Validating realism of the PaddleTrip treadmill system: Comparisons with a trip walkway and surface perturbation treadmill

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Vinuri Peiris1,2, Stephen Lord1,2, Matthew Brodie2, Juno Kim2, Daniel Treacy3, Peter Humburg2, Liao Wu2, Paulo Silva Pelicioni1,2, Carly Chaplin1, Kirsty McDonald2 , Yoshiro Okubo1,2

1. Neuroscience Research Australia, Sydney, Australia; 2. Engineering/Health, University of New South Wales, Sydney, Australia; 3. Prince of Wales Hospital, Sydney, Australia

Scientific Research

SP - Falls

Falls

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Abstract

Introduction:

We designed the PaddleTrip treadmill, equipped with rotating paddles, to induce trip-like perturbations. This study aimed to determine whether this PaddleTrip treadmill can generate realistic obstacle‑induced trips.

Methods:

Twenty healthy adults (38.3 ± 16.7 years; range: 21–72) fitted with a fall-arrest harness completed three walking‑perturbation conditions in random order: (A) PaddleTrip treadmill, (B) 8‑m walkway with two concealed trip boards, and (C) surface‑perturbation treadmill (12 m/s²; M‑Gait). The PaddleTrip treadmill and walkway condition included four trips targeting the left foot (two elevating and two lowering recovery steps). In the M-Gait treadmill condition, there was no swing‑foot obstruction, so four belt accelerations were delivered during right stance to ensure that the left foot initiated the first recovery step. Participants rated realism (relative to an overground obstacle trip), balance effort, anxiety, pain, and confidence in avoiding a fall using 21‑point scales.

Results:

The subjective realism score for PaddleTrip (median 14.5 [IQR 10-18]) was lower than the walkway (18 [17-20], P = .007), but higher than the surface-perturbation treadmill (5.5 [4-10.5], P = .004) which was also not as highly scored compared with the walkway (P < .001). Other subjective ratings were similar between conditions (P > .05). Average pain ratings were <2 across conditions and one adverse event occurred during the surface-perturbation treadmill where one participant reported delayed onset knee pain 24 hours post training. Five PaddleTrip (4.3%) and five walkway trials (4.8%) resulted in falls into the harness. No falls were observed on the surface-perturbation treadmill.

Conclusion:

Subjective ratings indicate that PaddleTrip‑induced trips feel less realistic than those on a walkway, but more realistic than treadmill surface accelerations. Future work is needed to confirm PaddleTrip trip kinematics resemble real overground trips, and subsequent trials should examine whether our cost-effective PaddleTrip perturbation training reduces falls risk.