Background: Falls are one of the major causes of injury in the elderly. Obesity may be related to the risk of falling. Understanding the dynamic stability mechanisms of obese elderly people during gait is important as it may be associated with fall protection.
Research question: Does obesity affect the dynamic walking stability of elderly people?
Methods: This is a prospective study. Fifty-three elderly participants, aged 60-82 years, were categorized into body mass index (BMI) groups. In single-limb support experiments, the center of mass velocity (COMv), center of mass acceleration (COMa), region of velocity stability (ROSv) and region of acceleration stability (ROSa) were calculated using kinematic data sampled from a motion analysis system. In addition, all participants were assessed for the dynamic balance ability test scale (DBATS). Statistical analyses were performed by one-way ANOVA, Kruskal-Wallis/Wilcoxon nonparametric tests, or bivariate Pearson/Spearman correlation analysis.
Results: During walking, peak COMv and COMa decreased with increasing BMI (Normal BMI: 1.20 ± 0.14 m/s, 1.66 ± 0.36 m/s2; High BMI: 1.14 ± 0.11 m/s, 1.56 ± 0.30 m/s2; Higher BMI: 1.04 ± 0.15 m/s, 1.47 ± 0.25 m/s2). At toe-off (TO), the normalized participants' center of mass (COM) is significantly more anterior in the Higher BMI group (Normal BMI: -0.30 ± 0.09, High BMI: -0.23 ± 0.07, Higher BMI: -0.16 ± 0.10), their normalized COMv and COMa (Normal BMI: 1.40 ± 0.16, 0.53 ± 0.11; High BMI: 1.33 ± 0.13, 0.49 ± 0.11; Higher BMI: 1.21 ± 0.16, 0.46 ± 0.11) are slower. The mean DBATS score of the Higher BMI group was the highest, indicating the weakest dynamic balance ability.
Significance: The COM dynamic stability parameters indicate that obesity may worsen balance, with the peak COMv and ROSv most affected. With increasing BMI, the dynamic stability and balance of elderly people both decreased.
Keywords: Body mass index; Center of mass; Gait; Postural balance.
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