Methodological aspects should be respected. Renato Monteiro Junior, Gama Filho University 21 January 2015 Commentary about paper: Dynamic stability requirements during gait and standing exergames on the Wii Fit(R) system in the elderly. Renato Sobral Monteiro Junior, M.Sc. There are not a mostly amount of evidences that support the benefits of VR for elderly subjects. More studies with methodological rigor are required to confirm these preliminary results. Recently Duclos et al. (1) investigated the dynamic stability requirements during gait and standing exercises with Nintendo Wii Fit® in elderly individuals. The authors reported that the requirements of stability of the exergames tested are not sufficient when compared to normal gait and fast speed. They showed that the stability index, stabilizing force and destabilizing force were small during Wii Fit® activities. However, some considerations should be made: 1) Although the authors have explained that number of sample maybe is not sufficient, they are used a statistical approach with parametrical analysis (repeated measures ANOVA). Moreover, the post hoc adjustment is not cited at the text. If this analysis was not used, how the P value was encountered in comparisons between tasks? It is unclear and could compromise the interpretation of the results. Moreover, the Kolmogorov-Smirnov Test was used to verify the distribution of the data and the authors showed that the normal curve was obtained. However, one of the assumptions for to use the Kolmogorov-Smirnov Test is that the sample size is large. Therefore, there was an equivocated application of the test used and the normal curve could be not correct. 2) The Wii Fit® activities tested are normally performed in the medial-lateral axis. In the 50/50 Challenge the weight distribution required is 50% for left and right sides. In the Ski Slalom the aim of the game is to deviate of the banner of side by side and a little displacements of the center of pressures (COP) is required. Soccer also requires higher movements in the medial-lateral axis and a little forward displacement is needed. Thus, the tasks of the Wii FitTM are very different of the gait and it is obvious that characteristics of movements will be discrepant because the specificity is not respected. Furthermore, older persons need of compliance for to perform these ¿exergames¿. A familiarization period would can helpful because these people have fear of falling (2) and this perhaps affect the COP excursion. Moreover, this kind of activity could requires a cognitive function (3) and this is reduced in this population. Thus data interpretation could be underestimated, since the authors did not evaluate the performance. The compliance for perform activities of daily living was evaluated by Yang et al. (4) and the subjects increased score of the Activities-specific balance confidence (ABC) scale and walking capacity also improved. Kim et al. (5) showed that the balance and gait speed increased in older with chronic stroke after a period of one month of training with virtual reality. Therefore, it is possible that sample of the Duclos´ study did not have expressed the stability variations like gait. 3) Finally, the authors cited three systematic reviews (6-8) about effect of the biofeedback in the balance control and they conclude that the results are limited. However, these reviews are not about VR. They are about several kind of training with biofeedback, including studies that investigated visual (COP excursion) and auditory stimulus (cadence of stride). These reviews, only one 8 did included a single study that verified the effect of training with tennis game on balance. The majority of the studies in these reviews did not offer the main aspects involved in VR: immersion and presence. Immersion is the quantity of apparatus and quality of the VR system to promote a virtual environment close to real world (9). Presence is a product of immersion, in other words, it is the sensation that the individual has of interaction with virtual environment. Perhaps, this can to do the difference. REFERENCES 1. Duclos, C., C. Mieville, D. Gagnon, and C. Leclerc, Dynamic stability requirements during gait and standing exergames on the wii fit(R) system in the elderly. J Neuroeng Rehabil, 2012. 9: p. 28. 2. Oya, T., Y. Uchiyama, H. Shimada, H. Makizako, T. Doi, et al., Factors associated with fear of falling among community-dwelling elderly adults without reduced performance in instrumental activities of daily living. Nihon Ronen Igakkai Zasshi, 2012. 49(4): p. 457-62. 3. Padala, K.P., P.R. Padala, and W.J. Burke, Wii-Fit as an adjunct for mild cognitive impairment: clinical perspectives. J Am Geriatr Soc, 2011. 59(5): p. 932-3. 4. Yang, Y.R., M.P. Tsai, T.Y. Chuang, W.H. Sung, and R.Y. Wang, Virtual reality-based training improves community ambulation in individuals with stroke: a randomized controlled trial. Gait Posture, 2008. 28(2): p. 201-6. 5. Kim, J.H., S.H. Jang, C.S. Kim, J.H. Jung, and J.H. You, Use of virtual reality to enhance balance and ambulation in chronic stroke: a double blind, randomized controlled study. Am J Phys Med Rehab, 2009. 88(9): p. 693-701. 6. Barclay-Goddard, R., T. Stevenson, W. Poluha, M.E. Moffatt, and S.P. Taback, Force platform feedback for standing balance training after stroke. Cochrane Database Syst Rev, 2004(4): p. CD004129. 7. Van, K., J.A. Hides, and C.A. Richardson, The use of real-time ultrasound imaging for biofeedback of lumbar multifidus muscle contraction in healthy subjects. J Orthop Sports Phys Ther, 2006. 36(12): p. 920-5. 8. Zijlstra, A., M. Mancini, L. Chiari, and W. Zijlstra, Biofeedback for training balance and mobility tasks in older populations: a systematic review. J Neuroeng Rehabil, 2010. 7: p. 58. 9. Bohil, C.J., B. Alicea, and F.A. Biocca, Virtual reality in neuroscience research and therapy. Nat Rev Neurosci, 2011. 12(12): p. 752-62. Competing interests No competing interest.