Ballet practice improves neuromuscular and biomechanical responses to an unexpected standing-slip in older adults.

Falls and fall-induced injuries are common and consequential in older adults. Ballet emphasizes full-body coordination, leg strength, and postural control. However, it remains unknown whether ballet can indeed reduce falls in older adults. This study examined biomechanical and neuromuscular responses of older recreational ballet dancers to an unexpected standing-slip. Twenty older ballet dancers (17 females, 3 males) and 23 age- and sex-matched nondancers (19 females, 4 males) were exposed to an unexpected slip during treadmill standing. The slip-faller rate was the primary outcome. The secondary outcomes were kinematic measurements, including dynamic gait stability, slip distance, and recovery stepping performance (step latency, duration, length, and speed). The tertiary outcome was the electromyography latency of leg muscles (bilateral tibialis anterior, medial gastrocnemius, rectus femoris, and biceps femoris). Fewer dancers fell than nondancers after the standing-slip (45% vs. 83%, P = 0.005, d = 0.970). Dancers displayed better stability at recovery foot liftoff (P = 0.006) and touchdown (P = 0.012), a shorter step latency (P = 0.020), shorter step duration (P = 0.011), faster step speed (P = 0.032), and shorter slip distance (P = 0.015) than nondancers. They also exhibited shorter latencies than nondancers for the standing leg rectus femoris (P = 0.028) and tibialis anterior (P = 0.002), and the stepping leg biceps femoris (P = 0.031), tibialis anterior (P = 0.017), and medial gastrocnemius (P = 0.030). The results suggest that older ballet dancers experience a lower fall risk and are more stable than nondancers following an unexpected standing-slip. The greater stability among dancers could be attributed to more biomechanically effective recovery stepping, possibly associated with the ballet-induced neuromuscular benefit-an earlier leg muscle activation.NEW & NOTEWORTHY This is the first study to examine how older ballet dancers respond to an unexpected external slip perturbation while standing. The results suggest that older ballet dancers experience a reduced fall risk after the slip than their nondancer counterparts. The lower fall risk can be accounted for by dancers' quicker neuromuscular reactions to the slip that result in a more effective recovery step and thus higher stability against backward falls due to the slip.

Commingling Effects of Anterior Load and Walking Surface on Dynamic Gait Stability in Young Adults.

Treadmill walking has been used as a surrogate for overground walking to examine how load carriage affects gait. The validity of using treadmill walking to investigate load carriage's effects on stability has not been established. Thirty young adults were randomized into 3 front-loaded groups (group 1: 0%, 2: 10%, or 3: 20% of bodyweight). Participants carried their load during overground and treadmill walking. Dynamic gait stability (primary outcome) was determined for 2 gait events (touchdown and liftoff). Secondary variables included step length, gait speed, and trunk angle. Groups 1 and 2 demonstrated similar stability between walking surfaces. Group 3 was less stable during treadmill walking than overground (P ≤ .005). Besides trunk angle, all secondary outcomes were similar between groups (P > .272) but different between surfaces (P ≤ .001). The trunk angle at both events showed significant group- and surface-related differences (P ≤ .046). Results suggested that walking with an anterior load of up to 10% bodyweight causes comparable stability between surfaces. A 20% bodyweight front load could render participants less stable on the treadmill than overground. This indicates that anteriorly loaded treadmill walking may not be interchangeable with overground walking concerning stability for anterior loads of 20% bodyweight.

Effects of vibration training on quality of life in older adults: a preliminary systematic review and meta-analysis.

PURPOSE: Older adults experience reduced quality of life (QOL). Vibration training has been applied in older adults. However, it remains inconclusive whether vibration training improves QOL in this population. This review summarized the effects of vibration training in changing eight domains of the Short Form-36 (SF-36) among older adults. METHODS: Five randomized controlled trials enrolling 212 participants were included. The mean difference (MD) was calculated as the effect size measurement. Meta-analyses were completed for each of the eight SF-36 domains. RESULTS: Relative to control groups, vibration training is more effective in improving five QOL domains: physical function (MD = 15.61, p < 0.001), physical role limitations (MD = 12.71, p = 0.001), general health (MD = 10.59, p < 0.001), social function (MD = 11.60, p < 0.001), and vitality (MD = 6.86, p = 0.002). Vibration training may not lead to greater improvements for the other three domains (MD = 0.13-3.25, p values = 0.21-0.96) than the control groups. Vibration training showed a low attrition rate of 7.1%. CONCLUSION: Vibration training programs may significantly improve five of eight SF-36 QOL domains. While three domains did not demonstrate significant improvements, results were slightly in favor of vibration training compared to the control groups. More rigorous studies are necessary to further confirm the effectiveness of vibration training on QOL in older adults.

Dynamic Gait Stability and Spatiotemporal Gait Parameters During Overground Walking in Professional Ballet Dancers.

Introduction: It has been recognized that practicing ballet could strengthen the leg muscles, improve balance, and reduce fall risk. However, few studies have investigated how ballet practice alters a person's gait pattern, and this knowledge gap could present a barrier to designing ballet-based training programs. This study examined dynamic gait stability and spatiotemporal gait parameters among professional ballet dancers during normal level overground walking. Methods: Twenty young adults were recruited: 10 ballet dancers (24.5 ± 4.9 years) and 10 age- and sex-matched non-dancers (22.6 ± 3.4 years). Participants walked on a 10 m linear walkway at their self-selected speed. Dynamic gait stability and common gait parameters (step length, step width, gait speed, and cadence) were determined from the collected kinematic data and compared between groups with a significance level of .05. Results: The results showed that both groups displayed comparable dynamic gait stability at touchdown (P = .140) and liftoff (P = .638). However, ballet dancers walked with a longer (P = .054), narrower (P = .009), and faster step (P = .014) at a marginally quicker speed (P = .063) than non-dancers. Conclusion: Our study suggests that young professional ballet dancers have different gait patterns, but similar dynamic gait stability compared to non-dancers. These findings not only provide insight into the mechanisms of dynamic stability control among young ballet dancers during gait but expand our understanding of the control of dynamic gait balance of human locomotion across a wide variety of populations and walking conditions.

Adipose tissue deposition region affects fall risk in people with obesity: A systematic review and meta-analysis.

This review sought to meta-analyze previous research observing the effects of fat mass distribution on the fall risk among people with obesity. The literature search yielded five qualified studies enrolling 1218 participants (650 with android vs. 568 with gynoid). The outcome variables included the annual fall prevalence (primary outcome) and the center of pressure (COP) movement measurements during a posturography test (secondary) among people with android or gynoid obesity. Meta-analyses were conducted using the inverse variance weighted random-effects model. The odds ratio (OR) and standardized mean difference (SMD) were used as the effect size for the primary and secondary variables, respectively. The results revealed that more people with android obesity fall annually than their gynoid obesity counterparts (OR = 1.78 [1.34, 2.37], p < 0.0001). People with android obesity also exhibited significantly faster overall COP velocity (SMD = 0.49 [0.11, 0.88], p = 0.01) during standing compared to individuals with gynoid obesity. Our results indicated that people with android obesity could have a greater fall risk than those with gynoid obesity. Given the limited number of studies included, more well-designed and quality work is desired to further clarify how fat mass distribution alters the fall risk among people with obesity. A standardized approach to quantify the fat mass distribution (android vs. gynoid) is imperatively needed for people with obesity.

A Meta-Analysis of Fall Risk in Older Adults With Alzheimer's Disease.

OBJECTIVES: Falls are the leading cause of injuries in older adults. Although it is well recognized that Alzheimer's disease (AD) increases the fall risk of older adults, the reported fall risk in people with AD varies drastically. The principal purpose of this study was to summarize and synthesize previous studies reporting fall risk-related metrics in people with AD. DESIGN: This was a meta-analysis. SETTING AND PARTICIPANTS: Thirty-one studies reporting relevant fall data among 4654 older adults with AD were included. METHODS: The fall prevalence, average number of falls, rate of recurrent fallers, and rate of injured fallers of included studies were meta-analyzed using random-effects models with inverse variance weights. RESULTS: The pooled annual fall prevalence in older people with AD is 44.27% with an average annual number of falls of 1.30/person and a yearly rate of recurrent fallers of 42.08%. The reported rate of injured fallers was 45.0%. CONCLUSIONS AND IMPLICATIONS: Our results reinforce that people with AD experience a higher fall risk than their cognitively healthy counterparts. The pooled fall metrics in this meta-analysis extend our understanding of the fall risk in people with AD. In addition, standardized approaches are needed to report fall-related data for people with AD.

Meta-Analysis-Based Comparison of Annual Fall Risk between Older Adults with Alzheimer's Disease and Mild Cognitive Impairment.

Background: Falls are a primary cause of injuries and hospitalization in older adults. It has been reported that cognitive impairments and dementia can increase fall risk in the older population; however, it remains unknown if fall risk differs among subgroups of dementia. This meta-analysis summarized previous studies reporting the annual fall risk of people with Alzheimer's disease (AD) or mild cognitive impairment (MCI) and compared the fall risk between these two groups of people with dementia. Methods: Thirty-five studies enrolling 7844 older adults with AD or MCI were included. The annual fall prevalence and average number of falls of the included studies were meta-analyzed and compared by random-effects models with inverse variance weights. Results: The annual fall prevalence in people with AD (43.55%) was significantly higher than MCI (35.26%, p < 0.001). A χ2 test indicated that the pooled fall prevalence is significantly higher in people with AD than MCI χ2 = 158.403, p < 0.001). Additionally, the yearly average number of falls in AD was higher than in MCI (1.30 vs 0.77 falls/person). Conclusions: The results showed that older people with AD experience a higher annual fall prevalence with a larger number of falls than older adults with MCI. The results suggested that the fall risk measurements should be reported separately between people with AD and MCI. The findings could provide preliminary guidance for the identification of individuals with dementia who experience a high fall risk.

Shoe sole impedes leg muscle activation and impairs dynamic balance responding to a standing-slip.

The shoe sole is identified as a fall risk factor since it may impede the afferent information about the outside world collected by the plantar sensory units. However, no study has directly quantified how the shoe sole compromises body balance and increases fall risk. This study aimed to inspect how the sole affects human balance after an unexpected standing-slip. It was hypothesized that individuals wearing the sole, relative to their barefoot counterparts, would exhibit 1) more impaired stability and 2) disrupted lower limb muscle activation following a standing-slip. Twenty young adults were evenly randomized into two groups: soled and barefoot. The soled group wore a pair of customized 10-mm thick soles, while the other group was bare-footed. Full-body kinematics and leg muscle electromyography (EMG) were collected during a standardized and unexpected standing-slip. The EMG electrodes were placed on the tibialis anterior, gastrocnemius, rectus femoris, and biceps femoris bilaterally. Dynamic stability, spatiotemporal gait parameters, and the EMG latency of the leg muscles were compared between groups. The sole impeded the initiation of the recovery step possibly because it interfered with the accurate detection of the external perturbation and subsequently activated the leg muscles later in the soled group than in the barefoot group. As a result, individuals in the soled group experienced a longer slip distance and were more unstable than the barefoot group at the recovery foot liftoff. The findings of this study could augment our understanding of how the shoe sole impairs body balance and increases the fall risk.

Android obesity could be associated with a higher fall risk than gynoid obesity following a standing-slip: A simulation-based biomechanical analysis.

It is well recognized that overall obesity increases fall risk. However, it remains unknown if the obesity-induced increase in the fall risk depends upon the adipose distribution (or obesity type: android vs. gynoid). This pilot study examined the effects of fat deposition region on fall risk following a standing-slip trial in young adults with simulated android or gynoid adiposity. Appropriate external weights were attached to two groups of healthy young lean adults at either the abdomen or upper thigh region to simulate android or gynoid adiposity, respectively, with a targeted body mass index of 32 kg/m2. Under the protection of a safety harness, both groups were exposed to an identical standing-slip on a treadmill with a maximum slip distance of 0.36 m. The primary (dynamic gait stability) and secondary (latency, length, duration, and speed of the recovery step, slip distance, and trunk velocity) outcome variables on the slip trial were compared between groups. The results revealed that the android group was more unstable with a longer slip distance and a slower trunk flexion velocity than the gynoid group at the recovery foot liftoff after the slip onset. The android group initiated the recovery step later but executed the step faster than the gynoid group. Biomechanically, the android adipose tissue may be associated with a higher fall risk than the gynoid fat tissue. Our findings could provide preliminary evidence for considering fat distribution as an additional fall risk factor to identify older adults with obesity at a high fall risk.

Impact of standing perturbation intensities on fall and stability outcomes in healthy young adults.

Motorized treadmills have been extensively used in investigating reactive balance control and developing perturbation-based interventions for fall prevention. However, the relationship between perturbation intensity and its outcome has not been quantified. The primary purpose of this study was to quantitatively analyze how the treadmill belt's peak velocity affects the perturbation outcome and other metrics related to the reactive balance in young adults while the total belt displacement is controlled at 0.36 m. Thirty-one healthy young adults were randomly assigned into three groups with different peak belt speeds: low (0.9 m/s), medium (1.2 m/s), and high (1.8 m/s). Protected by a safety harness, participants were exposed to a forward support surface translation while standing at an unexpected timing on an ActiveStep treadmill. The primary (perturbation outcome: fall vs. recovery) and secondary (dynamic stability, hip descent, belt distance at liftoff, and recovery step latency) outcome measures were compared among groups. Results revealed that a higher perturbation intensity is correlated with a greater faller rate (p < 0.001). Compared to the low- and medium-intensity groups, the high-intensity group was less stable (p < 0.001) with a larger hip descent (p < 0.001) and a longer belt distance (p < 0.001) at the recovery step liftoff. The results suggest that the increased perturbation intensity raises the risk of falling with larger instability and poorer reactive performance after a support surface translation-induced perturbation in healthy young adults. The findings could furnish preliminary guidance for us to design and select the optimal perturbation intensity that can maximize the effects of perturbation-based training protocols.

Hamstrings-quadriceps strength ratio could be related to falls in community-living older adults.

A prior study reported that the concentric strength imbalance between hamstrings and quadriceps is associated with falls in older adults. Given that the concentric strength may not be measured as conveniently as the isometric strength, it is meaningful to test whether the isometric hamstring-quadricep strength imbalance is related to falls among older adults. This study sought to explore whether the hamstrings-quadriceps ratio could differentiate fallers from non-fallers in community-dwelling older adults. One hundred and eleven older adults were included in this cross-sectional study. Their isometric knee joint strength capacity (extensors and flexors) was measured. Based on their fall history in the past year, they were classified as fallers (at least one fall) or non-fallers (no fall). The hamstrings-quadriceps ratio was compared between the faller and non-faller groups. The receiver operating characteristic analysis was used to determine the cutoff value of the hamstrings-quadriceps ratio able to best classify fallers and non-fallers. Fallers showed a significantly lower hamstrings-quadriceps ratio than non-fallers (p = 0.008). The receiver operating characteristic analysis identified 0.733 as the best ratio to differentiate fallers from non-fallers with an accuracy of 64.0 %. A 0.1-unit reduction in the hamstrings-quadriceps ratio increases the probability of falling by a factor of 1.30. The hamstrings-quadriceps ratio could be used as an additional fall risk factor when assessing the risk of falls among older adults. A smaller than 0.733 hamstring-quadriceps ratio may indicate a high risk of falls.

Dynamic gait stability in people with mild to moderate Parkinson's disease.

BACKGROUND: Falls are a serious health threat for people with Parkinson's disease. Dynamic gait stability has been associated with fall risk. Developing effective fall prevention interventions requires a sound understanding of how Parkinson's disease affects dynamic gait stability. This study compared dynamic gait stability within the Feasible Stability Region framework between people with and without Parkinson's disease during level walking at a self-selected speed. METHODS: Twenty adults with Parkinson's disease and twenty age- and gender-matched healthy individuals were recruited. Dynamic gait stability at two gait instants: touchdown and liftoff, was assessed as the primary outcome measurement. Spatiotemporal gait parameters, including stance phase duration, step length, gait speed, and cadence were determined as explanatory variables. FINDINGS: People with Parkinson's disease walked more slowly (p < 0.001) with a shorter step (p = 0.05), and prolonged stance phase (p = 0.04) than their healthy peers with moderate to large effect sizes. Dynamic gait stability did not show any group-associated differences (p > 0.36). INTERPRETATION: Despite the different gait parameters between groups, people with Parkinson's disease exhibited similar dynamic gait stability to their healthy counterparts. To compensate for the potential dynamic gait stability deficit resulting from slow gait speed, individuals with Parkinson's disease adopted a short step length to shift the center of mass motion state closer to the Feasible Stability Region. Our findings could provide insight into the impact of Parkinson's disease on the control of dynamic gait stability.

Do dance style and intervention duration matter in improving balance among people with Parkinson's disease? A systematic review with meta-analysis.

INTRODUCTION: Impaired balance is a common symptom that increases fall risk in people with Parkinson's disease (PwPD). Although previous meta-analyses concluded that dance-based interventions could improve balance in PwPD, they have limitations, such as small samples and low rigor. Another overlooked issue is whether the effects of dance-based interventions depend on dance style and training duration. The primary purpose of this meta-analysis was to further examine the efficacy of dance-based interventions in improving balance in PwPD. The secondary goals were to compare the intervention efficacy of different dance styles and durations. METHODS: Fourteen randomized controlled trials (RCT) examining the effect of dance-based treatment on improving balance among 612 PwPD were included. Effect size (ES) was calculated as the standardized mean difference. Meta-analyses (one primary analysis and three subgroup analyses) were completed using random-effects models. RESULTS: Results showed a medium overall ES of 0.57 (95% confidence interval or CI: [0.29,0.84], p < 0.0001) in favor of dance versus control on improving balance in PwPD. The subgroup analysis of six dance styles revealed various ES ranging 0.40-2.00. Balance was significantly improved with dance compared to control group for 12+ week interventions (ES = 0.72, 95%CI: [0.37,1.08], p < 0.0001). Interventions with 60- and 90-min classes produced similar ES for improving PwPD's balance (60-min ES = 0.54; 90-min ES = 0.68). CONCLUSION: Dance-based interventions (particularly of 12+ weeks) could effectively improve balance among PwPD. More high-quality RCT are needed to determine the most beneficial dance styles and session lengths. These findings could inform future studies for designing/deploying effective dance-based balance training and fall prevention programs for PwPD.

Adaptation to repeated standing-slips in professional ballet dancers.

Ballet training is being increasingly used to improve physical functions in older adults. Our previous work showed that ballet dancers react to a novel standing-slip more effectively than their non-dancer counterparts through better control of the recovery step and trunk movement. The purpose of this study was to test if and to what extent ballet dancers adapt differently to repeated standing-slips relative to non-dancers. Protected by a harness, twenty young adults (10 professional ballet dancers and 10 age/sex-matched non-dancers) experienced five repeated and standardized standing-slips on a treadmill. Changes from the first slip (S1) to the fifth slip (S5) in dynamic gait stability (primary outcome) and other variables, including the center of mass position and velocity, step latency, slip distance, ankle angle, and trunk angle (secondary outcomes) were compared between groups. Results revealed that both groups adopted similar proactive controls to improve dynamic gait stability by using the ankle and hip strategies. However, dancers showed a better reactive improvement in stability after the repeated slips than non-dancers. From S1 to S5, dancers reactively improved their dynamic gait stability more than non-dancers at the recovery step liftoff (p = 0.003). Dancers decreased their recovery step latency (p = 0.004) and shortened the slip distance (p = 0.004) significantly more than non-dancers from S1 to S5. These findings suggest that ballet dancers could facilitate the adaptation to repeated slips, which may be attributed to their ballet practice experience. This finding augments our understanding of the underlying mechanisms of ballet practice reducing falls.

A systematic review of perturbation-based balance training on reducing fall risk among individuals with stroke.

BACKGROUND: Perturbation-based balance training has been proven effective to reduce falls in older adults. However, it remains inconclusive if this training paradigm reduces falls in the stroke population. This review sought to summarize the existing literature to assess the effects of perturbation-based balance training on falls and some common fall risk factors in people with stroke. METHODS: Seven databases were searched for studies, which included at least one perturbation-based balance training group and a control group. The primary outcome was the proportion of fallers, and the secondary outcomes encompassed commonly used fall risk factors: balance, balance confidence, reactive stepping characteristics, functional mobility, and muscle strength. FINDINGS: This review included nine studies that enrolled 364 participants. The training protocols were significantly heterogeneous among studies, with variations in the training duration, number of sessions, session length, and type of devices used. The results indicated insufficient evidence supporting that perturbation-based balance training reduces falls in the laboratory and everyday living conditions for people with stroke. Furthermore, the effects of perturbation-based balance training on fall risk factors are also inconsistent between studies. INTERPRETATION: The existing evidence does not conclusively support the reduction in falls and improvements in fall risk factors resulting from perturbation-based balance training among people with stroke. Such an inconsistent finding could be due to the small sample sizes and variations in perturbation-based balance training protocols across studies. More high-quality studies are needed to further determine the effects of perturbation-based balance training on reducing fall risk in people with stroke.

Muscle power is more important than strength in preventing falls in community-dwelling older adults.

The primary purpose of this study was to determine whether muscle strength or power is a better predictor of fallers (including both single and recurrent) in everyday living conditions among community-dwelling older adults. Secondly, we identified the optimal threshold of the identified fall predictors to best differentiate fallers from non-fallers. Ninety-four healthy older adults (72.0 ± 5.5 years) participated in the study. After reporting retrospective falls from the past year, participants were assessed for isometric strength capacities of the knee extensors and flexors. Lower limb power performance was calculated based on the time used to complete the five times sit-to-stand (STS) test. Fifty-six participants (59.6%) reported not falling, and 38 participants (40.4%) reported one or more falls in the past year. No significant differences were found between non-fallers and fallers for knee extensor (p = 0.729) and flexor (p = 0.157) strength capabilities. Non-fallers took significantly less time to complete the STS test (p = 0.010) and demonstrated more leg muscle power (p = 0.016) than fallers. The overall accuracy of classifying fallers and non-fallers was 63.8% and 64.9% for leg muscle power and the STS duration, respectively. The leg power and STS duration optimal cutoff values to discriminate fallers and non-fallers were determined as 1.3 W/(kg × m) and 12 s. Results suggest that STS leg muscle power is more predictive of everyday living falls than strength in community-dwelling older adults. Findings provide valuable information to assist with screening high fall risk older adults and develop muscle power training-based interventions to prevent falls in this population.

Effects of anterior load carriage on gait parameters: A systematic review with meta-analysis.

Anterior load carriage is common in occupational work and daily activities. Our primary purpose was to systematically review previous work concerning the biomechanics of walking with anterior load carriage. A secondary goal was to conduct a meta-analysis on common gait parameters relevant to front load carriage. An electronic database search yielded eight qualified articles. Meta-analyses were performed for four gait variables: stride length, heel contact velocity, required coefficient of friction, double support time. When possible, subgroup analyses by age were conducted. Results suggest that walking with front load carriage may shorten the stride length, particularly among young adults, but has small effects on the other three variables. Findings should be interpreted with caution given the limited number of studies included and small sample size per study. Future work investigating these four variables and others is needed to further our understanding of the impact of front load carriage on gait.

Effects of anteriorly-loaded treadmill walking on dynamic gait stability in young adults.

BACKGROUND: Anteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body's center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk. RESEARCH QUESTION: How does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking? METHODS: In this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found. RESULTS: No significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η2 = 0.114) and liftoff (p = 0.122, η2 = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η2 = 0.648) and liftoff (p < 0.001, η2 = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η2 = 0.076). SIGNIFICANCE: Carrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.

Effects of anterior load carriage on dynamic gait stability during level overground walking.

Anterior load carriage, identified as a fall risk factor, is commonly required in daily living activities and occupations. Dynamic gait stability quantifies the kinematic relationship between the human body's center of mass and base of support and has been widely used to assess fall risk. The current study was conducted as a portion of a larger project exploring the effects of anterior load carriage on the control of body stability during various walking conditions. Particularly, this study examined the effect of anterior load carriage on dynamic gait stability during level overground walking among young adults. It was hypothesized that anterior load carriage would compromise dynamic gait stability during walking. Thirty young adults were evenly randomized into three groups: no load (Group 1), 10% body mass (bm) (Group 2), and 20% bm (Group 3). Each group walked overground at a self-selected speed carrying the assigned load. Kinematics were collected for the body and load through motion capture. Dynamic gait stability, gait speed, step length, and trunk angle were determined based on the kinematics and compared between groups. The results did not detect significant load-related effects on dynamic gait stability, step length, or gait speed. A significant load-related difference was found in trunk angle: the heavier the load, the more backward leaned trunk. Further analyses revealed a more posteriorly-leaned trunk in Groups 2 and 3 than Group 1 and in Group 3 than Group 2. The results indicated that young adults could maintain dynamic gait stability when carrying a front load by leaning the trunk backward but keeping other gait parameters unchanged.

Recovery from an unexpected standing-slip in professional ballet dancers.

Although interventional studies have suggested that dance-based training may reduce fall risk for older adults based on unperturbed assessments, it remains unknown whether dance (particularly ballet) enhances recovery from an external perturbation. This preliminary study sought to test if and how ballet dancers respond differently to a novel standing-slip perturbation relative to non-dancers. Ten young professional ballet dancers and 10 age/sex-matched non-dancers were exposed to an unannounced slip while standing on the treadmill. Their reactions to the slip, characterized by dynamic gait stability (primary outcome), and the recovery stepping and trunk movements (secondary outcomes), were compared between groups. No significant group difference in dynamic gait stability was found at slip onset and recovery step liftoff, but dancers were more stable than non-dancers at touchdown (p = 0.046). Compared to non-dancers, dancers took a longer (p = 0.049) and faster (p = 0.007) backward recovery step and exhibited a less backward leaned trunk at all instants (p ≤ 0.026). Our study suggests that professional ballet dancers are more stable after a novel standing-slip than non-dancers. This better slip-related fall resistance among dancers could result from their more effective recovery stepping strategy and better trunk movement control after the slip. Both reactions may be attributed to ballet training, which requires frequent backward stepping and an upright trunk. Our findings could potentially provide preliminary evidence for applying ballet training to reduce balance losses and falls in people at a high fall risk. More studies are needed to examine ballet training's effects among other populations with elevated fall risk in real-life situations.