Curved-Path Walking: When Variability Is Good

Abstract

Gait dysfunction in aging patients is often multi-factorial and unfortunately, ankle strength is infrequently measured. In our Balance Center we evaluated 13 females and 15 males, mean age 79.6 years, range 62-99. All had co-morbidities but primarily balance dysfunction, unsteady gait and some falls. Dysmobility and loss of balance can occur in any direction. The ankle contacts the ground first and gives critical proprioceptive and kinesthetic sensory information. Dorsiflexion (DF), Plantar Flexion (PF), Eversion (EV) and Inversion (IN) muscle strength was measured with a hand-held dynamometer and calculated as a percentage of body weight.The purpose of this study was to compare ankle strength in the patients with a control group without gait dysfunction which included 6 females and 4 males, mean age 75.3 years.The percentage of DF/PF strength was statistically significantly less in the patients, 13.4% versus 28.7%. The percentage of EV/IN was also statistically significantly less in the patients 13.2% versus 4.5%. Our patients with gait dysfunction were slightly more than 2 times weaker for DF/PF and almost 3 times weaker in EV/IN compared to controls.For EV/IN, 29% of the patients, but no control subjects, generated less than 5 pounds of force. Clinically, this mediolateral weakness appeared to be a motor control problem because many of the patients did not know how to evert or invert the ankle and they lacked the kinesthesia.In conclusion, our results indicate ankle weakness especially in the medio-lateral directions may be a factor in gait/ balance dysfunction and falls. Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada Recently, an emerging body of literature has indicated a strong association between poor gait speed and mortality. However, these studies have several methodological limitations. Based on secondary analysis of data from existing longitudinal studies of aging, they generally measure gait speed at a single time point and use this time point as the time origin in assessing the association between gait speed and survival over several years. The objective of this study is to estimate the association between gait speed and mortality, using a meaningful time axis, and accounting for the time-varying effects of other health characteristics. The study is based on data from the Cardiovascular Health Study, a study of 5,201 individuals aged 65 years and over, with annual measurements of gait speed and several covariates over a period of 10 years. Using age rather than time-on-study as the timeaxis, I apply a time-varying Cox model to estimate the independent effects of gait speed on morality, while accounting for the effects of health characteristics, including depression, cognitive function, and chronic disease. For comparison, I provide estimates of models where variables are treated as time-fixed. Overall, I found that the time-varying measure of gait speed yields a stronger association with mortality compared to the time-fixed measure. Furthermore, ...