Influence of moving visual environment on sit-to-stand kinematics in children and adults

The Untapped Potential of Virtual Reality in Rehabilitation of Balance and Gait in Neurological Disorders

Dynamic systems theory transformed our understanding of motor control by recognizing the continual interaction between the organism and the environment. Movement could no longer be visualized simply as a response to a pattern of stimuli or as a demonstration of prior intent; movement is context dependent and is continuously reshaped by the ongoing dynamics of the world around us. Virtual reality is one methodological variable that allows us to control and manipulate that environmental context. A large body of literature exists to support the impact of visual flow, visual conditions, and visual perception on the planning and execution of movement. In rehabilitative practice, however, this technology has been employed mostly as a tool for motivation and enjoyment of physical exercise. The opportunity to modulate motor behavior through the parameters of the virtual world is often ignored in practice. In this article we present the results of experiments from our laboratories and from others demonstrating that presenting particular characteristics of the virtual world through different sensory modalities will modify balance and locomotor behavior. We will discuss how movement in the virtual world opens a window into the motor planning processes and informs us about the relative weighting of visual and somatosensory signals. Finally, we discuss how these findings should influence future treatment design.

Visual dependence affects the motor behavior of older adults during the Timed Up and Go (TUG) test

BACKGROUND

Older adults show greater postural instabilities under misleading visual cues relative to younger adults. We investigated the effects of age-related visual dependence on motor performance under increased attention demands by adding a motor task and visual stimulus to the Timed Up and Go (TUG) test sub-components.

METHOD

We designed a cross-sectional quantitative study. Twenty-eight younger (n = 12) and older (n = 16) adults completed the TUG test while wearing a head-mounted display (HMD) that presented a visual stimulus and/or carrying a cup of water. Outcome measures were turning cadence; gait speed; pitch, yaw, and roll peak trunk velocities (PTVs); and acceleration ranges of sit-to-stand and stand-to-sit.

RESULTS

Wearing the HMD caused significant performance differences in the TUG test tasks due to age and visual dependence, although performance was lower across all groups with the HMD (p < 0.01). Older adults showed lower roll PTV in turning compared to younger adults (p = 0.03). Visually dependent older adults showed smaller mediolateral and vertical acceleration ranges (p < 0.04) in sit-to-stand compared to visually independent older adults.

CONCLUSION

The demand for orienting posture to a vertical position during sit-to-stand may differentiate older adults who are more visually dependent-and thus at greater fall risk- from those who are more visually independent. Age-related differences in turning behavior suggest a relationship with fall risk that warrants further investigation.

Kinematics of the Spine During Sit-to-Stand Movement Using Motion Analysis Systems: A Systematic Review of Literature

CONTEXT

Clinical evaluation of the spine is commonplace in musculoskeletal therapies, such as physiotherapy, physical medicine/rehabilitation, osteopathic, and chiropractic clinics. Sit-to-stand (STS) is one of the most mechanically demanding daily activities and crucial to independence. Difficulty or inability to perform STS is common in individuals with a variety of motor disabilities, such as low back pain (LBP).

OBJECTIVE

The purpose of this systematic review was to evaluate available evidence in literature to determine 2-dimensional and 3-dimensional kinematics of the spine during STS in patients with LBP and healthy young adult participants using motion analysis systems (electromagnetic and marker based).

METHODS

Electronic databases (PubMed/MEDLINE [National Library of Medicine], Scopus, ScienceDirect, and Google Scholar) were searched between January 2002 and February 2017. Additionally, the reference lists of the articles that met the inclusion criteria were also searched. Prospective studies published in peer-reviewed journals, with full text available in English, investigating the kinematics of the spine during STS in healthy subjects (mean age between 18 and 50 y) or in patients with LBP using motion analysis systems, were included. Sixteen studies fulfilled the eligibility criteria. All information relating to methodology and kinematic modeling of the spine segments along with the outcome measures was extracted from the studies identified for synthesis.

RESULTS

The results indicated that the kinematics of the spine are greatly changed in patients with LBP. In order to develop a better understanding of spine kinematics, studies recommended that the trunk should be analyzed as a multisegment. It has been shown that there is no difference between the kinematics of patients with LBP and healthy population when the spine is analyzed as a single segment. Furthermore, between-gender differences are present during STS movement.

CONCLUSION

This review provided a valuable summary of the research to date examining the kinematics of the spine during STS.

Postural responses accompanying Achilles tendon vibration stimulation during various phases of sit-to-stand movement

The aim of this study was to determine the postural response accompanying Achilles tendon vibration stimulation during various phases of the sit-to-stand movement. Twelve healthy young adults performed the sit-to-stand movement in response to an auditory signal 2 s after a first one. Vibration stimulation with a 100 Hz frequency was applied to both Achilles tendons during the following phases: (1) 10 s of sitting before standing up; (2) 10 s plus a period until the standing position was achieved; and (3) 5 s after standing. The postural response after standing was analyzed with the center of foot pressure in the anteroposterior direction. Forward-leaning responses were identified in 78.3% and 63.3% of trials under conditions 1 and 2, respectively. Backward-leaning responses were identified in 93.3% of the trials under condition 3. Response latency (+/- standard deviation) was significantly longer under conditions 1 and 2 than under condition 3 (1: 872 +/- 576, 2: 1026 +/- 542, and 3:555 +/- 322 ms; ps < 0.05). Sensory information at the standing point might be anticipated based on sensory information received while sitting. Consequently, postural response as a compensatory movement would occur via the sensory reference system within the supraspinal nervous system.