The effect of virtual reality on gait variability

Dimitrios Katsavelis, Mukul Mukherjee, Leslie Decker, Nicholas Stergiou

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Optic Flow (OF) plays an important role in human locomotion and manipulation of OF characteristics can cause changes in locomotion patterns. The purpose of the study was to investigate the effect of the velocity of optic flow on the amount and structure of gait variability. Each subject underwent four conditions of treadmill walking at their self-selected pace. In three conditions the subjects walked in an endless virtual corridor, while a fourth control condition was also included. The three virtual conditions differed in the speed of the optic flow displayed as follows - same speed (OFn), faster (OFf), and slower (OFs) than that of the treadmill. Gait kinematics were tracked with an optical motion capture system. Gait variability measures of the hip, knee and ankle range of motion and stride interval were analyzed. Amount of variability was evaluated with linear measures of variability - coefficient of variation, while structure of variability i.e., its organization over time, were measured with nonlinear measures - approximate entropy and detrended fluctuation analysis. The linear measures of variability, CV, did not show significant differences between Non-VR and VR conditions while nonlinear measures of variability identified significant differences at the hip, ankle, and in stride interval. In response to manipulation of the optic flow, significant differences were observed between the three virtual conditions in the following order: OFn > OFf > OFs. Measures of structure of variability are more sensitive to changes in gait due to manipulation of visual cues, whereas measures of the amount of variability may be concealed by adaptive mechanisms. Visual cues increase the complexity of gait variability and may increase the degrees of freedom available to the subject. Further exploration of the effects of optic flow manipulation on locomotion may provide us with an effective tool for rehabilitation of subjects with sensorimotor issues.

Original languageEnglish (US)
Pages (from-to)239-256
Number of pages18
JournalNonlinear Dynamics, Psychology, and Life Sciences
Issue number3
StatePublished - Jul 2010


  • Approximate entropy
  • Detrended fluctuation analysis
  • Locomotion
  • Optic flow
  • Virtual reality
  • Vision

ASJC Scopus subject areas

  • Applied Mathematics


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