Cited by 10Balance, Gait, and Falls PreventionHuman Pose and Action RecognitionContext-Aware Activity Recognition Systems

Estimating hip impact velocity and acceleration from video-captured falls using a pose estimation algorithm

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Michaels, Reese, Barreira, Tiago V., Robinovitch, Stephen N., Sosnoff, Jacob J., Moon, Yaejin·2025·Scientific Reports

Abstract

Analyzing video footage of falls in older adults has emerged as an alternative to traditional lab studies. However, this approach is limited by the labor-intensive process of manually labeling body parts. To address this limitation, we aimed to validate the use of the AI-based pose estimation algorithm (OpenPose) in assessing the hip impact velocity and acceleration of video-captured falls. We analyzed 110 videos of 13 older adults (64.0 ± 5.9 years old) falling sideways in an experimental setting. By applying OpenPose to each video, we generated a time series of hip positions in the video, which were then analyzed using custom MATLAB code to calculate hip impact velocity and acceleration. These calculations were compared against ground truth measurements obtained from motion capture systems (VICON for hip impact velocity) and inertial measurement units (MC10 for hip impact acceleration). We examined the agreement between the ground truth and OpenPose measurements in terms of mean of absolute error (MAE), mean of absolute percentage error (MAPE), and bias (mean of error). Results showed that OpenPose had a good accuracy in estimating hip impact velocity with minimal bias (MAE: 0.17 ± 0.13 m/s, MAPE: 7.28 ± 5.21%; percent bias: - 1.27%). However, its estimation of hip impact acceleration (i.e., peak vertical hip acceleration at impact) showed poor accuracy (MAPE: 26.3 ± 19.4%), showing substantial underestimation in instances of high acceleration impacts (> 3.0 g). Further ANOVA analysis revealed OpenPose's ability to discern significant differences in hip impact velocity and acceleration based on the movement response utilized during the fall (e.g., stick-like fall, tuck-and-roll, knee block). This is the first study to validate the use of a pose estimation algorithm for identifying the hip impact kinematics in video-captured falls among older adults. Future validation studies involving diverse camera settings, fall contexts, and biomechanical parameters are warranted to extend this support for using pose estimation algorithms in this field.

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  • Skill acquisition is better reflected in the consistency and smoothness of the trajectory rather than in suppressing peak forces governed by gravity.

    “This indicates that skill acquisition is better reflected in the consistency and smoothness of the trajectory rather than in suppressing peak forces governed by gravity [13].”

    From Safe Fall: Use of Predictive Modeling and Machine Vision Techniques for Fall Analysis and Fall Quality (2026) · cites this paper as [13]

    The Results (Characteristics of hip impact velocity and acceleration; page unavailable) compare impact measures across fall strategies, and the Discussion addresses the accuracy of video-based acceleration estimates. Neither section evaluates skill acquisition, trajectory consistency or smoothness, or whether those measures reflect skill better than peak forces. Searches for those concepts found no passage addressing the comparison. (LLM, conf=0.76)

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Research works printed but not linked: 4

  1. [21]Marshal, S., Raj, S. A., Jebaseeli, T. J. & Niranjan, S. In 2023 2nd International Conference on Automation, Computing and Renewable Systems (ICACRS) 493–498.
  2. [23]Huang, Z., Liu, Y., Fang, Y. & Horn, B. K. P. In 2018 4th International Conference on Universal Village (UV) 1–4.
  3. [40]Needham, C. J. & Boyle, R. D. in International Conference on Virtual Storytelling.
  4. [44]Artacho, B. & Savakis, A. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, 7035–7044.

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Authors
Michaels, R., Barreira, T. V., Robinovitch, S. N., Sosnoff, J. J., & Moon, Y.
Affiliations
  • Syracuse University (US)
  • Simon Fraser University (CA)
  • University of Kansas Medical Center (US)
Corresponding author
Moon, Yaejin
Venue
Scientific Reports
Published
2025-01-10
Volume
15
Issue
1
Pages
1558-1558
ISSN
2045-2322 (ISSN-L)
OpenAlex
W4406210708
Cited by
9
References
42
Citations by year
2026: 6 · 2025: 3
FWCI
19.60
Type
journal article
Language
en
Open access
Locations
  • Scientific Reports (publishedVersion, cc-by-nc-nd)
  • PubMed Central (publishedVersion, cc-by-nc-nd)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Topics
  • Health Sciences › Health Professions › Physical Therapy, Sports Therapy and Rehabilitation › Balance, Gait, and Falls Prevention
  • Physical Sciences › Computer Science › Computer Vision and Pattern Recognition › Human Pose and Action Recognition
  • Physical Sciences › Computer Science › Computer Vision and Pattern Recognition › Context-Aware Activity Recognition Systems
Keywords
falls in older adults, pose estimation, OpenPose, hip kinematics, inertial measurement unit, motion capture validation
MeSH terms
Acceleration, Accidental Falls, Aged, Algorithms, Biomechanical Phenomena, Female, Hip, Humans, Male, Middle Aged, Posture, Video Recording

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