A gait abnormality measure based on root mean square of trunk acceleration

Abstract

BackgroundRoot mean square (RMS) of trunk acceleration is seen frequently in gait analysis research. However, many studies have reported that the RMS value was related to walking speed. Therefore, the relationship between the RMS value and walking speed should be considered when the RMS value is used to assess gait abnormality. We hypothesized that the RMS values in three sensing axes exhibit common proportions for healthy people if they walk at their own preferred speed and that the RMS proportions in abnormal gait deviate from the common proportions. In this study, we proposed the RMS ratio (RMSR) as a gait abnormality measure and verified its ability to discriminate abnormal gait.MethodsForty-seven healthy male subjects (24–49 years) were recruited to examine the relationship between walking speed and the RMSR. To verify its ability to discriminate abnormal gait, twenty age-matched male hemiplegic patients (30–48 years) participated as typical subjects with gait abnormality. A tri-axial accelerometer was attached to their lower back, and they walked along a corridor at their own preferred speed. We defined the RMSR as the ratio between RMS in each direction and the RMS vector magnitude.ResultsIn the healthy subjects, the RMS in all directions related to preferred walking speed. In contrast, RMSR in the mediolateral (ML) direction did not correlate with preferred walking speed (rs = -0.10, p = 0.54) and represented the similar value among the healthy subjects. Moreover, the RMSR in the ML direction for the hemiplegic patients was significantly higher than that for the healthy subjects (p < 0.01).ConclusionsThese results suggest that the RMSR in the ML direction exhibits a common value when healthy subjects walk at their own preferred speed, even if their preferred walking speed were different. For subjects with gait abnormality, the RMSR in the ML direction deviates from the common value of healthy subjects. The RMSR in the ML direction may potentially be a quantitative measure of gait abnormality.

Relationship between trunk and foot accelerations during walking in healthy adults

“…To examine the acceleration time series, we employed both linear and nonlinear measures of variability. Linear measures of variability such as root mean square (RMS) give information about how much variability is present in the time series [15–17]. Since walking is a cyclic and repetitive activity, it is useful to examine not only the overall magnitude of variability but also the structure of the variability throughout the time series to assess adaptive and reactive strategies during walking [18–20].…”

Estimation of Gait Independence Using a Tri-Axial Accelerometer in Stroke Patients

“…The sensor size and weight were 40 × 55 × 20 mm and 37 g including a battery, respectively. The reliability of the sensor was tested sufficiently prior to this examination, and it was also used in the other report (Sekine et al, 2013;Zakaria et al, 2015). The sensor unit output digital data to a PC through a Bluetooth transmitter (ZEAL-S01, ADC Technology, CA, USA) after a 10-bit A/D conversion for later analysis.…”

“…The sensor unit output digital data to a PC through a Bluetooth transmitter (ZEAL-S01, ADC Technology, CA, USA) after a 10-bit A/D conversion for later analysis. The wireless sensor units were attached to the lumber region around the L3-L4 vertebrae and bilateral thigh, 7 cm above the lateral epicondyle, using an elastic belt (Henriksen, Lund, MoeNilssen, Bliddal, & Danneskiod-Samsøe, 2004;Higashi, Y., Yamakoshi, K., Fujimoto, T., Kobsar, Olson, Paranjape, Hadjistavropoulos, & Barden, 2008;Sekine, M., & Tamura, T, 2013). The sampling frequency was 100 Hz, and the response frequency was DC-30 Hz.…”

“…"Estimation of Gait Independence Using a Tri-Axial Accelerometer in Stroke Patients" by Kijima Y et al Journal of Aging and Physical Activity © 2017 Human Kinetics, Inc. In a gait analysis using an tri-axial accelerometer attached to the lumbar region, the disturbance of the trunk during walking was estimated by the root mean square (RMS; Sekine et al, 2013), and the gait regularity and symmetry were estimated by the autocorrelation methods (Kobsar, Olson, Paranjape, Hadjistavropoulos, & Barden, 2014). A previous study analyzed the effect of age on acceleration of the trunk during walking and found that older adults had a lower gait regularity than did young adults (Menz, 2003).…”

Optimal Conditions for Obtaining Valid Step Count Measurements in Hospitalized Patients with Abnormal Gait

“…12,13,18) In the current study, the results were influenced by gait abnormality and device performance. The acceleration at the lower back (the L3-L4 vertebrae) 21,22) and the GRF 23,24) have been investigated for subjects with gait abnormality. Moreover, differences in the acceleration or GRF between subjects with normal and abnormal gaits and differences in the acceleration or GRF between the unaffected side and the affected side have been reported.…”