Portability vs. Precedent: IMUs vs. 3D Motion Capture for Collecting Kinematic Data in Dancers

The emergence of portable kinematic data collection systems (Inertial Measurement Units - IMUs) have become a potential alternative to 3D video motion capture systems for real-world application. However, there remains little research on the application of IMU technology for the evaluation of dancers’ biomechanical movement. PURPOSE: To assess the validity of the Noraxon IMU system compared with the Cortex 3D video motion capture system for kinematic data collection during a sauté. METHODS: 10 healthy, advanced female dancers were equipped with both a Noraxon IMU (200Hz) system and reflective markers used with a 12-camera Motion Analysis system (Cortex, 250 Hz) for simultaneous data collection. Participants completed an independent After a 10-minute warmup, each participant performed one trial of 10 stationary sautés while barefoot, with feet in second position and arms in fifth position in time with music at 95 bpm. The middle 5 jumps of each participant’s trial were processed and analyzed with Visual3D and MATLAB for the Cortex data, and through Noraxon’s reporting system for the Noraxon data. All results were compared through SPSS with repeated-measures ANOVAs. RESULTS: A main effect of measurement system was found for peak joint angles in the sagittal ((6,4)=0.009, p \u3c 0.001), frontal ((9,1)=0.12, p \u3c 0.001), and transverse ((9,1)=0.009, p \u3c 0.001) planes. Pairwise comparisons revealed significant differences in peak hip flexion, hip extension, knee flexion, knee extension, ankle plantar flexion, ankle dorsiflexion, hip adduction, knee adduction, ankle inversion, hip internal rotation, hip external rotation, knee internal rotation, knee external rotation, and ankle internal rotation. No significant main effect was found between measurement systems for sagittal, frontal, and transverse plane joint excursions ((9,1)=0.12, p=0.253). CONCLUSION: Significant differences in most peak joint angles indicate that Noraxon IMUs do not have strong validity for capturing absolute joint angles compared to 3D video motion capture. However, joint excursion measurements were similar, indicating that Noraxon IMUs may be valid for measuring the total amount of motion during a particular movement. Additional analysis is warranted for further understanding of this technology

A.R.G! Augmented Reality and Gait: Analyzing the Influence of Cues on Gait Patterns in Augmented Reality

Use of Augmented Reality (AR) technology for rehabilitation has drastically increased in recent years. While theoretically AR can be used to cue gait adaptations such as changes to step length and cadence through visual and auditory cues, it is still unknown how people respond to the technology. PURPOSE: To assess the feasibility of external visual and auditory cues delivered through AR on spatiotemporal gait outcomes in a healthy, young population. METHODS: 20 healthy participants between age 18 and 35 were screened and recruited to perform randomized gait trials consisting of four different cueing conditions. The participants wore a Magic Leap One AR headset with a custom-designed cueing application. Participants were instructed to walk 10 steps under one of four cueing conditions provided by the AR application: No Cues (NC) (i.e., natural gait), Visual (V), Auditory (A), and Visual and Auditory (VA). Each condition was completed three times in a randomized order for a total of 12 trials per participant. An Inertial Measurement Unit (IMU) system was used to collect spatiotemporal gait data. A System Usability Survey (SUS) was administered after each participant completed their trials to determine the usability of our novel application and to determine whether the reported usability of the system was related to changes in gait variability. RESULTS: Preliminary results indicate all cueing conditions exhibited a significantly faster cadence compared to NC trials. Surprisingly, the cadence variability increased across all A trials. Increased system usability SUS results were significantly correlated with increased percent stance variability across A trials. V trials exhibited significantly decreased stride lengths compared to NC. Combined (AV) cues had no effect on gait outcomes. CONCLUSION: Our findings reinforced that certain visual and auditory cues affect gait parameters, albeit in a direction opposite of what was expected (e.g., greater cadence variability with auditory cues). These results provide insight into how healthy populations respond to cues delivered through AR, as well as provide a foundation for future studies to implement this technology with clinical populations such as those with Parkinson’s disease