Low back pain (LBP) is one of the world’s leading causes of disability [1-3]. In 2019, there were approximately 568.4 million prevalent cases, 223.5 million incident cases, and 63.7 million cases of years lived with disability owing to LBP reported globally [4]. LBP affects all ages and genders, but its prevalence increases with age, peaking at the age of approximately 45 to 54 years [4]. Approximately 70% to 85% of adults are expected to experience at least 1 episode of LBP in their lifetime [5]. Once predisposed to LBP, individuals are twice as likely to experience recurrent episodes of LBP [6]. Annually, LBP in the United States results in 149 million missed work days [7]. The total costs of LBP worldwide amount to approximately US $100 billion a year, with two-thirds of this amount owing to lost wages and decreased work productivity [8].

Physical therapy (PT) is a common, effective, evidence-based treatment for LBP [9,10]. Specifically, active interventions including exercises prescribed by a physical therapist are effective for prevention and treatment of LBP [11,12]. During an initial examination, a physical therapist can identify musculoskeletal and neuromuscular impairments associated with the LBP problem by conducting assessment of the patient’s posture and movement. Then, the physical therapist and patient can work together to promote strength, stability, and mobility with in-clinic sessions and an assigned home exercise program with the goal of decreasing pain and disability [10,13]. Monitoring the patient’s posture and movement can provide a basis for determining individualized factors associated with the LBP problem, which can then be addressed through targeted interventions.

Whether at home or at work, specific movement patterns that are performed repeatedly have been identified as a significant risk factor for the development and persistence of LBP [2,14,15]. These movement patterns of the low back region can be characterized by evaluating the angle, velocity, and acceleration [16] and can assist in LBP diagnosis, treatment, and prevention. There are several approaches to monitoring spine posture and movement. Generally, when conducting a PT examination, clinicians visually monitor posture and movement or use tools that measure the range of movement such as goniometers or inclinometers [17], but an alternative approach is to use technology to help better quantify the objective measures of spine posture and movement and offer potential benefits such as remote monitoring [16,18,19] while the patient is away from the clinic.

To date, existing technologies used to measure spine posture and movement in research and practice include optical motion capture, inertial measurement units (IMUs), and other wearable sensors [20-22]. Despite the variety of systems available, they generally present ≥1 limitation. Optical motion capture systems offer great precision and accuracy in monitoring human movement. However, their applications are limited owing to space needs, cost, and level of expertise needed. IMUs are portable devices that measure metrics such as acceleration and orientation [23] and include a variety of wearable sensors such as accelerometers, gyroscopes, and magnetometers, making them ideal for collecting data in a free-living environment. However, when used for monitoring human movement, IMUs have several limitations including decreased accuracy and precision for measuring slow movements [24,25], difficulty with measuring the axial plane movement accurately, inability to account for the multisegmented nature of the spine [26], and the need for multiple IMUs to triangulate posture and movement of a segment that can be cumbersome to the wearer [27].

Owing to the limitations of existing sensor systems for measuring spine posture and movement, there is a need to explore new sensor innovations to address this issue. Ideally, such an approach would be wearable, unobtrusive, and usable in a clinical environment during PT sessions and in a person’s natural environment to support home-based care. Another desired requirement would be high accuracy while collecting posture and movement data for a prolonged period.

Motion Tape, developed by Loh and Lin [28], is a disposable, self-adhesive skin-strain sensor system made using graphene nanosheets coated onto commercially available kinesiology tape (also known as K-Tape) [29-33]. Motion Tape has piezoresistive properties based on the deformation of the integrated graphene nanosheets in the tape that makes it sensitive to strain [33]. In previous studies, Motion Tape has demonstrated stable performance under cyclic strains [33,34]. In addition, the Motion Tape sensor system has been tested on human participants [33,34], displaying accuracy in measuring skin strains and angles across biceps, knees, shoulders, wrists, and various other body regions when compared with IMUs and skin strains estimated using optical motion capture systems [35]. Overall, Motion Tape offers noninvasive, comfortable, and practical skin-strain measurements and can comprehensively capture complex movements and muscle engagement, especially when applied as a network of sensors [35].

When used for a low back use case, Motion Tape provides a means to capture the lumbar spine’s multisegmental nature and multiplanar movements [36]. Motion Tape’s low-profile and stretchable nature allows it to be worn throughout the day for all human shapes and sizes, and it could be suitable for use in an individual’s natural environment with minimal interference to their daily activities. Motion Tape provides unique sensing streams that can be used in machine learning and artificial intelligence models to optimize inferences related to the management of LBP. Specifically, Motion Tape for a low back use case can address several key issues in a physical therapist’s management of LBP, including the following: expanding on the level of detail available during the clinical assessment of posture and movement, assessing spinal posture and movement in a free-living environment, use for the promotion of engagement and adherence with and precise performance of a prescribed home exercise program, and using the patient’s response to treatment to make informed decisions for future treatment or other patients [37]. Although there are several potential benefits that Motion Tape may add to personalized health care for LBP, the acceptability of Motion Tape among physical therapists has yet to be assessed.

The success of this device is dependent on user acceptance or one’s belief that the device will help them perform their work better (ie, perceived usefulness) and that the device’s performance benefits outweigh the effort of using the device (ie, perceived ease of use) [38]. Thus, it is vital to understand physical therapists’ perspectives about Motion Tape and their willingness to use it in their practice, to inform future developments and improvement of the technology.

The primary aim of this research study was to evaluate physical therapists’ acceptance of Motion Tape for the management of LBP. The secondary purpose was to explore physical therapists’ current needs and recommendations regarding future development of Motion Tape.

In this study, licensed physical therapists evaluated a prototype of Motion Tape and examples of data streams from the app for a low back use case. The Motion Tape samples evaluated in this study included the Motion Tape sensor system with conductive wire leads connected to both sides of the sample (Figure 1).

This exploratory, qualitative study was designed to explore physical therapists’ acceptance of Motion Tape to provide a basis for future device development (Figure 2). The study was conducted from a constructivist point of view, with the goal of gaining insightful accounts and narrations of clinicians’ lived experiences with technology and patients, rather than identifying an absolute truth [39]. We used semistructured focus groups (FGs) that incorporated human factor considerations to uncover real-world needs and obstacles and to ensure that the development of the sensor system can be informed by real-world PT clinical needs.

The Technology Acceptance Model (TAM) framework was used in this study to assess two determinants of user acceptance of or willingness to use a technology: (1) perceived usefulness and (2) perceived ease of use [38,40]. An additional factor of wearability was also assessed to examine physical therapists’ perceptions about patient-centered issues that would affect whether the device would be worn [41]. Recommendations for future improvements were also investigated to collect insight into data, device, and app developments that clinicians would like to see for Motion Tape.

This study was conducted at the American Physical Therapy Association’s (APTA’s) Combined Sections Meeting (San Diego, California) on February 24, 2023. Participants were recruited by sending study information via email to physical therapists who were members of the APTA Academy of Leadership Technology Special Interest Group. Members were also offered an opportunity to participate when they attended the Technology Special Interest Group in-person meeting at the APTA Combined Sections Meeting. Individuals were included in this study if they were a licensed physical therapist and were excluded from participating if they were unable to respond to questions in English. In total, 8 physical therapists were eligible and agreed to participate in 2 FGs of 4 clinicians each. A sample size of 8 people, in 2 FGs, was considered sufficient for this qualitative study to provide adequate variability and data saturation [43] and to provide a basis for device improvement. In addition, after data from the 2 FGs were collected and analyzed, the data were deemed saturated (ie, no new themes or codes were generated) and no further FGs were needed.

The study protocol was considered to be exempt from ethics approval by the San Diego State University institutional review board. Each participant provided written consent before participating.

An FG guide (Multimedia Appendix 1) was used to lead the group’s discussion. The FG guide was developed by investigators (AL, PD, and SG) to be semistructured with open-ended questions to explore the participants’ perspectives about the usefulness, usability, and wearability of Motion Tape and to collect insight into future improvements for the sensors and data visualization (Textbox 1). A template of the FG guide was piloted with a Doctor of Physical Therapy student and a physical therapist at San Diego State University to ensure credibility [44]. General domains for each construct were prespecified to correspond with each interview question. Domains were defined based on the TAM framework and included perceived usefulness and perceived ease of use. An additional domain of wearability also was assessed.

FGs were conducted by AL (a female Master of Science student investigator) and PD (a female PhD student investigator). Reflexivity was maintained by the research team by discussing assumptions and biases that may influence how the clinicians responded to the FG moderators, who were not licensed physical therapists. As SG is a licensed physical therapist and member of APTA, she was able to provide valuable insight during the development of the interview guide, analysis, and interpretation to ensure credibility of the findings [44].

FGs were anonymized, and each participant was assigned a color as a name to ensure confidentiality. Each FG lasted approximately 1 hour and was recorded using digital voice recorders (Olympus Voice Recorder; WS-853). Before asking the participants questions, the investigators gave each participant a sample of Motion Tape. Participants were then oriented to a poster that displayed the Motion Tape placement and app data output streams (Figure 3).

All FG audio data were downloaded to a HIPAA (Health Insurance Portability and Accountability Act)-compliant laboratory server, accessible only to the research staff, and removed from the digital voice recorder. The recordings were then transcribed, first using computer-based transcription (Word; Microsoft Corp). An investigator then checked and verified each transcription by listening to the original audio and reviewing and correcting the computer-based transcription.

Considering the need for timely feedback in the sensor development process, we adopted a rapid qualitative analysis (RQA) approach to explore themes regarding the acceptability and wearability of Motion Tape [45]. RQA was conducted by 3 investigators to assess the FG responses effectively and efficiently and to identify major themes. Codes and themes for RQA were deductively developed based on the TAM framework and the study objective [41]. We then used an inductive approach to generate RQA codes and themes, allowing for quick sorting of FG dialogue.

To ensure rigor and consistency of the method, a constant comparative approach with investigator triangulation was used at each stage [46]. First, the 3 investigators independently completed a summary report for each FG, with quotes and relevant topics under the respective themes and codes. Once the individual coding and summary reports for both FGs were completed, the investigators consolidated them into a combined rapid analysis summary report for each FG, unifying themes and reconciling discrepancies by consensus through discussion. The summary reports for each FG were then transferred into a matrix in which each row was a participant quote and each column was a domain. From this matrix, investigators identified the underlying themes and subthemes between the 2 FGs.

In total, 8 physical therapists (n=5, 63% men and n=3, 38% women), with a mean age of 47.5 (SD 5.6) years participated in this study. Participants reported obtaining PT degrees ranging from a bachelor’s degree to a Doctorate in Physical Therapy and had, on average, 20 (SD 8.5) years of clinical practice experience, and most reported practicing in an outpatient orthopedic setting. Of the 8 participants, 5 (63%) reported having advanced doctoral degrees (3/5, 60% PhD; 2/5, 40% EdD).

The qualitative results from the FGs were organized using the TAM for the acceptance of Motion Tape [38,40-42]. Data were organized based on the 3 main domains relevant to user acceptance (perceived wearability, perceived usefulness, and perceived ease of use) and 21 subthemes (Textbox 2). Subthemes were further designated using positive, negative, and neutral valences. Positive valence indicates that the FG participants perceived the Motion Tape attribute as positive. Negative valence indicates that the FG participants perceived the attribute as negative. Neutral valence indicates that the FG participants perceived the attribute as neither positive nor negative.

Regarding perceived wearability, all physical therapists were familiar with commercially available kinesiology tape. Thus, their thoughts about perceived wearability reflected their experience with kinesiology tape. For example, the physical therapists expected Motion Tape to last about 3 to 4 days. A physical therapist mentioned the following:

However, some physical therapists clarified that the longevity of Motion Tape’s adhesion depends on several factors. For example, 2 of the physical therapists expressed the following:

Regarding the fit aspect of wearability, physical therapists also believed that Motion Tape’s size was sufficiently small to be universal to the wearer and the placement location. They expressed the following:

Regarding the feel aspect of wearability, generally, physical therapists felt that patients would feel Motion Tape at first when applied but would become less aware over time until the tape starts to peel off:

However, physical therapists generally felt that with Motion Tape’s current design, patients would feel the wires snagging or the sensors rubbing on clothing. A physical therapist explained it as follows:

When removing Motion Tape, physical therapists said that patient feelings about the removal process would be quite variable. Some physical therapists felt that it was subjective to how the therapist removed Motion Tape and how much hair or oil the individual has on their skin. A physical therapist explained it as follows:

The physical therapists mentioned some wearability concerns during the FGs. A concern was about how patients with skin sensitivities would be able to use Motion Tape. A physical therapist asked the following:

Physical therapists expressed mixed feelings about whether Motion Tape would increase their efficiency with assessments of lumbar spine posture and movement. Some expressed that if all they had to do was apply the tape, then there would be increased efficiency:

However, others felt that it would reduce efficiency. A physical therapist explained the following:

A physical therapist felt that for the in-clinic assessments, Motion Tape would improve specificity:

Physical therapists also mentioned that they could envision Motion Tape as a useful tool for self-management and remote monitoring when used in combination with in-clinic PT. A physical therapist mentioned that the ability to monitor patients outside the clinic would be very meaningful:

Some physical therapists suggested that having patients wear these sensors would increase their awareness of being monitored and thus increase engagement with and adherence to the home exercise program:

Physical therapists expected patients to have a phenomenal experience with Motion Tape when used in a hybrid setting:

Specifically, several physical therapists expressed that Motion Tape would help with the identification of postures and movements in free-living environments that provoke pain, allowing for more meaningful interventions:

Some physical therapists did have some concerns about the usefulness of Motion Tape. A physical therapist expressed legal concerns regarding data responsibility:

Another concern was knowing what external factors affect Motion Tape’s signal and data reliability, mentioning that the use of Motion Tape in practice was “gonna depend on the reliability of the data” (FG2).

Several physical therapists felt that there were a variety of variables that might affect the reliability of the signal or data. They expressed the following:

Physical therapists felt that it would be easy to apply Motion Tape, given their background knowledge in human anatomy. A physical therapist stated the following:

When asked whether they would feel comfortable using Motion Tape with their patients, there were mixed responses among physical therapists. Some mentioned that it would depend on “cost and buy-in” (FG2) or how it was going to be “incorporated into the plan of care” (FG1). A physical therapist even explained the variability as follows:

There were also several concerns about the ease of use. Some physical therapists felt that they would have challenges with ease of use, specifically regarding interpretation of the data:

Additional concerns about the ease of use included that the amount of data presented was excessive and the type of data displayed was difficult to interpret. The physical therapists expressed a desire to see the range of motion displayed in degrees rather than resistance in ohms:

Another concern was about how challenging the self-application would be for patients:

Finally, another concern was that Motion Tape is a single-use product. A physical therapist explained the challenge of a single-use product as follows:

Future recommendations from the physical therapists were organized into 3 categories (Textbox 3): data, physical features, and app features.

Regarding the data recommendations, physical therapists expressed that data should be summarized in the form of an at-a-glance graph with 1 overall meaningful number, reflecting the range of motion. They would also like to know how the data change from person to person owing to morphology and how external factors (water, application stretch variability, and skin movement) affect the data. Additional data that would be useful for their job included comparative data, graphs with a color scale, and information about muscle activation. Participants in an FG expressed the following:

Regarding physical feature recommendations, physical therapists wanted a way to mitigate the wires, either by moving to a wireless system or making them removable. Physical therapists were also concerned about the limited stretchability of the short pieces of tape, as it would not be long enough in length for typical kinesiology tape use, and recommended making the length customizable to the physical therapists’ needs. Physical therapists were also concerned about Motion Tape’s single-use design and were curious about whether it could be reusable to reduce waste:

Regarding future app feature recommendations, physical therapists expressed a need for the capability to input factors such as BMI, activity changes, “flags” for events, and changes in pain to help label, compare, or contextualize the data.

There is a gap in the research between rehabilitation device development and evaluation of clinicians’ acceptance of such devices. Most existing studies have considered patient or user satisfaction [47,48], whereas others that consider the clinician’s perspective have not specifically evaluated sensors for measuring spine posture and movement [49,50]. In this study, several themes relating to physical therapists’ perspectives about Motion Tape’s wearability, usefulness, and ease of use for a low back use case were identified.

One of the most common challenges for wearable sensors is ensuring that they are unobtrusive to the wearer’s natural movement and environment [39]. The small form and fit of Motion Tape was considered by physical therapists to be ideal for a wearable sensor. However, similar to previous studies, the wires in the current design were considered to be not ideal [37]. Studies have shown that wireless technologies tend to be more widely used in many fields, especially in the field of wearable devices for health care [51]. Thus, a future iteration of Motion Tape without wires would be considered optimal. On the basis of feedback obtained from physical therapists, wearability for people with skin sensitivities also should be considered. Previous studies have shown that skin irritation is the most common concern when using kinesiology tape for extended periods of time [52,53]. Thus, future studies should explore whether a medium or substrate can be used under Motion Tape to mitigate skin irritation, possibly as an extension of recent research that integrated Motion Tape with elastic fabric for respiration monitoring [54].

There were mixed feelings among physical therapist participants about how efficient Motion Tape would be in the clinic. Overall, most physical therapists felt that Motion Tape would increase the specificity of their assessments, a characteristic that has been shown to be beneficial for LBP diagnosis and treatment [55]. Furthermore, Motion Tape’s ability to monitor the patient’s movements remotely was considered beneficial, as this feature may increase adherence to home exercise programs, which is an important component of effective treatment for LBP [56,57].

On the basis of physical therapists’ perspectives, Motion Tape would be easy to apply, but data would be difficult to interpret. Creating a device that is easy to use and understand is crucial because it predicts consumer use behavior [38,41]. Recommendations included presenting the data in units that physical therapists are more familiar with (ie, degrees of range of motion) and creating an app that requires minimal time for the physical therapists to use. These changes may promote increased device use and acceptance in PT.

On the basis of clinician feedback, Motion Tape appears to be a promising new technology that could be used for monitoring lumbar spine posture and movement in the management of patients with LBP. Future device development will be needed to address clinician recommendations obtained from this study in the domains of wearability and ease of use. In addition, future studies will be needed to validate Motion Tape in laboratory, clinical, and free-living environments and to investigate patient acceptance of Motion Tape.

A limitation of this study is that participants were physical therapists who were part of a Technology Special Interest Group and are likely to be more receptive to using technology in practice. Thus, this study’s results regarding Motion Tape’s acceptability may be biased in favor of Motion Tape’s ease of use, usefulness, and wearability. Future studies should also assess the acceptability of Motion Tape for clinicians who do not regularly use technology in their practice. Another limitation is that the physical therapists were not presented with active samples of Motion Tape with live data streams in the app. Instead, participants were given inactive samples of Motion Tape and presented with a poster with examples of app data streams. Future studies should provide an opportunity for physical therapists to apply Motion Tape to a person and use it with the app interface. Finally, there was a potential for investigator bias in the interpretation of the results, as several investigators of this study are actively working on the development of this device. However, 2 of the 3 investigators who conducted data analysis were outside the primary research team.

Physical therapists expressed overall acceptance of Motion Tape for its potential to monitor and assess low back posture and movement, both within and outside clinical settings. Physical therapist participants expressed that Motion Tape would be a valuable tool for personalized treatment of LBP but highlighted several future improvements needed for Motion Tape to be used in practice.