Objective: To investigate the effect of progressively increasing perceived fatigue on gait biomechanics in people with Parkinson’s disease (PD), considering the potential moderating role of age categories.

Background: Fatigue is a frequent and disabling symptom in PD and may substantially affect gait performance and stability [1]. However, the biomechanical adaptations that occur as perceived fatigue progressively increases during walking remain poorly understood, particularly when considering differences across age groups and their functional characteristics.

Method: Thirty-seven people with PD (69±6 years; mH&Y 2.5 [2–3]) underwent an instrumented gait assessment during a continuous walking protocol performed until high perceived exertion (Borg Rating of Perceived Exertion=17). Spatiotemporal, kinematic and kinetic gait parameters were repeatedly recorded using a motion capture system and force platforms. Participants were stratified into three age categories (non-elderly <65 years, young-old 65–74 years, old-old ≥75 years) [2]. Linear mixed-effects models were used to examine associations between perceived fatigue (RPE) and gait parameters, including age category and their interaction as fixed effects and participant as a random intercept.

Results: Participants were distributed across age categories as follows: non-elderly 24.3%, young-old 62.2%, and old-old 13.5%. Increasing perceived fatigue was significantly associated with reduced gait speed (m/s; β=−0.015, p<0.001) and cadence (steps/min; β=−0.755, p<0.001), decreased hip extension peak (deg; β=0.395, p<0.001), increased double support time (% stride; β=0.173, p=0.003), and greater mediolateral center-of-mass excursion during double support (mm; β=0.458, p<0.001). Significant interactions between fatigue and age categories were observed for gait speed, cadence and hip extension peak (all p<0.001), and for mediolateral center of mass excursion (p=0.048), indicating stronger fatigue-related gait changes in non-elderly participants compared with older individuals.

Conclusion: Progressive perceived fatigue induces a conservative gait strategy in PD characterised by reduced propulsion and increased instability. Age modulates these adaptations, with non-elderly individuals showing greater fatigue-related gait changes, while older participants exhibit attenuated biomechanical responses, possibly reflecting their reduced gait adaptive reserve.

References: [1] Majlesi M, Azadian E, Farahpour N, Bakhtiarian R, Nobari H. Fatigue-Inducing Protocols in Parkinson’s Disease: Implications for Gait Assessment and Rehabilitation: A Systematic Review. Parkinsons Dis. 2026 Jan 5; 2026:8822220.
[2] Lally M, Valentine-French S. Lifespan development: a psychological perspective. 4th ed. Santa Barbara (CA): LibreTexts; 2019

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MDS Abstracts - https://www.mdsabstracts.org/abstract/age-modulated-gait-adaptations-to-progressive-fatigue-in-parkinsons-disease/