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Chronic low back pain (cLBP) can interfere with daily activities, and individuals with elevated pain-related fear (also known as kinesiophobia or the fear of injury due to movement) can develop worse long-term disability. Graded exposure (GEXP) protocols use successive participation in avoided activities to help individuals overcome fearful movement appraisals and encourage activity. We sought to develop a series of GEXP virtual reality (VR) walking and reaching scenarios to increase the exposure and engagement of people with high kinesiophobia and cLBP.
This study aims to (1) determine GEXP content validity of the VR application and (2) determine the feasibility of individuals with cLBP performing locomotion-enabled physical activities.
We recruited 13 individuals with cLBP and high pain-related fear to experience six VR modules, which provide progressive movement exposure over three sessions in a 1 week period. At session 1, participants ranked each module by likelihood to avoid and assigned an expected pain and concern for harming their back rating to each module. Participants provided a rating of perceived exertion (RPE) after experiencing each module. To test feasibility, we administered the system usability scale (SUS) and treatment evaluation inventory (TEI) following the final session. In addition, we measured pain and pain-related fear at baseline and follow-up.
The 12 participants who completed the study period assigned higher avoidance (
The GEXP VR modules provided progressive exposure to physical challenges, and participants found the VR application acceptable and usable as a potential treatment option. Furthermore, the lack of significant change for pain and pain-related fear reflects that participants were able to complete the modules safely.
Chronic low back pain (cLBP)—low back pain present for longer than 3 months—is a common symptom with an estimated lifetime prevalence of 80% and is the second leading cause of disability in the United States [
The fear-avoidance model (FAM), a widely used theory that attempts to explain the development of chronic disability after a back injury, identifies pain-related fear as a central cognition that predicts long-term disability after musculoskeletal injury [
Treatments based on the FAM employ strategies to reduce pain-related fear and activity avoidance. Graded exposure (GEXP) is one such treatment, in which individuals with cLBP and high pain-related fear rank activities based on fearfulness and then progressively confront these fearful appraisals through activity [
GEXP protocols aim to correct catastrophic misinterpretations of pain sensations and reduce expectations of harm to the back, leading to functional improvements. A small number of randomized controlled trials have demonstrated that GEXP may clinically reduce fear of movement and disability among cLBP patients [
Virtual reality (VR) is a tool that can generate environments not otherwise possible in a clinical or laboratory setting. Previous research suggests that virtual environments can enhance rehabilitative training and improve physical outcomes [
Researchers and clinicians can categorize movement tasks by body orientation (providing stability or transport), environment (stationary or in motion), and object manipulation requirements (holding an object or not) [
In response, we have developed an engaging, locomotion-enabled GEXP VR application to address the lack of applications that provide progressive movement challenges for individuals with cLBP. The VR application, Lucid, consists of six 3-min modules that challenge participants to complete engaging activities in VR that require progressively more challenging walking and reaching movements in real life. The progressive modules deliver exposure over 3 study sessions in a weeklong training period, where users experience 2 modules at each session.
Before evaluating the efficacy of the GEXP VR application on pain-related health outcomes, we needed to evaluate the basic parameters of the application’s GEXP content and establish how potential users respond to the application. In this study, we aimed to measure the
Before exposure to the VR modules, participants would report higher expected ranked avoidance, higher expected pain ratings, and higher expected back-related concern ratings for the more challenging modules compared with less challenging modules.
Participants would report that the VR application is acceptable and usable, as determined by acceptability and usability scores above the respective cutoff values.
The VR application would be safe for participants with cLBP to complete, as determined by no significant increase in pain or pain-related fear over the study period.
We used a commercially available self-driven treadmill and a VR system to deliver the VR walking experience (
Walking and reaching virtual reality application setup.
Weighted sword and shield hand-held controllers.
We designed and developed the novel VR application, Lucid, that encourages participants to practice real-world movement tasks in a fun and engaging VR world. First, we identified functional movements used in real-world activities by using the movements included in the PHODA. The PHODA includes 8 movement types (ie, lifting, bending, turning, reaching, falling, intermittent load, unexpected movement, long-lasting load instance, or sit with limited dynamics) performed in either static or dynamic positions [
Movement requirements and activity goals for the virtual reality modules.
Session | Module | Movement requirements | VRa activity goal |
1 (low-intensity challenge) | 1 |
Walking: any pace Reaching: requires one hand Bending: no Carry weights: no |
“Walk at your own pace and rid the realm of monsters. Swing your sword to damage foes and block their attacks with your shield.” |
1 (low-intensity challenge) | 2 |
Walking: walking quickly Reaching: requires one hand Bending: no Carry weights: no |
“Walk at an increased pace to save as many animals as you can. Monsters have started to prey on the wildlife, and it’s up to you to save the animals before the monster consumes them.” |
2 (medium-intensity challenge) | 3 |
Walking: any pace Reaching: requires both hands Bending: no Carry weights: no |
“The monsters have desolated the land, and it’s up to you to collect food and coins for the realm. You are given two swords to reach both your foes and your items in all directions.” |
2 (medium-intensity challenge) | 4 |
Walking: any pace Reaching: requires one hand Bending: yes Carry weights: no |
“Crouch under trees and tunnels to explore more of the realm. You’ll want to make sure you avoid limbs and the ceiling, or you’ll bring your journey to an end.” |
3 (high-intensity challenge) | 5 |
Walking: any pace Reaching: requires both hands Bending: yes Carry weights: yes |
“Wield a weighted sword and shield while you crouch under trees and tunnels to explore more of the realm. You’ll want to make sure you avoid limbs and the ceiling, or you’ll bring your journey to an end.” |
3 (high-intensity challenge) | 6 |
Walking: walking quickly Reaching: requires both hands Bending: yes Carry weights: yes |
“Wield a weighted sword and shield to defeat your enemies.” |
aVR: virtual reality.
In the HMD, participants navigated a walking path and utilized a VR sword and shield (
View through the head-mounted display as a user combats a monster while holding the virtual reality sword and shield.
We recruited potential participants through fliers, through the web-based clinical trial registration, and from individuals who participated in previous studies in our lab. We included potential participants aged 18-65 years so that we could test the feasibility in a wide age range of individuals who may benefit from a GEXP intervention. We screened individuals over the phone, and individuals were deemed eligible if they self-reported low back pain for longer than 3 months, experienced interference caused by their back pain in daily life, and reported elevated pain-related fear. Participants were determined to have a high level of fear if they scored greater than 10 points on a 4-question pain-related fear screen that consisted of the 4 highest loaded items from the Tampa scale for kinesiophobia (TSK) [
There were 12 participants (aged 43-60 years) with cLBP and high pain-related fear that completed the study protocol (
Participant characteristics (N=12).
Characteristics | Values | |
Age (years), mean (SD) | 54.3 (5.1) | |
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Male | 4 (33) |
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Female | 8 (67) |
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Black | 12 (100) |
MPQ-sfa PRIb (possible score range 0-45), mean (SD) | 14.8 (9.4) | |
MPQ-sf VASc (possible score range 0-100), mean (SD) | 52.3 (23.6) | |
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No pain | 0 (0) |
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Mild | 1 (8) |
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Discomforting | 0 (0) |
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Distressing | 10 (83) |
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Horrible | 1 (8) |
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Excruciating | 0 (0) |
TSKe (possible score range 17-68), mean (SD) | 44.2 (8.0) | |
Walking speed in VRf (m/s), mean (SD) | 1.1 (0.2) |
aMPQ-sf: McGill pain questionnaire-short form.
bPRI: pain rating index.
cVAS: visual analog scale.
dPPI: present pain intensity.
eTSK: Tampa scale for kinesiophobia (scores >37 are indicative of high fear).
fVR: virtual reality.
Participants attended 3 VR sessions (sessions 1-3) over a 1-week period and a follow-up session 3 to 5 days after session 3. During each VR session, participants tested 2 Lucid VR modules in progressive order. Participants completed a baseline questionnaire at the beginning of session 1 and then a follow-up questionnaire at the follow-up session. The questionnaire at session 1 included basic demographics, including gender, age, and race. The institutional review board at the University of Alabama at Birmingham approved the study design, all participants provided written informed consent, and we compensated participants for their time. The study sessions were conducted at a laboratory in the University of Alabama at Birmingham.
Our primary
Secondarily, we also asked participants to provide their rating of perceived exertion (RPE) after each VR module to measure how participants rated their perceived effort during each VR module [
At the follow-up session, we administered the treatment evaluation inventory-short form (TEI-sf) as the primary measure of
To measure pain changes immediately following each module, we asked participants to mark their pain along a VAS before and after each module. VAS measurements are a valid and reliable method to measure pain in individuals with cLBP [
This study aimed to (1) determine the
To examine the GEXP content validity of the graded modules, we used Friedman tests and Dunn post hoc pairwise comparisons with Bonferroni corrections to analyze ordinal data across sessions (avoidance rank and RPE). For continuous data (expected pain and expected concern), we performed a repeated measures analysis of variance (ANOVA) across the VR sessions and performed post hoc pairwise comparisons with Bonferroni corrections. We reported the means and SDs of how participants rated each session’s difficulty compared with the previous sessions.
To evaluate the feasibility of the VR application, we calculated the means and SDs of the TEI-sf, SUS, and postsession questionnaire. We performed paired
We performed Shapiro-Wilk normality tests to confirm the normality of the distribution for dependent variables. For all analyses, we collapsed the VR modules into 3 groups (session 1, session 2, and session 3), based on the 3 VR sessions. We set the alpha level of significance to .05 (two tailed) for all statistical tests. We checked the data for underlying assumptions, and data were described and analyzed using IBM SPSS 25 (IBM Corp).
Participants assigned higher avoidance, expected pain, and expected concern to the Lucid sessions that are designed to be more challenging (
Avoidance rank, expected pain, and expected concern for harm.
Measures and sessions | Values | 95% CI | |
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Session 1 | 2.5 (1.4)a | 2.0-2.8 |
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Session 2 | 3.3 (1.8) | 2.6-3.0 |
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Session 3 | 5.5 (0.8)a | 4.7-5.6 |
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Session 1 | 38.3 (25.4)a,b | 22.2-54.5 |
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Session 2 | 54.2 (25.2)b,c | 38.2-70.2 |
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Session 3 | 69.4 (22.2)a,c | 55.3-83.5 |
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Session 1 | 42.3 (27.5)b,c | 24.8-59.8 |
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Session 2 | 57.5 (31.2)b,c | 37.7-77.3 |
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Session 3 | 74.4 (30.9)a,c | 54.7-94.9 |
aSignificant pairwise comparison between sessions 1 and 3.
bSignificant pairwise comparison between sessions 1 and 2.
cSignificant pairwise comparison between sessions 2 and 3.
The average RPE slightly increased over the sessions, and 83% (10/12) of the participants reported a higher exertion on session 3 compared with session 1 (
Rating of perceived exertion.
Sessions | Median (IQR)a | 95% CI |
1 | 14.0 (4.75)b | 13.2-16.3 |
2 | 15.0 (4.75) | 14.6-17.5 |
3 | 17.0 (4.75)b | 15.4-18.2 |
aPossible scores from 6 to 20.
bSignificant pairwise comparison between sessions 1 and 3.
On the difficulty rating questions, participants reported that the session 3 modules were more difficult than the session 1 modules (mean 6.1, SD 3.6) and session 2 modules (mean 5.9, SD 3.5).
Participants responded positively to the VR application as an acceptable potential intervention for cLBP. The average TEI score was 32.5 (SD 4.9), which is above the acceptability cutoff score of 27. Scores ranged from 26 to 41, and 92% (11/12) of participants responded at the cutoff score or above.
The average SUS score was 76.7 (SD 13.0). Scores ranged from 52.5 to 92.5, and 75% (9/12) of the participants reported that the system was usable.
From baseline to follow-up, there were no overall changes in the MPQ-sf PRI (
In most of the VR modules, there were no statistically significant changes in VAS pain ratings. However, VAS pain significantly increased during module 6 (
In this study, we aimed to (1) determine the GEXP content validity of the VR application and (2) determine the feasibility of individuals with cLBP performing integrated physical activities. Participant responses supported that the VR modules provided progressive exposure to fearfully perceived tasks by assigning greater avoidance to the modules designed to elicit greater fearful appraisals and present greater challenges. In concurrence with the FAM, participants assigned the highest expected pain and concern for harming their back to the modules that they ranked with higher avoidance. For feasibility, the TEI and SUS scores indicated that participants with high fear and cLBP found the VR application an acceptable approach to treat cLBP and usable as a system. Additionally, the VR application was safe, as participants successfully completed the GEXP VR protocol without negative effects on pain or pain-related fear.
The GEXP VR application is an important step in using VR as a potential treatment option because it allowed participants to gradually practice real-life movements through VR activities that require combinations of walking and reaching. Many daily tasks require a person to combine walking and reaching abilities, such as walking to open a door or carrying a bag of groceries. Previous applications have provided exposure to stationary tasks, but by incorporating these tasks into a walking environment, there may be greater potential to translate learning into real-world activities.
The participant feedback we captured is consistent with other studies that have tested VR apps designed for individuals with cLBP. Thomas et al [
Although we intentionally used a GEXP mechanism in the Lucid VR application to decrease the physical limitations caused by activity avoidance, other factors may have helped participants complete the modules. Distraction from pain is a well-studied mechanism commonly used in acute pain [
The lack of observed elevations for pain and pain-related fear across the study sessions reflects that individuals with high fear and cLBP were able to successfully complete the challenging activities without adverse consequences in these domains. In line with our long-term intervention goal to reduce deficits in physical ability caused by activity avoidance, participants with cLBP and elevated pain-related fear exhibited their ability to perform functional movement activities such as walking, reaching, carrying, and crouching despite experiencing pain and pain-related fear.
Our study goal was to test the GEXP content and feasibility of the VR application, which we designed to improve the physical abilities of individuals with cLBP by gradually exposing participants to more difficult challenges. Given that chronic pain can significantly interfere with one’s goals and ability to complete everyday activities, interventions that increase physical ability are valuable. This VR application allows individuals not only to interact in an interesting and challenging VR world, but it provided physical challenges that incorporated body transport and reaching movements in a dynamic and motivating environment.
As our study design was to establish the content validity and feasibility of the GEXP app, all participants received the same activities in the same order. The lack of personalization could have limited the GEXP experience for some of our participants as we only provided exposure to these predefined movement combinations. We do not believe this limitation had a significant effect on our study outcomes as participants generally ranked the activities by avoidance in the expected order. In addition, although we used RPE to measure perceived effort, we did not ask participants to specifically rate the difficulty of each module given their back pain. Participants may have assigned greater effort to the higher intensity modules for reasons other than back-related challenges. Participants who walked faster may have had higher exposure as they were able to progress further along the trail in 3 min. Additionally, we only recruited 13 individuals to test the VR app, and this potentially limits our statistical power. To our knowledge, this is the first study to test a VR GEXP walking protocol for individuals with cLBP, and it was essential to determine whether individuals with cLBP could engage with the system and perform the challenges in the novel walking environment before expanding into a larger sample size.
The next step in this line of research is to explore the efficacy of the VR application on pain-related health outcomes. For this, we would need a larger sample size and a longer study duration. Although this study focused on GEXP content and feasibility, we would also need to explore how the VR exposure training translates to real-world activities by measuring changes in avoidance, disability, and physical function outside of the VR setting. Additionally, future iterations could improve the GEXP experience by allowing the participants to rank a greater number of activities and then experience modules tailored to how they rank their avoidance of each task. This would improve the personalization of the VR application and could allow participants to experience a tailored program more relevant to their daily living. Although our study focused on the general perceived effort of module activities, future studies could also specifically ask about the perceived back-related challenge of activities to better characterize the GEXP. In line with using VR to provide a tailored therapeutic experience, future studies should also explore how age, gender, and pain status influence participation in GEXP VR therapies.
We have established that the VR modules provided progressive challenges and were feasible for individuals with cLBP and high pain-related fear. The locomotion-enabled VR modules allowed users to freely walk and complete challenging physical activities in a motivating environment that participants thought was acceptable, usable, and safe. Expectation ratings, RPE, and module difficulty responses support that the sessions and comprising modules provided a progressive challenge, in line with GEXP protocols. Despite presenting activities likely for individuals with high fear to avoid, the graded VR walking challenges did not increase pain or fear of movement. The VR modules provided exposure to physical activity challenges that integrate reaching, walking, crouching, and carrying weights while also providing a safe bout of exercise and an enjoyable gaming experience.
Postsession questionnaire and responses.
analysis of variance
chronic low back pain
fear-avoidance model
graded exposure
head-mounted display
KineAssist-MX
McGill pain questionnaire-short form
pain rating index
rating of perceived exertion
system usability scale
treatment evaluation inventory-short-form
Tampa scale for kinesiophobia
visual analog scale
virtual reality
This research was supported by the National Institutes of Health/National Institute of Child Health and Human Development of the National Institutes of Health under award number #1R43HD093522-01 and through a grant from the University of Alabama at Birmingham Health Services Foundation General Endowment Fund (PIs: Carmen Capo-Lugo [PT, PhD] and DB [PT, PhD]). The authors would like to thank Jennifer Uzochukwu and Caroline Springer for their assistance with data collection and data entry.
ZT and DB designed the study and provided their expertise during game development so that the game elements incorporate important and challenging physical activities appropriate for individuals with chronic pain. MC designed, built, and integrated the VR application with the KA-MX. RH collected and analyzed the data, and DR collected data and assisted with the study design.
DB receives royalties on sales of the KineAssist MX device used in this study. MC with From the From the Future LLC sells virtual reality software as a KineAssist MX device add-on. All other authors have no financial interest to disclose.