put them at risk for tripping or imbalance when stepping over an obstacle.
Obstacle crossing deficits in older adults: A systematic review
Gait & Posture, 2009
This systematic review and critical evaluation of the literature investigates whether advanced age compromises obstacle crossing for unconstrained and time-constrained conditions. Eight electronic databases were searched for articles with terms relating to obstacle crossing during walking in their title, abstract or keywords. 15 articles were reviewed from an initial yield of 727 articles. The methodological quality of each article was critiqued and data extracted by two reviewers. Young and older adults were shown to contact obstacles infrequently when adequate time was available to adapt foot placement in relation to the obstacle. When less time was available to adjust the foot trajectory, older adults contacted obstacles more often than younger people. Older adults adopted a slower, more conservative obstacle crossing strategy. They demonstrated greater hip flexion during the swing phase of gait for the lead and trail limbs as well as greater hip flexion, hip adduction and ankle dorsiflexion during the stance phase for the lead and trail limbs. There was also evidence of reduced internal moments across the hip and ankle during key events in the obstacle crossing gait cycle in older adults. Despite using a more conservative obstacle crossing strategy, older adults are at greater risk of contacting obstacles for time-constrained conditions. ß
Kinematic and kinetic characteristics of stepping over a 10-cm-high obstacle in older adults
Aino Journal, 2010
The purpose of this research was to clarify the common responses shared by a high-falldown-risk group of older adults and develop an exercise-learning program to prevent falls. [Subjects] Thirty-four subjects were chosen from those who use the daycare program of a nursing home at least once a week. [Methods] All subjects were categorized in longer or shorter-MSL groups. Ninety-second stepping from two force plates to a 10-cmhigh box was executed under three conditions. The locus length of the COP, toe-obstacle distance, and step length were used as experimental data. [Results] The coefficient between the MSL and COP was from 0.69 to 0.73. The shorter-MSL group showed smaller COP movements in the A-P direction and a smaller toe-obstacle distance between the single stepping and stepping with the visual task and between the single stepping and stepping with the auditory task. No significant difference was noted in the step length between the two groups. [Conclusion] The shorter-MSL group was easily affected by the dual-task, suggesting that the shorter-MSL group has a high risk of falling when negotiating obstacles. Stepping exercise with the dual-task using the COP movements as a feedback index may be useful for older adults who have a smaller MSL.
Effects of conflicting constraints and age on strategy choice in stepping down during gait
Gait & Posture, 2009
For negotiating a step down during gait, as in stepping from a curb, two different strategies can be used, i.e. heel landing and toe landing. Toe landing allows more negative work by the leading leg to reduce the momentum gained during the descent, which facilitates maintaining stability but reduces walking velocity. We therefore hypothesized that subjects would use a toe landing less frequently when instructed to walk faster and when negotiating smaller height differences. Furthermore, expecting that older adults would prioritize stability over maintaining gait velocity, we hypothesized that they would use toe landing more frequently than young adults. Two groups (young: 23+/-1 years, n=8; old: 73+/-5 years, n=17) walked over a 10-m walkway at 3-5 km/h to step down a single step of 5-15 cm halfway. In both groups, toe landing was used less frequently for lower steps and less frequently at higher velocities. Older participants used toe landing more frequently and more consistently than young participants. This preference for toe landing is suggested to reflect adaptive behavior to enhance gait stability, rather than an inability to use a heel landing.
Stumbling Over Obstacles in Older Adults Compared to Young Adults
Journal of Neurophysiology, 2005
Falls are a major problem in older adults. Many falls occur because of stumbling. The aim of the present study is to investigate stumbling reactions of older adults and to compare them with young adults. While subjects walked on a treadmill, a rigid obstacle unexpectedly obstructed the forward sway of the foot. In general, older adults used the same movement strategies as young adults ("elevating" and "lowering"). The electromyographic responses were categorized according to latencies: short-latency (about 45 ms, RP1), medium-latency (about 80 ms, RP2), and long-latency responses (about 110 ms, RP3; about 160 ms, RP4). Latencies of RP1 responses increased by about 6 ms and of RP2 by 10-19 ms in older adults compared with the young. Amplitudes of RP1 were similar for both age groups, whereas amplitudes of RP2-RP4 could differ. In the early-swing elevating strategy (perturbed foot directly lifted over the obstacle) older adults showed smaller responses in ipsilateral upperleg muscles (biceps femoris and rectus femoris). This was related to shorter swing durations, more shortened step distances, and more failures in clearing the obstacle. In parallel, RP4 activity in the contralateral biceps femoris was enhanced, possibly pointing to a higher demand for trunk stabilization. In the late-swing lowering strategy (foot placed on the treadmill before clearing the obstacle) older adults showed lower RP2-RP3 responses in most muscles measured. However, kinematic responses were similar to those of the young. It is concluded that the changes in muscular responses in older adults induce a greater risk of falling after tripping, especially in early swing.
Age-related changes in gait adaptability in response to unpredictable obstacles and stepping targets
Gait & Posture, 2016
Background: A large proportion of falls in older people occur when walking. Limitations in gait adaptability might contribute to tripping; a frequently reported cause of falls in this group. Objective: To evaluate age-related changes in gait adaptability in response to obstacles or stepping targets presented at short notice, i.e.: approximately two steps ahead. Methods: Fifty older adults (aged 74 AE 7 years; 34 females) and 21 young adults (aged 26 AE 4 years; 12 females) completed 3 usual gait speed (baseline) trials. They then completed the following randomly presented gait adaptability trials: obstacle avoidance, short stepping target, long stepping target and no target/obstacle (3 trials of each). Results: Compared with the young, the older adults slowed significantly in no target/obstacle trials compared with the baseline trials. They took more steps and spent more time in double support while approaching the obstacle and stepping targets, demonstrated poorer stepping accuracy and made more stepping errors (failed to hit the stepping targets/avoid the obstacle). The older adults also reduced velocity of the two preceding steps and shortened the previous step in the long stepping target condition and in the obstacle avoidance condition. Conclusion: Compared with their younger counterparts, the older adults exhibited a more conservative adaptation strategy characterised by slow, short and multiple steps with longer time in double support. Even so, they demonstrated poorer stepping accuracy and made more stepping errors. This reduced gait adaptability may place older adults at increased risk of falling when negotiating unexpected hazards.