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Improvements are often observed as individuals undergo repeated testing, and changes in gait kinematics may result following the use of treadmills to retrain gait in post-stroke patients. Mere exposure to multiple testing sessions, pre-intervention and post-intervention testing, on a treadmill may induce improvements due to a learning effect that can mask any changes caused by the intervention itself.

To address this, researchers from the University of Delaware investigated the immediate effect of repeated treadmill testing on the gait of post-stroke patients to determine if there were any changes in knee and ankle kinematics across testing sessions.

“The reason why we undertook this investigation was because in healthy individuals, and some patient populations, we see that mere testing produces a learning effect where improvements in various measures are evident across testing sessions,” Louis Awad, PT, DPT, a doctoral student of biomechanics and movement science at the University Delaware, told O&P Business News. “The repeated testing of a post-stroke subject on a treadmill may induce changes in their kinematics, and this would have a consequence on our ability to determine the effectiveness of interventions. Thus, we decided to examine the stability of baseline post-stroke gait patterns across multiple testing sessions.”

Repeated testing

The study included nine participants with hemiparesis secondary to a stroke. Data was collected with an eight-camera motion analysis system as each participant walked on a dual-belt treadmill at a self-selected speed first without functional electrical stimulation (FES) and then with FES delivered to the ankle dorsiflexor musculature. A single testing session consisted of 18 treadmill walking trials of 20 seconds to 40 seconds each. All nine participants underwent at least two testing sessions, and five of the nine subjects participated in an additional three sessions.

“With the increased prevalence of treadmills as tools for gait evaluation and retraining, it is important to determine the effects of repeated treadmill testing on gait performance,” the authors wrote in the study. “Also, considering the common addition of FES to post-stroke gait retraining protocols, understanding the effects of electrical stimulation on the consistency of post-stroke gait is warranted.”

The researchers found that there were no systematic changes in peak knee or ankle angles and peak knee or ankle angle variances across multiple testing sessions. They also found that the addition of FES did not alter this kinematic stability.

“Our study demonstrates that post-stroke knee and ankle gait kinematics do not exhibit systematic changes across multiple treadmill walking sessions,” the authors wrote in the study. “This stability of post-stroke knee and ankle gait kinematics is further supported by our similar finding of no systematic changes in gait kinematics across testing sessions even with the addition of FES during walking.”

“Our results were confirming in the sense that without stimulation, they are stable. And even with the stimulation, they are also stable,” Awad added.

Single testing sessions

The results indicate that clinicians may not need to dedicate as much time and resources to multiple testing sessions when assessing gait kinematics in post-stroke patients.

“Most clinicians and researchers conduct at least two sessions, taking the average or best of the two, to determine baseline measurements,” Awad said. “So these results may save us a little time and energy.”

According to Awad, baseline knee and ankle kinematics may be determined by a single testing session.

“Clinicians and researchers who are working with post-stroke individuals may not need to conduct multiple acclimatization or testing sessions to determine baseline abilities,” Awad said. “The takeaway [from this study] is that a single session may be sufficient for assessing post-stroke gait.” — Megan Gilbride

For more information:
Awad LN. Gait & Posture. 2013;37:67-71. doi: 10.1016/j.gaitpost.2012.06.00.

Disclosure: The authors have no relevant financial disclosures.

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