Effects of obesity on dynamic stability control during recovery from a treadmill-induced slip among young adults

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.

Multimorbidity patterns and the risk of falls among older adults: a community-based study in China

BACKGROUND

Due to the high prevalence of multimorbidity and realistic health service demands for fall prevention, there is growing interest in the association between multimorbidity and falls. Our study aimed to identify multimorbidity patterns among Chinese older adults and explore the association between multimorbidity patterns and falls.

METHODS

Data from 4,579 Chinese community-dwelling older adults was included in this analysis. Information regarding falls and 10 chronic conditions was collected. An exploratory factor analysis was performed to determine multimorbidity patterns. Regression models were fitted to explore the associations of individual chronic disease or multimorbidity patterns with falls.

RESULTS

Among 4,579 participants, 368 (8.0%) were defined as fallers, including 92 (2.0%) frequent fallers, and multimorbidity affected 2,503 (54.7%) participants. Older adults with multimorbidity were more likely to be fallers [odds ratio (OR) = 1.3, P = 0.02] and frequent fallers (OR = 1.7, P = 0.04). Three multimorbidity patterns were identified (i.e., cardiovascular-metabolic diseases, psycho-cognitive diseases and organic diseases), and the associations between psycho-cognitive diseases/organic diseases and prevalent falls or frequent falls were found to be significant.

CONCLUSIONS

The psycho-cognitive disease pattern and organic disease pattern are significantly associated with falls. Therefore, more attention should be paid to patients with psycho-cognitive diseases and timely, targeted diagnostic and treatment services should be provided in fall prevention.

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.

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.

Technological Solutions for Human Movement Analysis in Obese Subjects: A Systematic Review

Obesity has a critical impact on musculoskeletal systems, and excessive weight directly affects the ability of subjects to realize movements. It is important to monitor the activities of obese subjects, their functional limitations, and the overall risks related to specific motor tasks. From this perspective, this systematic review identified and summarized the main technologies specifically used to acquire and quantify movements in scientific studies involving obese subjects. The search for articles was carried out on electronic databases, i.e., PubMed, Scopus, and Web of Science. We included observational studies performed on adult obese subjects whenever reporting quantitative information concerning their movement. The articles must have been written in English, published after 2010, and concerned subjects who were primarily diagnosed with obesity, thus excluding confounding diseases. Marker-based optoelectronic stereophotogrammetric systems resulted to be the most adopted solution for movement analysis focused on obesity; indeed, wearable technologies based on magneto-inertial measurement units (MIMUs) were recently adopted for analyzing obese subjects. Further, these systems are usually integrated with force platforms, so as to have information about the ground reaction forces. However, few studies specifically reported the reliability and limitations of these approaches due to soft tissue artifacts and crosstalk, which turned out to be the most relevant problems to deal with in this context. In this perspective, in spite of their inherent limitations, medical imaging techniques-such as Magnetic Resonance Imaging (MRI) and biplane radiography-should be used to improve the accuracy of biomechanical evaluations in obese people, and to systematically validate less-invasive approaches.

Vibration training reducing falls in community-living older adults: a pilot randomized controlled trial

BACKGROUND

Although vibration training has been applied in older adults, it remains unclear if it can reduce falls.

AIMS

This pilot randomized-controlled trial aimed to test the effects of an 8-week vibration training program on reducing falls among community-dwelling adults.

METHODS

Forty-eight older adults were randomized to two groups: training and control. The training group received three weekly training sessions over eight weeks while the control group maintained their normal lifestyle over the 8-week period. Immediately before (or baseline), following (post-training), and three months after (retest) the 8-week training course, a group of fall risk factors were assessed for all participants. Each participant was also exposed to an unexpected gait-slip on a treadmill during post-training and retest sessions. Their daily-living fall incidence was collected for 12 months after the baseline test. The slip fall was the primary outcome, prospective all-cause falls were the secondary outcome, and fall risk factors acted as the tertiary ones.

RESULTS

The vibration training program significantly reduced the risk of slip-falls and improved all fall risk factors immediately after the training course. The training effect may be carried over for three months. The 8-week training program could also lower the number of falls between the baseline test and retest and reduce the recurrent faller rate across the 12 months after the baseline test.

DISCUSSION

This study indicates that vibration training might have some effects on fall-related measures in older adults.

CONCLUSIONS

An 8-week vibration training program could be effective to reduce falls in older adults.

CLINICALTRIALS

GOV REGISTRATION NUMBER

NCT02694666.

Are multimorbidity patterns associated with fear of falling in community-dwelling older adults?

Background

Multimorbidity is defined as the co-occurrence of multiple chronic or acute diseases and medical conditions in the same individual and can be grouped into different patterns based on the type of disease. These patterns are associated with poorer quality of life and premature death. It is believed that these patterns entail functional limitations, which may contribute to the fear of falling; however, this association remains unknown. Identifying this possible association is fundamental for developing individual and collective care approaches aimed at preventing the different patterns of chronic diseases in older adults in order to decrease the fear of falling. The objective of this study was to investigate the association between multimorbidity patterns and fear of falling in older adults.

Methods

This was a cross-sectional study including 308 older adults. The exposure variables were the presence of three multimorbidity patterns (cardiopulmonary, musculoskeletal, and vascular-metabolic) and pattern association assessed by self-report of two or more similar coexisting chronic diseases. The outcome was fear of falling assessed by the Brazilian version of Falls Efficacy Scale-International (cut-off point ≥ 23 points). Multivariable logistic regression was used to analyze the association between variables.

Results

Older adults with cardiopulmonary, musculoskeletal, vascular-metabolic patterns and pattern association had 3.49 (95%CI 1.13; 10.78), 2.03 (95%CI 1.13; 3.64), 2.14 (95%CI 1.20; 3.82), and 4.84 (95%CI 2.19; 10.68), respectively, greater chances of presenting fear of falling when compared to older adults without the patterns.

Conclusions

The presence of multimorbidity patterns is associated with higher chances of reporting fear of falling. It is emphasized that the introduction of public health programs aimed at preventing multimorbidity patterns is essential to reduce possible adverse health outcomes, including fear of falling and its negative consequences for older adult health.

Preferred Limb Reaction, Swing and Recovery Step Times between Subjects with and without Chronic Low Back Pain

A compensatory stepping strategy following repeated perturbations may compromise dynamic balance and postural stability. However, there is a lack of study on preferred limb reaction, swing, and step time adjustments. The purpose of this study was to investigate limb reaction, swing, and recovery step times following repeated trip perturbations in individuals with and without non-specific chronic low back pain (LBP). There were 30 subjects with LBP and 50 control subjects who participated in the study. The limb reaction, swing, and recovery step times (s) were measured following treadmill-induced random repeated perturbations (0.12 m/s velocity for 62.5 cm displacement), which caused subjects to move forward for 4.90 s. Both groups demonstrated a significant interaction of repetitions and times (F = 4.39, p = 0.03). Specifically, the recovery step time was significantly shorter in the LBP group during the first trip (t = 2.23, p = 0.03). There was a significant interaction on repetitions and times (F = 6.03, p = 0.02) in the LBP group, and the times were significantly different (F = 45.04, p = 0.001). The initial limb reaction time of the LBP group was significantly correlated with three repeated swing times to avoid falls. The novelty of the first trip tends to enhance a protective strategy implemented by the LBP group. Although limb preference did not demonstrate a significant difference between groups, the LBP group demonstrated shorter recovery step times on their preferred limb initially in order to implement an adaptive strategy to avoid fall injuries following repeated perturbations.

Fall Prevalence and Contributors to the Likelihood of Falling in Persons With Upper Limb Loss

BACKGROUND

Arms are important for locomotor stability and preventing falls by controlling whole-body angular momentum, redirecting the body's center of mass, and providing support to arrest descent. Hence, upper limb loss (ULL) can increase fall risk. However, the prevalence of falls and factors that influence fall risk have not previously been reported for people with ULL.

OBJECTIVE

This study quantified fall prevalence in persons with ULL at or proximal to the wrist and identified clinical factors that contributed to the likelihood of falling.

DESIGN

This was a cross-sectional study.

METHODS

Factors including body and health characteristics, activity level, fall history, prosthesis use, and balance confidence were determined for persons with ULL proximal to the wrist using an online survey. Logistic regression analyses assessed the contribution of these factors to the classification of fallers (≥2 falls in previous year) and nonfallers.

RESULTS

A percentage (28.6%) of participants (n = 105) reported experiencing 2 or more falls in the past year. The regression model (R2 = 0.473) correctly classified 84.5% of cases and indicated that increased likelihood of falling was significantly influenced by reduced balance confidence, use of upper limb prostheses, and reduced physical capabilities.

LIMITATIONS

Data were collected online from a convenience sample, and fall classification was based on retrospective data.

CONCLUSIONS

Falls in persons with ULL are prevalent, suggesting that clinicians should use screening methods to identify at-risk individuals. Balance confidence, use of upper limb prostheses, and perceived physical capabilities could be useful screening metrics. Research is warranted to better understand the factors that underlie fall risk in persons with ULL and the efficacy of therapeutic interventions capable of mitigating fall risk.

Fear of falling in obese women under 50 years of age: a cross-sectional study with exploration of the relationship with physical activity

Background

An understanding of capacity for physical activity in obese populations should help guide interventions to promote physical activity. Fear of falling is a phenomenon reported in the elderly, which is associated with reduced mobility and lower physical activity levels. However, although falls are reportedly common in obese adults, fear of falling and its relationship with activity has not been investigated in younger obese populations.

Methods

In a cross-sectional study, fear of falling was measured in 63 women aged 18 to 49 years, with mean BMI 42.1 kg/m² (SD 10.3) using the Modified Falls Efficacy (MFES), the Consequences of Falling (COF) and the Modified Survey of Activities and Fear of Falling in the Elderly (MSAFFE) scales. The choice of scales was informed by prior qualitative interviews with obese younger women. Physical activity levels were measured at the same time using the International Physical Activity Questionnaire. The mean score for fear of falling scales, with 95% confidence intervals, were estimated. Chi-square tests and t-tests were used to explore differences in age, body mass index and fear of falling scores between fallers and non-fallers. For each fear of falling scale, binomial logistic regression was used to explore its relationship with physical activity.

Results

Mean scores suggested high levels of fear of falling: MFES [mean 7.7 (SD 2.7); median 8.5]; COF [mean 31.3 (SD 9.4)]; MSAFFE [mean 25.9 (SD 8.7); median 23]. Scores were significantly worse in fallers (n = 42) compared to non-fallers (n = 21). MFES and MSAFFE were independently associated with lower levels of physical activity [odds ratio = 0.65, 95% Cl 0.44 to 0.96 and odds ratio = 1.14, 95% CI 1.01 to 1.28 respectively], when adjusted for age, BMI and depression.

Conclusions

This study confirms that fear of falling is present in obese women under 50 years of age. It suggests that it is associated with low levels of physical activity. These novel findings warrant further research to understand capacity for physical and incidental activity in obese adults in both genders and suggest innovative interventions to promote lifestyle changes and/or consideration of falls prevention in this population.

The accuracy of rapid treadmill-belt movements as a means to deliver standing postural perturbations

Treadmill-induced postural perturbations are a promising tool in assessing and reducing the risk of falls. We evaluated the accuracy with which two treadmills (Simbex ActiveStep^® and an AMTI instrumented treadmill) achieved commanded displacements, peak velocities, and average initial accelerations. To do so, we included a range of perturbation magnitudes (20, 30, and 40 cm displacements) applied in unweighted and weighted (body mass = 46-84 kg) conditions. Across treadmills and perturbation magnitudes, absolute errors in displacement (< 0.5 cm) and peak velocity (< 4 cm/s) were small (relative error < 5%). Between-treadmill differences in displacement and peak velocity were marginal (< 3%), regardless of the perturbation magnitude and participant body mass. Observed accelerations were more than 5% smaller than commanded values. The front, but not back, AMTI belt demonstrated less acceleration accuracy than the ActiveStep^® (≈ 5% difference). In summary, both treadmills demonstrated a reasonable, consistent level of accuracy in delivering postural perturbations.

Trunk sway response to consecutive slip perturbations between subjects with and without recurrent low back pain

BACKGROUND

Trunk sway responses following perturbations are critical to develop adequate prevention strategies. It is unclear how postural responses with a handheld task can validly be transferred to treadmill-induced slip perturbations in subjects with recurrent low back pain (LBP).

OBJECTIVE

To compare trunk sway angle, velocity, and reaction time following treadmill-induced perturbations while subjects with and without LBP held a tray.

DESIGN

Cross-sectional study.

METHODS

There were 30 subjects with LBP and 50 control subjects who participated in the study. Each participant stood on the treadmill while he/she held a tray to produce a functional task. Three levels of consecutive slips were introduced based on the specific duration, velocity, and displacement.

RESULTS

The trunk extension angle was significantly different (F = 4.22, p = 0.04) and demonstrated a significant interaction with groups and levels of perturbation (F = 6.83, p = 0.01). However, the reaction time was not significantly different based on the levels of perturbation (F = 0.43, p = 0.51). The LBP group increased trunk extension only at level 1 slip perturbation (t = 2.86, p = 0.005).

CONCLUSION

The increased trunk extension following the first perturbation indicated a delay in adjusting trunk stability in the LBP group. However, there was no group difference with higher magnitudes of perturbations. These results indicated that the LBP group was able to minimize trunk sway with higher perturbations following the first perturbation.