Gait plasticity impairment as an early frailty biomarker.

Background/objectives: To assess whether gait plasticity and gait reserve, valid measures of gait adaptation to environmental stressors, are associated with frailty.

Design: Cross-sectional sub-analysis of the FISTAC study (Identification of the Physical Attributes of the Fear of Falling Syndrome).

Setting: Community-dwelling women from the Falls Unit of a Geriatrics Department.

Participants: One hundred and twenty-nine women with an age ≥ 70 years old and presence of at least one previous fall in the last year.

Measures: Age, comorbidity, nutritional status, cognitive status, depression, medications, disability, fear of falling, physical function, hand grip strength, 1RM leg-press strength, maximum and mean leg-press power were determined. Frailty was assessed using the frailty phenotype criteria. Gait plasticity parameters were measured by walking at normal pace, fast pace, and slow pace, and mean (left and right) stride velocity and stride variability (SD) for the three walks were determined independently and for the sum of the three walks. Gait reserve was calculated as the difference in stride velocity from normal to fast pace. ROC curves were constructed to determine the best association between gait plasticity parameters and frailty.

Results: The mean age of the participants was 79 years (SD 8.0). The median of normal, fast, slow and three-walks pace stride velocity were 68.9 cm/s (interquartile range [IQR 33.8]), 96.1 cm/s (IQR 38.3), 51.6 cm/s (IQR 19.8), and 72.7 cm/s (IQR 20.7) respectively. The median of normal, fast, slow and three-walks pace stride variability were 4.5 cm/s (IQR 3.3), 5.4 cm/s (IQR 3.8), 3.6 cm/s (IQR 2.3) and 15.9 cm/s (IQR 16.5) respectively. The median of gait reserve was 23 cm/s (IQR 46). Gait reserve and fast pace stride velocity were associated not only with frailty, but also with a lower age, disability, depression, physical function, muscle strength and power, and fear of falling, more than gait velocity. Areas under the curve (95% CI) for gait parameters with stronger association with frailty were fast pace stride velocity 0.801 (0.723-0.880), three-walk mean stride velocity 0.761 (0.678-0.845), three-walks stride variability 0.724 (0.635-0.81) and gait reserve 0.727 (0.635-0.818).

Conclusions: Lower gait reserve and lower gait plasticity have a stronger association with frailty than gait speed in older women. Our results may support the use of these gait parameters to early identify frailty in community-dwelling older women.