Stride dynamics, gait variability and prospective falls risk in active community dwelling older women
Introduction
Research suggests that measures of gait instability, such as stride dynamics and variability, can identify older adult fallers who already display signs of frailty or a clinical disorder [1], [2]. However no research has investigated whether these measures can prospectively identify falls in active older adults. This information may guide interventions to reduce falls risk and associated morbidity in an otherwise healthy population.
Stride dynamics measure change in the underlying structure of stride fluctuations over time. During walking, long range correlations have been found in stride time fluctuations of healthy adults [3], [4], and these correlations have been shown to break down in healthy ageing [5]. To date, only one retrospective study has investigated stride dynamics in older adult fallers, albeit using a clinical population [1]. As such, it is unknown if age-related alterations in dynamic coordination decrease gait stability and increase falls risk in healthy older adults. Additionally, of the two studies to investigate age-related alterations in stride dynamics, only data recorded from one limb were analyzed [1], [5], despite evidence that inter-limb temporal control is altered in older fallers [6], [7]. Therefore, further investigation of the influence of inter-limb dynamics on falls is warranted.
Gait variability quantifies the magnitude of stride fluctuations during walking. Although the etiology of increased variability is yet to be determined, it has been associated with a range of central and peripheral pathologies (e.g. [5], [8], [9], [10], [11]). These increased fluctuations may indicate instability, and potentially predispose older adults to falls from a trip or mis-step. Indeed, increased variability in many common gait parameters has been shown to predict falls in older adults [2], [12], [13]. However, these prospective studies examined adults with mobility limitations such as requiring gait aids. Therefore, the ability of gait variability to predict falls in more active older adults remains unknown.
Measures of stride dynamics and gait variability may be markers of early falls risk. Investigating these measures in active older adults is valuable since there is potential to prevent early falls and avoid subsequent activity curtailment, morbidity and institutionalization in an otherwise healthy individual. To date, few studies have investigated falls risk in active older adults, and measures of gait instability are yet to be explored in this population. The aim of this study was to determine whether measures of inter and intra limb stride dynamics and gait variability differ between active older fallers and non-fallers, and whether these measures are able to predict falls in this population.
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Participants
One hundred and eight women volunteers (55–90 years) were recruited through information letters sent to community groups. The lower age of 55 years was chosen as alterations in common gait parameters has been shown for women aged 50–59 years [14]. Women were chosen because of a higher incidence of falls and fall-related morbidity in this population [15]. Eligibility for the study included the ability to walk unassisted for 10 min and current participation in at least 30 min of exercise on one or
Results
Fifty-four participants (55.7%) reported at least one fall; 25 (25.8%) fell once and 29 (29.9%) fell more than once. Outdoor falls away from home were most prevalent (50.4%) with the majority of fallers reporting no injury (46.1%). The most common injury was a bruise (28.4%), cut or graze (14.9%), with 3.6% of falls resulting in a fractured bone.
Demographic information and spatiotemporal gait data for fallers and non-fallers are listed in Table 1, Table 2. No significant differences between
Discussion
This is the first known prospective study to explore stride dynamics and gait variability in active older adult fallers and non-fallers. Significant differences were found between the left and right fractal scaling index values in active community dwelling adults aged over 55 years who experienced two or more falls (multiple fallers) and in active adults aged over 70 years who experienced one or more falls (fallers). Effect sizes were moderate to large suggesting the differences are clinically
Conclusions
A measure of stride dynamics (the fractal scaling index) was significantly more asymmetrical in active older women aged over 70 years who fell one or more times, and in women aged over 55 years who fell two or more times during a prospective 12 month period. Other gait measures, including gait variability, and measures of physical function and balance did not differ between groups. These findings suggest that alterations in inter-limb dynamics could be a sensitive marker of reduced stability
Acknowledgements
The authors would like to sincerely thank all the women who kindly volunteered to participate in this study, and in particular, Heather Chapman from the Yarra City Living Longer Living Stronger program for her generous assistance with recruitment. This work was supported by a grant from the Centre of Physical Activity Across the Lifespan, School of Exercise Science, Australian Catholic University.
Conflict of interest statement
The authors declare that there are no conflicts of interest.
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