Stepping With Confidence: Footwear's Positive Influence On Entropy In Senior Gait

Aging alters musculoskeletal function and movement complexity, including gait, which is essential for independence. Entropy (measured by Approximate Entropy; ApEn) is a measure of repeatability of patterns within a time series and is useful for scientists and practitioners who seek to understand movement complexity. A lower ApEn value represents better motor control and allows for more complex movements. Further, ApEn is a good predictor of muscular function and movement complexity related to motor skills competence. PURPOSE: To analyze the effect of footwear on ApEn of center of mass (COM) during a 6-minute walking test in older adults. METHODS: 20 older adults (10 females and 10 males), mean age 72 ± 7 yrs., mass 72 ± 10.2kgs., and height 163.6 ± 7.5 cm, were recruited from the Comprehensive Program for the Elderly at the University of Costa Rica. All participants signed an informed consent and completed three trials of the 6-minute walk test in three different footwear conditions: wearing flat shoes (FS), barefoot (BF), and sports shoes (SS) with 20-minute resting periods between each trial. These conditions were randomly assigned, and the participants were instructed to walk quickly. In each attempt, the participant wore an inertial measurement unit (IMU) (WIMU PRO™, Real Track Systems, Almería, Spain) with a sampling frequency of 100 Hz, located at the third lumbar vertebrae (a surrogate for COM). A one-way ANOVA was performed using R Studio 3.3.0+ (α = 0.05) to compare the differences in ApEn between the 3 footwear conditions (FS, BF and SS). Post hoc tests were conducted using Tukey's method. RESULTS: We observed a significant difference in ApEn (F = 102.91; p = 0.001) between footwear conditions. Our sample of older adults walked with a higher ApEn during BF compared to FS (t = 11.77; p = 0.001) and BF compared to SS (t = 12.99; p = 0.001). The average entropy in the COM increased by at least 0.06 m/s2 with 95% confidence when participants walked barefoot compared to flat shoes and standard shoes. CONCLUSION: Footwear affects the ApEn values in a 6-minute walk test in older adults; this means that our sample of older adults who walk barefoot have lower capabilities for complex movements (higher ApEn values). This information is useful in determining footwear selection and interventions related to fall risk while walking.