The commentary by Deutsch et al1 focuses on the strengths and weaknesses of virtual reality (VR)–augmented therapy in our study.2 Their invaluable suggestions about VR applications for balance and mobility training are highly appreciated. Mirelman et al3 trained people with Parkinson disease (PD) using treadmill plus VR training for about 40 minutes per session, 3 sessions per week, for 6 weeks, and we agree that our training dosage was low. However, in their study of people with stroke, Yang et al4 used treadmill plus VR training for 20 minutes per session, 3 sessions per week, over a 3-week period. Thus, in VR training in neurological rehabilitation, the session lengths and numbers and training periods vary widely.5
As mentioned in the commentary, a head-mounted display can deliver a virtual task matched with an identical real-world task. However, flatscreen VR also is recommended for older adults to prevent cybersickness and restricted movement of head.6 Because dynamic balance training on a tilting board is challenging, flatscreen VR was used in our study. The participants were satisfied with this VR setting and did not complain of dizziness during dynamic balance training.
In terms of the number of movement repetitions and exposures to the exercise, we controlled the duration instead of repetitions of exercise in both the VR-augmented balance training group and the conventional balance training group. Future studies are suggested to quantify the movement repetitions during training. Reassessing the speed threshold setting once a week for treadmill training is a good guideline for intensity adjustment.3 We have designed the assessment of maximal weight shift in 4 directions in our VR programs, but it was not sensitive enough to detect the minor changes for monitoring the difficulty of progression. In our study, the platform sensitivity and movement direction were adjusted every week by the error of performance shown on the screen and the self-perceived exertion of the participants. Deutsch et al suggested adding more cognitive training for fall-risk reduction, so that attention strategy, such as traffic auditory distraction and traffic light recognition, would be considered in future design of VR balance training with dual tasks.7,8
- © 2011 American Physical Therapy Association
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