Self-Monitoring of Balance Performance can Reduce the Rate of Falls Among Older Adults.

Background: 29% of older adults fall annually, resulting in the leading cause of accidental death. Fall prevention programs typically include exercise training and self-monitoring of physical activity has a positive effect on the self-efficacy and self-regulation of exercise behaviors. We assessed if self-monitoring of fall risk, without an intervention, impacts fall rates. Methods: Fifty-three older adults had open access to a balance measuring platform which allowed them to self-monitor their postural stability and fall risk using a simple 1-min standing balance test. 12-month retrospective fall history was collected and a monthly/bimonthly fall log captured prospective falls. Participants had access to self-monitoring for up to 2.2 years. Fall history and fall incidence rate ratios and their confidence intervals were compared between the periods of time with and without access to self-monitoring. Results: A 54% reduction in the number of people who fell and a 74% reduction in the number of falls was observed when participants were able to self-monitor their postural stability and fall risk, after normalizing for participation length. Further, 42.9% of individuals identified as having high fall risk at baseline shifted to a lower risk category at a median 34 days and voluntarily measured themselves for a longer period of time. Discussion: We attribute this reduction in falls to changes in health behaviors achieved through empowerment from improved self-efficacy and self-regulation. Providing older adults with the ability to self-monitor their postural stability and intuit their risk of falling appears to have modified their health behaviors to successfully reduce fall rates.

A Postural Assessment Utilizing Machine Learning Prospectively Identifies Older Adults at a High Risk of Falling.

Introduction: Falls are the leading cause of accidental death in older adults. Each year, 28.7% of US adults over 65 years experience a fall resulting in over 300,000 hip fractures and $50 billion in medical costs. Annual fall risk assessments have become part of the standard care plan for older adults. However, the effectiveness of these assessments in identifying at-risk individuals remains limited. This study characterizes the performance of a commercially available, automated method, for assessing fall risk using machine learning. Methods: Participants (N = 209) were recruited from eight senior living facilities and from adults living in the community (five local community centers in Houston, TX) to participate in a 12-month retrospective and a 12-month prospective cohort study. Upon enrollment, each participant stood for 60 s, with eyes open, on a commercial balance measurement platform which uses force-plate technology to capture center-of-pressure (60 Hz frequency). Linear and non-linear components of the center-of-pressure were analyzed using a machine-learning algorithm resulting in a postural stability (PS) score (range 1-10). A higher PS score indicated greater stability. Participants were contacted monthly for a year to track fall events and determine fall circumstances. Reliability among repeated trials, past and future fall prediction, as well as survival analyses, were assessed. Results: Measurement reliability was found to be high (ICC(2,1) [95% CI]=0.78 [0.76-0.81]). Individuals in the high-risk range (1-3) were three times more likely to fall within a year than those in low-risk (7-10). They were also an order of magnitude more likely (12/104 vs. 1/105) to suffer a spontaneous fall i.e., a fall where no cause was self-reported. Survival analyses suggests a fall event within 9 months (median) for high risk individuals. Conclusions: We demonstrate that an easy-to-use, automated method for assessing fall risk can reliably predict falls a year in advance. Objective identification of at-risk patients will aid clinicians in providing individualized fall prevention care.

Plantar stimulation as a possible countermeasure to microgravity-induced neuromotor degradation.

Since the early days of human spaceflight it has been reported that extended exposure to gravitational unloading results in a myriad of neuromotor adaptations that, while appropriate for microgravity, are maladaptive upon return to Earth. If not countered, these adverse effects of microgravity can result in negative health consequences and place crewmembers at risk for injury. The most commonly used countermeasures in today's space programs are those requiring active participation in prescribed exercise regimes that are time intensive, not completely effective, and have led to relatively low compliance. In this paper we review evidence that suggests a "passive" countermeasure in the form of dynamic foot stimulation (DFS) to the plantar surfaces of the feet may be a useful supplement to more traditional exercise countermeasures. This includes reports from both Russian and American investigators using both human and animal models indicating the overall effectiveness of DFS, the specific stimulation parameters involved, and a physiological explanation for the outcomes associated with the exposure to microgravity. Additionally, the use of DFS has the potential to benefit those at risk for muscle atrophy, including those experiencing extended bedrest, the elderly, and those with spinal cord injuries.

Neuromuscular responses to mechanical foot stimulation: the influence of loading and postural context.

INTRODUCTION: Recent work indicates mechanical stimulation of soles may attenuate muscle atrophy initiated by gravitational unloading, including that experienced during spaceflight. The aim of the present study was to determine the modulating effect of unloading and body configurations on the neuromuscular response to mechanical foot stimulation. METHODS: A solenoid (2.5-cm2 surface area) embedded within a platform provided non-noxious stimulation to the lateral foot sole: 100 ms duration, 3-mm protrusion. Stimulation was applied while measuring root mean square electromyography of the soleus and lateral gastrocnemius. Experiment 1 compared seated and standing conditions, as well as different levels of gravitational unloading created by suspension. Experiment 2 altered postural stability by varying leg stance widths during a static stepping posture. Either the foot of the support leg or the nonsupport leg was stimulated. Reduced levels of loading further altered the level of postural challenge and support while maintaining the same body configuration. RESULTS: In both experiments, loading was not a modulating factor to the response, supporting the use of mechanical foot pressure as a countermeasure for spaceflight. Body configuration and postural instability both modulated the response, independently of load. DISCUSSION: In conclusion, an application of dynamic foot stimulation could be used to elicit neuromuscular activity without the need of background muscle activity or gravitational loading. However, the body configuration of the user with respect to postural stability needs to be considered in the application, and may provide further scope of benefits extending to the activation of postural synergies.

Age associated differences in postural equilibrium control: a comparison between EQscore and minimum time to contact (TTC(min)).

Increased postural instability and the subsequent elevation in fall incidence with increasing age are important contributors for hip fractures and developing frailty. When testing for such instability, most studies characterize balance in terms of center-of-mass (COM) deviation from a finite point, the "equilibrium point", located at the center of a subject's stance. For example, the clinically accepted equilibrium score (EQscore) represents instability as the maximum peak-to-peak sway about the "equilibrium point". An alternative theory views balance as being controlled within a "stability margin" in which all corrective actions are based on the time to contact (TTC) of the body's COM with that margin. This study examines the differences offered by evaluating balance control using the EQscore and TTC approach across several age groups and sessions. Consenting subjects from the Baltimore Longitudinal Study of Aging were recruited (N=155) from each age decade (20s-80s) who were generally healthy and free from neurological diagnoses. Results showed TTC tests detected significant variations in eyes open versus eyes closed testing that were unpredictable by EQscore. Further, TTC produced differences in age-related stability threats not seen using EQscore. The TTC data also provided a discriminating difference between subjects who fell in the difficult tests and those who maintained posture. Overall, these data suggest EQscore might not sufficiently account for dynamic control components the body may be using to maintain balance. TTC may offer a more accurate estimate of postural stability (functional ability) than EQscore based on its inclusion of a velocity component to detect dynamic changes.

Spatial factors and muscle spindle input influence the generation of neuromuscular responses to stimulation of the human foot.

Removal of the mechanical pressure gradient on the soles leads to physiological adaptations that ultimately result in neuromotor degradation during spaceflight. We propose that mechanical stimulation of the soles serves to partially restore the afference associated with bipedal loading and assists in attenuating the negative neuromotor consequences of spaceflight. A dynamic foot stimulus device was used to stimulate the soles in a variety of conditions with different stimulation locations, stimulation patterns and muscle spindle input. Surface electromyography revealed the lateral side of the sole elicited the greatest neuromuscular response in ankle musculature, followed by the medial side, then the heel. These responses were modified by preceding stimulation. Neuromuscular responses were also influenced by the level of muscle spindle input. These results provide important information that can be used to guide the development of a "passive" countermeasure that relies on sole stimulation and can supplement existing exercise protocols during spaceflight.

Voluntary neuromuscular activation is enhanced when paired with a mechanical stimulus to human plantar soles.

The purpose of this investigation was to determine if the location and the timing relative to muscle activation onset, of a mechanical stimulus applied to the soles impacted the neuromuscular activation associated with a voluntary movement. The subjects completed a series of dorsiflexion or plantarflexion movements during which a stimulus was applied to either the heel or ball of the foot at one of three time periods relative to the initiation of the agonist muscle. Surface electromyography from the tibialis anterior and soleus was collected during the movements. The results show that if the stimulus was applied shortly before agonist muscle activation, regardless of stimulation site, the neuromuscular activity associated with the movement was greatly increased.

Estimating functional stability boundaries for bipedal stance.

We propose a technique to estimate functional limits of stability (LOS) during bipedal stance using a controlled, low speed, voluntary leaning protocol requiring feet to remain in contact with the ground. LOS are estimated from ellipses fit to center-of-mass position data obtained during the leaning protocol. The LOS of nine healthy subjects were found to be 20-59% closer to the center of stance than the more frequently used anatomical boundaries and were reduced by closing the eyes. We conclude that functional stability boundaries should be used when the outcome measure is related to fall risk.