Associations between physical function, balance confidence, and the probability of walking instability among older adults.

BackgroundAdvanced age brings a loss of plantar sensation, represented, for example, as higher sensation thresholds in standardized testing. This is thought to contribute to an increased risk of falls among older adults – an intuitive premise that has yet to be fully investigated, especially in the context of walking balance. The purpose of this study was to quantify the association between plantar sensation and the instability elicited by a suite of walking balance perturbations that differ in direction and context in a cohort of n = 28 older adults (73.0 ± 5.9 yrs).MethodsWe measured plantar sensation using Semmes-Weinstein monofilaments and quantified margins of stability (MoS) and whole-body angular momentum (WBAM) during habitual walking and in response to optical flow perturbations, lateral waist-pull perturbations, and treadmill-induced slips.ResultsOur two major results were that higher monofilament thresholds (i.e., worse plantar sensation) in older adults associated with: (1) larger anterior-posterior (AP) and mediolateral (ML) MoS and increased transverse plane WBAM (p ≤ 0.031) during habitual walking, and (2) larger decreases in MoSAP, MoSML and larger increases in transverse plane WBAM in response to lateral waist pull perturbations (p ≤ 0.018). We found no associations between plantar sensation and responses to other perturbation contexts.ConclusionsWe conclude that there is an association between worse plantar sensation and gait instability, both during habitual unperturbed walking and in response to some perturbation contexts. These results should build confidence that interventions designed to improve plantar sensation for older adults, possibly through insoles or footwear modifications, could be critical for reducing gait-related falls in at-risk populations.

Effects of narrow base gait on mediolateral balance control in young and older adults

Dynamic stability during increased walking speeds is related to balance confidence of older adults: a pilot study

Perturbation-based gait assessment has been used to quantify gait stability in older adults. However, knowledge on which perturbation type is most suitable to identify poor gait stability is lacking. We evaluated the effects of ipsi- and contra-lateral sway, belt acceleration and deceleration, and visual and auditory perturbations on medio-lateral (ML) and anterior-posterior (AP) margins of stability (MoS) in young and older adults. We aimed to evaluate (1) which perturbation type disturbed the gait pattern substantially, (2) how participants recovered, and (3) whether recovery responses could discriminate between young and older adults. Nine young (25.1 ± 3.4 years) and nine older (70.1 ± 7.6 years) adults walked on the CAREN Extended (Motek BV, The Netherlands). The perturbation effect was quantified by deviation in MoS over six post-perturbation steps compared to baseline walking. Contra-lateral sway and deceleration perturbations resulted in the largest ML (1.9–4 times larger than other types) and AP (1.6–5.6 times larger than other types) perturbation effects, respectively. After both perturbation types, participants increased MoS by taking wider, shorter, and faster steps. No differences between young and older adults were found. We suggest to evaluate the potential of using contra-lateral sway and deceleration perturbations for fall risk identification by including both healthy and frail older adults.Graphical abstractMargins of stability during steady state (left) and perturbed (right) gait to quantify reactive gait stability in response to various perturbation types in young and older adults.

Contribution of Lower Limb Eccentric Control to Balance Recovery From Surface Drop Perturbations

BackgroundRoot mean square (RMS) of trunk acceleration is seen frequently in gait analysis research. However, many studies have reported that the RMS value was related to walking speed. Therefore, the relationship between the RMS value and walking speed should be considered when the RMS value is used to assess gait abnormality. We hypothesized that the RMS values in three sensing axes exhibit common proportions for healthy people if they walk at their own preferred speed and that the RMS proportions in abnormal gait deviate from the common proportions. In this study, we proposed the RMS ratio (RMSR) as a gait abnormality measure and verified its ability to discriminate abnormal gait.MethodsForty-seven healthy male subjects (24–49 years) were recruited to examine the relationship between walking speed and the RMSR. To verify its ability to discriminate abnormal gait, twenty age-matched male hemiplegic patients (30–48 years) participated as typical subjects with gait abnormality. A tri-axial accelerometer was attached to their lower back, and they walked along a corridor at their own preferred speed. We defined the RMSR as the ratio between RMS in each direction and the RMS vector magnitude.ResultsIn the healthy subjects, the RMS in all directions related to preferred walking speed. In contrast, RMSR in the mediolateral (ML) direction did not correlate with preferred walking speed (rs = -0.10, p = 0.54) and represented the similar value among the healthy subjects. Moreover, the RMSR in the ML direction for the hemiplegic patients was significantly higher than that for the healthy subjects (p < 0.01).ConclusionsThese results suggest that the RMSR in the ML direction exhibits a common value when healthy subjects walk at their own preferred speed, even if their preferred walking speed were different. For subjects with gait abnormality, the RMSR in the ML direction deviates from the common value of healthy subjects. The RMSR in the ML direction may potentially be a quantitative measure of gait abnormality.

Previous research indicates the correlation structure of gait parameters (i.e., fractal dynamics) decreases with age. This decrease is suggested to reflect a reduced capacity for locomotor adaptation in older adults. The purpose of this study was to investigate potential differences between physical activity-matched young and older adults’ fractal dynamics and gait adaptability during unperturbed and asymmetric walking, and to determine if fractal dynamics predict adaptive capacity. Fifteen young (28.9 ± 5.6 years, nine women) and 15 older (64.7 ± 2.7, nine women) adults with similar habitual physical activity levels walked at preferred speed, half of preferred speed, and asymmetrically whereby their dominant and non-dominant legs moved at preferred and half-preferred speed, respectively. Fractal correlations (scaling exponent α) of stride times were assessed through detrended fluctuation analysis, and gait adaptation to asymmetric walking on the basis of lower limb relative phase. Both cohorts displayed similar fractal dynamics at preferred speed and asymmetric walking, while older adults exhibited greater α during slow walking. Both groups exhibited comparable gait adaptation to split-belt walking based on analysis of lower limb relative phase. Fractal dynamics during preferred speed and asymmetric walking was moderately associated with gait adaptation in the young and older adult cohorts, respectively. In these activity-matched groups, there were no age-based reductions in fractal dynamics or gait adaptation, and fractal scaling α was moderately associated with gait adaptation. These findings suggest that stride time fractal dynamics and gait adaptation may be preserved in older adults who habitually perform moderate intensity physical activity.

Dual task performance in older adults: Examining visual discrimination performance whilst treadmill walking at preferred and non-preferred speeds

PurposeThe purpose of this study was to determine whether net metabolic cost of walking is affected by age per se.MethodsWe selected 10 healthy, active older adults (mean age 75 years) and 10 young adults (mean age 26 years), and determined their preferred overground walking speed. On the same day, in a morning and afternoon session, we had them walk at that speed overground and on a treadmill while we measured oxygen consumption rate. From the latter we subtracted the rate in sitting and calculated net metabolic cost.ResultsAnthropometrics were not different between the groups nor was preferred walking speed (1.27 m s−1 both groups). There was no difference in net metabolic cost of overground walking between older and young adults (e.g., in the morning 2.64 and 2.56 J kg−1 m−1, respectively, p > 0.05). In the morning session, net metabolic cost of walking was higher on the treadmill than overground in our older adults by 0.6 J kg−1 m−1 (p < 0.05), but not in young adults.ConclusionFirst, there is no effect of age per se on metabolic cost of overground walking. Second, older adults tend to have higher metabolic cost of walking on a treadmill than walking overground at preferred speed, and adaptation may take a long time. The commonly reported age-related elevation of metabolic cost of walking may be due to confounding factors causing preferred walking speed to be lower in older adults, and/or due to older adults reacting differently to treadmill walking than young adults.

Dynamic margins of stability during human walking in destabilizing environments

Dynamic margin of stability during gait is altered in persons with multiple sclerosis

Older adults with chronic diabetes have been shown to exhibit reduced balance function and increased fear of falling; however, the contextual inter-relationships between diabetes and its psychological consequences on physical functioning are not fully understood. This study examined the relationships between diabetes disease status, balance confidence, fear of falling avoidance behavior, and changes in performance and confidence after massed practice of a balance task in participants with and without diabetes (PWD and PWOD). Older adult PWD and PWOD were recruited for the pre-post control group study (n=27 PWD, n =26 PWOD). Participants underwent practice of a novel stabilometer-based balance task over a 2-day period (40 practice trials in 8 blocks). Changes in balance task performance and balance confidence were assessed pre- and post-training. Balance confidence and activity avoidance behavior associated with fear of falling were assessed using the Activities-Specific Balance Confidence Scale and Fear of Falling Avoidance Behavior Questionnaire, respectively. Repeated measures analysis of variance and mediation analyses were conducted to examine the effects of diabetes and training on balance performance and confidence, as well as how baseline balance confidence affects the training outcomes. Fifty-three participants (27 with type II diabetes, 29 men, 23 women, and 1 gender nonconforming, mean age=63.8, range 50-89years) were enrolled in the study. Of them, 48 (90.6%) successfully completed the balance training with significant balance task performance improvement of approximately 30% in both groups (PWD: 3.04 [95% confidence interval, 1.77-4.31], P <.001; PWOD: 4.39 [95% confidence interval, 3.04-5.74], P <.001). Activities-Specific Balance Confidence Scale score significantly mediated the effect of diabetes on balance confidence after training and fear of falling avoidance behavior. Despite the physical and psychological deficits associated with diabetes, individuals with chronic diabetes are capable of improving balance confidence and performance through targeted training. Balance confidence was identified as an important mediating factor, explaining the relationship between diabetes disease status and activity-related psycho-physical outcomes. Future research should focus on the potentially self-reinforcing effects of psycho-physical gains induced by exercise training.

Dynamic stability control in younger and older adults during stair descent

Soleus fascicle length changes are conserved between young and old adults at their preferred walking speed

Falls are the leading cause of injury and mortality among older adults—one in four individuals 65 years old and above experiences falls. Thus, balance training interventions that improve balance ability and reduce the risk of falls are of critical importance. Through two complementary interventions, our research sought to determine the effects of Virtual Reality (VR) compared to Robotic-Assisted Balance Training (RABT) on balance ability and balance confidence in older adults. The VR intervention utilized Oculus headsets to create immersive balance exercises, while the RABT employed a multidirectional overground robotic system (NaviGAITor). Participants (aged 60–85 years old) underwent a 6-week training protocol consisting of two 30 min sessions per week. Balance ability was quantified using center of pressure (COP) parameters and the Balance Error Scoring System (BESS), while balance confidence was measured using the Activities-Specific Balance Confidence (ABC) scale. Results indicated no statistically significant differences between the training methods. However, the RABT group showed trends toward enhanced balance performance, with observed decreases in mediolateral (ML) maximum displacement during wide stance conditions and reductions in BESS errors on both firm and foam surfaces. The VR group demonstrated significant changes in ML RMS values during tandem stance (p = 0.045) and improved participants’ relationship with perceived and actual balance ability (increased correlation between BESS errors and ABC scores from R2 = 0.00 pre-training to R2 = 0.65 post-training). Balance confidence did not significantly increase in either group. These findings suggest that while RABT may trend toward improvements in objective balance parameters, VR training appears to enhance participants’ perceptual accuracy of their balance capabilities.