Abstract
General fatigue impacts both physiological and neuromuscular systems, leading to mechanical consequences in the musculoskeletal system that manifest as alterations and variability in gait patterns. The Bruce Protocol ends at maximal exertion, providing a window to study fatigue-linked gait deviations. Purpose: To investigate whether step-by-step gait during the terminal stages of the Bruce Protocol departs from a subject’s normal pattern. Methods: 24 Division I athletes completed the Bruce Protocol while spatiotemporal gait parameters were captured with OptoGait. Features included normalized parameters plus within- and between-limb variability metrics. Redundant features were removed using hierarchical clustering. A deep autoencoder was trained on non-fatigued steps (all stages except the terminal stage) to learn normal gait pattern; then it was fine-tuned per subject to account for individual patterns. Anomalies were defined by reconstruction error. We derived an anomaly persistence marker: the first step at which the cumulative anomaly count exceeded the subject-specific 90th percentile, indicating sustained deviation. Results: Anomalous steps increased with protocol progression and concentrated near test termination. The anomaly persistence marker clustered in the terminal portion (>90% of progression) across subjects, reinforcing our assumption that meaningful anomalies are more likely to emerge toward the end of the protocol as fatigue accumulates. Variability based features (within- and between-limb) contributed most to high reconstruction error, aligning with earlier studies linking fatigue to spatiotemporal gait variability. Conclusion: Step-level deviations are observed towards the end of the Bruce Protocol, consistent with fatigue emergence. Given that the fatigue was proxied by the Borg Rate of Perceived Exertion of 20, which may blend physical and mental load, future work should isolate physical fatigue to assess whether gait variability remains.
Recommended Citation
Boolani, Ali and Asadi, Azarang
(2025)
"Subject Specific Autoencoders Reveal Terminal Stage Gait Variability in the Bruce Protocol,"
International Journal of Exercise Science: Conference Proceedings: Vol. 15:
Iss.
7, Article 31.
Available at:
https://digitalcommons.wku.edu/ijesab/vol15/iss7/31