The walk ratio: Investigation of invariance across walking conditions and gender in community-dwelling older people.

Background: The step length-cadence ratio, also called the walk ratio (WR; cm/steps/min) is a measure of cautious gait, poor balance control or impaired gait, but has not been investigated for both genders in a general population of older adults across different speeds and conditions.

Method: The participants were community-dwelling volunteers between 70 and 81 years. They walked 6.5 m under four different conditions: At preferred speed, fast speed, during a dual task condition and on an uneven surface. Step length (cm) and cadence (steps/minute) was captured using a body-worn sensor. Both cadence and step lengths were adjusted for body height.

Results: 70 older adults participated (mean age 75.5 (SD 3.4), 60 percent women). The WR was 0.60 cm/steps/min (SD 0.07) during preferred speed walking, 0.58 cm/steps/min (SD 0.07) during fast walking, 0.68 cm/steps/min (SD 0.18) during dual task-walking and 0.59 cm/steps/min (0.07) during uneven surface-walking. In planned pairwise comparisons, the WR during dual task was significantly different from preferred speed walking (mean difference -0.087 cm/steps/min, 95% CI -0.140, -0.033), from fast speed walking (mean difference -0.098 cm/steps/min, 95% CI -0.154, -0.041) and uneven surface walking (mean difference 0.092 cm/steps/min, 95% CI 0.040, 0.145). There were no gender differences except during the fast walking condition, where women had a significantly lower WR than the men (0.56 cm/steps/min vs 0.61 cm/steps/min, p = 0.002).

Discussion: We found that the WR is invariant during different speeds, and during an uneven surface condition, but is affected during a dual task-condition, when attention must be divided between a cognitive and a motor task.