Classifying Step and Spin Turns Using Wireless Gyroscopes and Implications for Fall Risk Assessments

Abstract

Recent studies have reported a greater prevalence of spin turns, which are more unstable than step turns, in older adults compared to young adults in laboratory settings. Currently, turning strategies can only be identified through visual observation, either in-person or through video. This paper presents two unique methods and their combination to remotely monitor turning behavior using three uniaxial gyroscopes. Five young adults performed 90° turns at slow, normal, and fast walking speeds around a variety of obstacles while instrumented with three IMUs (attached on the trunk, left and right shank). Raw data from 360 trials were analyzed. Compared to visual classification, the two IMU methods’ sensitivity/specificity to detecting spin turns were 76.1%/76.7% and 76.1%/84.4%, respectively. When the two methods were combined, the IMU had an overall 86.8% sensitivity and 92.2% specificity, with 89.4%/100% sensitivity/specificity at slow speeds. This combined method can be implemented into wireless fall prevention systems and used to identify increased use of spin turns. This method allows for longitudinal monitoring of turning strategies and allows researchers to test for potential associations between the frequency of spin turns and clinically relevant outcomes (e.g., falls) in non-laboratory settings.

A Novel Simplified System to Estimate Lower-Limb Joint Moments during Sit-to-Stand

“…After the subject begins to stand up, it is not possible to use the inverse kinematic approach above to obtain θ shank and θ thigh because the body segments are not in contact with the chair. In this study, from θ shank,sit in (3), θ shank was calculated by integrating shank angular velocity along the sagittal plane measured by an inertial sensor attached to the middle of the shank [ 36 , 37 ] ( Figure 2 ). Here, the integration was started at the beginning of the STS motion, which was detected by using a z-directional ground reaction force (GRF) [ 38 ].…”

Observational Study of 180° Turning Strategies Using Inertial Measurement Units and Fall Risk in Poststroke Hemiparetic Patients

“…For each participant, we observed the spontaneous turn side and determined the stance limb during the first step of the turn (i.e., first stance limb), given by the 180° turning representation. According to an extension of previous literature that defined turning strategies for 90° turns in healthy populations ( 13 , 19 ), we defined four turning strategies in our patients: strategy 1, turn toward the healthy side with a healthy first stance limb; strategy 2, turn toward the healthy side with a paretic first stance limb; strategy 3, turn toward the paretic side with a healthy first stance limb; and strategy 4, turn toward the paretic side with a paretic first stance limb.…”

“…Two main turning strategies have been identified: the spin turn involves a change in direction toward the side of the stance limb and the step turn involves a change in direction away from the stance limb ( 12 , 13 ). The spin strategy is less stable because it leads to a reduced base of support ( 12 , 13 , 17 – 19 ). Clinically, the number of external steps and the turn duration are used to evaluate turning ( 11 ).…”

Quantifying performance on an outdoor agility drill using foot-mounted inertial measurement units

“…Wearable IMUs have been used previously to study turning agility in a variety of contexts. Trunk- or pelvis-mounted IMUs have been employed to evaluate running agility in a five-cone drill [ 11 ], turning-while-walking activities [ 6 , 18 – 21 ] and turning strategies in slalom skiing [ 22 ]. Mancini et al [ 23 ] and El-Gohary et al [ 24 ] used foot and torso mounted IMUs to learn that people with Parkinson’s disease tended to use more footfalls and smaller turn angles (larger turning radii) than healthy controls.…”